Attachment #195530 for bug #275047

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import signal
import sys
import textwrap
import weakref
import gc
import os, stat
import platform



from portage import digraph
from portage.const import NEWS_LIB_PATH
from portage.cache.mappings import slot_dict_class

import _emerge.help
import portage.xpak, commands, errno, re, socket, time
from portage.output import blue, bold, colorize, darkgreen, \
	red, xtermTitleReset, yellow
	xtermTitleReset, yellow
from portage.output import create_color_func
good = create_color_func("GOOD")
bad = create_color_func("BAD")

import portage.exception
from portage.cache.cache_errors import CacheError
from portage.data import secpass
from portage.elog.messages import eerror
from portage.util import normalize_path as normpath
from portage.util import cmp_sort_key, writemsg, writemsg_level
from portage.sets import load_default_config, SETPREFIX


from itertools import chain, izip

from _emerge.clear_caches import clear_caches
from _emerge.countdown import countdown
from _emerge.create_depgraph_params import create_depgraph_params
from _emerge.Dependency import Dependency
from _emerge.depgraph import depgraph, resume_depgraph
from _emerge.DepPrioritySatisfiedRange import DepPrioritySatisfiedRange
from _emerge.emergelog import emergelog
from _emerge._flush_elog_mod_echo import _flush_elog_mod_echo
from _emerge.is_valid_package_atom import is_valid_package_atom
from _emerge.MetadataRegen import MetadataRegen
from _emerge.Package import Package
from _emerge.Blocker import Blocker
from _emerge.BlockerDB import BlockerDB
from _emerge.EbuildFetcher import EbuildFetcher
from _emerge.EbuildPhase import EbuildPhase
from _emerge.BinpkgPrefetcher import BinpkgPrefetcher
from _emerge.PackageMerge import PackageMerge
from _emerge.DependencyArg import DependencyArg
from _emerge.AtomArg import AtomArg
from _emerge.PackageArg import PackageArg
from _emerge.SetArg import SetArg
from _emerge.Dependency import Dependency
from _emerge.BlockerCache import BlockerCache
from _emerge.PackageVirtualDbapi import PackageVirtualDbapi
from _emerge.RepoDisplay import RepoDisplay
from _emerge.UseFlagDisplay import UseFlagDisplay
from _emerge.SequentialTaskQueue import SequentialTaskQueue
from _emerge.ProgressHandler import ProgressHandler
from _emerge.stdout_spinner import stdout_spinner
from _emerge.JobStatusDisplay import JobStatusDisplay
from _emerge.PollScheduler import PollScheduler
from _emerge.search import search
from _emerge.visible import visible
from _emerge.emergelog import emergelog, _emerge_log_dir
from _emerge.userquery import userquery
from _emerge.countdown import countdown
from _emerge.unmerge import unmerge
from _emerge.MergeListItem import MergeListItem
from _emerge.MetadataRegen import MetadataRegen
from _emerge.RootConfig import RootConfig
from _emerge.Scheduler import Scheduler
from _emerge.search import search
from _emerge.SetArg import SetArg
from _emerge.show_invalid_depstring_notice import show_invalid_depstring_notice
from _emerge.stdout_spinner import stdout_spinner
from _emerge.unmerge import unmerge
from _emerge.UnmergeDepPriority import UnmergeDepPriority
from _emerge.UseFlagDisplay import UseFlagDisplay
from _emerge.userquery import userquery


actions = frozenset([
"clean", "config", "depclean",
"info", "list-sets", "metadata",


	return "Portage " + portage.VERSION +" ("+profilever+", "+gccver+", "+libcver+", "+unameout+")"

def create_depgraph_params(myopts, myaction):
	#configure emerge engine parameters
	#
	# self:      include _this_ package regardless of if it is merged.
	# selective: exclude the package if it is merged
	# recurse:   go into the dependencies
	# deep:      go into the dependencies of already merged packages
	# empty:     pretend nothing is merged
	# complete:  completely account for all known dependencies
	# remove:    build graph for use in removing packages
	myparams = set(["recurse"])

	if myaction == "remove":
		myparams.add("remove")
		myparams.add("complete")
		return myparams

	if "--update" in myopts or \
		"--newuse" in myopts or \
		"--reinstall" in myopts or \
		"--noreplace" in myopts:
		myparams.add("selective")
	if "--emptytree" in myopts:
		myparams.add("empty")
		myparams.discard("selective")
	if "--nodeps" in myopts:
		myparams.discard("recurse")
	if "--deep" in myopts:
		myparams.add("deep")
	if "--complete-graph" in myopts:
		myparams.add("complete")
	return myparams

def create_world_atom(pkg, args_set, root_config):
	"""Create a new atom for the world file if one does not exist.  If the
	argument atom is precise enough to identify a specific slot then a slot
	atom will be returned. Atoms that are in the system set may also be stored
	in world since system atoms can only match one slot while world atoms can
	be greedy with respect to slots.  Unslotted system packages will not be
	stored in world."""

	arg_atom = args_set.findAtomForPackage(pkg)
	if not arg_atom:
		return None
	cp = portage.dep_getkey(arg_atom)
	new_world_atom = cp
	sets = root_config.sets
	portdb = root_config.trees["porttree"].dbapi
	vardb = root_config.trees["vartree"].dbapi
	available_slots = set(portdb.aux_get(cpv, ["SLOT"])[0] \
		for cpv in portdb.match(cp))
	slotted = len(available_slots) > 1 or \
		(len(available_slots) == 1 and "0" not in available_slots)
	if not slotted:
		# check the vdb in case this is multislot
		available_slots = set(vardb.aux_get(cpv, ["SLOT"])[0] \
			for cpv in vardb.match(cp))
		slotted = len(available_slots) > 1 or \
			(len(available_slots) == 1 and "0" not in available_slots)
	if slotted and arg_atom != cp:
		# If the user gave a specific atom, store it as a
		# slot atom in the world file.
		slot_atom = pkg.slot_atom

		# For USE=multislot, there are a couple of cases to
		# handle here:
		#
		# 1) SLOT="0", but the real SLOT spontaneously changed to some
		#    unknown value, so just record an unslotted atom.
		#
		# 2) SLOT comes from an installed package and there is no
		#    matching SLOT in the portage tree.
		#
		# Make sure that the slot atom is available in either the
		# portdb or the vardb, since otherwise the user certainly
		# doesn't want the SLOT atom recorded in the world file
		# (case 1 above).  If it's only available in the vardb,
		# the user may be trying to prevent a USE=multislot
		# package from being removed by --depclean (case 2 above).

		mydb = portdb
		if not portdb.match(slot_atom):
			# SLOT seems to come from an installed multislot package
			mydb = vardb
		# If there is no installed package matching the SLOT atom,
		# it probably changed SLOT spontaneously due to USE=multislot,
		# so just record an unslotted atom.
		if vardb.match(slot_atom):
			# Now verify that the argument is precise
			# enough to identify a specific slot.
			matches = mydb.match(arg_atom)
			matched_slots = set()
			for cpv in matches:
				matched_slots.add(mydb.aux_get(cpv, ["SLOT"])[0])
			if len(matched_slots) == 1:
				new_world_atom = slot_atom

	if new_world_atom == sets["world"].findAtomForPackage(pkg):
		# Both atoms would be identical, so there's nothing to add.
		return None
	if not slotted:
		# Unlike world atoms, system atoms are not greedy for slots, so they
		# can't be safely excluded from world if they are slotted.
		system_atom = sets["system"].findAtomForPackage(pkg)
		if system_atom:
			if not portage.dep_getkey(system_atom).startswith("virtual/"):
				return None
			# System virtuals aren't safe to exclude from world since they can
			# match multiple old-style virtuals but only one of them will be
			# pulled in by update or depclean.
			providers = portdb.mysettings.getvirtuals().get(
				portage.dep_getkey(system_atom))
			if providers and len(providers) == 1 and providers[0] == cp:
				return None
	return new_world_atom

def filter_iuse_defaults(iuse):
	for flag in iuse:
		if flag.startswith("+") or flag.startswith("-"):
			yield flag[1:]
		else:
			yield flag

def _find_deep_system_runtime_deps(graph):
	deep_system_deps = set()
	node_stack = []
	for node in graph:
		if not isinstance(node, Package) or \
			node.operation == 'uninstall':
			continue
		if node.root_config.sets['system'].findAtomForPackage(node):
			node_stack.append(node)

	def ignore_priority(priority):
		"""
		Ignore non-runtime priorities.
		"""
		if isinstance(priority, DepPriority) and \
			(priority.runtime or priority.runtime_post):
			return False
		return True

	while node_stack:
		node = node_stack.pop()
		if node in deep_system_deps:
			continue
		deep_system_deps.add(node)
		for child in graph.child_nodes(node, ignore_priority=ignore_priority):
			if not isinstance(child, Package) or \
				child.operation == 'uninstall':
				continue
			node_stack.append(child)

	return deep_system_deps

def get_masking_status(pkg, pkgsettings, root_config):

	mreasons = portage.getmaskingstatus(
		pkg, settings=pkgsettings,
		portdb=root_config.trees["porttree"].dbapi)

	if not pkg.installed:
		if not pkgsettings._accept_chost(pkg.cpv, pkg.metadata):
			mreasons.append("CHOST: %s" % \
				pkg.metadata["CHOST"])

	if not pkg.metadata["SLOT"]:
		mreasons.append("invalid: SLOT is undefined")

	return mreasons

def get_mask_info(root_config, cpv, pkgsettings,
	db, pkg_type, built, installed, db_keys):
	eapi_masked = False
	try:
		metadata = dict(izip(db_keys,
			db.aux_get(cpv, db_keys)))
	except KeyError:
		metadata = None
	if metadata and not built:
		pkgsettings.setcpv(cpv, mydb=metadata)
		metadata["USE"] = pkgsettings["PORTAGE_USE"]
		metadata['CHOST'] = pkgsettings.get('CHOST', '')
	if metadata is None:
		mreasons = ["corruption"]
	else:
		eapi = metadata['EAPI']
		if eapi[:1] == '-':
			eapi = eapi[1:]
		if not portage.eapi_is_supported(eapi):
			mreasons = ['EAPI %s' % eapi]
		else:
			pkg = Package(type_name=pkg_type, root_config=root_config,
				cpv=cpv, built=built, installed=installed, metadata=metadata)
			mreasons = get_masking_status(pkg, pkgsettings, root_config)
	return metadata, mreasons

def show_masked_packages(masked_packages):
	shown_licenses = set()
	shown_comments = set()
	# Maybe there is both an ebuild and a binary. Only
	# show one of them to avoid redundant appearance.
	shown_cpvs = set()
	have_eapi_mask = False
	for (root_config, pkgsettings, cpv,
		metadata, mreasons) in masked_packages:
		if cpv in shown_cpvs:
			continue
		shown_cpvs.add(cpv)
		comment, filename = None, None
		if "package.mask" in mreasons:
			comment, filename = \
				portage.getmaskingreason(
				cpv, metadata=metadata,
				settings=pkgsettings,
				portdb=root_config.trees["porttree"].dbapi,
				return_location=True)
		missing_licenses = []
		if metadata:
			if not portage.eapi_is_supported(metadata["EAPI"]):
				have_eapi_mask = True
			try:
				missing_licenses = \
					pkgsettings._getMissingLicenses(
						cpv, metadata)
			except portage.exception.InvalidDependString:
				# This will have already been reported
				# above via mreasons.
				pass

		print "- "+cpv+" (masked by: "+", ".join(mreasons)+")"
		if comment and comment not in shown_comments:
			print filename+":"
			print comment
			shown_comments.add(comment)
		portdb = root_config.trees["porttree"].dbapi
		for l in missing_licenses:
			l_path = portdb.findLicensePath(l)
			if l in shown_licenses:
				continue
			msg = ("A copy of the '%s' license" + \
			" is located at '%s'.") % (l, l_path)
			print msg
			print
			shown_licenses.add(l)
	return have_eapi_mask

class depgraph(object):

	pkg_tree_map = RootConfig.pkg_tree_map

	_dep_keys = ["DEPEND", "RDEPEND", "PDEPEND"]

	def __init__(self, settings, trees, myopts, myparams, spinner):
		self.settings = settings
		self.target_root = settings["ROOT"]
		self.myopts = myopts
		self.myparams = myparams
		self.edebug = 0
		if settings.get("PORTAGE_DEBUG", "") == "1":
			self.edebug = 1
		self.spinner = spinner
		self._running_root = trees["/"]["root_config"]
		self._opts_no_restart = Scheduler._opts_no_restart
		self.pkgsettings = {}
		# Maps slot atom to package for each Package added to the graph.
		self._slot_pkg_map = {}
		# Maps nodes to the reasons they were selected for reinstallation.
		self._reinstall_nodes = {}
		self.mydbapi = {}
		self.trees = {}
		self._trees_orig = trees
		self.roots = {}
		# Contains a filtered view of preferred packages that are selected
		# from available repositories.
		self._filtered_trees = {}
		# Contains installed packages and new packages that have been added
		# to the graph.
		self._graph_trees = {}
		# All Package instances
		self._pkg_cache = {}
		for myroot in trees:
			self.trees[myroot] = {}
			# Create a RootConfig instance that references
			# the FakeVartree instead of the real one.
			self.roots[myroot] = RootConfig(
				trees[myroot]["vartree"].settings,
				self.trees[myroot],
				trees[myroot]["root_config"].setconfig)
			for tree in ("porttree", "bintree"):
				self.trees[myroot][tree] = trees[myroot][tree]
			self.trees[myroot]["vartree"] = \
				FakeVartree(trees[myroot]["root_config"],
					pkg_cache=self._pkg_cache)
			self.pkgsettings[myroot] = portage.config(
				clone=self.trees[myroot]["vartree"].settings)
			self._slot_pkg_map[myroot] = {}
			vardb = self.trees[myroot]["vartree"].dbapi
			preload_installed_pkgs = "--nodeps" not in self.myopts and \
				"--buildpkgonly" not in self.myopts
			# This fakedbapi instance will model the state that the vdb will
			# have after new packages have been installed.
			fakedb = PackageVirtualDbapi(vardb.settings)
			if preload_installed_pkgs:
				for pkg in vardb:
					self.spinner.update()
					# This triggers metadata updates via FakeVartree.
					vardb.aux_get(pkg.cpv, [])
					fakedb.cpv_inject(pkg)

			# Now that the vardb state is cached in our FakeVartree,
			# we won't be needing the real vartree cache for awhile.
			# To make some room on the heap, clear the vardbapi
			# caches.
			trees[myroot]["vartree"].dbapi._clear_cache()
			gc.collect()

			self.mydbapi[myroot] = fakedb
			def graph_tree():
				pass
			graph_tree.dbapi = fakedb
			self._graph_trees[myroot] = {}
			self._filtered_trees[myroot] = {}
			# Substitute the graph tree for the vartree in dep_check() since we
			# want atom selections to be consistent with package selections
			# have already been made.
			self._graph_trees[myroot]["porttree"]   = graph_tree
			self._graph_trees[myroot]["vartree"]    = graph_tree
			def filtered_tree():
				pass
			filtered_tree.dbapi = self._dep_check_composite_db(self, myroot)
			self._filtered_trees[myroot]["porttree"] = filtered_tree

			# Passing in graph_tree as the vartree here could lead to better
			# atom selections in some cases by causing atoms for packages that
			# have been added to the graph to be preferred over other choices.
			# However, it can trigger atom selections that result in
			# unresolvable direct circular dependencies. For example, this
			# happens with gwydion-dylan which depends on either itself or
			# gwydion-dylan-bin. In case gwydion-dylan is not yet installed,
			# gwydion-dylan-bin needs to be selected in order to avoid a
			# an unresolvable direct circular dependency.
			#
			# To solve the problem described above, pass in "graph_db" so that
			# packages that have been added to the graph are distinguishable
			# from other available packages and installed packages. Also, pass
			# the parent package into self._select_atoms() calls so that
			# unresolvable direct circular dependencies can be detected and
			# avoided when possible.
			self._filtered_trees[myroot]["graph_db"] = graph_tree.dbapi
			self._filtered_trees[myroot]["vartree"] = self.trees[myroot]["vartree"]

			dbs = []
			portdb = self.trees[myroot]["porttree"].dbapi
			bindb  = self.trees[myroot]["bintree"].dbapi
			vardb  = self.trees[myroot]["vartree"].dbapi
			#               (db, pkg_type, built, installed, db_keys)
			if "--usepkgonly" not in self.myopts:
				db_keys = list(portdb._aux_cache_keys)
				dbs.append((portdb, "ebuild", False, False, db_keys))
			if "--usepkg" in self.myopts:
				db_keys = list(bindb._aux_cache_keys)
				dbs.append((bindb,  "binary", True, False, db_keys))
			db_keys = list(trees[myroot]["vartree"].dbapi._aux_cache_keys)
			dbs.append((vardb, "installed", True, True, db_keys))
			self._filtered_trees[myroot]["dbs"] = dbs
			if "--usepkg" in self.myopts:
				self.trees[myroot]["bintree"].populate(
					"--getbinpkg" in self.myopts,
					"--getbinpkgonly" in self.myopts)
		del trees

		self.digraph=portage.digraph()
		# contains all sets added to the graph
		self._sets = {}
		# contains atoms given as arguments
		self._sets["args"] = InternalPackageSet()
		# contains all atoms from all sets added to the graph, including
		# atoms given as arguments
		self._set_atoms = InternalPackageSet()
		self._atom_arg_map = {}
		# contains all nodes pulled in by self._set_atoms
		self._set_nodes = set()
		# Contains only Blocker -> Uninstall edges
		self._blocker_uninstalls = digraph()
		# Contains only Package -> Blocker edges
		self._blocker_parents = digraph()
		# Contains only irrelevant Package -> Blocker edges
		self._irrelevant_blockers = digraph()
		# Contains only unsolvable Package -> Blocker edges
		self._unsolvable_blockers = digraph()
		# Contains all Blocker -> Blocked Package edges
		self._blocked_pkgs = digraph()
		# Contains world packages that have been protected from
		# uninstallation but may not have been added to the graph
		# if the graph is not complete yet.
		self._blocked_world_pkgs = {}
		self._slot_collision_info = {}
		# Slot collision nodes are not allowed to block other packages since
		# blocker validation is only able to account for one package per slot.
		self._slot_collision_nodes = set()
		self._parent_atoms = {}
		self._slot_conflict_parent_atoms = set()
		self._serialized_tasks_cache = None
		self._scheduler_graph = None
		self._displayed_list = None
		self._pprovided_args = []
		self._missing_args = []
		self._masked_installed = set()
		self._unsatisfied_deps_for_display = []
		self._unsatisfied_blockers_for_display = None
		self._circular_deps_for_display = None
		self._dep_stack = []
		self._dep_disjunctive_stack = []
		self._unsatisfied_deps = []
		self._initially_unsatisfied_deps = []
		self._ignored_deps = []
		self._required_set_names = set(["system", "world"])
		self._select_atoms = self._select_atoms_highest_available
		self._select_package = self._select_pkg_highest_available
		self._highest_pkg_cache = {}

	def _show_slot_collision_notice(self):
		"""Show an informational message advising the user to mask one of the
		the packages. In some cases it may be possible to resolve this
		automatically, but support for backtracking (removal nodes that have
		already been selected) will be required in order to handle all possible
		cases.
		"""

		if not self._slot_collision_info:
			return

		self._show_merge_list()

		msg = []
		msg.append("\n!!! Multiple package instances within a single " + \
			"package slot have been pulled\n")
		msg.append("!!! into the dependency graph, resulting" + \
			" in a slot conflict:\n\n")
		indent = "  "
		# Max number of parents shown, to avoid flooding the display.
		max_parents = 3
		explanation_columns = 70
		explanations = 0
		for (slot_atom, root), slot_nodes \
			in self._slot_collision_info.iteritems():
			msg.append(str(slot_atom))
			msg.append("\n\n")

			for node in slot_nodes:
				msg.append(indent)
				msg.append(str(node))
				parent_atoms = self._parent_atoms.get(node)
				if parent_atoms:
					pruned_list = set()
					# Prefer conflict atoms over others.
					for parent_atom in parent_atoms:
						if len(pruned_list) >= max_parents:
							break
						if parent_atom in self._slot_conflict_parent_atoms:
							pruned_list.add(parent_atom)

					# If this package was pulled in by conflict atoms then
					# show those alone since those are the most interesting.
					if not pruned_list:
						# When generating the pruned list, prefer instances
						# of DependencyArg over instances of Package.
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							parent, atom = parent_atom
							if isinstance(parent, DependencyArg):
								pruned_list.add(parent_atom)
						# Prefer Packages instances that themselves have been
						# pulled into collision slots.
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							parent, atom = parent_atom
							if isinstance(parent, Package) and \
								(parent.slot_atom, parent.root) \
								in self._slot_collision_info:
								pruned_list.add(parent_atom)
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							pruned_list.add(parent_atom)
					omitted_parents = len(parent_atoms) - len(pruned_list)
					parent_atoms = pruned_list
					msg.append(" pulled in by\n")
					for parent_atom in parent_atoms:
						parent, atom = parent_atom
						msg.append(2*indent)
						if isinstance(parent,
							(PackageArg, AtomArg)):
							# For PackageArg and AtomArg types, it's
							# redundant to display the atom attribute.
							msg.append(str(parent))
						else:
							# Display the specific atom from SetArg or
							# Package types.
							msg.append("%s required by %s" % (atom, parent))
						msg.append("\n")
					if omitted_parents:
						msg.append(2*indent)
						msg.append("(and %d more)\n" % omitted_parents)
				else:
					msg.append(" (no parents)\n")
				msg.append("\n")
			explanation = self._slot_conflict_explanation(slot_nodes)
			if explanation:
				explanations += 1
				msg.append(indent + "Explanation:\n\n")
				for line in textwrap.wrap(explanation, explanation_columns):
					msg.append(2*indent + line + "\n")
				msg.append("\n")
		msg.append("\n")
		sys.stderr.write("".join(msg))
		sys.stderr.flush()

		explanations_for_all = explanations == len(self._slot_collision_info)

		if explanations_for_all or "--quiet" in self.myopts:
			return

		msg = []
		msg.append("It may be possible to solve this problem ")
		msg.append("by using package.mask to prevent one of ")
		msg.append("those packages from being selected. ")
		msg.append("However, it is also possible that conflicting ")
		msg.append("dependencies exist such that they are impossible to ")
		msg.append("satisfy simultaneously.  If such a conflict exists in ")
		msg.append("the dependencies of two different packages, then those ")
		msg.append("packages can not be installed simultaneously.")

		from formatter import AbstractFormatter, DumbWriter
		f = AbstractFormatter(DumbWriter(sys.stderr, maxcol=72))
		for x in msg:
			f.add_flowing_data(x)
		f.end_paragraph(1)

		msg = []
		msg.append("For more information, see MASKED PACKAGES ")
		msg.append("section in the emerge man page or refer ")
		msg.append("to the Gentoo Handbook.")
		for x in msg:
			f.add_flowing_data(x)
		f.end_paragraph(1)
		f.writer.flush()

	def _slot_conflict_explanation(self, slot_nodes):
		"""
		When a slot conflict occurs due to USE deps, there are a few
		different cases to consider:

		1) New USE are correctly set but --newuse wasn't requested so an
		   installed package with incorrect USE happened to get pulled
		   into graph before the new one.

		2) New USE are incorrectly set but an installed package has correct
		   USE so it got pulled into the graph, and a new instance also got
		   pulled in due to --newuse or an upgrade.

		3) Multiple USE deps exist that can't be satisfied simultaneously,
		   and multiple package instances got pulled into the same slot to
		   satisfy the conflicting deps.

		Currently, explanations and suggested courses of action are generated
		for cases 1 and 2. Case 3 is too complex to give a useful suggestion.
		"""

		if len(slot_nodes) != 2:
			# Suggestions are only implemented for
			# conflicts between two packages.
			return None

		all_conflict_atoms = self._slot_conflict_parent_atoms
		matched_node = None
		matched_atoms = None
		unmatched_node = None
		for node in slot_nodes:
			parent_atoms = self._parent_atoms.get(node)
			if not parent_atoms:
				# Normally, there are always parent atoms. If there are
				# none then something unexpected is happening and there's
				# currently no suggestion for this case.
				return None
			conflict_atoms = all_conflict_atoms.intersection(parent_atoms)
			for parent_atom in conflict_atoms:
				parent, atom = parent_atom
				if not atom.use:
					# Suggestions are currently only implemented for cases
					# in which all conflict atoms have USE deps.
					return None
			if conflict_atoms:
				if matched_node is not None:
					# If conflict atoms match multiple nodes
					# then there's no suggestion.
					return None
				matched_node = node
				matched_atoms = conflict_atoms
			else:
				if unmatched_node is not None:
					# Neither node is matched by conflict atoms, and
					# there is no suggestion for this case.
					return None
				unmatched_node = node

		if matched_node is None or unmatched_node is None:
			# This shouldn't happen.
			return None

		if unmatched_node.installed and not matched_node.installed and \
			unmatched_node.cpv == matched_node.cpv:
			# If the conflicting packages are the same version then
			# --newuse should be all that's needed. If they are different
			# versions then there's some other problem.
			return "New USE are correctly set, but --newuse wasn't" + \
				" requested, so an installed package with incorrect USE " + \
				"happened to get pulled into the dependency graph. " + \
				"In order to solve " + \
				"this, either specify the --newuse option or explicitly " + \
				" reinstall '%s'." % matched_node.slot_atom

		if matched_node.installed and not unmatched_node.installed:
			atoms = sorted(set(atom for parent, atom in matched_atoms))
			explanation = ("New USE for '%s' are incorrectly set. " + \
				"In order to solve this, adjust USE to satisfy '%s'") % \
				(matched_node.slot_atom, atoms[0])
			if len(atoms) > 1:
				for atom in atoms[1:-1]:
					explanation += ", '%s'" % (atom,)
				if len(atoms) > 2:
					explanation += ","
				explanation += " and '%s'" % (atoms[-1],)
			explanation += "."
			return explanation

		return None

	def _process_slot_conflicts(self):
		"""
		Process slot conflict data to identify specific atoms which
		lead to conflict. These atoms only match a subset of the
		packages that have been pulled into a given slot.
		"""
		for (slot_atom, root), slot_nodes \
			in self._slot_collision_info.iteritems():

			all_parent_atoms = set()
			for pkg in slot_nodes:
				parent_atoms = self._parent_atoms.get(pkg)
				if not parent_atoms:
					continue
				all_parent_atoms.update(parent_atoms)

			for pkg in slot_nodes:
				parent_atoms = self._parent_atoms.get(pkg)
				if parent_atoms is None:
					parent_atoms = set()
					self._parent_atoms[pkg] = parent_atoms
				for parent_atom in all_parent_atoms:
					if parent_atom in parent_atoms:
						continue
					# Use package set for matching since it will match via
					# PROVIDE when necessary, while match_from_list does not.
					parent, atom = parent_atom
					atom_set = InternalPackageSet(
						initial_atoms=(atom,))
					if atom_set.findAtomForPackage(pkg):
						parent_atoms.add(parent_atom)
					else:
						self._slot_conflict_parent_atoms.add(parent_atom)

	def _reinstall_for_flags(self, forced_flags,
		orig_use, orig_iuse, cur_use, cur_iuse):
		"""Return a set of flags that trigger reinstallation, or None if there
		are no such flags."""
		if "--newuse" in self.myopts:
			flags = set(orig_iuse.symmetric_difference(
				cur_iuse).difference(forced_flags))
			flags.update(orig_iuse.intersection(orig_use).symmetric_difference(
				cur_iuse.intersection(cur_use)))
			if flags:
				return flags
		elif "changed-use" == self.myopts.get("--reinstall"):
			flags = orig_iuse.intersection(orig_use).symmetric_difference(
				cur_iuse.intersection(cur_use))
			if flags:
				return flags
		return None

	def _create_graph(self, allow_unsatisfied=False):
		dep_stack = self._dep_stack
		dep_disjunctive_stack = self._dep_disjunctive_stack
		while dep_stack or dep_disjunctive_stack:
			self.spinner.update()
			while dep_stack:
				dep = dep_stack.pop()
				if isinstance(dep, Package):
					if not self._add_pkg_deps(dep,
						allow_unsatisfied=allow_unsatisfied):
						return 0
					continue
				if not self._add_dep(dep, allow_unsatisfied=allow_unsatisfied):
					return 0
			if dep_disjunctive_stack:
				if not self._pop_disjunction(allow_unsatisfied):
					return 0
		return 1

	def _add_dep(self, dep, allow_unsatisfied=False):
		debug = "--debug" in self.myopts
		buildpkgonly = "--buildpkgonly" in self.myopts
		nodeps = "--nodeps" in self.myopts
		empty = "empty" in self.myparams
		deep = "deep" in self.myparams
		update = "--update" in self.myopts and dep.depth <= 1
		if dep.blocker:
			if not buildpkgonly and \
				not nodeps and \
				dep.parent not in self._slot_collision_nodes:
				if dep.parent.onlydeps:
					# It's safe to ignore blockers if the
					# parent is an --onlydeps node.
					return 1
				# The blocker applies to the root where
				# the parent is or will be installed.
				blocker = Blocker(atom=dep.atom,
					eapi=dep.parent.metadata["EAPI"],
					root=dep.parent.root)
				self._blocker_parents.add(blocker, dep.parent)
			return 1
		dep_pkg, existing_node = self._select_package(dep.root, dep.atom,
			onlydeps=dep.onlydeps)
		if not dep_pkg:
			if dep.priority.optional:
				# This could be an unecessary build-time dep
				# pulled in by --with-bdeps=y.
				return 1
			if allow_unsatisfied:
				self._unsatisfied_deps.append(dep)
				return 1
			self._unsatisfied_deps_for_display.append(
				((dep.root, dep.atom), {"myparent":dep.parent}))
			return 0
		# In some cases, dep_check will return deps that shouldn't
		# be proccessed any further, so they are identified and
		# discarded here. Try to discard as few as possible since
		# discarded dependencies reduce the amount of information
		# available for optimization of merge order.
		if dep.priority.satisfied and \
			not dep_pkg.installed and \
			not (existing_node or empty or deep or update):
			myarg = None
			if dep.root == self.target_root:
				try:
					myarg = self._iter_atoms_for_pkg(dep_pkg).next()
				except StopIteration:
					pass
				except portage.exception.InvalidDependString:
					if not dep_pkg.installed:
						# This shouldn't happen since the package
						# should have been masked.
						raise
			if not myarg:
				self._ignored_deps.append(dep)
				return 1

		if not self._add_pkg(dep_pkg, dep):
			return 0
		return 1

	def _add_pkg(self, pkg, dep):
		myparent = None
		priority = None
		depth = 0
		if dep is None:
			dep = Dependency()
		else:
			myparent = dep.parent
			priority = dep.priority
			depth = dep.depth
		if priority is None:
			priority = DepPriority()
		"""
		Fills the digraph with nodes comprised of packages to merge.
		mybigkey is the package spec of the package to merge.
		myparent is the package depending on mybigkey ( or None )
		addme = Should we add this package to the digraph or are we just looking at it's deps?
			Think --onlydeps, we need to ignore packages in that case.
		#stuff to add:
		#SLOT-aware emerge
		#IUSE-aware emerge -> USE DEP aware depgraph
		#"no downgrade" emerge
		"""
		# Ensure that the dependencies of the same package
		# are never processed more than once.
		previously_added = pkg in self.digraph

		# select the correct /var database that we'll be checking against
		vardbapi = self.trees[pkg.root]["vartree"].dbapi
		pkgsettings = self.pkgsettings[pkg.root]

		arg_atoms = None
		if True:
			try:
				arg_atoms = list(self._iter_atoms_for_pkg(pkg))
			except portage.exception.InvalidDependString, e:
				if not pkg.installed:
					show_invalid_depstring_notice(
						pkg, pkg.metadata["PROVIDE"], str(e))
					return 0
				del e

		if not pkg.onlydeps:
			if not pkg.installed and \
				"empty" not in self.myparams and \
				vardbapi.match(pkg.slot_atom):
				# Increase the priority of dependencies on packages that
				# are being rebuilt. This optimizes merge order so that
				# dependencies are rebuilt/updated as soon as possible,
				# which is needed especially when emerge is called by
				# revdep-rebuild since dependencies may be affected by ABI
				# breakage that has rendered them useless. Don't adjust
				# priority here when in "empty" mode since all packages
				# are being merged in that case.
				priority.rebuild = True

			existing_node = self._slot_pkg_map[pkg.root].get(pkg.slot_atom)
			slot_collision = False
			if existing_node:
				existing_node_matches = pkg.cpv == existing_node.cpv
				if existing_node_matches and \
					pkg != existing_node and \
					dep.atom is not None:
					# Use package set for matching since it will match via
					# PROVIDE when necessary, while match_from_list does not.
					atom_set = InternalPackageSet(initial_atoms=[dep.atom])
					if not atom_set.findAtomForPackage(existing_node):
						existing_node_matches = False
				if existing_node_matches:
					# The existing node can be reused.
					if arg_atoms:
						for parent_atom in arg_atoms:
							parent, atom = parent_atom
							self.digraph.add(existing_node, parent,
								priority=priority)
							self._add_parent_atom(existing_node, parent_atom)
					# If a direct circular dependency is not an unsatisfied
					# buildtime dependency then drop it here since otherwise
					# it can skew the merge order calculation in an unwanted
					# way.
					if existing_node != myparent or \
						(priority.buildtime and not priority.satisfied):
						self.digraph.addnode(existing_node, myparent,
							priority=priority)
						if dep.atom is not None and dep.parent is not None:
							self._add_parent_atom(existing_node,
								(dep.parent, dep.atom))
					return 1
				else:

					# A slot collision has occurred.  Sometimes this coincides
					# with unresolvable blockers, so the slot collision will be
					# shown later if there are no unresolvable blockers.
					self._add_slot_conflict(pkg)
					slot_collision = True

			if slot_collision:
				# Now add this node to the graph so that self.display()
				# can show use flags and --tree portage.output.  This node is
				# only being partially added to the graph.  It must not be
				# allowed to interfere with the other nodes that have been
				# added.  Do not overwrite data for existing nodes in
				# self.mydbapi since that data will be used for blocker
				# validation.
				# Even though the graph is now invalid, continue to process
				# dependencies so that things like --fetchonly can still
				# function despite collisions.
				pass
			elif not previously_added:
				self._slot_pkg_map[pkg.root][pkg.slot_atom] = pkg
				self.mydbapi[pkg.root].cpv_inject(pkg)
				self._filtered_trees[pkg.root]["porttree"].dbapi._clear_cache()

			if not pkg.installed:
				# Allow this package to satisfy old-style virtuals in case it
				# doesn't already. Any pre-existing providers will be preferred
				# over this one.
				try:
					pkgsettings.setinst(pkg.cpv, pkg.metadata)
					# For consistency, also update the global virtuals.
					settings = self.roots[pkg.root].settings
					settings.unlock()
					settings.setinst(pkg.cpv, pkg.metadata)
					settings.lock()
				except portage.exception.InvalidDependString, e:
					show_invalid_depstring_notice(
						pkg, pkg.metadata["PROVIDE"], str(e))
					del e
					return 0

		if arg_atoms:
			self._set_nodes.add(pkg)

		# Do this even when addme is False (--onlydeps) so that the
		# parent/child relationship is always known in case
		# self._show_slot_collision_notice() needs to be called later.
		self.digraph.add(pkg, myparent, priority=priority)
		if dep.atom is not None and dep.parent is not None:
			self._add_parent_atom(pkg, (dep.parent, dep.atom))

		if arg_atoms:
			for parent_atom in arg_atoms:
				parent, atom = parent_atom
				self.digraph.add(pkg, parent, priority=priority)
				self._add_parent_atom(pkg, parent_atom)

		""" This section determines whether we go deeper into dependencies or not.
		    We want to go deeper on a few occasions:
		    Installing package A, we need to make sure package A's deps are met.
		    emerge --deep <pkgspec>; we need to recursively check dependencies of pkgspec
		    If we are in --nodeps (no recursion) mode, we obviously only check 1 level of dependencies.
		"""
		dep_stack = self._dep_stack
		if "recurse" not in self.myparams:
			return 1
		elif pkg.installed and \
			"deep" not in self.myparams:
			dep_stack = self._ignored_deps

		self.spinner.update()

		if arg_atoms:
			depth = 0
		pkg.depth = depth
		if not previously_added:
			dep_stack.append(pkg)
		return 1

	def _add_parent_atom(self, pkg, parent_atom):
		parent_atoms = self._parent_atoms.get(pkg)
		if parent_atoms is None:
			parent_atoms = set()
			self._parent_atoms[pkg] = parent_atoms
		parent_atoms.add(parent_atom)

	def _add_slot_conflict(self, pkg):
		self._slot_collision_nodes.add(pkg)
		slot_key = (pkg.slot_atom, pkg.root)
		slot_nodes = self._slot_collision_info.get(slot_key)
		if slot_nodes is None:
			slot_nodes = set()
			slot_nodes.add(self._slot_pkg_map[pkg.root][pkg.slot_atom])
			self._slot_collision_info[slot_key] = slot_nodes
		slot_nodes.add(pkg)

	def _add_pkg_deps(self, pkg, allow_unsatisfied=False):

		mytype = pkg.type_name
		myroot = pkg.root
		mykey = pkg.cpv
		metadata = pkg.metadata
		myuse = pkg.use.enabled
		jbigkey = pkg
		depth = pkg.depth + 1
		removal_action = "remove" in self.myparams

		edepend={}
		depkeys = ["DEPEND","RDEPEND","PDEPEND"]
		for k in depkeys:
			edepend[k] = metadata[k]

		if not pkg.built and \
			"--buildpkgonly" in self.myopts and \
			"deep" not in self.myparams and \
			"empty" not in self.myparams:
			edepend["RDEPEND"] = ""
			edepend["PDEPEND"] = ""
		bdeps_optional = False

		if pkg.built and not removal_action:
			if self.myopts.get("--with-bdeps", "n") == "y":
				# Pull in build time deps as requested, but marked them as
				# "optional" since they are not strictly required. This allows
				# more freedom in the merge order calculation for solving
				# circular dependencies. Don't convert to PDEPEND since that
				# could make --with-bdeps=y less effective if it is used to
				# adjust merge order to prevent built_with_use() calls from
				# failing.
				bdeps_optional = True
			else:
				# built packages do not have build time dependencies.
				edepend["DEPEND"] = ""

		if removal_action and self.myopts.get("--with-bdeps", "y") == "n":
			edepend["DEPEND"] = ""

		bdeps_root = "/"
		root_deps = self.myopts.get("--root-deps")
		if root_deps is not None:
			if root_deps is True:
				bdeps_root = myroot
			elif root_deps == "rdeps":
				edepend["DEPEND"] = ""

		deps = (
			(bdeps_root, edepend["DEPEND"],
				self._priority(buildtime=(not bdeps_optional),
				optional=bdeps_optional)),
			(myroot, edepend["RDEPEND"], self._priority(runtime=True)),
			(myroot, edepend["PDEPEND"], self._priority(runtime_post=True))
		)

		debug = "--debug" in self.myopts
		strict = mytype != "installed"
		try:
			if not strict:
				portage.dep._dep_check_strict = False

			for dep_root, dep_string, dep_priority in deps:
				if not dep_string:
					continue
				if debug:
					print
					print "Parent:   ", jbigkey
					print "Depstring:", dep_string
					print "Priority:", dep_priority

				try:

					dep_string = portage.dep.paren_normalize(
						portage.dep.use_reduce(
						portage.dep.paren_reduce(dep_string),
						uselist=pkg.use.enabled))

					dep_string = list(self._queue_disjunctive_deps(
						pkg, dep_root, dep_priority, dep_string))

				except portage.exception.InvalidDependString, e:
					if pkg.installed:
						del e
						continue
					show_invalid_depstring_notice(pkg, dep_string, str(e))
					return 0

				if not dep_string:
					continue

				dep_string = portage.dep.paren_enclose(dep_string)

				if not self._add_pkg_dep_string(
					pkg, dep_root, dep_priority, dep_string,
					allow_unsatisfied):
					return 0

		except portage.exception.AmbiguousPackageName, e:
			pkgs = e.args[0]
			portage.writemsg("\n\n!!! An atom in the dependencies " + \
				"is not fully-qualified. Multiple matches:\n\n", noiselevel=-1)
			for cpv in pkgs:
				portage.writemsg("    %s\n" % cpv, noiselevel=-1)
			portage.writemsg("\n", noiselevel=-1)
			if mytype == "binary":
				portage.writemsg(
					"!!! This binary package cannot be installed: '%s'\n" % \
					mykey, noiselevel=-1)
			elif mytype == "ebuild":
				portdb = self.roots[myroot].trees["porttree"].dbapi
				myebuild, mylocation = portdb.findname2(mykey)
				portage.writemsg("!!! This ebuild cannot be installed: " + \
					"'%s'\n" % myebuild, noiselevel=-1)
			portage.writemsg("!!! Please notify the package maintainer " + \
				"that atoms must be fully-qualified.\n", noiselevel=-1)
			return 0
		finally:
			portage.dep._dep_check_strict = True
		return 1

	def _add_pkg_dep_string(self, pkg, dep_root, dep_priority, dep_string,
		allow_unsatisfied):
		depth = pkg.depth + 1
		debug = "--debug" in self.myopts
		strict = pkg.type_name != "installed"

		if debug:
			print
			print "Parent:   ", pkg
			print "Depstring:", dep_string
			print "Priority:", dep_priority

		try:
			selected_atoms = self._select_atoms(dep_root,
				dep_string, myuse=pkg.use.enabled, parent=pkg,
				strict=strict, priority=dep_priority)
		except portage.exception.InvalidDependString, e:
			show_invalid_depstring_notice(pkg, dep_string, str(e))
			del e
			if pkg.installed:
				return 1
			return 0

		if debug:
			print "Candidates:", selected_atoms

		vardb = self.roots[dep_root].trees["vartree"].dbapi

		for atom in selected_atoms:
			try:

				atom = portage.dep.Atom(atom)

				mypriority = dep_priority.copy()
				if not atom.blocker and vardb.match(atom):
					mypriority.satisfied = True

				if not self._add_dep(Dependency(atom=atom,
					blocker=atom.blocker, depth=depth, parent=pkg,
					priority=mypriority, root=dep_root),
					allow_unsatisfied=allow_unsatisfied):
					return 0

			except portage.exception.InvalidAtom, e:
				show_invalid_depstring_notice(
					pkg, dep_string, str(e))
				del e
				if not pkg.installed:
					return 0

		if debug:
			print "Exiting...", pkg

		return 1

	def _queue_disjunctive_deps(self, pkg, dep_root, dep_priority, dep_struct):
		"""
		Queue disjunctive (virtual and ||) deps in self._dep_disjunctive_stack.
		Yields non-disjunctive deps. Raises InvalidDependString when 
		necessary.
		"""
		i = 0
		while i < len(dep_struct):
			x = dep_struct[i]
			if isinstance(x, list):
				for y in self._queue_disjunctive_deps(
					pkg, dep_root, dep_priority, x):
					yield y
			elif x == "||":
				self._queue_disjunction(pkg, dep_root, dep_priority,
					[ x, dep_struct[ i + 1 ] ] )
				i += 1
			else:
				try:
					x = portage.dep.Atom(x)
				except portage.exception.InvalidAtom:
					if not pkg.installed:
						raise portage.exception.InvalidDependString(
							"invalid atom: '%s'" % x)
				else:
					# Note: Eventually this will check for PROPERTIES=virtual
					# or whatever other metadata gets implemented for this
					# purpose.
					if x.cp.startswith('virtual/'):
						self._queue_disjunction( pkg, dep_root,
							dep_priority, [ str(x) ] )
					else:
						yield str(x)
			i += 1

	def _queue_disjunction(self, pkg, dep_root, dep_priority, dep_struct):
		self._dep_disjunctive_stack.append(
			(pkg, dep_root, dep_priority, dep_struct))

	def _pop_disjunction(self, allow_unsatisfied):
		"""
		Pop one disjunctive dep from self._dep_disjunctive_stack, and use it to
		populate self._dep_stack.
		"""
		pkg, dep_root, dep_priority, dep_struct = \
			self._dep_disjunctive_stack.pop()
		dep_string = portage.dep.paren_enclose(dep_struct)
		if not self._add_pkg_dep_string(
			pkg, dep_root, dep_priority, dep_string, allow_unsatisfied):
			return 0
		return 1

	def _priority(self, **kwargs):
		if "remove" in self.myparams:
			priority_constructor = UnmergeDepPriority
		else:
			priority_constructor = DepPriority
		return priority_constructor(**kwargs)

	def _dep_expand(self, root_config, atom_without_category):
		"""
		@param root_config: a root config instance
		@type root_config: RootConfig
		@param atom_without_category: an atom without a category component
		@type atom_without_category: String
		@rtype: list
		@returns: a list of atoms containing categories (possibly empty)
		"""
		null_cp = portage.dep_getkey(insert_category_into_atom(
			atom_without_category, "null"))
		cat, atom_pn = portage.catsplit(null_cp)

		dbs = self._filtered_trees[root_config.root]["dbs"]
		categories = set()
		for db, pkg_type, built, installed, db_keys in dbs:
			for cat in db.categories:
				if db.cp_list("%s/%s" % (cat, atom_pn)):
					categories.add(cat)

		deps = []
		for cat in categories:
			deps.append(insert_category_into_atom(
				atom_without_category, cat))
		return deps

	def _have_new_virt(self, root, atom_cp):
		ret = False
		for db, pkg_type, built, installed, db_keys in \
			self._filtered_trees[root]["dbs"]:
			if db.cp_list(atom_cp):
				ret = True
				break
		return ret

	def _iter_atoms_for_pkg(self, pkg):
		# TODO: add multiple $ROOT support
		if pkg.root != self.target_root:
			return
		atom_arg_map = self._atom_arg_map
		root_config = self.roots[pkg.root]
		for atom in self._set_atoms.iterAtomsForPackage(pkg):
			atom_cp = portage.dep_getkey(atom)
			if atom_cp != pkg.cp and \
				self._have_new_virt(pkg.root, atom_cp):
				continue
			visible_pkgs = root_config.visible_pkgs.match_pkgs(atom)
			visible_pkgs.reverse() # descending order
			higher_slot = None
			for visible_pkg in visible_pkgs:
				if visible_pkg.cp != atom_cp:
					continue
				if pkg >= visible_pkg:
					# This is descending order, and we're not
					# interested in any versions <= pkg given.
					break
				if pkg.slot_atom != visible_pkg.slot_atom:
					higher_slot = visible_pkg
					break
			if higher_slot is not None:
				continue
			for arg in atom_arg_map[(atom, pkg.root)]:
				if isinstance(arg, PackageArg) and \
					arg.package != pkg:
					continue
				yield arg, atom

	def select_files(self, myfiles):
		"""Given a list of .tbz2s, .ebuilds sets, and deps, create the
		appropriate depgraph and return a favorite list."""
		debug = "--debug" in self.myopts
		root_config = self.roots[self.target_root]
		sets = root_config.sets
		getSetAtoms = root_config.setconfig.getSetAtoms
		myfavorites=[]
		myroot = self.target_root
		dbs = self._filtered_trees[myroot]["dbs"]
		vardb = self.trees[myroot]["vartree"].dbapi
		real_vardb = self._trees_orig[myroot]["vartree"].dbapi
		portdb = self.trees[myroot]["porttree"].dbapi
		bindb = self.trees[myroot]["bintree"].dbapi
		pkgsettings = self.pkgsettings[myroot]
		args = []
		onlydeps = "--onlydeps" in self.myopts
		lookup_owners = []
		for x in myfiles:
			ext = os.path.splitext(x)[1]
			if ext==".tbz2":
				if not os.path.exists(x):
					if os.path.exists(
						os.path.join(pkgsettings["PKGDIR"], "All", x)):
						x = os.path.join(pkgsettings["PKGDIR"], "All", x)
					elif os.path.exists(
						os.path.join(pkgsettings["PKGDIR"], x)):
						x = os.path.join(pkgsettings["PKGDIR"], x)
					else:
						print "\n\n!!! Binary package '"+str(x)+"' does not exist."
						print "!!! Please ensure the tbz2 exists as specified.\n"
						return 0, myfavorites
				mytbz2=portage.xpak.tbz2(x)
				mykey=mytbz2.getelements("CATEGORY")[0]+"/"+os.path.splitext(os.path.basename(x))[0]
				if os.path.realpath(x) != \
					os.path.realpath(self.trees[myroot]["bintree"].getname(mykey)):
					print colorize("BAD", "\n*** You need to adjust PKGDIR to emerge this package.\n")
					return 0, myfavorites
				db_keys = list(bindb._aux_cache_keys)
				metadata = izip(db_keys, bindb.aux_get(mykey, db_keys))
				pkg = Package(type_name="binary", root_config=root_config,
					cpv=mykey, built=True, metadata=metadata,
					onlydeps=onlydeps)
				self._pkg_cache[pkg] = pkg
				args.append(PackageArg(arg=x, package=pkg,
					root_config=root_config))
			elif ext==".ebuild":
				ebuild_path = portage.util.normalize_path(os.path.abspath(x))
				pkgdir = os.path.dirname(ebuild_path)
				tree_root = os.path.dirname(os.path.dirname(pkgdir))
				cp = pkgdir[len(tree_root)+1:]
				e = portage.exception.PackageNotFound(
					("%s is not in a valid portage tree " + \
					"hierarchy or does not exist") % x)
				if not portage.isvalidatom(cp):
					raise e
				cat = portage.catsplit(cp)[0]
				mykey = cat + "/" + os.path.basename(ebuild_path[:-7])
				if not portage.isvalidatom("="+mykey):
					raise e
				ebuild_path = portdb.findname(mykey)
				if ebuild_path:
					if ebuild_path != os.path.join(os.path.realpath(tree_root),
						cp, os.path.basename(ebuild_path)):
						print colorize("BAD", "\n*** You need to adjust PORTDIR or PORTDIR_OVERLAY to emerge this package.\n")
						return 0, myfavorites
					if mykey not in portdb.xmatch(
						"match-visible", portage.dep_getkey(mykey)):
						print colorize("BAD", "\n*** You are emerging a masked package. It is MUCH better to use")
						print colorize("BAD", "*** /etc/portage/package.* to accomplish this. See portage(5) man")
						print colorize("BAD", "*** page for details.")
						countdown(int(self.settings["EMERGE_WARNING_DELAY"]),
							"Continuing...")
				else:
					raise portage.exception.PackageNotFound(
						"%s is not in a valid portage tree hierarchy or does not exist" % x)
				db_keys = list(portdb._aux_cache_keys)
				metadata = izip(db_keys, portdb.aux_get(mykey, db_keys))
				pkg = Package(type_name="ebuild", root_config=root_config,
					cpv=mykey, metadata=metadata, onlydeps=onlydeps)
				pkgsettings.setcpv(pkg)
				pkg.metadata["USE"] = pkgsettings["PORTAGE_USE"]
				pkg.metadata['CHOST'] = pkgsettings.get('CHOST', '')
				self._pkg_cache[pkg] = pkg
				args.append(PackageArg(arg=x, package=pkg,
					root_config=root_config))
			elif x.startswith(os.path.sep):
				if not x.startswith(myroot):
					portage.writemsg(("\n\n!!! '%s' does not start with" + \
						" $ROOT.\n") % x, noiselevel=-1)
					return 0, []
				# Queue these up since it's most efficient to handle
				# multiple files in a single iter_owners() call.
				lookup_owners.append(x)
			else:
				if x in ("system", "world"):
					x = SETPREFIX + x
				if x.startswith(SETPREFIX):
					s = x[len(SETPREFIX):]
					if s not in sets:
						raise portage.exception.PackageSetNotFound(s)
					if s in self._sets:
						continue
					# Recursively expand sets so that containment tests in
					# self._get_parent_sets() properly match atoms in nested
					# sets (like if world contains system).
					expanded_set = InternalPackageSet(
						initial_atoms=getSetAtoms(s))
					self._sets[s] = expanded_set
					args.append(SetArg(arg=x, set=expanded_set,
						root_config=root_config))
					continue
				if not is_valid_package_atom(x):
					portage.writemsg("\n\n!!! '%s' is not a valid package atom.\n" % x,
						noiselevel=-1)
					portage.writemsg("!!! Please check ebuild(5) for full details.\n")
					portage.writemsg("!!! (Did you specify a version but forget to prefix with '='?)\n")
					return (0,[])
				# Don't expand categories or old-style virtuals here unless
				# necessary. Expansion of old-style virtuals here causes at
				# least the following problems:
				#   1) It's more difficult to determine which set(s) an atom
				#      came from, if any.
				#   2) It takes away freedom from the resolver to choose other
				#      possible expansions when necessary.
				if "/" in x:
					args.append(AtomArg(arg=x, atom=x,
						root_config=root_config))
					continue
				expanded_atoms = self._dep_expand(root_config, x)
				installed_cp_set = set()
				for atom in expanded_atoms:
					atom_cp = portage.dep_getkey(atom)
					if vardb.cp_list(atom_cp):
						installed_cp_set.add(atom_cp)

				if len(installed_cp_set) > 1:
					non_virtual_cps = set()
					for atom_cp in installed_cp_set:
						if not atom_cp.startswith("virtual/"):
							non_virtual_cps.add(atom_cp)
					if len(non_virtual_cps) == 1:
						installed_cp_set = non_virtual_cps

				if len(expanded_atoms) > 1 and len(installed_cp_set) == 1:
					installed_cp = iter(installed_cp_set).next()
					expanded_atoms = [atom for atom in expanded_atoms \
						if portage.dep_getkey(atom) == installed_cp]

				if len(expanded_atoms) > 1:
					print
					print
					ambiguous_package_name(x, expanded_atoms, root_config,
						self.spinner, self.myopts)
					return False, myfavorites
				if expanded_atoms:
					atom = expanded_atoms[0]
				else:
					null_atom = insert_category_into_atom(x, "null")
					null_cp = portage.dep_getkey(null_atom)
					cat, atom_pn = portage.catsplit(null_cp)
					virts_p = root_config.settings.get_virts_p().get(atom_pn)
					if virts_p:
						# Allow the depgraph to choose which virtual.
						atom = insert_category_into_atom(x, "virtual")
					else:
						atom = insert_category_into_atom(x, "null")

				args.append(AtomArg(arg=x, atom=atom,
					root_config=root_config))

		if lookup_owners:
			relative_paths = []
			search_for_multiple = False
			if len(lookup_owners) > 1:
				search_for_multiple = True

			for x in lookup_owners:
				if not search_for_multiple and os.path.isdir(x):
					search_for_multiple = True
				relative_paths.append(x[len(myroot):])

			owners = set()
			for pkg, relative_path in \
				real_vardb._owners.iter_owners(relative_paths):
				owners.add(pkg.mycpv)
				if not search_for_multiple:
					break

			if not owners:
				portage.writemsg(("\n\n!!! '%s' is not claimed " + \
					"by any package.\n") % lookup_owners[0], noiselevel=-1)
				return 0, []

			for cpv in owners:
				slot = vardb.aux_get(cpv, ["SLOT"])[0]
				if not slot:
					# portage now masks packages with missing slot, but it's
					# possible that one was installed by an older version
					atom = portage.cpv_getkey(cpv)
				else:
					atom = "%s:%s" % (portage.cpv_getkey(cpv), slot)
				args.append(AtomArg(arg=atom, atom=atom,
					root_config=root_config))

		if "--update" in self.myopts:
			# In some cases, the greedy slots behavior can pull in a slot that
			# the user would want to uninstall due to it being blocked by a
			# newer version in a different slot. Therefore, it's necessary to
			# detect and discard any that should be uninstalled. Each time
			# that arguments are updated, package selections are repeated in
			# order to ensure consistency with the current arguments:
			#
			#  1) Initialize args
			#  2) Select packages and generate initial greedy atoms
			#  3) Update args with greedy atoms
			#  4) Select packages and generate greedy atoms again, while
			#     accounting for any blockers between selected packages
			#  5) Update args with revised greedy atoms

			self._set_args(args)
			greedy_args = []
			for arg in args:
				greedy_args.append(arg)
				if not isinstance(arg, AtomArg):
					continue
				for atom in self._greedy_slots(arg.root_config, arg.atom):
					greedy_args.append(
						AtomArg(arg=arg.arg, atom=atom,
							root_config=arg.root_config))

			self._set_args(greedy_args)
			del greedy_args

			# Revise greedy atoms, accounting for any blockers
			# between selected packages.
			revised_greedy_args = []
			for arg in args:
				revised_greedy_args.append(arg)
				if not isinstance(arg, AtomArg):
					continue
				for atom in self._greedy_slots(arg.root_config, arg.atom,
					blocker_lookahead=True):
					revised_greedy_args.append(
						AtomArg(arg=arg.arg, atom=atom,
							root_config=arg.root_config))
			args = revised_greedy_args
			del revised_greedy_args

		self._set_args(args)

		myfavorites = set(myfavorites)
		for arg in args:
			if isinstance(arg, (AtomArg, PackageArg)):
				myfavorites.add(arg.atom)
			elif isinstance(arg, SetArg):
				myfavorites.add(arg.arg)
		myfavorites = list(myfavorites)

		pprovideddict = pkgsettings.pprovideddict
		if debug:
			portage.writemsg("\n", noiselevel=-1)
		# Order needs to be preserved since a feature of --nodeps
		# is to allow the user to force a specific merge order.
		args.reverse()
		while args:
			arg = args.pop()
			for atom in arg.set:
				self.spinner.update()
				dep = Dependency(atom=atom, onlydeps=onlydeps,
					root=myroot, parent=arg)
				atom_cp = portage.dep_getkey(atom)
				try:
					pprovided = pprovideddict.get(portage.dep_getkey(atom))
					if pprovided and portage.match_from_list(atom, pprovided):
						# A provided package has been specified on the command line.
						self._pprovided_args.append((arg, atom))
						continue
					if isinstance(arg, PackageArg):
						if not self._add_pkg(arg.package, dep) or \
							not self._create_graph():
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s\n") % arg.arg)
							return 0, myfavorites
						continue
					if debug:
						portage.writemsg("      Arg: %s\n     Atom: %s\n" % \
							(arg, atom), noiselevel=-1)
					pkg, existing_node = self._select_package(
						myroot, atom, onlydeps=onlydeps)
					if not pkg:
						if not (isinstance(arg, SetArg) and \
							arg.name in ("system", "world")):
							self._unsatisfied_deps_for_display.append(
								((myroot, atom), {}))
							return 0, myfavorites
						self._missing_args.append((arg, atom))
						continue
					if atom_cp != pkg.cp:
						# For old-style virtuals, we need to repeat the
						# package.provided check against the selected package.
						expanded_atom = atom.replace(atom_cp, pkg.cp)
						pprovided = pprovideddict.get(pkg.cp)
						if pprovided and \
							portage.match_from_list(expanded_atom, pprovided):
							# A provided package has been
							# specified on the command line.
							self._pprovided_args.append((arg, atom))
							continue
					if pkg.installed and "selective" not in self.myparams:
						self._unsatisfied_deps_for_display.append(
							((myroot, atom), {}))
						# Previous behavior was to bail out in this case, but
						# since the dep is satisfied by the installed package,
						# it's more friendly to continue building the graph
						# and just show a warning message. Therefore, only bail
						# out here if the atom is not from either the system or
						# world set.
						if not (isinstance(arg, SetArg) and \
							arg.name in ("system", "world")):
							return 0, myfavorites

					# Add the selected package to the graph as soon as possible
					# so that later dep_check() calls can use it as feedback
					# for making more consistent atom selections.
					if not self._add_pkg(pkg, dep):
						if isinstance(arg, SetArg):
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s from %s\n") % \
								(atom, arg.arg))
						else:
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s\n") % atom)
						return 0, myfavorites

				except portage.exception.MissingSignature, e:
					portage.writemsg("\n\n!!! A missing gpg signature is preventing portage from calculating the\n")
					portage.writemsg("!!! required dependencies. This is a security feature enabled by the admin\n")
					portage.writemsg("!!! to aid in the detection of malicious intent.\n\n")
					portage.writemsg("!!! THIS IS A POSSIBLE INDICATION OF TAMPERED FILES -- CHECK CAREFULLY.\n")
					portage.writemsg("!!! Affected file: %s\n" % (e), noiselevel=-1)
					return 0, myfavorites
				except portage.exception.InvalidSignature, e:
					portage.writemsg("\n\n!!! An invalid gpg signature is preventing portage from calculating the\n")
					portage.writemsg("!!! required dependencies. This is a security feature enabled by the admin\n")
					portage.writemsg("!!! to aid in the detection of malicious intent.\n\n")
					portage.writemsg("!!! THIS IS A POSSIBLE INDICATION OF TAMPERED FILES -- CHECK CAREFULLY.\n")
					portage.writemsg("!!! Affected file: %s\n" % (e), noiselevel=-1)
					return 0, myfavorites
				except SystemExit, e:
					raise # Needed else can't exit
				except Exception, e:
					print >> sys.stderr, "\n\n!!! Problem in '%s' dependencies." % atom
					print >> sys.stderr, "!!!", str(e), getattr(e, "__module__", None)
					raise

		# Now that the root packages have been added to the graph,
		# process the dependencies.
		if not self._create_graph():
			return 0, myfavorites

		missing=0
		if "--usepkgonly" in self.myopts:
			for xs in self.digraph.all_nodes():
				if not isinstance(xs, Package):
					continue
				if len(xs) >= 4 and xs[0] != "binary" and xs[3] == "merge":
					if missing == 0:
						print
					missing += 1
					print "Missing binary for:",xs[2]

		try:
			self.altlist()
		except self._unknown_internal_error:
			return False, myfavorites

		# We're true here unless we are missing binaries.
		return (not missing,myfavorites)

	def _set_args(self, args):
		"""
		Create the "args" package set from atoms and packages given as
		arguments. This method can be called multiple times if necessary.
		The package selection cache is automatically invalidated, since
		arguments influence package selections.
		"""
		args_set = self._sets["args"]
		args_set.clear()
		for arg in args:
			if not isinstance(arg, (AtomArg, PackageArg)):
				continue
			atom = arg.atom
			if atom in args_set:
				continue
			args_set.add(atom)

		self._set_atoms.clear()
		self._set_atoms.update(chain(*self._sets.itervalues()))
		atom_arg_map = self._atom_arg_map
		atom_arg_map.clear()
		for arg in args:
			for atom in arg.set:
				atom_key = (atom, arg.root_config.root)
				refs = atom_arg_map.get(atom_key)
				if refs is None:
					refs = []
					atom_arg_map[atom_key] = refs
					if arg not in refs:
						refs.append(arg)

		# Invalidate the package selection cache, since
		# arguments influence package selections.
		self._highest_pkg_cache.clear()
		for trees in self._filtered_trees.itervalues():
			trees["porttree"].dbapi._clear_cache()

	def _greedy_slots(self, root_config, atom, blocker_lookahead=False):
		"""
		Return a list of slot atoms corresponding to installed slots that
		differ from the slot of the highest visible match. When
		blocker_lookahead is True, slot atoms that would trigger a blocker
		conflict are automatically discarded, potentially allowing automatic
		uninstallation of older slots when appropriate.
		"""
		highest_pkg, in_graph = self._select_package(root_config.root, atom)
		if highest_pkg is None:
			return []
		vardb = root_config.trees["vartree"].dbapi
		slots = set()
		for cpv in vardb.match(atom):
			# don't mix new virtuals with old virtuals
			if portage.cpv_getkey(cpv) == highest_pkg.cp:
				slots.add(vardb.aux_get(cpv, ["SLOT"])[0])

		slots.add(highest_pkg.metadata["SLOT"])
		if len(slots) == 1:
			return []
		greedy_pkgs = []
		slots.remove(highest_pkg.metadata["SLOT"])
		while slots:
			slot = slots.pop()
			slot_atom = portage.dep.Atom("%s:%s" % (highest_pkg.cp, slot))
			pkg, in_graph = self._select_package(root_config.root, slot_atom)
			if pkg is not None and \
				pkg.cp == highest_pkg.cp and pkg < highest_pkg:
				greedy_pkgs.append(pkg)
		if not greedy_pkgs:
			return []
		if not blocker_lookahead:
			return [pkg.slot_atom for pkg in greedy_pkgs]

		blockers = {}
		blocker_dep_keys = ["DEPEND", "PDEPEND", "RDEPEND"]
		for pkg in greedy_pkgs + [highest_pkg]:
			dep_str = " ".join(pkg.metadata[k] for k in blocker_dep_keys)
			try:
				atoms = self._select_atoms(
					pkg.root, dep_str, pkg.use.enabled,
					parent=pkg, strict=True)
			except portage.exception.InvalidDependString:
				continue
			blocker_atoms = (x for x in atoms if x.blocker)
			blockers[pkg] = InternalPackageSet(initial_atoms=blocker_atoms)

		if highest_pkg not in blockers:
			return []

		# filter packages with invalid deps
		greedy_pkgs = [pkg for pkg in greedy_pkgs if pkg in blockers]

		# filter packages that conflict with highest_pkg
		greedy_pkgs = [pkg for pkg in greedy_pkgs if not \
			(blockers[highest_pkg].findAtomForPackage(pkg) or \
			blockers[pkg].findAtomForPackage(highest_pkg))]

		if not greedy_pkgs:
			return []

		# If two packages conflict, discard the lower version.
		discard_pkgs = set()
		greedy_pkgs.sort(reverse=True)
		for i in xrange(len(greedy_pkgs) - 1):
			pkg1 = greedy_pkgs[i]
			if pkg1 in discard_pkgs:
				continue
			for j in xrange(i + 1, len(greedy_pkgs)):
				pkg2 = greedy_pkgs[j]
				if pkg2 in discard_pkgs:
					continue
				if blockers[pkg1].findAtomForPackage(pkg2) or \
					blockers[pkg2].findAtomForPackage(pkg1):
					# pkg1 > pkg2
					discard_pkgs.add(pkg2)

		return [pkg.slot_atom for pkg in greedy_pkgs \
			if pkg not in discard_pkgs]

	def _select_atoms_from_graph(self, *pargs, **kwargs):
		"""
		Prefer atoms matching packages that have already been
		added to the graph or those that are installed and have
		not been scheduled for replacement.
		"""
		kwargs["trees"] = self._graph_trees
		return self._select_atoms_highest_available(*pargs, **kwargs)

	def _select_atoms_highest_available(self, root, depstring,
		myuse=None, parent=None, strict=True, trees=None, priority=None):
		"""This will raise InvalidDependString if necessary. If trees is
		None then self._filtered_trees is used."""
		pkgsettings = self.pkgsettings[root]
		if trees is None:
			trees = self._filtered_trees
		if not getattr(priority, "buildtime", False):
			# The parent should only be passed to dep_check() for buildtime
			# dependencies since that's the only case when it's appropriate
			# to trigger the circular dependency avoidance code which uses it.
			# It's important not to trigger the same circular dependency
			# avoidance code for runtime dependencies since it's not needed
			# and it can promote an incorrect package choice.
			parent = None
		if True:
			try:
				if parent is not None:
					trees[root]["parent"] = parent
				if not strict:
					portage.dep._dep_check_strict = False
				mycheck = portage.dep_check(depstring, None,
					pkgsettings, myuse=myuse,
					myroot=root, trees=trees)
			finally:
				if parent is not None:
					trees[root].pop("parent")
				portage.dep._dep_check_strict = True
			if not mycheck[0]:
				raise portage.exception.InvalidDependString(mycheck[1])
			selected_atoms = mycheck[1]
		return selected_atoms

	def _show_unsatisfied_dep(self, root, atom, myparent=None, arg=None):
		atom = portage.dep.Atom(atom)
		atom_set = InternalPackageSet(initial_atoms=(atom,))
		atom_without_use = atom
		if atom.use:
			atom_without_use = portage.dep.remove_slot(atom)
			if atom.slot:
				atom_without_use += ":" + atom.slot
			atom_without_use = portage.dep.Atom(atom_without_use)
		xinfo = '"%s"' % atom
		if arg:
			xinfo='"%s"' % arg
		# Discard null/ from failed cpv_expand category expansion.
		xinfo = xinfo.replace("null/", "")
		masked_packages = []
		missing_use = []
		masked_pkg_instances = set()
		missing_licenses = []
		have_eapi_mask = False
		pkgsettings = self.pkgsettings[root]
		implicit_iuse = pkgsettings._get_implicit_iuse()
		root_config = self.roots[root]
		portdb = self.roots[root].trees["porttree"].dbapi
		dbs = self._filtered_trees[root]["dbs"]
		for db, pkg_type, built, installed, db_keys in dbs:
			if installed:
				continue
			match = db.match
			if hasattr(db, "xmatch"):
				cpv_list = db.xmatch("match-all", atom_without_use)
			else:
				cpv_list = db.match(atom_without_use)
			# descending order
			cpv_list.reverse()
			for cpv in cpv_list:
				metadata, mreasons  = get_mask_info(root_config, cpv,
					pkgsettings, db, pkg_type, built, installed, db_keys)
				if metadata is not None:
					pkg = Package(built=built, cpv=cpv,
						installed=installed, metadata=metadata,
						root_config=root_config)
					if pkg.cp != atom.cp:
						# A cpv can be returned from dbapi.match() as an
						# old-style virtual match even in cases when the
						# package does not actually PROVIDE the virtual.
						# Filter out any such false matches here.
						if not atom_set.findAtomForPackage(pkg):
							continue
					if mreasons:
						masked_pkg_instances.add(pkg)
					if atom.use:
						missing_use.append(pkg)
						if not mreasons:
							continue
				masked_packages.append(
					(root_config, pkgsettings, cpv, metadata, mreasons))

		missing_use_reasons = []
		missing_iuse_reasons = []
		for pkg in missing_use:
			use = pkg.use.enabled
			iuse = implicit_iuse.union(re.escape(x) for x in pkg.iuse.all)
			iuse_re = re.compile("^(%s)$" % "|".join(iuse))
			missing_iuse = []
			for x in atom.use.required:
				if iuse_re.match(x) is None:
					missing_iuse.append(x)
			mreasons = []
			if missing_iuse:
				mreasons.append("Missing IUSE: %s" % " ".join(missing_iuse))
				missing_iuse_reasons.append((pkg, mreasons))
			else:
				need_enable = sorted(atom.use.enabled.difference(use))
				need_disable = sorted(atom.use.disabled.intersection(use))
				if need_enable or need_disable:
					changes = []
					changes.extend(colorize("red", "+" + x) \
						for x in need_enable)
					changes.extend(colorize("blue", "-" + x) \
						for x in need_disable)
					mreasons.append("Change USE: %s" % " ".join(changes))
					missing_use_reasons.append((pkg, mreasons))

		unmasked_use_reasons = [(pkg, mreasons) for (pkg, mreasons) \
			in missing_use_reasons if pkg not in masked_pkg_instances]

		unmasked_iuse_reasons = [(pkg, mreasons) for (pkg, mreasons) \
			in missing_iuse_reasons if pkg not in masked_pkg_instances]

		show_missing_use = False
		if unmasked_use_reasons:
			# Only show the latest version.
			show_missing_use = unmasked_use_reasons[:1]
		elif unmasked_iuse_reasons:
			if missing_use_reasons:
				# All packages with required IUSE are masked,
				# so display a normal masking message.
				pass
			else:
				show_missing_use = unmasked_iuse_reasons

		if show_missing_use:
			print "\nemerge: there are no ebuilds built with USE flags to satisfy "+green(xinfo)+"."
			print "!!! One of the following packages is required to complete your request:"
			for pkg, mreasons in show_missing_use:
				print "- "+pkg.cpv+" ("+", ".join(mreasons)+")"

		elif masked_packages:
			print "\n!!! " + \
				colorize("BAD", "All ebuilds that could satisfy ") + \
				colorize("INFORM", xinfo) + \
				colorize("BAD", " have been masked.")
			print "!!! One of the following masked packages is required to complete your request:"
			have_eapi_mask = show_masked_packages(masked_packages)
			if have_eapi_mask:
				print
				msg = ("The current version of portage supports " + \
					"EAPI '%s'. You must upgrade to a newer version" + \
					" of portage before EAPI masked packages can" + \
					" be installed.") % portage.const.EAPI
				from textwrap import wrap
				for line in wrap(msg, 75):
					print line
			print
			show_mask_docs()
		else:
			print "\nemerge: there are no ebuilds to satisfy "+green(xinfo)+"."

		# Show parent nodes and the argument that pulled them in.
		traversed_nodes = set()
		node = myparent
		msg = []
		while node is not None:
			traversed_nodes.add(node)
			msg.append('(dependency required by "%s" [%s])' % \
				(colorize('INFORM', str(node.cpv)), node.type_name))
			# When traversing to parents, prefer arguments over packages
			# since arguments are root nodes. Never traverse the same
			# package twice, in order to prevent an infinite loop.
			selected_parent = None
			for parent in self.digraph.parent_nodes(node):
				if isinstance(parent, DependencyArg):
					msg.append('(dependency required by "%s" [argument])' % \
						(colorize('INFORM', str(parent))))
					selected_parent = None
					break
				if parent not in traversed_nodes:
					selected_parent = parent
			node = selected_parent
		for line in msg:
			print line

		print

	def _select_pkg_highest_available(self, root, atom, onlydeps=False):
		cache_key = (root, atom, onlydeps)
		ret = self._highest_pkg_cache.get(cache_key)
		if ret is not None:
			pkg, existing = ret
			if pkg and not existing:
				existing = self._slot_pkg_map[root].get(pkg.slot_atom)
				if existing and existing == pkg:
					# Update the cache to reflect that the
					# package has been added to the graph.
					ret = pkg, pkg
					self._highest_pkg_cache[cache_key] = ret
			return ret
		ret = self._select_pkg_highest_available_imp(root, atom, onlydeps=onlydeps)
		self._highest_pkg_cache[cache_key] = ret
		pkg, existing = ret
		if pkg is not None:
			settings = pkg.root_config.settings
			if visible(settings, pkg) and not (pkg.installed and \
				settings._getMissingKeywords(pkg.cpv, pkg.metadata)):
				pkg.root_config.visible_pkgs.cpv_inject(pkg)
		return ret

	def _select_pkg_highest_available_imp(self, root, atom, onlydeps=False):
		root_config = self.roots[root]
		pkgsettings = self.pkgsettings[root]
		dbs = self._filtered_trees[root]["dbs"]
		vardb = self.roots[root].trees["vartree"].dbapi
		portdb = self.roots[root].trees["porttree"].dbapi
		# List of acceptable packages, ordered by type preference.
		matched_packages = []
		highest_version = None
		if not isinstance(atom, portage.dep.Atom):
			atom = portage.dep.Atom(atom)
		atom_cp = atom.cp
		atom_set = InternalPackageSet(initial_atoms=(atom,))
		existing_node = None
		myeb = None
		usepkgonly = "--usepkgonly" in self.myopts
		empty = "empty" in self.myparams
		selective = "selective" in self.myparams
		reinstall = False
		noreplace = "--noreplace" in self.myopts
		# Behavior of the "selective" parameter depends on
		# whether or not a package matches an argument atom.
		# If an installed package provides an old-style
		# virtual that is no longer provided by an available
		# package, the installed package may match an argument
		# atom even though none of the available packages do.
		# Therefore, "selective" logic does not consider
		# whether or not an installed package matches an
		# argument atom. It only considers whether or not
		# available packages match argument atoms, which is
		# represented by the found_available_arg flag.
		found_available_arg = False
		for find_existing_node in True, False:
			if existing_node:
				break
			for db, pkg_type, built, installed, db_keys in dbs:
				if existing_node:
					break
				if installed and not find_existing_node:
					want_reinstall = reinstall or empty or \
						(found_available_arg and not selective)
					if want_reinstall and matched_packages:
						continue
				if hasattr(db, "xmatch"):
					cpv_list = db.xmatch("match-all", atom)
				else:
					cpv_list = db.match(atom)

				# USE=multislot can make an installed package appear as if
				# it doesn't satisfy a slot dependency. Rebuilding the ebuild
				# won't do any good as long as USE=multislot is enabled since
				# the newly built package still won't have the expected slot.
				# Therefore, assume that such SLOT dependencies are already
				# satisfied rather than forcing a rebuild.
				if installed and not cpv_list and atom.slot:
					for cpv in db.match(atom.cp):
						slot_available = False
						for other_db, other_type, other_built, \
							other_installed, other_keys in dbs:
							try:
								if atom.slot == \
									other_db.aux_get(cpv, ["SLOT"])[0]:
									slot_available = True
									break
							except KeyError:
								pass
						if not slot_available:
							continue
						inst_pkg = self._pkg(cpv, "installed",
							root_config, installed=installed)
						# Remove the slot from the atom and verify that
						# the package matches the resulting atom.
						atom_without_slot = portage.dep.remove_slot(atom)
						if atom.use:
							atom_without_slot += str(atom.use)
						atom_without_slot = portage.dep.Atom(atom_without_slot)
						if portage.match_from_list(
							atom_without_slot, [inst_pkg]):
							cpv_list = [inst_pkg.cpv]
						break

				if not cpv_list:
					continue
				pkg_status = "merge"
				if installed or onlydeps:
					pkg_status = "nomerge"
				# descending order
				cpv_list.reverse()
				for cpv in cpv_list:
					# Make --noreplace take precedence over --newuse.
					if not installed and noreplace and \
						cpv in vardb.match(atom):
						# If the installed version is masked, it may
						# be necessary to look at lower versions,
						# in case there is a visible downgrade.
						continue
					reinstall_for_flags = None
					cache_key = (pkg_type, root, cpv, pkg_status)
					calculated_use = True
					pkg = self._pkg_cache.get(cache_key)
					if pkg is None:
						calculated_use = False
						try:
							metadata = izip(db_keys, db.aux_get(cpv, db_keys))
						except KeyError:
							continue
						pkg = Package(built=built, cpv=cpv,
							installed=installed, metadata=metadata,
							onlydeps=onlydeps, root_config=root_config,
							type_name=pkg_type)
						metadata = pkg.metadata
						if not built:
							metadata['CHOST'] = pkgsettings.get('CHOST', '')
						if not built and ("?" in metadata["LICENSE"] or \
							"?" in metadata["PROVIDE"]):
							# This is avoided whenever possible because
							# it's expensive. It only needs to be done here
							# if it has an effect on visibility.
							pkgsettings.setcpv(pkg)
							metadata["USE"] = pkgsettings["PORTAGE_USE"]
							calculated_use = True
						self._pkg_cache[pkg] = pkg

					if not installed or (built and matched_packages):
						# Only enforce visibility on installed packages
						# if there is at least one other visible package
						# available. By filtering installed masked packages
						# here, packages that have been masked since they
						# were installed can be automatically downgraded
						# to an unmasked version.
						try:
							if not visible(pkgsettings, pkg):
								continue
						except portage.exception.InvalidDependString:
							if not installed:
								continue

						# Enable upgrade or downgrade to a version
						# with visible KEYWORDS when the installed
						# version is masked by KEYWORDS, but never
						# reinstall the same exact version only due
						# to a KEYWORDS mask.
						if built and matched_packages:

							different_version = None
							for avail_pkg in matched_packages:
								if not portage.dep.cpvequal(
									pkg.cpv, avail_pkg.cpv):
									different_version = avail_pkg
									break
							if different_version is not None:

								if installed and \
									pkgsettings._getMissingKeywords(
									pkg.cpv, pkg.metadata):
									continue

								# If the ebuild no longer exists or it's
								# keywords have been dropped, reject built
								# instances (installed or binary).
								# If --usepkgonly is enabled, assume that
								# the ebuild status should be ignored.
								if not usepkgonly:
									try:
										pkg_eb = self._pkg(
											pkg.cpv, "ebuild", root_config)
									except portage.exception.PackageNotFound:
										continue
									else:
										if not visible(pkgsettings, pkg_eb):
											continue

					if not pkg.built and not calculated_use:
						# This is avoided whenever possible because
						# it's expensive.
						pkgsettings.setcpv(pkg)
						pkg.metadata["USE"] = pkgsettings["PORTAGE_USE"]

					if pkg.cp != atom.cp:
						# A cpv can be returned from dbapi.match() as an
						# old-style virtual match even in cases when the
						# package does not actually PROVIDE the virtual.
						# Filter out any such false matches here.
						if not atom_set.findAtomForPackage(pkg):
							continue

					myarg = None
					if root == self.target_root:
						try:
							# Ebuild USE must have been calculated prior
							# to this point, in case atoms have USE deps.
							myarg = self._iter_atoms_for_pkg(pkg).next()
						except StopIteration:
							pass
						except portage.exception.InvalidDependString:
							if not installed:
								# masked by corruption
								continue
					if not installed and myarg:
						found_available_arg = True

					if atom.use and not pkg.built:
						use = pkg.use.enabled
						if atom.use.enabled.difference(use):
							continue
						if atom.use.disabled.intersection(use):
							continue
					if pkg.cp == atom_cp:
						if highest_version is None:
							highest_version = pkg
						elif pkg > highest_version:
							highest_version = pkg
					# At this point, we've found the highest visible
					# match from the current repo. Any lower versions
					# from this repo are ignored, so this so the loop
					# will always end with a break statement below
					# this point.
					if find_existing_node:
						e_pkg = self._slot_pkg_map[root].get(pkg.slot_atom)
						if not e_pkg:
							break
						if portage.dep.match_from_list(atom, [e_pkg]):
							if highest_version and \
								e_pkg.cp == atom_cp and \
								e_pkg < highest_version and \
								e_pkg.slot_atom != highest_version.slot_atom:
								# There is a higher version available in a
								# different slot, so this existing node is
								# irrelevant.
								pass
							else:
								matched_packages.append(e_pkg)
								existing_node = e_pkg
						break
					# Compare built package to current config and
					# reject the built package if necessary.
					if built and not installed and \
						("--newuse" in self.myopts or \
						"--reinstall" in self.myopts):
						iuses = pkg.iuse.all
						old_use = pkg.use.enabled
						if myeb:
							pkgsettings.setcpv(myeb)
						else:
							pkgsettings.setcpv(pkg)
						now_use = pkgsettings["PORTAGE_USE"].split()
						forced_flags = set()
						forced_flags.update(pkgsettings.useforce)
						forced_flags.update(pkgsettings.usemask)
						cur_iuse = iuses
						if myeb and not usepkgonly:
							cur_iuse = myeb.iuse.all
						if self._reinstall_for_flags(forced_flags,
							old_use, iuses,
							now_use, cur_iuse):
							break
					# Compare current config to installed package
					# and do not reinstall if possible.
					if not installed and \
						("--newuse" in self.myopts or \
						"--reinstall" in self.myopts) and \
						cpv in vardb.match(atom):
						pkgsettings.setcpv(pkg)
						forced_flags = set()
						forced_flags.update(pkgsettings.useforce)
						forced_flags.update(pkgsettings.usemask)
						old_use = vardb.aux_get(cpv, ["USE"])[0].split()
						old_iuse = set(filter_iuse_defaults(
							vardb.aux_get(cpv, ["IUSE"])[0].split()))
						cur_use = pkg.use.enabled
						cur_iuse = pkg.iuse.all
						reinstall_for_flags = \
							self._reinstall_for_flags(
							forced_flags, old_use, old_iuse,
							cur_use, cur_iuse)
						if reinstall_for_flags:
							reinstall = True
					if not built:
						myeb = pkg
					matched_packages.append(pkg)
					if reinstall_for_flags:
						self._reinstall_nodes[pkg] = \
							reinstall_for_flags
					break

		if not matched_packages:
			return None, None

		if "--debug" in self.myopts:
			for pkg in matched_packages:
				portage.writemsg("%s %s\n" % \
					((pkg.type_name + ":").rjust(10), pkg.cpv), noiselevel=-1)

		# Filter out any old-style virtual matches if they are
		# mixed with new-style virtual matches.
		cp = portage.dep_getkey(atom)
		if len(matched_packages) > 1 and \
			"virtual" == portage.catsplit(cp)[0]:
			for pkg in matched_packages:
				if pkg.cp != cp:
					continue
				# Got a new-style virtual, so filter
				# out any old-style virtuals.
				matched_packages = [pkg for pkg in matched_packages \
					if pkg.cp == cp]
				break

		if len(matched_packages) > 1:
			bestmatch = portage.best(
				[pkg.cpv for pkg in matched_packages])
			matched_packages = [pkg for pkg in matched_packages \
				if portage.dep.cpvequal(pkg.cpv, bestmatch)]

		# ordered by type preference ("ebuild" type is the last resort)
		return  matched_packages[-1], existing_node

	def _select_pkg_from_graph(self, root, atom, onlydeps=False):
		"""
		Select packages that have already been added to the graph or
		those that are installed and have not been scheduled for
		replacement.
		"""
		graph_db = self._graph_trees[root]["porttree"].dbapi
		matches = graph_db.match_pkgs(atom)
		if not matches:
			return None, None
		pkg = matches[-1] # highest match
		in_graph = self._slot_pkg_map[root].get(pkg.slot_atom)
		return pkg, in_graph

	def _complete_graph(self):
		"""
		Add any deep dependencies of required sets (args, system, world) that
		have not been pulled into the graph yet. This ensures that the graph
		is consistent such that initially satisfied deep dependencies are not
		broken in the new graph. Initially unsatisfied dependencies are
		irrelevant since we only want to avoid breaking dependencies that are
		intially satisfied.

		Since this method can consume enough time to disturb users, it is
		currently only enabled by the --complete-graph option.
		"""
		if "--buildpkgonly" in self.myopts or \
			"recurse" not in self.myparams:
			return 1

		if "complete" not in self.myparams:
			# Skip this to avoid consuming enough time to disturb users.
			return 1

		# Put the depgraph into a mode that causes it to only
		# select packages that have already been added to the
		# graph or those that are installed and have not been
		# scheduled for replacement. Also, toggle the "deep"
		# parameter so that all dependencies are traversed and
		# accounted for.
		self._select_atoms = self._select_atoms_from_graph
		self._select_package = self._select_pkg_from_graph
		already_deep = "deep" in self.myparams
		if not already_deep:
			self.myparams.add("deep")

		for root in self.roots:
			required_set_names = self._required_set_names.copy()
			if root == self.target_root and \
				(already_deep or "empty" in self.myparams):
				required_set_names.difference_update(self._sets)
			if not required_set_names and not self._ignored_deps:
				continue
			root_config = self.roots[root]
			setconfig = root_config.setconfig
			args = []
			# Reuse existing SetArg instances when available.
			for arg in self.digraph.root_nodes():
				if not isinstance(arg, SetArg):
					continue
				if arg.root_config != root_config:
					continue
				if arg.name in required_set_names:
					args.append(arg)
					required_set_names.remove(arg.name)
			# Create new SetArg instances only when necessary.
			for s in required_set_names:
				expanded_set = InternalPackageSet(
					initial_atoms=setconfig.getSetAtoms(s))
				atom = SETPREFIX + s
				args.append(SetArg(arg=atom, set=expanded_set,
					root_config=root_config))
			vardb = root_config.trees["vartree"].dbapi
			for arg in args:
				for atom in arg.set:
					self._dep_stack.append(
						Dependency(atom=atom, root=root, parent=arg))
			if self._ignored_deps:
				self._dep_stack.extend(self._ignored_deps)
				self._ignored_deps = []
			if not self._create_graph(allow_unsatisfied=True):
				return 0
			# Check the unsatisfied deps to see if any initially satisfied deps
			# will become unsatisfied due to an upgrade. Initially unsatisfied
			# deps are irrelevant since we only want to avoid breaking deps
			# that are initially satisfied.
			while self._unsatisfied_deps:
				dep = self._unsatisfied_deps.pop()
				matches = vardb.match_pkgs(dep.atom)
				if not matches:
					self._initially_unsatisfied_deps.append(dep)
					continue
				# An scheduled installation broke a deep dependency.
				# Add the installed package to the graph so that it
				# will be appropriately reported as a slot collision
				# (possibly solvable via backtracking).
				pkg = matches[-1] # highest match
				if not self._add_pkg(pkg, dep):
					return 0
				if not self._create_graph(allow_unsatisfied=True):
					return 0
		return 1

	def _pkg(self, cpv, type_name, root_config, installed=False):
		"""
		Get a package instance from the cache, or create a new
		one if necessary. Raises KeyError from aux_get if it
		failures for some reason (package does not exist or is
		corrupt).
		"""
		operation = "merge"
		if installed:
			operation = "nomerge"
		pkg = self._pkg_cache.get(
			(type_name, root_config.root, cpv, operation))
		if pkg is None:
			tree_type = self.pkg_tree_map[type_name]
			db = root_config.trees[tree_type].dbapi
			db_keys = list(self._trees_orig[root_config.root][
				tree_type].dbapi._aux_cache_keys)
			try:
				metadata = izip(db_keys, db.aux_get(cpv, db_keys))
			except KeyError:
				raise portage.exception.PackageNotFound(cpv)
			pkg = Package(cpv=cpv, metadata=metadata,
				root_config=root_config, installed=installed)
			if type_name == "ebuild":
				settings = self.pkgsettings[root_config.root]
				settings.setcpv(pkg)
				pkg.metadata["USE"] = settings["PORTAGE_USE"]
				pkg.metadata['CHOST'] = settings.get('CHOST', '')
			self._pkg_cache[pkg] = pkg
		return pkg

	def validate_blockers(self):
		"""Remove any blockers from the digraph that do not match any of the
		packages within the graph.  If necessary, create hard deps to ensure
		correct merge order such that mutually blocking packages are never
		installed simultaneously."""

		if "--buildpkgonly" in self.myopts or \
			"--nodeps" in self.myopts:
			return True

		#if "deep" in self.myparams:
		if True:
			# Pull in blockers from all installed packages that haven't already
			# been pulled into the depgraph.  This is not enabled by default
			# due to the performance penalty that is incurred by all the
			# additional dep_check calls that are required.

			dep_keys = ["DEPEND","RDEPEND","PDEPEND"]
			for myroot in self.trees:
				vardb = self.trees[myroot]["vartree"].dbapi
				portdb = self.trees[myroot]["porttree"].dbapi
				pkgsettings = self.pkgsettings[myroot]
				final_db = self.mydbapi[myroot]

				blocker_cache = BlockerCache(myroot, vardb)
				stale_cache = set(blocker_cache)
				for pkg in vardb:
					cpv = pkg.cpv
					stale_cache.discard(cpv)
					pkg_in_graph = self.digraph.contains(pkg)

					# Check for masked installed packages. Only warn about
					# packages that are in the graph in order to avoid warning
					# about those that will be automatically uninstalled during
					# the merge process or by --depclean.
					if pkg in final_db:
						if pkg_in_graph and not visible(pkgsettings, pkg):
							self._masked_installed.add(pkg)

					blocker_atoms = None
					blockers = None
					if pkg_in_graph:
						blockers = []
						try:
							blockers.extend(
								self._blocker_parents.child_nodes(pkg))
						except KeyError:
							pass
						try:
							blockers.extend(
								self._irrelevant_blockers.child_nodes(pkg))
						except KeyError:
							pass
					if blockers is not None:
						blockers = set(str(blocker.atom) \
							for blocker in blockers)

					# If this node has any blockers, create a "nomerge"
					# node for it so that they can be enforced.
					self.spinner.update()
					blocker_data = blocker_cache.get(cpv)
					if blocker_data is not None and \
						blocker_data.counter != long(pkg.metadata["COUNTER"]):
						blocker_data = None

					# If blocker data from the graph is available, use
					# it to validate the cache and update the cache if
					# it seems invalid.
					if blocker_data is not None and \
						blockers is not None:
						if not blockers.symmetric_difference(
							blocker_data.atoms):
							continue
						blocker_data = None

					if blocker_data is None and \
						blockers is not None:
						# Re-use the blockers from the graph.
						blocker_atoms = sorted(blockers)
						counter = long(pkg.metadata["COUNTER"])
						blocker_data = \
							blocker_cache.BlockerData(counter, blocker_atoms)
						blocker_cache[pkg.cpv] = blocker_data
						continue

					if blocker_data:
						blocker_atoms = blocker_data.atoms
					else:
						# Use aux_get() to trigger FakeVartree global
						# updates on *DEPEND when appropriate.
						depstr = " ".join(vardb.aux_get(pkg.cpv, dep_keys))
						# It is crucial to pass in final_db here in order to
						# optimize dep_check calls by eliminating atoms via
						# dep_wordreduce and dep_eval calls.
						try:
							portage.dep._dep_check_strict = False
							try:
								success, atoms = portage.dep_check(depstr,
									final_db, pkgsettings, myuse=pkg.use.enabled,
									trees=self._graph_trees, myroot=myroot)
							except Exception, e:
								if isinstance(e, SystemExit):
									raise
								# This is helpful, for example, if a ValueError
								# is thrown from cpv_expand due to multiple
								# matches (this can happen if an atom lacks a
								# category).
								show_invalid_depstring_notice(
									pkg, depstr, str(e))
								del e
								raise
						finally:
							portage.dep._dep_check_strict = True
						if not success:
							replacement_pkg = final_db.match_pkgs(pkg.slot_atom)
							if replacement_pkg and \
								replacement_pkg[0].operation == "merge":
								# This package is being replaced anyway, so
								# ignore invalid dependencies so as not to
								# annoy the user too much (otherwise they'd be
								# forced to manually unmerge it first).
								continue
							show_invalid_depstring_notice(pkg, depstr, atoms)
							return False
						blocker_atoms = [myatom for myatom in atoms \
							if myatom.startswith("!")]
						blocker_atoms.sort()
						counter = long(pkg.metadata["COUNTER"])
						blocker_cache[cpv] = \
							blocker_cache.BlockerData(counter, blocker_atoms)
					if blocker_atoms:
						try:
							for atom in blocker_atoms:
								blocker = Blocker(atom=portage.dep.Atom(atom),
									eapi=pkg.metadata["EAPI"], root=myroot)
								self._blocker_parents.add(blocker, pkg)
						except portage.exception.InvalidAtom, e:
							depstr = " ".join(vardb.aux_get(pkg.cpv, dep_keys))
							show_invalid_depstring_notice(
								pkg, depstr, "Invalid Atom: %s" % (e,))
							return False
				for cpv in stale_cache:
					del blocker_cache[cpv]
				blocker_cache.flush()
				del blocker_cache

		# Discard any "uninstall" tasks scheduled by previous calls
		# to this method, since those tasks may not make sense given
		# the current graph state.
		previous_uninstall_tasks = self._blocker_uninstalls.leaf_nodes()
		if previous_uninstall_tasks:
			self._blocker_uninstalls = digraph()
			self.digraph.difference_update(previous_uninstall_tasks)

		for blocker in self._blocker_parents.leaf_nodes():
			self.spinner.update()
			root_config = self.roots[blocker.root]
			virtuals = root_config.settings.getvirtuals()
			myroot = blocker.root
			initial_db = self.trees[myroot]["vartree"].dbapi
			final_db = self.mydbapi[myroot]
			
			provider_virtual = False
			if blocker.cp in virtuals and \
				not self._have_new_virt(blocker.root, blocker.cp):
				provider_virtual = True

			# Use this to check PROVIDE for each matched package
			# when necessary.
			atom_set = InternalPackageSet(
				initial_atoms=[blocker.atom])

			if provider_virtual:
				atoms = []
				for provider_entry in virtuals[blocker.cp]:
					provider_cp = \
						portage.dep_getkey(provider_entry)
					atoms.append(blocker.atom.replace(
						blocker.cp, provider_cp))
			else:
				atoms = [blocker.atom]

			blocked_initial = set()
			for atom in atoms:
				for pkg in initial_db.match_pkgs(atom):
					if atom_set.findAtomForPackage(pkg):
						blocked_initial.add(pkg)

			blocked_final = set()
			for atom in atoms:
				for pkg in final_db.match_pkgs(atom):
					if atom_set.findAtomForPackage(pkg):
						blocked_final.add(pkg)

			if not blocked_initial and not blocked_final:
				parent_pkgs = self._blocker_parents.parent_nodes(blocker)
				self._blocker_parents.remove(blocker)
				# Discard any parents that don't have any more blockers.
				for pkg in parent_pkgs:
					self._irrelevant_blockers.add(blocker, pkg)
					if not self._blocker_parents.child_nodes(pkg):
						self._blocker_parents.remove(pkg)
				continue
			for parent in self._blocker_parents.parent_nodes(blocker):
				unresolved_blocks = False
				depends_on_order = set()
				for pkg in blocked_initial:
					if pkg.slot_atom == parent.slot_atom:
						# TODO: Support blocks within slots in cases where it
						# might make sense.  For example, a new version might
						# require that the old version be uninstalled at build
						# time.
						continue
					if parent.installed:
						# Two currently installed packages conflict with
						# eachother. Ignore this case since the damage
						# is already done and this would be likely to
						# confuse users if displayed like a normal blocker.
						continue

					self._blocked_pkgs.add(pkg, blocker)

					if parent.operation == "merge":
						# Maybe the blocked package can be replaced or simply
						# unmerged to resolve this block.
						depends_on_order.add((pkg, parent))
						continue
					# None of the above blocker resolutions techniques apply,
					# so apparently this one is unresolvable.
					unresolved_blocks = True
				for pkg in blocked_final:
					if pkg.slot_atom == parent.slot_atom:
						# TODO: Support blocks within slots.
						continue
					if parent.operation == "nomerge" and \
						pkg.operation == "nomerge":
						# This blocker will be handled the next time that a
						# merge of either package is triggered.
						continue

					self._blocked_pkgs.add(pkg, blocker)

					# Maybe the blocking package can be
					# unmerged to resolve this block.
					if parent.operation == "merge" and pkg.installed:
						depends_on_order.add((pkg, parent))
						continue
					elif parent.operation == "nomerge":
						depends_on_order.add((parent, pkg))
						continue
					# None of the above blocker resolutions techniques apply,
					# so apparently this one is unresolvable.
					unresolved_blocks = True

				# Make sure we don't unmerge any package that have been pulled
				# into the graph.
				if not unresolved_blocks and depends_on_order:
					for inst_pkg, inst_task in depends_on_order:
						if self.digraph.contains(inst_pkg) and \
							self.digraph.parent_nodes(inst_pkg):
							unresolved_blocks = True
							break

				if not unresolved_blocks and depends_on_order:
					for inst_pkg, inst_task in depends_on_order:
						uninst_task = Package(built=inst_pkg.built,
							cpv=inst_pkg.cpv, installed=inst_pkg.installed,
							metadata=inst_pkg.metadata,
							operation="uninstall",
							root_config=inst_pkg.root_config,
							type_name=inst_pkg.type_name)
						self._pkg_cache[uninst_task] = uninst_task
						# Enforce correct merge order with a hard dep.
						self.digraph.addnode(uninst_task, inst_task,
							priority=BlockerDepPriority.instance)
						# Count references to this blocker so that it can be
						# invalidated after nodes referencing it have been
						# merged.
						self._blocker_uninstalls.addnode(uninst_task, blocker)
				if not unresolved_blocks and not depends_on_order:
					self._irrelevant_blockers.add(blocker, parent)
					self._blocker_parents.remove_edge(blocker, parent)
					if not self._blocker_parents.parent_nodes(blocker):
						self._blocker_parents.remove(blocker)
					if not self._blocker_parents.child_nodes(parent):
						self._blocker_parents.remove(parent)
				if unresolved_blocks:
					self._unsolvable_blockers.add(blocker, parent)

		return True

	def _accept_blocker_conflicts(self):
		acceptable = False
		for x in ("--buildpkgonly", "--fetchonly",
			"--fetch-all-uri", "--nodeps"):
			if x in self.myopts:
				acceptable = True
				break
		return acceptable

	def _merge_order_bias(self, mygraph):
		"""
		For optimal leaf node selection, promote deep system runtime deps and
		order nodes from highest to lowest overall reference count.
		"""

		node_info = {}
		for node in mygraph.order:
			node_info[node] = len(mygraph.parent_nodes(node))
		deep_system_deps = _find_deep_system_runtime_deps(mygraph)

		def cmp_merge_preference(node1, node2):

			if node1.operation == 'uninstall':
				if node2.operation == 'uninstall':
					return 0
				return 1

			if node2.operation == 'uninstall':
				if node1.operation == 'uninstall':
					return 0
				return -1

			node1_sys = node1 in deep_system_deps
			node2_sys = node2 in deep_system_deps
			if node1_sys != node2_sys:
				if node1_sys:
					return -1
				return 1

			return node_info[node2] - node_info[node1]

		mygraph.order.sort(key=cmp_sort_key(cmp_merge_preference))

	def altlist(self, reversed=False):

		while self._serialized_tasks_cache is None:
			self._resolve_conflicts()
			try:
				self._serialized_tasks_cache, self._scheduler_graph = \
					self._serialize_tasks()
			except self._serialize_tasks_retry:
				pass

		retlist = self._serialized_tasks_cache[:]
		if reversed:
			retlist.reverse()
		return retlist

	def schedulerGraph(self):
		"""
		The scheduler graph is identical to the normal one except that
		uninstall edges are reversed in specific cases that require
		conflicting packages to be temporarily installed simultaneously.
		This is intended for use by the Scheduler in it's parallelization
		logic. It ensures that temporary simultaneous installation of
		conflicting packages is avoided when appropriate (especially for
		!!atom blockers), but allowed in specific cases that require it.

		Note that this method calls break_refs() which alters the state of
		internal Package instances such that this depgraph instance should
		not be used to perform any more calculations.
		"""
		if self._scheduler_graph is None:
			self.altlist()
		self.break_refs(self._scheduler_graph.order)
		return self._scheduler_graph

	def break_refs(self, nodes):
		"""
		Take a mergelist like that returned from self.altlist() and
		break any references that lead back to the depgraph. This is
		useful if you want to hold references to packages without
		also holding the depgraph on the heap.
		"""
		for node in nodes:
			if hasattr(node, "root_config"):
				# The FakeVartree references the _package_cache which
				# references the depgraph. So that Package instances don't
				# hold the depgraph and FakeVartree on the heap, replace
				# the RootConfig that references the FakeVartree with the
				# original RootConfig instance which references the actual
				# vartree.
				node.root_config = \
					self._trees_orig[node.root_config.root]["root_config"]

	def _resolve_conflicts(self):
		if not self._complete_graph():
			raise self._unknown_internal_error()

		if not self.validate_blockers():
			raise self._unknown_internal_error()

		if self._slot_collision_info:
			self._process_slot_conflicts()

	def _serialize_tasks(self):

		if "--debug" in self.myopts:
			writemsg("\ndigraph:\n\n", noiselevel=-1)
			self.digraph.debug_print()
			writemsg("\n", noiselevel=-1)

		scheduler_graph = self.digraph.copy()

		if '--nodeps' in self.myopts:
			# Preserve the package order given on the command line.
			return ([node for node in scheduler_graph \
				if isinstance(node, Package) \
				and node.operation == 'merge'], scheduler_graph)

		mygraph=self.digraph.copy()
		# Prune "nomerge" root nodes if nothing depends on them, since
		# otherwise they slow down merge order calculation. Don't remove
		# non-root nodes since they help optimize merge order in some cases
		# such as revdep-rebuild.
		removed_nodes = set()
		while True:
			for node in mygraph.root_nodes():
				if not isinstance(node, Package) or \
					node.installed or node.onlydeps:
					removed_nodes.add(node)
			if removed_nodes:
				self.spinner.update()
				mygraph.difference_update(removed_nodes)
			if not removed_nodes:
				break
			removed_nodes.clear()
		self._merge_order_bias(mygraph)
		def cmp_circular_bias(n1, n2):
			"""
			RDEPEND is stronger than PDEPEND and this function
			measures such a strength bias within a circular
			dependency relationship.
			"""
			n1_n2_medium = n2 in mygraph.child_nodes(n1,
				ignore_priority=priority_range.ignore_medium_soft)
			n2_n1_medium = n1 in mygraph.child_nodes(n2,
				ignore_priority=priority_range.ignore_medium_soft)
			if n1_n2_medium == n2_n1_medium:
				return 0
			elif n1_n2_medium:
				return 1
			return -1
		myblocker_uninstalls = self._blocker_uninstalls.copy()
		retlist=[]
		# Contains uninstall tasks that have been scheduled to
		# occur after overlapping blockers have been installed.
		scheduled_uninstalls = set()
		# Contains any Uninstall tasks that have been ignored
		# in order to avoid the circular deps code path. These
		# correspond to blocker conflicts that could not be
		# resolved.
		ignored_uninstall_tasks = set()
		have_uninstall_task = False
		complete = "complete" in self.myparams
		asap_nodes = []

		def get_nodes(**kwargs):
			"""
			Returns leaf nodes excluding Uninstall instances
			since those should be executed as late as possible.
			"""
			return [node for node in mygraph.leaf_nodes(**kwargs) \
				if isinstance(node, Package) and \
					(node.operation != "uninstall" or \
					node in scheduled_uninstalls)]

		# sys-apps/portage needs special treatment if ROOT="/"
		running_root = self._running_root.root
		from portage.const import PORTAGE_PACKAGE_ATOM
		runtime_deps = InternalPackageSet(
			initial_atoms=[PORTAGE_PACKAGE_ATOM])
		running_portage = self.trees[running_root]["vartree"].dbapi.match_pkgs(
			PORTAGE_PACKAGE_ATOM)
		replacement_portage = self.mydbapi[running_root].match_pkgs(
			PORTAGE_PACKAGE_ATOM)

		if running_portage:
			running_portage = running_portage[0]
		else:
			running_portage = None

		if replacement_portage:
			replacement_portage = replacement_portage[0]
		else:
			replacement_portage = None

		if replacement_portage == running_portage:
			replacement_portage = None

		if replacement_portage is not None:
			# update from running_portage to replacement_portage asap
			asap_nodes.append(replacement_portage)

		if running_portage is not None:
			try:
				portage_rdepend = self._select_atoms_highest_available(
					running_root, running_portage.metadata["RDEPEND"],
					myuse=running_portage.use.enabled,
					parent=running_portage, strict=False)
			except portage.exception.InvalidDependString, e:
				portage.writemsg("!!! Invalid RDEPEND in " + \
					"'%svar/db/pkg/%s/RDEPEND': %s\n" % \
					(running_root, running_portage.cpv, e), noiselevel=-1)
				del e
				portage_rdepend = []
			runtime_deps.update(atom for atom in portage_rdepend \
				if not atom.startswith("!"))

		def gather_deps(ignore_priority, mergeable_nodes,
			selected_nodes, node):
			"""
			Recursively gather a group of nodes that RDEPEND on
			eachother. This ensures that they are merged as a group
			and get their RDEPENDs satisfied as soon as possible.
			"""
			if node in selected_nodes:
				return True
			if node not in mergeable_nodes:
				return False
			if node == replacement_portage and \
				mygraph.child_nodes(node,
				ignore_priority=priority_range.ignore_medium_soft):
				# Make sure that portage always has all of it's
				# RDEPENDs installed first.
				return False
			selected_nodes.add(node)
			for child in mygraph.child_nodes(node,
				ignore_priority=ignore_priority):
				if not gather_deps(ignore_priority,
					mergeable_nodes, selected_nodes, child):
					return False
			return True

		def ignore_uninst_or_med(priority):
			if priority is BlockerDepPriority.instance:
				return True
			return priority_range.ignore_medium(priority)

		def ignore_uninst_or_med_soft(priority):
			if priority is BlockerDepPriority.instance:
				return True
			return priority_range.ignore_medium_soft(priority)

		tree_mode = "--tree" in self.myopts
		# Tracks whether or not the current iteration should prefer asap_nodes
		# if available.  This is set to False when the previous iteration
		# failed to select any nodes.  It is reset whenever nodes are
		# successfully selected.
		prefer_asap = True

		# Controls whether or not the current iteration should drop edges that
		# are "satisfied" by installed packages, in order to solve circular
		# dependencies. The deep runtime dependencies of installed packages are
		# not checked in this case (bug #199856), so it must be avoided
		# whenever possible.
		drop_satisfied = False

		# State of variables for successive iterations that loosen the
		# criteria for node selection.
		#
		# iteration   prefer_asap   drop_satisfied
		# 1           True          False
		# 2           False         False
		# 3           False         True
		#
		# If no nodes are selected on the last iteration, it is due to
		# unresolved blockers or circular dependencies.

		while not mygraph.empty():
			self.spinner.update()
			selected_nodes = None
			ignore_priority = None
			if drop_satisfied or (prefer_asap and asap_nodes):
				priority_range = DepPrioritySatisfiedRange
			else:
				priority_range = DepPriorityNormalRange
			if prefer_asap and asap_nodes:
				# ASAP nodes are merged before their soft deps. Go ahead and
				# select root nodes here if necessary, since it's typical for
				# the parent to have been removed from the graph already.
				asap_nodes = [node for node in asap_nodes \
					if mygraph.contains(node)]
				for node in asap_nodes:
					if not mygraph.child_nodes(node,
						ignore_priority=priority_range.ignore_soft):
						selected_nodes = [node]
						asap_nodes.remove(node)
						break
			if not selected_nodes and \
				not (prefer_asap and asap_nodes):
				for i in xrange(priority_range.NONE,
					priority_range.MEDIUM_SOFT + 1):
					ignore_priority = priority_range.ignore_priority[i]
					nodes = get_nodes(ignore_priority=ignore_priority)
					if nodes:
						# If there is a mix of uninstall nodes with other
						# types, save the uninstall nodes for later since
						# sometimes a merge node will render an uninstall
						# node unnecessary (due to occupying the same slot),
						# and we want to avoid executing a separate uninstall
						# task in that case.
						if len(nodes) > 1:
							good_uninstalls = []
							with_some_uninstalls_excluded = []
							for node in nodes:
								if node.operation == "uninstall":
									slot_node = self.mydbapi[node.root
										].match_pkgs(node.slot_atom)
									if slot_node and \
										slot_node[0].operation == "merge":
										continue
									good_uninstalls.append(node)
								with_some_uninstalls_excluded.append(node)
							if good_uninstalls:
								nodes = good_uninstalls
							elif with_some_uninstalls_excluded:
								nodes = with_some_uninstalls_excluded
							else:
								nodes = nodes

						if ignore_priority is None and not tree_mode:
							# Greedily pop all of these nodes since no
							# relationship has been ignored. This optimization
							# destroys --tree output, so it's disabled in tree
							# mode.
							selected_nodes = nodes
						else:
							# For optimal merge order:
							#  * Only pop one node.
							#  * Removing a root node (node without a parent)
							#    will not produce a leaf node, so avoid it.
							#  * It's normal for a selected uninstall to be a
							#    root node, so don't check them for parents.
							for node in nodes:
								if node.operation == "uninstall" or \
									mygraph.parent_nodes(node):
									selected_nodes = [node]
									break

						if selected_nodes:
							break

			if not selected_nodes:
				nodes = get_nodes(ignore_priority=priority_range.ignore_medium)
				if nodes:
					mergeable_nodes = set(nodes)
					if prefer_asap and asap_nodes:
						nodes = asap_nodes
					for i in xrange(priority_range.SOFT,
						priority_range.MEDIUM_SOFT + 1):
						ignore_priority = priority_range.ignore_priority[i]
						for node in nodes:
							if not mygraph.parent_nodes(node):
								continue
							selected_nodes = set()
							if gather_deps(ignore_priority,
								mergeable_nodes, selected_nodes, node):
								break
							else:
								selected_nodes = None
						if selected_nodes:
							break

					if prefer_asap and asap_nodes and not selected_nodes:
						# We failed to find any asap nodes to merge, so ignore
						# them for the next iteration.
						prefer_asap = False
						continue

			if selected_nodes and ignore_priority is not None:
				# Try to merge ignored medium_soft deps as soon as possible
				# if they're not satisfied by installed packages.
				for node in selected_nodes:
					children = set(mygraph.child_nodes(node))
					soft = children.difference(
						mygraph.child_nodes(node,
						ignore_priority=DepPrioritySatisfiedRange.ignore_soft))
					medium_soft = children.difference(
						mygraph.child_nodes(node,
							ignore_priority = \
							DepPrioritySatisfiedRange.ignore_medium_soft))
					medium_soft.difference_update(soft)
					for child in medium_soft:
						if child in selected_nodes:
							continue
						if child in asap_nodes:
							continue
						asap_nodes.append(child)

			if selected_nodes and len(selected_nodes) > 1:
				if not isinstance(selected_nodes, list):
					selected_nodes = list(selected_nodes)
				selected_nodes.sort(key=cmp_sort_key(cmp_circular_bias))

			if not selected_nodes and not myblocker_uninstalls.is_empty():
				# An Uninstall task needs to be executed in order to
				# avoid conflict if possible.

				if drop_satisfied:
					priority_range = DepPrioritySatisfiedRange
				else:
					priority_range = DepPriorityNormalRange

				mergeable_nodes = get_nodes(
					ignore_priority=ignore_uninst_or_med)

				min_parent_deps = None
				uninst_task = None
				for task in myblocker_uninstalls.leaf_nodes():
					# Do some sanity checks so that system or world packages
					# don't get uninstalled inappropriately here (only really
					# necessary when --complete-graph has not been enabled).

					if task in ignored_uninstall_tasks:
						continue

					if task in scheduled_uninstalls:
						# It's been scheduled but it hasn't
						# been executed yet due to dependence
						# on installation of blocking packages.
						continue

					root_config = self.roots[task.root]
					inst_pkg = self._pkg_cache[
						("installed", task.root, task.cpv, "nomerge")]

					if self.digraph.contains(inst_pkg):
						continue

					forbid_overlap = False
					heuristic_overlap = False
					for blocker in myblocker_uninstalls.parent_nodes(task):
						if blocker.eapi in ("0", "1"):
							heuristic_overlap = True
						elif blocker.atom.blocker.overlap.forbid:
							forbid_overlap = True
							break
					if forbid_overlap and running_root == task.root:
						continue

					if heuristic_overlap and running_root == task.root:
						# Never uninstall sys-apps/portage or it's essential
						# dependencies, except through replacement.
						try:
							runtime_dep_atoms = \
								list(runtime_deps.iterAtomsForPackage(task))
						except portage.exception.InvalidDependString, e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							continue

						# Don't uninstall a runtime dep if it appears
						# to be the only suitable one installed.
						skip = False
						vardb = root_config.trees["vartree"].dbapi
						for atom in runtime_dep_atoms:
							other_version = None
							for pkg in vardb.match_pkgs(atom):
								if pkg.cpv == task.cpv and \
									pkg.metadata["COUNTER"] == \
									task.metadata["COUNTER"]:
									continue
								other_version = pkg
								break
							if other_version is None:
								skip = True
								break
						if skip:
							continue

						# For packages in the system set, don't take
						# any chances. If the conflict can't be resolved
						# by a normal replacement operation then abort.
						skip = False
						try:
							for atom in root_config.sets[
								"system"].iterAtomsForPackage(task):
								skip = True
								break
						except portage.exception.InvalidDependString, e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							skip = True
						if skip:
							continue

					# Note that the world check isn't always
					# necessary since self._complete_graph() will
					# add all packages from the system and world sets to the
					# graph. This just allows unresolved conflicts to be
					# detected as early as possible, which makes it possible
					# to avoid calling self._complete_graph() when it is
					# unnecessary due to blockers triggering an abortion.
					if not complete:
						# For packages in the world set, go ahead an uninstall
						# when necessary, as long as the atom will be satisfied
						# in the final state.
						graph_db = self.mydbapi[task.root]
						skip = False
						try:
							for atom in root_config.sets[
								"world"].iterAtomsForPackage(task):
								satisfied = False
								for pkg in graph_db.match_pkgs(atom):
									if pkg == inst_pkg:
										continue
									satisfied = True
									break
								if not satisfied:
									skip = True
									self._blocked_world_pkgs[inst_pkg] = atom
									break
						except portage.exception.InvalidDependString, e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							skip = True
						if skip:
							continue

					# Check the deps of parent nodes to ensure that
					# the chosen task produces a leaf node. Maybe
					# this can be optimized some more to make the
					# best possible choice, but the current algorithm
					# is simple and should be near optimal for most
					# common cases.
					mergeable_parent = False
					parent_deps = set()
					for parent in mygraph.parent_nodes(task):
						parent_deps.update(mygraph.child_nodes(parent,
							ignore_priority=priority_range.ignore_medium_soft))
						if parent in mergeable_nodes and \
							gather_deps(ignore_uninst_or_med_soft,
							mergeable_nodes, set(), parent):
							mergeable_parent = True

					if not mergeable_parent:
						continue

					parent_deps.remove(task)
					if min_parent_deps is None or \
						len(parent_deps) < min_parent_deps:
						min_parent_deps = len(parent_deps)
						uninst_task = task

				if uninst_task is not None:
					# The uninstall is performed only after blocking
					# packages have been merged on top of it. File
					# collisions between blocking packages are detected
					# and removed from the list of files to be uninstalled.
					scheduled_uninstalls.add(uninst_task)
					parent_nodes = mygraph.parent_nodes(uninst_task)

					# Reverse the parent -> uninstall edges since we want
					# to do the uninstall after blocking packages have
					# been merged on top of it.
					mygraph.remove(uninst_task)
					for blocked_pkg in parent_nodes:
						mygraph.add(blocked_pkg, uninst_task,
							priority=BlockerDepPriority.instance)
						scheduler_graph.remove_edge(uninst_task, blocked_pkg)
						scheduler_graph.add(blocked_pkg, uninst_task,
							priority=BlockerDepPriority.instance)

					# Reset the state variables for leaf node selection and
					# continue trying to select leaf nodes.
					prefer_asap = True
					drop_satisfied = False
					continue

			if not selected_nodes:
				# Only select root nodes as a last resort. This case should
				# only trigger when the graph is nearly empty and the only
				# remaining nodes are isolated (no parents or children). Since
				# the nodes must be isolated, ignore_priority is not needed.
				selected_nodes = get_nodes()

			if not selected_nodes and not drop_satisfied:
				drop_satisfied = True
				continue

			if not selected_nodes and not myblocker_uninstalls.is_empty():
				# If possible, drop an uninstall task here in order to avoid
				# the circular deps code path. The corresponding blocker will
				# still be counted as an unresolved conflict.
				uninst_task = None
				for node in myblocker_uninstalls.leaf_nodes():
					try:
						mygraph.remove(node)
					except KeyError:
						pass
					else:
						uninst_task = node
						ignored_uninstall_tasks.add(node)
						break

				if uninst_task is not None:
					# Reset the state variables for leaf node selection and
					# continue trying to select leaf nodes.
					prefer_asap = True
					drop_satisfied = False
					continue

			if not selected_nodes:
				self._circular_deps_for_display = mygraph
				raise self._unknown_internal_error()

			# At this point, we've succeeded in selecting one or more nodes, so
			# reset state variables for leaf node selection.
			prefer_asap = True
			drop_satisfied = False

			mygraph.difference_update(selected_nodes)

			for node in selected_nodes:
				if isinstance(node, Package) and \
					node.operation == "nomerge":
					continue

				# Handle interactions between blockers
				# and uninstallation tasks.
				solved_blockers = set()
				uninst_task = None
				if isinstance(node, Package) and \
					"uninstall" == node.operation:
					have_uninstall_task = True
					uninst_task = node
				else:
					vardb = self.trees[node.root]["vartree"].dbapi
					previous_cpv = vardb.match(node.slot_atom)
					if previous_cpv:
						# The package will be replaced by this one, so remove
						# the corresponding Uninstall task if necessary.
						previous_cpv = previous_cpv[0]
						uninst_task = \
							("installed", node.root, previous_cpv, "uninstall")
						try:
							mygraph.remove(uninst_task)
						except KeyError:
							pass

				if uninst_task is not None and \
					uninst_task not in ignored_uninstall_tasks and \
					myblocker_uninstalls.contains(uninst_task):
					blocker_nodes = myblocker_uninstalls.parent_nodes(uninst_task)
					myblocker_uninstalls.remove(uninst_task)
					# Discard any blockers that this Uninstall solves.
					for blocker in blocker_nodes:
						if not myblocker_uninstalls.child_nodes(blocker):
							myblocker_uninstalls.remove(blocker)
							solved_blockers.add(blocker)

				retlist.append(node)

				if (isinstance(node, Package) and \
					"uninstall" == node.operation) or \
					(uninst_task is not None and \
					uninst_task in scheduled_uninstalls):
					# Include satisfied blockers in the merge list
					# since the user might be interested and also
					# it serves as an indicator that blocking packages
					# will be temporarily installed simultaneously.
					for blocker in solved_blockers:
						retlist.append(Blocker(atom=blocker.atom,
							root=blocker.root, eapi=blocker.eapi,
							satisfied=True))

		unsolvable_blockers = set(self._unsolvable_blockers.leaf_nodes())
		for node in myblocker_uninstalls.root_nodes():
			unsolvable_blockers.add(node)

		for blocker in unsolvable_blockers:
			retlist.append(blocker)

		# If any Uninstall tasks need to be executed in order
		# to avoid a conflict, complete the graph with any
		# dependencies that may have been initially
		# neglected (to ensure that unsafe Uninstall tasks
		# are properly identified and blocked from execution).
		if have_uninstall_task and \
			not complete and \
			not unsolvable_blockers:
			self.myparams.add("complete")
			raise self._serialize_tasks_retry("")

		if unsolvable_blockers and \
			not self._accept_blocker_conflicts():
			self._unsatisfied_blockers_for_display = unsolvable_blockers
			self._serialized_tasks_cache = retlist[:]
			self._scheduler_graph = scheduler_graph
			raise self._unknown_internal_error()

		if self._slot_collision_info and \
			not self._accept_blocker_conflicts():
			self._serialized_tasks_cache = retlist[:]
			self._scheduler_graph = scheduler_graph
			raise self._unknown_internal_error()

		return retlist, scheduler_graph

	def _show_circular_deps(self, mygraph):
		# No leaf nodes are available, so we have a circular
		# dependency panic situation.  Reduce the noise level to a
		# minimum via repeated elimination of root nodes since they
		# have no parents and thus can not be part of a cycle.
		while True:
			root_nodes = mygraph.root_nodes(
				ignore_priority=DepPrioritySatisfiedRange.ignore_medium_soft)
			if not root_nodes:
				break
			mygraph.difference_update(root_nodes)
		# Display the USE flags that are enabled on nodes that are part
		# of dependency cycles in case that helps the user decide to
		# disable some of them.
		display_order = []
		tempgraph = mygraph.copy()
		while not tempgraph.empty():
			nodes = tempgraph.leaf_nodes()
			if not nodes:
				node = tempgraph.order[0]
			else:
				node = nodes[0]
			display_order.append(node)
			tempgraph.remove(node)
		display_order.reverse()
		self.myopts.pop("--quiet", None)
		self.myopts.pop("--verbose", None)
		self.myopts["--tree"] = True
		portage.writemsg("\n\n", noiselevel=-1)
		self.display(display_order)
		prefix = colorize("BAD", " * ")
		portage.writemsg("\n", noiselevel=-1)
		portage.writemsg(prefix + "Error: circular dependencies:\n",
			noiselevel=-1)
		portage.writemsg("\n", noiselevel=-1)
		mygraph.debug_print()
		portage.writemsg("\n", noiselevel=-1)
		portage.writemsg(prefix + "Note that circular dependencies " + \
			"can often be avoided by temporarily\n", noiselevel=-1)
		portage.writemsg(prefix + "disabling USE flags that trigger " + \
			"optional dependencies.\n", noiselevel=-1)

	def _show_merge_list(self):
		if self._serialized_tasks_cache is not None and \
			not (self._displayed_list and \
			(self._displayed_list == self._serialized_tasks_cache or \
			self._displayed_list == \
				list(reversed(self._serialized_tasks_cache)))):
			display_list = self._serialized_tasks_cache[:]
			if "--tree" in self.myopts:
				display_list.reverse()
			self.display(display_list)

	def _show_unsatisfied_blockers(self, blockers):
		self._show_merge_list()
		msg = "Error: The above package list contains " + \
			"packages which cannot be installed " + \
			"at the same time on the same system."
		prefix = colorize("BAD", " * ")
		from textwrap import wrap
		portage.writemsg("\n", noiselevel=-1)
		for line in wrap(msg, 70):
			portage.writemsg(prefix + line + "\n", noiselevel=-1)

		# Display the conflicting packages along with the packages
		# that pulled them in. This is helpful for troubleshooting
		# cases in which blockers don't solve automatically and
		# the reasons are not apparent from the normal merge list
		# display.

		conflict_pkgs = {}
		for blocker in blockers:
			for pkg in chain(self._blocked_pkgs.child_nodes(blocker), \
				self._blocker_parents.parent_nodes(blocker)):
				parent_atoms = self._parent_atoms.get(pkg)
				if not parent_atoms:
					atom = self._blocked_world_pkgs.get(pkg)
					if atom is not None:
						parent_atoms = set([("@world", atom)])
				if parent_atoms:
					conflict_pkgs[pkg] = parent_atoms

		if conflict_pkgs:
			# Reduce noise by pruning packages that are only
			# pulled in by other conflict packages.
			pruned_pkgs = set()
			for pkg, parent_atoms in conflict_pkgs.iteritems():
				relevant_parent = False
				for parent, atom in parent_atoms:
					if parent not in conflict_pkgs:
						relevant_parent = True
						break
				if not relevant_parent:
					pruned_pkgs.add(pkg)
			for pkg in pruned_pkgs:
				del conflict_pkgs[pkg]

		if conflict_pkgs:
			msg = []
			msg.append("\n")
			indent = "  "
			# Max number of parents shown, to avoid flooding the display.
			max_parents = 3
			for pkg, parent_atoms in conflict_pkgs.iteritems():

				pruned_list = set()

				# Prefer packages that are not directly involved in a conflict.
				for parent_atom in parent_atoms:
					if len(pruned_list) >= max_parents:
						break
					parent, atom = parent_atom
					if parent not in conflict_pkgs:
						pruned_list.add(parent_atom)

				for parent_atom in parent_atoms:
					if len(pruned_list) >= max_parents:
						break
					pruned_list.add(parent_atom)

				omitted_parents = len(parent_atoms) - len(pruned_list)
				msg.append(indent + "%s pulled in by\n" % pkg)

				for parent_atom in pruned_list:
					parent, atom = parent_atom
					msg.append(2*indent)
					if isinstance(parent,
						(PackageArg, AtomArg)):
						# For PackageArg and AtomArg types, it's
						# redundant to display the atom attribute.
						msg.append(str(parent))
					else:
						# Display the specific atom from SetArg or
						# Package types.
						msg.append("%s required by %s" % (atom, parent))
					msg.append("\n")

				if omitted_parents:
					msg.append(2*indent)
					msg.append("(and %d more)\n" % omitted_parents)

				msg.append("\n")

			sys.stderr.write("".join(msg))
			sys.stderr.flush()

		if "--quiet" not in self.myopts:
			show_blocker_docs_link()

	def display(self, mylist, favorites=[], verbosity=None):

		# This is used to prevent display_problems() from
		# redundantly displaying this exact same merge list
		# again via _show_merge_list().
		self._displayed_list = mylist

		if verbosity is None:
			verbosity = ("--quiet" in self.myopts and 1 or \
				"--verbose" in self.myopts and 3 or 2)
		favorites_set = InternalPackageSet(favorites)
		oneshot = "--oneshot" in self.myopts or \
			"--onlydeps" in self.myopts
		columns = "--columns" in self.myopts
		changelogs=[]
		p=[]
		blockers = []

		counters = PackageCounters()

		if verbosity == 1 and "--verbose" not in self.myopts:
			def create_use_string(*args):
				return ""
		else:
			def create_use_string(name, cur_iuse, iuse_forced, cur_use,
				old_iuse, old_use,
				is_new, reinst_flags,
				all_flags=(verbosity == 3 or "--quiet" in self.myopts),
				alphabetical=("--alphabetical" in self.myopts)):
				enabled = []
				if alphabetical:
					disabled = enabled
					removed = enabled
				else:
					disabled = []
					removed = []
				cur_iuse = set(cur_iuse)
				enabled_flags = cur_iuse.intersection(cur_use)
				removed_iuse = set(old_iuse).difference(cur_iuse)
				any_iuse = cur_iuse.union(old_iuse)
				any_iuse = list(any_iuse)
				any_iuse.sort()
				for flag in any_iuse:
					flag_str = None
					isEnabled = False
					reinst_flag = reinst_flags and flag in reinst_flags
					if flag in enabled_flags:
						isEnabled = True
						if is_new or flag in old_use and \
							(all_flags or reinst_flag):
							flag_str = red(flag)
						elif flag not in old_iuse:
							flag_str = yellow(flag) + "%*"
						elif flag not in old_use:
							flag_str = green(flag) + "*"
					elif flag in removed_iuse:
						if all_flags or reinst_flag:
							flag_str = yellow("-" + flag) + "%"
							if flag in old_use:
								flag_str += "*"
							flag_str = "(" + flag_str + ")"
							removed.append(flag_str)
						continue
					else:
						if is_new or flag in old_iuse and \
							flag not in old_use and \
							(all_flags or reinst_flag):
							flag_str = blue("-" + flag)
						elif flag not in old_iuse:
							flag_str = yellow("-" + flag)
							if flag not in iuse_forced:
								flag_str += "%"
						elif flag in old_use:
							flag_str = green("-" + flag) + "*"
					if flag_str:
						if flag in iuse_forced:
							flag_str = "(" + flag_str + ")"
						if isEnabled:
							enabled.append(flag_str)
						else:
							disabled.append(flag_str)

				if alphabetical:
					ret = " ".join(enabled)
				else:
					ret = " ".join(enabled + disabled + removed)
				if ret:
					ret = '%s="%s" ' % (name, ret)
				return ret

		repo_display = RepoDisplay(self.roots)

		tree_nodes = []
		display_list = []
		mygraph = self.digraph.copy()

		# If there are any Uninstall instances, add the corresponding
		# blockers to the digraph (useful for --tree display).

		executed_uninstalls = set(node for node in mylist \
			if isinstance(node, Package) and node.operation == "unmerge")

		for uninstall in self._blocker_uninstalls.leaf_nodes():
			uninstall_parents = \
				self._blocker_uninstalls.parent_nodes(uninstall)
			if not uninstall_parents:
				continue

			# Remove the corresponding "nomerge" node and substitute
			# the Uninstall node.
			inst_pkg = self._pkg_cache[
				("installed", uninstall.root, uninstall.cpv, "nomerge")]
			try:
				mygraph.remove(inst_pkg)
			except KeyError:
				pass

			try:
				inst_pkg_blockers = self._blocker_parents.child_nodes(inst_pkg)
			except KeyError:
				inst_pkg_blockers = []

			# Break the Package -> Uninstall edges.
			mygraph.remove(uninstall)

			# Resolution of a package's blockers
			# depend on it's own uninstallation.
			for blocker in inst_pkg_blockers:
				mygraph.add(uninstall, blocker)

			# Expand Package -> Uninstall edges into
			# Package -> Blocker -> Uninstall edges.
			for blocker in uninstall_parents:
				mygraph.add(uninstall, blocker)
				for parent in self._blocker_parents.parent_nodes(blocker):
					if parent != inst_pkg:
						mygraph.add(blocker, parent)

			# If the uninstall task did not need to be executed because
			# of an upgrade, display Blocker -> Upgrade edges since the
			# corresponding Blocker -> Uninstall edges will not be shown.
			upgrade_node = \
				self._slot_pkg_map[uninstall.root].get(uninstall.slot_atom)
			if upgrade_node is not None and \
				uninstall not in executed_uninstalls:
				for blocker in uninstall_parents:
					mygraph.add(upgrade_node, blocker)

		unsatisfied_blockers = []
		i = 0
		depth = 0
		shown_edges = set()
		for x in mylist:
			if isinstance(x, Blocker) and not x.satisfied:
				unsatisfied_blockers.append(x)
				continue
			graph_key = x
			if "--tree" in self.myopts:
				depth = len(tree_nodes)
				while depth and graph_key not in \
					mygraph.child_nodes(tree_nodes[depth-1]):
						depth -= 1
				if depth:
					tree_nodes = tree_nodes[:depth]
					tree_nodes.append(graph_key)
					display_list.append((x, depth, True))
					shown_edges.add((graph_key, tree_nodes[depth-1]))
				else:
					traversed_nodes = set() # prevent endless circles
					traversed_nodes.add(graph_key)
					def add_parents(current_node, ordered):
						parent_nodes = None
						# Do not traverse to parents if this node is an
						# an argument or a direct member of a set that has
						# been specified as an argument (system or world).
						if current_node not in self._set_nodes:
							parent_nodes = mygraph.parent_nodes(current_node)
						if parent_nodes:
							child_nodes = set(mygraph.child_nodes(current_node))
							selected_parent = None
							# First, try to avoid a direct cycle.
							for node in parent_nodes:
								if not isinstance(node, (Blocker, Package)):
									continue
								if node not in traversed_nodes and \
									node not in child_nodes:
									edge = (current_node, node)
									if edge in shown_edges:
										continue
									selected_parent = node
									break
							if not selected_parent:
								# A direct cycle is unavoidable.
								for node in parent_nodes:
									if not isinstance(node, (Blocker, Package)):
										continue
									if node not in traversed_nodes:
										edge = (current_node, node)
										if edge in shown_edges:
											continue
										selected_parent = node
										break
							if selected_parent:
								shown_edges.add((current_node, selected_parent))
								traversed_nodes.add(selected_parent)
								add_parents(selected_parent, False)
						display_list.append((current_node,
							len(tree_nodes), ordered))
						tree_nodes.append(current_node)
					tree_nodes = []
					add_parents(graph_key, True)
			else:
				display_list.append((x, depth, True))
		mylist = display_list
		for x in unsatisfied_blockers:
			mylist.append((x, 0, True))

		last_merge_depth = 0
		for i in xrange(len(mylist)-1,-1,-1):
			graph_key, depth, ordered = mylist[i]
			if not ordered and depth == 0 and i > 0 \
				and graph_key == mylist[i-1][0] and \
				mylist[i-1][1] == 0:
				# An ordered node got a consecutive duplicate when the tree was
				# being filled in.
				del mylist[i]
				continue
			if ordered and graph_key[-1] != "nomerge":
				last_merge_depth = depth
				continue
			if depth >= last_merge_depth or \
				i < len(mylist) - 1 and \
				depth >= mylist[i+1][1]:
					del mylist[i]

		from portage import flatten
		from portage.dep import use_reduce, paren_reduce
		# files to fetch list - avoids counting a same file twice
		# in size display (verbose mode)
		myfetchlist=[]

		# Use this set to detect when all the "repoadd" strings are "[0]"
		# and disable the entire repo display in this case.
		repoadd_set = set()

		for mylist_index in xrange(len(mylist)):
			x, depth, ordered = mylist[mylist_index]
			pkg_type = x[0]
			myroot = x[1]
			pkg_key = x[2]
			portdb = self.trees[myroot]["porttree"].dbapi
			bindb  = self.trees[myroot]["bintree"].dbapi
			vardb = self.trees[myroot]["vartree"].dbapi
			vartree = self.trees[myroot]["vartree"]
			pkgsettings = self.pkgsettings[myroot]

			fetch=" "
			indent = " " * depth

			if isinstance(x, Blocker):
				if x.satisfied:
					blocker_style = "PKG_BLOCKER_SATISFIED"
					addl = "%s  %s  " % (colorize(blocker_style, "b"), fetch)
				else:
					blocker_style = "PKG_BLOCKER"
					addl = "%s  %s  " % (colorize(blocker_style, "B"), fetch)
				if ordered:
					counters.blocks += 1
					if x.satisfied:
						counters.blocks_satisfied += 1
				resolved = portage.key_expand(
					str(x.atom).lstrip("!"), mydb=vardb, settings=pkgsettings)
				if "--columns" in self.myopts and "--quiet" in self.myopts:
					addl += " " + colorize(blocker_style, resolved)
				else:
					addl = "[%s %s] %s%s" % \
						(colorize(blocker_style, "blocks"),
						addl, indent, colorize(blocker_style, resolved))
				block_parents = self._blocker_parents.parent_nodes(x)
				block_parents = set([pnode[2] for pnode in block_parents])
				block_parents = ", ".join(block_parents)
				if resolved!=x[2]:
					addl += colorize(blocker_style,
						" (\"%s\" is blocking %s)") % \
						(str(x.atom).lstrip("!"), block_parents)
				else:
					addl += colorize(blocker_style,
						" (is blocking %s)") % block_parents
				if isinstance(x, Blocker) and x.satisfied:
					if columns:
						continue
					p.append(addl)
				else:
					blockers.append(addl)
			else:
				pkg_status = x[3]
				pkg_merge = ordered and pkg_status == "merge"
				if not pkg_merge and pkg_status == "merge":
					pkg_status = "nomerge"
				built = pkg_type != "ebuild"
				installed = pkg_type == "installed"
				pkg = x
				metadata = pkg.metadata
				ebuild_path = None
				repo_name = metadata["repository"]
				if pkg_type == "ebuild":
					ebuild_path = portdb.findname(pkg_key)
					if not ebuild_path: # shouldn't happen
						raise portage.exception.PackageNotFound(pkg_key)
					repo_path_real = os.path.dirname(os.path.dirname(
						os.path.dirname(ebuild_path)))
				else:
					repo_path_real = portdb.getRepositoryPath(repo_name)
				pkg_use = list(pkg.use.enabled)
				try:
					restrict = flatten(use_reduce(paren_reduce(
						pkg.metadata["RESTRICT"]), uselist=pkg_use))
				except portage.exception.InvalidDependString, e:
					if not pkg.installed:
						show_invalid_depstring_notice(x,
							pkg.metadata["RESTRICT"], str(e))
						del e
						return 1
					restrict = []
				if "ebuild" == pkg_type and x[3] != "nomerge" and \
					"fetch" in restrict:
					fetch = red("F")
					if ordered:
						counters.restrict_fetch += 1
					if portdb.fetch_check(pkg_key, pkg_use):
						fetch = green("f")
						if ordered:
							counters.restrict_fetch_satisfied += 1

				#we need to use "--emptrytree" testing here rather than "empty" param testing because "empty"
				#param is used for -u, where you still *do* want to see when something is being upgraded.
				myoldbest = []
				myinslotlist = None
				installed_versions = vardb.match(portage.cpv_getkey(pkg_key))
				if vardb.cpv_exists(pkg_key):
					addl="  "+yellow("R")+fetch+"  "
					if ordered:
						if pkg_merge:
							counters.reinst += 1
						elif pkg_status == "uninstall":
							counters.uninst += 1
				# filter out old-style virtual matches
				elif installed_versions and \
					portage.cpv_getkey(installed_versions[0]) == \
					portage.cpv_getkey(pkg_key):
					myinslotlist = vardb.match(pkg.slot_atom)
					# If this is the first install of a new-style virtual, we
					# need to filter out old-style virtual matches.
					if myinslotlist and \
						portage.cpv_getkey(myinslotlist[0]) != \
						portage.cpv_getkey(pkg_key):
						myinslotlist = None
					if myinslotlist:
						myoldbest = myinslotlist[:]
						addl = "   " + fetch
						if not portage.dep.cpvequal(pkg_key,
							portage.best([pkg_key] + myoldbest)):
							# Downgrade in slot
							addl += turquoise("U")+blue("D")
							if ordered:
								counters.downgrades += 1
						else:
							# Update in slot
							addl += turquoise("U") + " "
							if ordered:
								counters.upgrades += 1
					else:
						# New slot, mark it new.
						addl = " " + green("NS") + fetch + "  "
						myoldbest = vardb.match(portage.cpv_getkey(pkg_key))
						if ordered:
							counters.newslot += 1

					if "--changelog" in self.myopts:
						inst_matches = vardb.match(pkg.slot_atom)
						if inst_matches:
							changelogs.extend(self.calc_changelog(
								portdb.findname(pkg_key),
								inst_matches[0], pkg_key))
				else:
					addl = " " + green("N") + " " + fetch + "  "
					if ordered:
						counters.new += 1

				verboseadd = ""
				repoadd = None

				if True:
					# USE flag display
					forced_flags = set()
					pkgsettings.setcpv(pkg) # for package.use.{mask,force}
					forced_flags.update(pkgsettings.useforce)
					forced_flags.update(pkgsettings.usemask)

					cur_use = [flag for flag in pkg.use.enabled \
						if flag in pkg.iuse.all]
					cur_iuse = sorted(pkg.iuse.all)

					if myoldbest and myinslotlist:
						previous_cpv = myoldbest[0]
					else:
						previous_cpv = pkg.cpv
					if vardb.cpv_exists(previous_cpv):
						old_iuse, old_use = vardb.aux_get(
								previous_cpv, ["IUSE", "USE"])
						old_iuse = list(set(
							filter_iuse_defaults(old_iuse.split())))
						old_iuse.sort()
						old_use = old_use.split()
						is_new = False
					else:
						old_iuse = []
						old_use = []
						is_new = True

					old_use = [flag for flag in old_use if flag in old_iuse]

					use_expand = pkgsettings["USE_EXPAND"].lower().split()
					use_expand.sort()
					use_expand.reverse()
					use_expand_hidden = \
						pkgsettings["USE_EXPAND_HIDDEN"].lower().split()

					def map_to_use_expand(myvals, forcedFlags=False,
						removeHidden=True):
						ret = {}
						forced = {}
						for exp in use_expand:
							ret[exp] = []
							forced[exp] = set()
							for val in myvals[:]:
								if val.startswith(exp.lower()+"_"):
									if val in forced_flags:
										forced[exp].add(val[len(exp)+1:])
									ret[exp].append(val[len(exp)+1:])
									myvals.remove(val)
						ret["USE"] = myvals
						forced["USE"] = [val for val in myvals \
							if val in forced_flags]
						if removeHidden:
							for exp in use_expand_hidden:
								ret.pop(exp, None)
						if forcedFlags:
							return ret, forced
						return ret

					# Prevent USE_EXPAND_HIDDEN flags from being hidden if they
					# are the only thing that triggered reinstallation.
					reinst_flags_map = {}
					reinstall_for_flags = self._reinstall_nodes.get(pkg)
					reinst_expand_map = None
					if reinstall_for_flags:
						reinst_flags_map = map_to_use_expand(
							list(reinstall_for_flags), removeHidden=False)
						for k in list(reinst_flags_map):
							if not reinst_flags_map[k]:
								del reinst_flags_map[k]
						if not reinst_flags_map.get("USE"):
							reinst_expand_map = reinst_flags_map.copy()
							reinst_expand_map.pop("USE", None)
					if reinst_expand_map and \
						not set(reinst_expand_map).difference(
						use_expand_hidden):
						use_expand_hidden = \
							set(use_expand_hidden).difference(
							reinst_expand_map)

					cur_iuse_map, iuse_forced = \
						map_to_use_expand(cur_iuse, forcedFlags=True)
					cur_use_map = map_to_use_expand(cur_use)
					old_iuse_map = map_to_use_expand(old_iuse)
					old_use_map = map_to_use_expand(old_use)

					use_expand.sort()
					use_expand.insert(0, "USE")
					
					for key in use_expand:
						if key in use_expand_hidden:
							continue
						verboseadd += create_use_string(key.upper(),
							cur_iuse_map[key], iuse_forced[key],
							cur_use_map[key], old_iuse_map[key],
							old_use_map[key], is_new,
							reinst_flags_map.get(key))

				if verbosity == 3:
					# size verbose
					mysize=0
					if pkg_type == "ebuild" and pkg_merge:
						try:
							myfilesdict = portdb.getfetchsizes(pkg_key,
								useflags=pkg_use, debug=self.edebug)
						except portage.exception.InvalidDependString, e:
							src_uri = portdb.aux_get(pkg_key, ["SRC_URI"])[0]
							show_invalid_depstring_notice(x, src_uri, str(e))
							del e
							return 1
						if myfilesdict is None:
							myfilesdict="[empty/missing/bad digest]"
						else:
							for myfetchfile in myfilesdict:
								if myfetchfile not in myfetchlist:
									mysize+=myfilesdict[myfetchfile]
									myfetchlist.append(myfetchfile)
							if ordered:
								counters.totalsize += mysize
						verboseadd += format_size(mysize)

					# overlay verbose
					# assign index for a previous version in the same slot
					has_previous = False
					repo_name_prev = None
					slot_atom = "%s:%s" % (portage.dep_getkey(pkg_key),
						metadata["SLOT"])
					slot_matches = vardb.match(slot_atom)
					if slot_matches:
						has_previous = True
						repo_name_prev = vardb.aux_get(slot_matches[0],
							["repository"])[0]

					# now use the data to generate output
					if pkg.installed or not has_previous:
						repoadd = repo_display.repoStr(repo_path_real)
					else:
						repo_path_prev = None
						if repo_name_prev:
							repo_path_prev = portdb.getRepositoryPath(
								repo_name_prev)
						if repo_path_prev == repo_path_real:
							repoadd = repo_display.repoStr(repo_path_real)
						else:
							repoadd = "%s=>%s" % (
								repo_display.repoStr(repo_path_prev),
								repo_display.repoStr(repo_path_real))
					if repoadd:
						repoadd_set.add(repoadd)

				xs = [portage.cpv_getkey(pkg_key)] + \
					list(portage.catpkgsplit(pkg_key)[2:])
				if xs[2] == "r0":
					xs[2] = ""
				else:
					xs[2] = "-" + xs[2]

				mywidth = 130
				if "COLUMNWIDTH" in self.settings:
					try:
						mywidth = int(self.settings["COLUMNWIDTH"])
					except ValueError, e:
						portage.writemsg("!!! %s\n" % str(e), noiselevel=-1)
						portage.writemsg(
							"!!! Unable to parse COLUMNWIDTH='%s'\n" % \
							self.settings["COLUMNWIDTH"], noiselevel=-1)
						del e
				oldlp = mywidth - 30
				newlp = oldlp - 30

				# Convert myoldbest from a list to a string.
				if not myoldbest:
					myoldbest = ""
				else:
					for pos, key in enumerate(myoldbest):
						key = portage.catpkgsplit(key)[2] + \
							"-" + portage.catpkgsplit(key)[3]
						if key[-3:] == "-r0":
							key = key[:-3]
						myoldbest[pos] = key
					myoldbest = blue("["+", ".join(myoldbest)+"]")

				pkg_cp = xs[0]
				root_config = self.roots[myroot]
				system_set = root_config.sets["system"]
				world_set  = root_config.sets["world"]

				pkg_system = False
				pkg_world = False
				try:
					pkg_system = system_set.findAtomForPackage(pkg)
					pkg_world  = world_set.findAtomForPackage(pkg)
					if not (oneshot or pkg_world) and \
						myroot == self.target_root and \
						favorites_set.findAtomForPackage(pkg):
						# Maybe it will be added to world now.
						if create_world_atom(pkg, favorites_set, root_config):
							pkg_world = True
				except portage.exception.InvalidDependString:
					# This is reported elsewhere if relevant.
					pass

				def pkgprint(pkg_str):
					if pkg_merge:
						if pkg_system:
							return colorize("PKG_MERGE_SYSTEM", pkg_str)
						elif pkg_world:
							return colorize("PKG_MERGE_WORLD", pkg_str)
						else:
							return colorize("PKG_MERGE", pkg_str)
					elif pkg_status == "uninstall":
						return colorize("PKG_UNINSTALL", pkg_str)
					else:
						if pkg_system:
							return colorize("PKG_NOMERGE_SYSTEM", pkg_str)
						elif pkg_world:
							return colorize("PKG_NOMERGE_WORLD", pkg_str)
						else:
							return colorize("PKG_NOMERGE", pkg_str)

				try:
					properties = flatten(use_reduce(paren_reduce(
						pkg.metadata["PROPERTIES"]), uselist=pkg.use.enabled))
				except portage.exception.InvalidDependString, e:
					if not pkg.installed:
						show_invalid_depstring_notice(pkg,
							pkg.metadata["PROPERTIES"], str(e))
						del e
						return 1
					properties = []
				interactive = "interactive" in properties
				if interactive and pkg.operation == "merge":
					addl = colorize("WARN", "I") + addl[1:]
					if ordered:
						counters.interactive += 1

				if x[1]!="/":
					if myoldbest:
						myoldbest +=" "
					if "--columns" in self.myopts:
						if "--quiet" in self.myopts:
							myprint=addl+" "+indent+pkgprint(pkg_cp)
							myprint=myprint+darkblue(" "+xs[1]+xs[2])+" "
							myprint=myprint+myoldbest
							myprint=myprint+darkgreen("to "+x[1])
							verboseadd = None
						else:
							if not pkg_merge:
								myprint = "[%s] %s%s" % \
									(pkgprint(pkg_status.ljust(13)),
									indent, pkgprint(pkg.cp))
							else:
								myprint = "[%s %s] %s%s" % \
									(pkgprint(pkg.type_name), addl,
									indent, pkgprint(pkg.cp))
							if (newlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(newlp-nc_len(myprint)))
							myprint=myprint+"["+darkblue(xs[1]+xs[2])+"] "
							if (oldlp-nc_len(myprint)) > 0:
								myprint=myprint+" "*(oldlp-nc_len(myprint))
							myprint=myprint+myoldbest
							myprint += darkgreen("to " + pkg.root)
					else:
						if not pkg_merge:
							myprint = "[%s] " % pkgprint(pkg_status.ljust(13))
						else:
							myprint = "[%s %s] " % (pkgprint(pkg_type), addl)
						myprint += indent + pkgprint(pkg_key) + " " + \
							myoldbest + darkgreen("to " + myroot)
				else:
					if "--columns" in self.myopts:
						if "--quiet" in self.myopts:
							myprint=addl+" "+indent+pkgprint(pkg_cp)
							myprint=myprint+" "+green(xs[1]+xs[2])+" "
							myprint=myprint+myoldbest
							verboseadd = None
						else:
							if not pkg_merge:
								myprint = "[%s] %s%s" % \
									(pkgprint(pkg_status.ljust(13)),
									indent, pkgprint(pkg.cp))
							else:
								myprint = "[%s %s] %s%s" % \
									(pkgprint(pkg.type_name), addl,
									indent, pkgprint(pkg.cp))
							if (newlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(newlp-nc_len(myprint)))
							myprint=myprint+green(" ["+xs[1]+xs[2]+"] ")
							if (oldlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(oldlp-nc_len(myprint)))
							myprint += myoldbest
					else:
						if not pkg_merge:
							myprint = "[%s] %s%s %s" % \
								(pkgprint(pkg_status.ljust(13)),
								indent, pkgprint(pkg.cpv),
								myoldbest)
						else:
							myprint = "[%s %s] %s%s %s" % \
								(pkgprint(pkg_type), addl, indent,
								pkgprint(pkg.cpv), myoldbest)

				if columns and pkg.operation == "uninstall":
					continue
				p.append((myprint, verboseadd, repoadd))

				if "--tree" not in self.myopts and \
					"--quiet" not in self.myopts and \
					not self._opts_no_restart.intersection(self.myopts) and \
					pkg.root == self._running_root.root and \
					portage.match_from_list(
					portage.const.PORTAGE_PACKAGE_ATOM, [pkg]) and \
					not vardb.cpv_exists(pkg.cpv) and \
					"--quiet" not in self.myopts:
						if mylist_index < len(mylist) - 1:
							p.append(colorize("WARN", "*** Portage will stop merging at this point and reload itself,"))
							p.append(colorize("WARN", "    then resume the merge."))

		out = sys.stdout
		show_repos = repoadd_set and repoadd_set != set(["0"])

		for x in p:
			if isinstance(x, basestring):
				out.write("%s\n" % (x,))
				continue

			myprint, verboseadd, repoadd = x

			if verboseadd:
				myprint += " " + verboseadd

			if show_repos and repoadd:
				myprint += " " + teal("[%s]" % repoadd)

			out.write("%s\n" % (myprint,))

		for x in blockers:
			print x

		if verbosity == 3:
			print
			print counters
			if show_repos:
				sys.stdout.write(str(repo_display))

		if "--changelog" in self.myopts:
			print
			for revision,text in changelogs:
				print bold('*'+revision)
				sys.stdout.write(text)

		sys.stdout.flush()
		return os.EX_OK

	def display_problems(self):
		"""
		Display problems with the dependency graph such as slot collisions.
		This is called internally by display() to show the problems _after_
		the merge list where it is most likely to be seen, but if display()
		is not going to be called then this method should be called explicitly
		to ensure that the user is notified of problems with the graph.

		All output goes to stderr, except for unsatisfied dependencies which
		go to stdout for parsing by programs such as autounmask.
		"""

		# Note that show_masked_packages() sends it's output to
		# stdout, and some programs such as autounmask parse the
		# output in cases when emerge bails out. However, when
		# show_masked_packages() is called for installed packages
		# here, the message is a warning that is more appropriate
		# to send to stderr, so temporarily redirect stdout to
		# stderr. TODO: Fix output code so there's a cleaner way
		# to redirect everything to stderr.
		sys.stdout.flush()
		sys.stderr.flush()
		stdout = sys.stdout
		try:
			sys.stdout = sys.stderr
			self._display_problems()
		finally:
			sys.stdout = stdout
			sys.stdout.flush()
			sys.stderr.flush()

		# This goes to stdout for parsing by programs like autounmask.
		for pargs, kwargs in self._unsatisfied_deps_for_display:
			self._show_unsatisfied_dep(*pargs, **kwargs)

	def _display_problems(self):
		if self._circular_deps_for_display is not None:
			self._show_circular_deps(
				self._circular_deps_for_display)

		# The user is only notified of a slot conflict if
		# there are no unresolvable blocker conflicts.
		if self._unsatisfied_blockers_for_display is not None:
			self._show_unsatisfied_blockers(
				self._unsatisfied_blockers_for_display)
		else:
			self._show_slot_collision_notice()

		# TODO: Add generic support for "set problem" handlers so that
		# the below warnings aren't special cases for world only.

		if self._missing_args:
			world_problems = False
			if "world" in self._sets:
				# Filter out indirect members of world (from nested sets)
				# since only direct members of world are desired here.
				world_set = self.roots[self.target_root].sets["world"]
				for arg, atom in self._missing_args:
					if arg.name == "world" and atom in world_set:
						world_problems = True
						break

			if world_problems:
				sys.stderr.write("\n!!! Problems have been " + \
					"detected with your world file\n")
				sys.stderr.write("!!! Please run " + \
					green("emaint --check world")+"\n\n")

		if self._missing_args:
			sys.stderr.write("\n" + colorize("BAD", "!!!") + \
				" Ebuilds for the following packages are either all\n")
			sys.stderr.write(colorize("BAD", "!!!") + \
				" masked or don't exist:\n")
			sys.stderr.write(" ".join(str(atom) for arg, atom in \
				self._missing_args) + "\n")

		if self._pprovided_args:
			arg_refs = {}
			for arg, atom in self._pprovided_args:
				if isinstance(arg, SetArg):
					parent = arg.name
					arg_atom = (atom, atom)
				else:
					parent = "args"
					arg_atom = (arg.arg, atom)
				refs = arg_refs.setdefault(arg_atom, [])
				if parent not in refs:
					refs.append(parent)
			msg = []
			msg.append(bad("\nWARNING: "))
			if len(self._pprovided_args) > 1:
				msg.append("Requested packages will not be " + \
					"merged because they are listed in\n")
			else:
				msg.append("A requested package will not be " + \
					"merged because it is listed in\n")
			msg.append("package.provided:\n\n")
			problems_sets = set()
			for (arg, atom), refs in arg_refs.iteritems():
				ref_string = ""
				if refs:
					problems_sets.update(refs)
					refs.sort()
					ref_string = ", ".join(["'%s'" % name for name in refs])
					ref_string = " pulled in by " + ref_string
				msg.append("  %s%s\n" % (colorize("INFORM", str(arg)), ref_string))
			msg.append("\n")
			if "world" in problems_sets:
				msg.append("This problem can be solved in one of the following ways:\n\n")
				msg.append("  A) Use emaint to clean offending packages from world (if not installed).\n")
				msg.append("  B) Uninstall offending packages (cleans them from world).\n")
				msg.append("  C) Remove offending entries from package.provided.\n\n")
				msg.append("The best course of action depends on the reason that an offending\n")
				msg.append("package.provided entry exists.\n\n")
			sys.stderr.write("".join(msg))

		masked_packages = []
		for pkg in self._masked_installed:
			root_config = pkg.root_config
			pkgsettings = self.pkgsettings[pkg.root]
			mreasons = get_masking_status(pkg, pkgsettings, root_config)
			masked_packages.append((root_config, pkgsettings,
				pkg.cpv, pkg.metadata, mreasons))
		if masked_packages:
			sys.stderr.write("\n" + colorize("BAD", "!!!") + \
				" The following installed packages are masked:\n")
			show_masked_packages(masked_packages)
			show_mask_docs()
			print

	def calc_changelog(self,ebuildpath,current,next):
		if ebuildpath == None or not os.path.exists(ebuildpath):
			return []
		current = '-'.join(portage.catpkgsplit(current)[1:])
		if current.endswith('-r0'):
			current = current[:-3]
		next = '-'.join(portage.catpkgsplit(next)[1:])
		if next.endswith('-r0'):
			next = next[:-3]
		changelogpath = os.path.join(os.path.split(ebuildpath)[0],'ChangeLog')
		try:
			changelog = open(changelogpath).read()
		except SystemExit, e:
			raise # Needed else can't exit
		except:
			return []
		divisions = self.find_changelog_tags(changelog)
		#print 'XX from',current,'to',next
		#for div,text in divisions: print 'XX',div
		# skip entries for all revisions above the one we are about to emerge
		for i in range(len(divisions)):
			if divisions[i][0]==next:
				divisions = divisions[i:]
				break
		# find out how many entries we are going to display
		for i in range(len(divisions)):
			if divisions[i][0]==current:
				divisions = divisions[:i]
				break
		else:
		    # couldnt find the current revision in the list. display nothing
			return []
		return divisions

	def find_changelog_tags(self,changelog):
		divs = []
		release = None
		while 1:
			match = re.search(r'^\*\ ?([-a-zA-Z0-9_.+]*)(?:\ .*)?\n',changelog,re.M)
			if match is None:
				if release is not None:
					divs.append((release,changelog))
				return divs
			if release is not None:
				divs.append((release,changelog[:match.start()]))
			changelog = changelog[match.end():]
			release = match.group(1)
			if release.endswith('.ebuild'):
				release = release[:-7]
			if release.endswith('-r0'):
				release = release[:-3]

	def saveNomergeFavorites(self):
		"""Find atoms in favorites that are not in the mergelist and add them
		to the world file if necessary."""
		for x in ("--buildpkgonly", "--fetchonly", "--fetch-all-uri",
			"--oneshot", "--onlydeps", "--pretend"):
			if x in self.myopts:
				return
		root_config = self.roots[self.target_root]
		world_set = root_config.sets["world"]

		world_locked = False
		if hasattr(world_set, "lock"):
			world_set.lock()
			world_locked = True

		if hasattr(world_set, "load"):
			world_set.load() # maybe it's changed on disk

		args_set = self._sets["args"]
		portdb = self.trees[self.target_root]["porttree"].dbapi
		added_favorites = set()
		for x in self._set_nodes:
			pkg_type, root, pkg_key, pkg_status = x
			if pkg_status != "nomerge":
				continue

			try:
				myfavkey = create_world_atom(x, args_set, root_config)
				if myfavkey:
					if myfavkey in added_favorites:
						continue
					added_favorites.add(myfavkey)
			except portage.exception.InvalidDependString, e:
				writemsg("\n\n!!! '%s' has invalid PROVIDE: %s\n" % \
					(pkg_key, str(e)), noiselevel=-1)
				writemsg("!!! see '%s'\n\n" % os.path.join(
					root, portage.VDB_PATH, pkg_key, "PROVIDE"), noiselevel=-1)
				del e
		all_added = []
		for k in self._sets:
			if k in ("args", "world") or not root_config.sets[k].world_candidate:
				continue
			s = SETPREFIX + k
			if s in world_set:
				continue
			all_added.append(SETPREFIX + k)
		all_added.extend(added_favorites)
		all_added.sort()
		for a in all_added:
			print ">>> Recording %s in \"world\" favorites file..." % \
				colorize("INFORM", str(a))
		if all_added:
			world_set.update(all_added)

		if world_locked:
			world_set.unlock()

	def loadResumeCommand(self, resume_data, skip_masked=True,
		skip_missing=True):
		"""
		Add a resume command to the graph and validate it in the process.  This
		will raise a PackageNotFound exception if a package is not available.
		"""

		if not isinstance(resume_data, dict):
			return False

		mergelist = resume_data.get("mergelist")
		if not isinstance(mergelist, list):
			mergelist = []

		fakedb = self.mydbapi
		trees = self.trees
		serialized_tasks = []
		masked_tasks = []
		for x in mergelist:
			if not (isinstance(x, list) and len(x) == 4):
				continue
			pkg_type, myroot, pkg_key, action = x
			if pkg_type not in self.pkg_tree_map:
				continue
			if action != "merge":
				continue
			tree_type = self.pkg_tree_map[pkg_type]
			mydb = trees[myroot][tree_type].dbapi
			db_keys = list(self._trees_orig[myroot][
				tree_type].dbapi._aux_cache_keys)
			try:
				metadata = izip(db_keys, mydb.aux_get(pkg_key, db_keys))
			except KeyError:
				# It does no exist or it is corrupt.
				if action == "uninstall":
					continue
				if skip_missing:
					# TODO: log these somewhere
					continue
				raise portage.exception.PackageNotFound(pkg_key)
			installed = action == "uninstall"
			built = pkg_type != "ebuild"
			root_config = self.roots[myroot]
			pkg = Package(built=built, cpv=pkg_key,
				installed=installed, metadata=metadata,
				operation=action, root_config=root_config,
				type_name=pkg_type)
			if pkg_type == "ebuild":
				pkgsettings = self.pkgsettings[myroot]
				pkgsettings.setcpv(pkg)
				pkg.metadata["USE"] = pkgsettings["PORTAGE_USE"]
				pkg.metadata['CHOST'] = pkgsettings.get('CHOST', '')
			self._pkg_cache[pkg] = pkg

			root_config = self.roots[pkg.root]
			if "merge" == pkg.operation and \
				not visible(root_config.settings, pkg):
				if skip_masked:
					masked_tasks.append(Dependency(root=pkg.root, parent=pkg))
				else:
					self._unsatisfied_deps_for_display.append(
						((pkg.root, "="+pkg.cpv), {"myparent":None}))

			fakedb[myroot].cpv_inject(pkg)
			serialized_tasks.append(pkg)
			self.spinner.update()

		if self._unsatisfied_deps_for_display:
			return False

		if not serialized_tasks or "--nodeps" in self.myopts:
			self._serialized_tasks_cache = serialized_tasks
			self._scheduler_graph = self.digraph
		else:
			self._select_package = self._select_pkg_from_graph
			self.myparams.add("selective")
			# Always traverse deep dependencies in order to account for
			# potentially unsatisfied dependencies of installed packages.
			# This is necessary for correct --keep-going or --resume operation
			# in case a package from a group of circularly dependent packages
			# fails. In this case, a package which has recently been installed
			# may have an unsatisfied circular dependency (pulled in by
			# PDEPEND, for example). So, even though a package is already
			# installed, it may not have all of it's dependencies satisfied, so
			# it may not be usable. If such a package is in the subgraph of
			# deep depenedencies of a scheduled build, that build needs to
			# be cancelled. In order for this type of situation to be
			# recognized, deep traversal of dependencies is required.
			self.myparams.add("deep")

			favorites = resume_data.get("favorites")
			args_set = self._sets["args"]
			if isinstance(favorites, list):
				args = self._load_favorites(favorites)
			else:
				args = []

			for task in serialized_tasks:
				if isinstance(task, Package) and \
					task.operation == "merge":
					if not self._add_pkg(task, None):
						return False

			# Packages for argument atoms need to be explicitly
			# added via _add_pkg() so that they are included in the
			# digraph (needed at least for --tree display).
			for arg in args:
				for atom in arg.set:
					pkg, existing_node = self._select_package(
						arg.root_config.root, atom)
					if existing_node is None and \
						pkg is not None:
						if not self._add_pkg(pkg, Dependency(atom=atom,
							root=pkg.root, parent=arg)):
							return False

			# Allow unsatisfied deps here to avoid showing a masking
			# message for an unsatisfied dep that isn't necessarily
			# masked.
			if not self._create_graph(allow_unsatisfied=True):
				return False

			unsatisfied_deps = []
			for dep in self._unsatisfied_deps:
				if not isinstance(dep.parent, Package):
					continue
				if dep.parent.operation == "merge":
					unsatisfied_deps.append(dep)
					continue

				# For unsatisfied deps of installed packages, only account for
				# them if they are in the subgraph of dependencies of a package
				# which is scheduled to be installed.
				unsatisfied_install = False
				traversed = set()
				dep_stack = self.digraph.parent_nodes(dep.parent)
				while dep_stack:
					node = dep_stack.pop()
					if not isinstance(node, Package):
						continue
					if node.operation == "merge":
						unsatisfied_install = True
						break
					if node in traversed:
						continue
					traversed.add(node)
					dep_stack.extend(self.digraph.parent_nodes(node))

				if unsatisfied_install:
					unsatisfied_deps.append(dep)

			if masked_tasks or unsatisfied_deps:
				# This probably means that a required package
				# was dropped via --skipfirst. It makes the
				# resume list invalid, so convert it to a
				# UnsatisfiedResumeDep exception.
				raise self.UnsatisfiedResumeDep(self,
					masked_tasks + unsatisfied_deps)
			self._serialized_tasks_cache = None
			try:
				self.altlist()
			except self._unknown_internal_error:
				return False

		return True

	def _load_favorites(self, favorites):
		"""
		Use a list of favorites to resume state from a
		previous select_files() call. This creates similar
		DependencyArg instances to those that would have
		been created by the original select_files() call.
		This allows Package instances to be matched with
		DependencyArg instances during graph creation.
		"""
		root_config = self.roots[self.target_root]
		getSetAtoms = root_config.setconfig.getSetAtoms
		sets = root_config.sets
		args = []
		for x in favorites:
			if not isinstance(x, basestring):
				continue
			if x in ("system", "world"):
				x = SETPREFIX + x
			if x.startswith(SETPREFIX):
				s = x[len(SETPREFIX):]
				if s not in sets:
					continue
				if s in self._sets:
					continue
				# Recursively expand sets so that containment tests in
				# self._get_parent_sets() properly match atoms in nested
				# sets (like if world contains system).
				expanded_set = InternalPackageSet(
					initial_atoms=getSetAtoms(s))
				self._sets[s] = expanded_set
				args.append(SetArg(arg=x, set=expanded_set,
					root_config=root_config))
			else:
				if not portage.isvalidatom(x):
					continue
				args.append(AtomArg(arg=x, atom=x,
					root_config=root_config))

		self._set_args(args)
		return args

	class UnsatisfiedResumeDep(portage.exception.PortageException):
		"""
		A dependency of a resume list is not installed. This
		can occur when a required package is dropped from the
		merge list via --skipfirst.
		"""
		def __init__(self, depgraph, value):
			portage.exception.PortageException.__init__(self, value)
			self.depgraph = depgraph

	class _internal_exception(portage.exception.PortageException):
		def __init__(self, value=""):
			portage.exception.PortageException.__init__(self, value)

	class _unknown_internal_error(_internal_exception):
		"""
		Used by the depgraph internally to terminate graph creation.
		The specific reason for the failure should have been dumped
		to stderr, unfortunately, the exact reason for the failure
		may not be known.
		"""

	class _serialize_tasks_retry(_internal_exception):
		"""
		This is raised by the _serialize_tasks() method when it needs to
		be called again for some reason. The only case that it's currently
		used for is when neglected dependencies need to be added to the
		graph in order to avoid making a potentially unsafe decision.
		"""

	class _dep_check_composite_db(portage.dbapi):
		"""
		A dbapi-like interface that is optimized for use in dep_check() calls.
		This is built on top of the existing depgraph package selection logic.
		Some packages that have been added to the graph may be masked from this
		view in order to influence the atom preference selection that occurs
		via dep_check().
		"""
		def __init__(self, depgraph, root):
			portage.dbapi.__init__(self)
			self._depgraph = depgraph
			self._root = root
			self._match_cache = {}
			self._cpv_pkg_map = {}

		def _clear_cache(self):
			self._match_cache.clear()
			self._cpv_pkg_map.clear()

		def match(self, atom):
			ret = self._match_cache.get(atom)
			if ret is not None:
				return ret[:]
			orig_atom = atom
			if "/" not in atom:
				atom = self._dep_expand(atom)
			pkg, existing = self._depgraph._select_package(self._root, atom)
			if not pkg:
				ret = []
			else:
				# Return the highest available from select_package() as well as
				# any matching slots in the graph db.
				slots = set()
				slots.add(pkg.metadata["SLOT"])
				atom_cp = portage.dep_getkey(atom)
				if pkg.cp.startswith("virtual/"):
					# For new-style virtual lookahead that occurs inside
					# dep_check(), examine all slots. This is needed
					# so that newer slots will not unnecessarily be pulled in
					# when a satisfying lower slot is already installed. For
					# example, if virtual/jdk-1.4 is satisfied via kaffe then
					# there's no need to pull in a newer slot to satisfy a
					# virtual/jdk dependency.
					for db, pkg_type, built, installed, db_keys in \
						self._depgraph._filtered_trees[self._root]["dbs"]:
						for cpv in db.match(atom):
							if portage.cpv_getkey(cpv) != pkg.cp:
								continue
							slots.add(db.aux_get(cpv, ["SLOT"])[0])
				ret = []
				if self._visible(pkg):
					self._cpv_pkg_map[pkg.cpv] = pkg
					ret.append(pkg.cpv)
				slots.remove(pkg.metadata["SLOT"])
				while slots:
					slot_atom = "%s:%s" % (atom_cp, slots.pop())
					pkg, existing = self._depgraph._select_package(
						self._root, slot_atom)
					if not pkg:
						continue
					if not self._visible(pkg):
						continue
					self._cpv_pkg_map[pkg.cpv] = pkg
					ret.append(pkg.cpv)
				if ret:
					self._cpv_sort_ascending(ret)
			self._match_cache[orig_atom] = ret
			return ret[:]

		def _visible(self, pkg):
			if pkg.installed and "selective" not in self._depgraph.myparams:
				try:
					arg = self._depgraph._iter_atoms_for_pkg(pkg).next()
				except (StopIteration, portage.exception.InvalidDependString):
					arg = None
				if arg:
					return False
			if pkg.installed:
				try:
					if not visible(
						self._depgraph.pkgsettings[pkg.root], pkg):
						return False
				except portage.exception.InvalidDependString:
					pass
			in_graph = self._depgraph._slot_pkg_map[
				self._root].get(pkg.slot_atom)
			if in_graph is None:
				# Mask choices for packages which are not the highest visible
				# version within their slot (since they usually trigger slot
				# conflicts).
				highest_visible, in_graph = self._depgraph._select_package(
					self._root, pkg.slot_atom)
				if pkg != highest_visible:
					return False
			elif in_graph != pkg:
				# Mask choices for packages that would trigger a slot
				# conflict with a previously selected package.
				return False
			return True

		def _dep_expand(self, atom):
			"""
			This is only needed for old installed packages that may
			contain atoms that are not fully qualified with a specific
			category. Emulate the cpv_expand() function that's used by
			dbapi.match() in cases like this. If there are multiple
			matches, it's often due to a new-style virtual that has
			been added, so try to filter those out to avoid raising
			a ValueError.
			"""
			root_config = self._depgraph.roots[self._root]
			orig_atom = atom
			expanded_atoms = self._depgraph._dep_expand(root_config, atom)
			if len(expanded_atoms) > 1:
				non_virtual_atoms = []
				for x in expanded_atoms:
					if not portage.dep_getkey(x).startswith("virtual/"):
						non_virtual_atoms.append(x)
				if len(non_virtual_atoms) == 1:
					expanded_atoms = non_virtual_atoms
			if len(expanded_atoms) > 1:
				# compatible with portage.cpv_expand()
				raise portage.exception.AmbiguousPackageName(
					[portage.dep_getkey(x) for x in expanded_atoms])
			if expanded_atoms:
				atom = expanded_atoms[0]
			else:
				null_atom = insert_category_into_atom(atom, "null")
				null_cp = portage.dep_getkey(null_atom)
				cat, atom_pn = portage.catsplit(null_cp)
				virts_p = root_config.settings.get_virts_p().get(atom_pn)
				if virts_p:
					# Allow the resolver to choose which virtual.
					atom = insert_category_into_atom(atom, "virtual")
				else:
					atom = insert_category_into_atom(atom, "null")
			return atom

		def aux_get(self, cpv, wants):
			metadata = self._cpv_pkg_map[cpv].metadata
			return [metadata.get(x, "") for x in wants]

class Scheduler(PollScheduler):

	_opts_ignore_blockers = \
		frozenset(["--buildpkgonly",
		"--fetchonly", "--fetch-all-uri",
		"--nodeps", "--pretend"])

	_opts_no_background = \
		frozenset(["--pretend",
		"--fetchonly", "--fetch-all-uri"])

	_opts_no_restart = frozenset(["--buildpkgonly",
		"--fetchonly", "--fetch-all-uri", "--pretend"])

	_bad_resume_opts = set(["--ask", "--changelog",
		"--resume", "--skipfirst"])

	_fetch_log = os.path.join(_emerge_log_dir, 'emerge-fetch.log')

	class _iface_class(SlotObject):
		__slots__ = ("dblinkEbuildPhase", "dblinkDisplayMerge",
			"dblinkElog", "dblinkEmergeLog", "fetch", "register", "schedule",
			"scheduleSetup", "scheduleUnpack", "scheduleYield",
			"unregister")

	class _fetch_iface_class(SlotObject):
		__slots__ = ("log_file", "schedule")

	_task_queues_class = slot_dict_class(
		("merge", "jobs", "fetch", "unpack"), prefix="")

	class _build_opts_class(SlotObject):
		__slots__ = ("buildpkg", "buildpkgonly",
			"fetch_all_uri", "fetchonly", "pretend")

	class _binpkg_opts_class(SlotObject):
		__slots__ = ("fetchonly", "getbinpkg", "pretend")

	class _pkg_count_class(SlotObject):
		__slots__ = ("curval", "maxval")

	class _emerge_log_class(SlotObject):
		__slots__ = ("xterm_titles",)

		def log(self, *pargs, **kwargs):
			if not self.xterm_titles:
				# Avoid interference with the scheduler's status display.
				kwargs.pop("short_msg", None)
			emergelog(self.xterm_titles, *pargs, **kwargs)

	class _failed_pkg(SlotObject):
		__slots__ = ("build_dir", "build_log", "pkg", "returncode")

	class _ConfigPool(object):
		"""Interface for a task to temporarily allocate a config
		instance from a pool. This allows a task to be constructed
		long before the config instance actually becomes needed, like
		when prefetchers are constructed for the whole merge list."""
		__slots__ = ("_root", "_allocate", "_deallocate")
		def __init__(self, root, allocate, deallocate):
			self._root = root
			self._allocate = allocate
			self._deallocate = deallocate
		def allocate(self):
			return self._allocate(self._root)
		def deallocate(self, settings):
			self._deallocate(settings)

	class _unknown_internal_error(portage.exception.PortageException):
		"""
		Used internally to terminate scheduling. The specific reason for
		the failure should have been dumped to stderr.
		"""
		def __init__(self, value=""):
			portage.exception.PortageException.__init__(self, value)

	def __init__(self, settings, trees, mtimedb, myopts,
		spinner, mergelist, favorites, digraph):
		PollScheduler.__init__(self)
		self.settings = settings
		self.target_root = settings["ROOT"]
		self.trees = trees
		self.myopts = myopts
		self._spinner = spinner
		self._mtimedb = mtimedb
		self._mergelist = mergelist
		self._favorites = favorites
		self._args_set = InternalPackageSet(favorites)
		self._build_opts = self._build_opts_class()
		for k in self._build_opts.__slots__:
			setattr(self._build_opts, k, "--" + k.replace("_", "-") in myopts)
		self._binpkg_opts = self._binpkg_opts_class()
		for k in self._binpkg_opts.__slots__:
			setattr(self._binpkg_opts, k, "--" + k.replace("_", "-") in myopts)

		self.curval = 0
		self._logger = self._emerge_log_class()
		self._task_queues = self._task_queues_class()
		for k in self._task_queues.allowed_keys:
			setattr(self._task_queues, k,
				SequentialTaskQueue())

		# Holds merges that will wait to be executed when no builds are
		# executing. This is useful for system packages since dependencies
		# on system packages are frequently unspecified.
		self._merge_wait_queue = []
		# Holds merges that have been transfered from the merge_wait_queue to
		# the actual merge queue. They are removed from this list upon
		# completion. Other packages can start building only when this list is
		# empty.
		self._merge_wait_scheduled = []

		# Holds system packages and their deep runtime dependencies. Before
		# being merged, these packages go to merge_wait_queue, to be merged
		# when no other packages are building.
		self._deep_system_deps = set()

		# Holds packages to merge which will satisfy currently unsatisfied
		# deep runtime dependencies of system packages. If this is not empty
		# then no parallel builds will be spawned until it is empty. This
		# minimizes the possibility that a build will fail due to the system
		# being in a fragile state. For example, see bug #259954.
		self._unsatisfied_system_deps = set()

		self._status_display = JobStatusDisplay(
			xterm_titles=('notitles' not in settings.features))
		self._max_load = myopts.get("--load-average")
		max_jobs = myopts.get("--jobs")
		if max_jobs is None:
			max_jobs = 1
		self._set_max_jobs(max_jobs)

		# The root where the currently running
		# portage instance is installed.
		self._running_root = trees["/"]["root_config"]
		self.edebug = 0
		if settings.get("PORTAGE_DEBUG", "") == "1":
			self.edebug = 1
		self.pkgsettings = {}
		self._config_pool = {}
		self._blocker_db = {}
		for root in trees:
			self._config_pool[root] = []
			self._blocker_db[root] = BlockerDB(trees[root]["root_config"])

		fetch_iface = self._fetch_iface_class(log_file=self._fetch_log,
			schedule=self._schedule_fetch)
		self._sched_iface = self._iface_class(
			dblinkEbuildPhase=self._dblink_ebuild_phase,
			dblinkDisplayMerge=self._dblink_display_merge,
			dblinkElog=self._dblink_elog,
			dblinkEmergeLog=self._dblink_emerge_log,
			fetch=fetch_iface, register=self._register,
			schedule=self._schedule_wait,
			scheduleSetup=self._schedule_setup,
			scheduleUnpack=self._schedule_unpack,
			scheduleYield=self._schedule_yield,
			unregister=self._unregister)

		self._prefetchers = weakref.WeakValueDictionary()
		self._pkg_queue = []
		self._completed_tasks = set()

		self._failed_pkgs = []
		self._failed_pkgs_all = []
		self._failed_pkgs_die_msgs = []
		self._post_mod_echo_msgs = []
		self._parallel_fetch = False
		merge_count = len([x for x in mergelist \
			if isinstance(x, Package) and x.operation == "merge"])
		self._pkg_count = self._pkg_count_class(
			curval=0, maxval=merge_count)
		self._status_display.maxval = self._pkg_count.maxval

		# The load average takes some time to respond when new
		# jobs are added, so we need to limit the rate of adding
		# new jobs.
		self._job_delay_max = 10
		self._job_delay_factor = 1.0
		self._job_delay_exp = 1.5
		self._previous_job_start_time = None

		self._set_digraph(digraph)

		# This is used to memoize the _choose_pkg() result when
		# no packages can be chosen until one of the existing
		# jobs completes.
		self._choose_pkg_return_early = False

		features = self.settings.features
		if "parallel-fetch" in features and \
			not ("--pretend" in self.myopts or \
			"--fetch-all-uri" in self.myopts or \
			"--fetchonly" in self.myopts):
			if "distlocks" not in features:
				portage.writemsg(red("!!!")+"\n", noiselevel=-1)
				portage.writemsg(red("!!!")+" parallel-fetching " + \
					"requires the distlocks feature enabled"+"\n",
					noiselevel=-1)
				portage.writemsg(red("!!!")+" you have it disabled, " + \
					"thus parallel-fetching is being disabled"+"\n",
					noiselevel=-1)
				portage.writemsg(red("!!!")+"\n", noiselevel=-1)
			elif len(mergelist) > 1:
				self._parallel_fetch = True

		if self._parallel_fetch:
				# clear out existing fetch log if it exists
				try:
					open(self._fetch_log, 'w')
				except EnvironmentError:
					pass

		self._running_portage = None
		portage_match = self._running_root.trees["vartree"].dbapi.match(
			portage.const.PORTAGE_PACKAGE_ATOM)
		if portage_match:
			cpv = portage_match.pop()
			self._running_portage = self._pkg(cpv, "installed",
				self._running_root, installed=True)

	def _poll(self, timeout=None):
		self._schedule()
		PollScheduler._poll(self, timeout=timeout)

	def _set_max_jobs(self, max_jobs):
		self._max_jobs = max_jobs
		self._task_queues.jobs.max_jobs = max_jobs

	def _background_mode(self):
		"""
		Check if background mode is enabled and adjust states as necessary.

		@rtype: bool
		@returns: True if background mode is enabled, False otherwise.
		"""
		background = (self._max_jobs is True or \
			self._max_jobs > 1 or "--quiet" in self.myopts) and \
			not bool(self._opts_no_background.intersection(self.myopts))

		if background:
			interactive_tasks = self._get_interactive_tasks()
			if interactive_tasks:
				background = False
				writemsg_level(">>> Sending package output to stdio due " + \
					"to interactive package(s):\n",
					level=logging.INFO, noiselevel=-1)
				msg = [""]
				for pkg in interactive_tasks:
					pkg_str = "  " + colorize("INFORM", str(pkg.cpv))
					if pkg.root != "/":
						pkg_str += " for " + pkg.root
					msg.append(pkg_str)
				msg.append("")
				writemsg_level("".join("%s\n" % (l,) for l in msg),
					level=logging.INFO, noiselevel=-1)
				if self._max_jobs is True or self._max_jobs > 1:
					self._set_max_jobs(1)
					writemsg_level(">>> Setting --jobs=1 due " + \
						"to the above interactive package(s)\n",
						level=logging.INFO, noiselevel=-1)

		self._status_display.quiet = \
			not background or \
			("--quiet" in self.myopts and \
			"--verbose" not in self.myopts)

		self._logger.xterm_titles = \
			"notitles" not in self.settings.features and \
			self._status_display.quiet

		return background

	def _get_interactive_tasks(self):
		from portage import flatten
		from portage.dep import use_reduce, paren_reduce
		interactive_tasks = []
		for task in self._mergelist:
			if not (isinstance(task, Package) and \
				task.operation == "merge"):
				continue
			try:
				properties = flatten(use_reduce(paren_reduce(
					task.metadata["PROPERTIES"]), uselist=task.use.enabled))
			except portage.exception.InvalidDependString, e:
				show_invalid_depstring_notice(task,
					task.metadata["PROPERTIES"], str(e))
				raise self._unknown_internal_error()
			if "interactive" in properties:
				interactive_tasks.append(task)
		return interactive_tasks

	def _set_digraph(self, digraph):
		if "--nodeps" in self.myopts or \
			(self._max_jobs is not True and self._max_jobs < 2):
			# save some memory
			self._digraph = None
			return

		self._digraph = digraph
		self._find_system_deps()
		self._prune_digraph()
		self._prevent_builddir_collisions()

	def _find_system_deps(self):
		"""
		Find system packages and their deep runtime dependencies. Before being
		merged, these packages go to merge_wait_queue, to be merged when no
		other packages are building.
		"""
		deep_system_deps = self._deep_system_deps
		deep_system_deps.clear()
		deep_system_deps.update(
			_find_deep_system_runtime_deps(self._digraph))
		deep_system_deps.difference_update([pkg for pkg in \
			deep_system_deps if pkg.operation != "merge"])

	def _prune_digraph(self):
		"""
		Prune any root nodes that are irrelevant.
		"""

		graph = self._digraph
		completed_tasks = self._completed_tasks
		removed_nodes = set()
		while True:
			for node in graph.root_nodes():
				if not isinstance(node, Package) or \
					(node.installed and node.operation == "nomerge") or \
					node.onlydeps or \
					node in completed_tasks:
					removed_nodes.add(node)
			if removed_nodes:
				graph.difference_update(removed_nodes)
			if not removed_nodes:
				break
			removed_nodes.clear()

	def _prevent_builddir_collisions(self):
		"""
		When building stages, sometimes the same exact cpv needs to be merged
		to both $ROOTs. Add edges to the digraph in order to avoid collisions
		in the builddir. Currently, normal file locks would be inappropriate
		for this purpose since emerge holds all of it's build dir locks from
		the main process.
		"""
		cpv_map = {}
		for pkg in self._mergelist:
			if not isinstance(pkg, Package):
				# a satisfied blocker
				continue
			if pkg.installed:
				continue
			if pkg.cpv not in cpv_map:
				cpv_map[pkg.cpv] = [pkg]
				continue
			for earlier_pkg in cpv_map[pkg.cpv]:
				self._digraph.add(earlier_pkg, pkg,
					priority=DepPriority(buildtime=True))
			cpv_map[pkg.cpv].append(pkg)

	class _pkg_failure(portage.exception.PortageException):
		"""
		An instance of this class is raised by unmerge() when
		an uninstallation fails.
		"""
		status = 1
		def __init__(self, *pargs):
			portage.exception.PortageException.__init__(self, pargs)
			if pargs:
				self.status = pargs[0]

	def _schedule_fetch(self, fetcher):
		"""
		Schedule a fetcher on the fetch queue, in order to
		serialize access to the fetch log.
		"""
		self._task_queues.fetch.addFront(fetcher)

	def _schedule_setup(self, setup_phase):
		"""
		Schedule a setup phase on the merge queue, in order to
		serialize unsandboxed access to the live filesystem.
		"""
		self._task_queues.merge.addFront(setup_phase)
		self._schedule()

	def _schedule_unpack(self, unpack_phase):
		"""
		Schedule an unpack phase on the unpack queue, in order
		to serialize $DISTDIR access for live ebuilds.
		"""
		self._task_queues.unpack.add(unpack_phase)

	def _find_blockers(self, new_pkg):
		"""
		Returns a callable which should be called only when
		the vdb lock has been acquired.
		"""
		def get_blockers():
			return self._find_blockers_with_lock(new_pkg, acquire_lock=0)
		return get_blockers

	def _find_blockers_with_lock(self, new_pkg, acquire_lock=0):
		if self._opts_ignore_blockers.intersection(self.myopts):
			return None

		# Call gc.collect() here to avoid heap overflow that
		# triggers 'Cannot allocate memory' errors (reported
		# with python-2.5).
		import gc
		gc.collect()

		blocker_db = self._blocker_db[new_pkg.root]

		blocker_dblinks = []
		for blocking_pkg in blocker_db.findInstalledBlockers(
			new_pkg, acquire_lock=acquire_lock):
			if new_pkg.slot_atom == blocking_pkg.slot_atom:
				continue
			if new_pkg.cpv == blocking_pkg.cpv:
				continue
			blocker_dblinks.append(portage.dblink(
				blocking_pkg.category, blocking_pkg.pf, blocking_pkg.root,
				self.pkgsettings[blocking_pkg.root], treetype="vartree",
				vartree=self.trees[blocking_pkg.root]["vartree"]))

		gc.collect()

		return blocker_dblinks

	def _dblink_pkg(self, pkg_dblink):
		cpv = pkg_dblink.mycpv
		type_name = RootConfig.tree_pkg_map[pkg_dblink.treetype]
		root_config = self.trees[pkg_dblink.myroot]["root_config"]
		installed = type_name == "installed"
		return self._pkg(cpv, type_name, root_config, installed=installed)

	def _append_to_log_path(self, log_path, msg):
		f = open(log_path, 'a')
		try:
			f.write(msg)
		finally:
			f.close()

	def _dblink_elog(self, pkg_dblink, phase, func, msgs):

		log_path = pkg_dblink.settings.get("PORTAGE_LOG_FILE")
		log_file = None
		out = sys.stdout
		background = self._background

		if background and log_path is not None:
			log_file = open(log_path, 'a')
			out = log_file

		try:
			for msg in msgs:
				func(msg, phase=phase, key=pkg_dblink.mycpv, out=out)
		finally:
			if log_file is not None:
				log_file.close()

	def _dblink_emerge_log(self, msg):
		self._logger.log(msg)

	def _dblink_display_merge(self, pkg_dblink, msg, level=0, noiselevel=0):
		log_path = pkg_dblink.settings.get("PORTAGE_LOG_FILE")
		background = self._background

		if log_path is None:
			if not (background and level < logging.WARN):
				portage.util.writemsg_level(msg,
					level=level, noiselevel=noiselevel)
		else:
			if not background:
				portage.util.writemsg_level(msg,
					level=level, noiselevel=noiselevel)
			self._append_to_log_path(log_path, msg)

	def _dblink_ebuild_phase(self,
		pkg_dblink, pkg_dbapi, ebuild_path, phase):
		"""
		Using this callback for merge phases allows the scheduler
		to run while these phases execute asynchronously, and allows
		the scheduler control output handling.
		"""

		scheduler = self._sched_iface
		settings = pkg_dblink.settings
		pkg = self._dblink_pkg(pkg_dblink)
		background = self._background
		log_path = settings.get("PORTAGE_LOG_FILE")

		ebuild_phase = EbuildPhase(background=background,
			pkg=pkg, phase=phase, scheduler=scheduler,
			settings=settings, tree=pkg_dblink.treetype)
		ebuild_phase.start()
		ebuild_phase.wait()

		return ebuild_phase.returncode

	def _generate_digests(self):
		"""
		Generate digests if necessary for --digests or FEATURES=digest.
		In order to avoid interference, this must done before parallel
		tasks are started.
		"""

		if '--fetchonly' in self.myopts:
			return os.EX_OK

		digest = '--digest' in self.myopts
		if not digest:
			for pkgsettings in self.pkgsettings.itervalues():
				if 'digest' in pkgsettings.features:
					digest = True
					break

		if not digest:
			return os.EX_OK

		for x in self._mergelist:
			if not isinstance(x, Package) or \
				x.type_name != 'ebuild' or \
				x.operation != 'merge':
				continue
			pkgsettings = self.pkgsettings[x.root]
			if '--digest' not in self.myopts and \
				'digest' not in pkgsettings.features:
				continue
			portdb = x.root_config.trees['porttree'].dbapi
			ebuild_path = portdb.findname(x.cpv)
			if not ebuild_path:
				writemsg_level(
					"!!! Could not locate ebuild for '%s'.\n" \
					% x.cpv, level=logging.ERROR, noiselevel=-1)
				return 1
			pkgsettings['O'] = os.path.dirname(ebuild_path)
			if not portage.digestgen([], pkgsettings, myportdb=portdb):
				writemsg_level(
					"!!! Unable to generate manifest for '%s'.\n" \
					% x.cpv, level=logging.ERROR, noiselevel=-1)
				return 1

		return os.EX_OK

	def _check_manifests(self):
		# Verify all the manifests now so that the user is notified of failure
		# as soon as possible.
		if "strict" not in self.settings.features or \
			"--fetchonly" in self.myopts or \
			"--fetch-all-uri" in self.myopts:
			return os.EX_OK

		shown_verifying_msg = False
		quiet_settings = {}
		for myroot, pkgsettings in self.pkgsettings.iteritems():
			quiet_config = portage.config(clone=pkgsettings)
			quiet_config["PORTAGE_QUIET"] = "1"
			quiet_config.backup_changes("PORTAGE_QUIET")
			quiet_settings[myroot] = quiet_config
			del quiet_config

		for x in self._mergelist:
			if not isinstance(x, Package) or \
				x.type_name != "ebuild":
				continue

			if not shown_verifying_msg:
				shown_verifying_msg = True
				self._status_msg("Verifying ebuild manifests")

			root_config = x.root_config
			portdb = root_config.trees["porttree"].dbapi
			quiet_config = quiet_settings[root_config.root]
			quiet_config["O"] = os.path.dirname(portdb.findname(x.cpv))
			if not portage.digestcheck([], quiet_config, strict=True):
				return 1

		return os.EX_OK

	def _add_prefetchers(self):

		if not self._parallel_fetch:
			return

		if self._parallel_fetch:
			self._status_msg("Starting parallel fetch")

			prefetchers = self._prefetchers
			getbinpkg = "--getbinpkg" in self.myopts

			# In order to avoid "waiting for lock" messages
			# at the beginning, which annoy users, never
			# spawn a prefetcher for the first package.
			for pkg in self._mergelist[1:]:
				prefetcher = self._create_prefetcher(pkg)
				if prefetcher is not None:
					self._task_queues.fetch.add(prefetcher)
					prefetchers[pkg] = prefetcher

	def _create_prefetcher(self, pkg):
		"""
		@return: a prefetcher, or None if not applicable
		"""
		prefetcher = None

		if not isinstance(pkg, Package):
			pass

		elif pkg.type_name == "ebuild":

			prefetcher = EbuildFetcher(background=True,
				config_pool=self._ConfigPool(pkg.root,
				self._allocate_config, self._deallocate_config),
				fetchonly=1, logfile=self._fetch_log,
				pkg=pkg, prefetch=True, scheduler=self._sched_iface)

		elif pkg.type_name == "binary" and \
			"--getbinpkg" in self.myopts and \
			pkg.root_config.trees["bintree"].isremote(pkg.cpv):

			prefetcher = BinpkgPrefetcher(background=True,
				pkg=pkg, scheduler=self._sched_iface)

		return prefetcher

	def _is_restart_scheduled(self):
		"""
		Check if the merge list contains a replacement
		for the current running instance, that will result
		in restart after merge.
		@rtype: bool
		@returns: True if a restart is scheduled, False otherwise.
		"""
		if self._opts_no_restart.intersection(self.myopts):
			return False

		mergelist = self._mergelist

		for i, pkg in enumerate(mergelist):
			if self._is_restart_necessary(pkg) and \
				i != len(mergelist) - 1:
				return True

		return False

	def _is_restart_necessary(self, pkg):
		"""
		@return: True if merging the given package
			requires restart, False otherwise.
		"""

		# Figure out if we need a restart.
		if pkg.root == self._running_root.root and \
			portage.match_from_list(
			portage.const.PORTAGE_PACKAGE_ATOM, [pkg]):
			if self._running_portage:
				return pkg.cpv != self._running_portage.cpv
			return True
		return False

	def _restart_if_necessary(self, pkg):
		"""
		Use execv() to restart emerge. This happens
		if portage upgrades itself and there are
		remaining packages in the list.
		"""

		if self._opts_no_restart.intersection(self.myopts):
			return

		if not self._is_restart_necessary(pkg):
			return

		if pkg == self._mergelist[-1]:
			return

		self._main_loop_cleanup()

		logger = self._logger
		pkg_count = self._pkg_count
		mtimedb = self._mtimedb
		bad_resume_opts = self._bad_resume_opts

		logger.log(" ::: completed emerge (%s of %s) %s to %s" % \
			(pkg_count.curval, pkg_count.maxval, pkg.cpv, pkg.root))

		logger.log(" *** RESTARTING " + \
			"emerge via exec() after change of " + \
			"portage version.")

		mtimedb["resume"]["mergelist"].remove(list(pkg))
		mtimedb.commit()
		portage.run_exitfuncs()
		mynewargv = [sys.argv[0], "--resume"]
		resume_opts = self.myopts.copy()
		# For automatic resume, we need to prevent
		# any of bad_resume_opts from leaking in
		# via EMERGE_DEFAULT_OPTS.
		resume_opts["--ignore-default-opts"] = True
		for myopt, myarg in resume_opts.iteritems():
			if myopt not in bad_resume_opts:
				if myarg is True:
					mynewargv.append(myopt)
				else:
					mynewargv.append(myopt +"="+ str(myarg))
		# priority only needs to be adjusted on the first run
		os.environ["PORTAGE_NICENESS"] = "0"
		os.execv(mynewargv[0], mynewargv)

	def merge(self):

		if "--resume" in self.myopts:
			# We're resuming.
			portage.writemsg_stdout(
				colorize("GOOD", "*** Resuming merge...\n"), noiselevel=-1)
			self._logger.log(" *** Resuming merge...")

		self._save_resume_list()

		try:
			self._background = self._background_mode()
		except self._unknown_internal_error:
			return 1

		for root in self.trees:
			root_config = self.trees[root]["root_config"]

			# Even for --pretend --fetch mode, PORTAGE_TMPDIR is required
			# since it might spawn pkg_nofetch which requires PORTAGE_BUILDDIR
			# for ensuring sane $PWD (bug #239560) and storing elog messages.
			tmpdir = root_config.settings.get("PORTAGE_TMPDIR", "")
			if not tmpdir or not os.path.isdir(tmpdir):
				msg = "The directory specified in your " + \
					"PORTAGE_TMPDIR variable, '%s', " % tmpdir + \
				"does not exist. Please create this " + \
				"directory or correct your PORTAGE_TMPDIR setting."
				msg = textwrap.wrap(msg, 70)
				out = portage.output.EOutput()
				for l in msg:
					out.eerror(l)
				return 1

			if self._background:
				root_config.settings.unlock()
				root_config.settings["PORTAGE_BACKGROUND"] = "1"
				root_config.settings.backup_changes("PORTAGE_BACKGROUND")
				root_config.settings.lock()

			self.pkgsettings[root] = portage.config(
				clone=root_config.settings)

		rval = self._generate_digests()
		if rval != os.EX_OK:
			return rval

		rval = self._check_manifests()
		if rval != os.EX_OK:
			return rval

		keep_going = "--keep-going" in self.myopts
		fetchonly = self._build_opts.fetchonly
		mtimedb = self._mtimedb
		failed_pkgs = self._failed_pkgs

		while True:
			rval = self._merge()
			if rval == os.EX_OK or fetchonly or not keep_going:
				break
			if "resume" not in mtimedb:
				break
			mergelist = self._mtimedb["resume"].get("mergelist")
			if not mergelist:
				break

			if not failed_pkgs:
				break

			for failed_pkg in failed_pkgs:
				mergelist.remove(list(failed_pkg.pkg))

			self._failed_pkgs_all.extend(failed_pkgs)
			del failed_pkgs[:]

			if not mergelist:
				break

			if not self._calc_resume_list():
				break

			clear_caches(self.trees)
			if not self._mergelist:
				break

			self._save_resume_list()
			self._pkg_count.curval = 0
			self._pkg_count.maxval = len([x for x in self._mergelist \
				if isinstance(x, Package) and x.operation == "merge"])
			self._status_display.maxval = self._pkg_count.maxval

		self._logger.log(" *** Finished. Cleaning up...")

		if failed_pkgs:
			self._failed_pkgs_all.extend(failed_pkgs)
			del failed_pkgs[:]

		background = self._background
		failure_log_shown = False
		if background and len(self._failed_pkgs_all) == 1:
			# If only one package failed then just show it's
			# whole log for easy viewing.
			failed_pkg = self._failed_pkgs_all[-1]
			build_dir = failed_pkg.build_dir
			log_file = None

			log_paths = [failed_pkg.build_log]

			log_path = self._locate_failure_log(failed_pkg)
			if log_path is not None:
				try:
					log_file = open(log_path)
				except IOError:
					pass

			if log_file is not None:
				try:
					for line in log_file:
						writemsg_level(line, noiselevel=-1)
				finally:
					log_file.close()
				failure_log_shown = True

		# Dump mod_echo output now since it tends to flood the terminal.
		# This allows us to avoid having more important output, generated
		# later, from being swept away by the mod_echo output.
		mod_echo_output =  _flush_elog_mod_echo()

		if background and not failure_log_shown and \
			self._failed_pkgs_all and \
			self._failed_pkgs_die_msgs and \
			not mod_echo_output:

			printer = portage.output.EOutput()
			for mysettings, key, logentries in self._failed_pkgs_die_msgs:
				root_msg = ""
				if mysettings["ROOT"] != "/":
					root_msg = " merged to %s" % mysettings["ROOT"]
				print
				printer.einfo("Error messages for package %s%s:" % \
					(colorize("INFORM", key), root_msg))
				print
				for phase in portage.const.EBUILD_PHASES:
					if phase not in logentries:
						continue
					for msgtype, msgcontent in logentries[phase]:
						if isinstance(msgcontent, basestring):
							msgcontent = [msgcontent]
						for line in msgcontent:
							printer.eerror(line.strip("\n"))

		if self._post_mod_echo_msgs:
			for msg in self._post_mod_echo_msgs:
				msg()

		if len(self._failed_pkgs_all) > 1 or \
			(self._failed_pkgs_all and "--keep-going" in self.myopts):
			if len(self._failed_pkgs_all) > 1:
				msg = "The following %d packages have " % \
					len(self._failed_pkgs_all) + \
					"failed to build or install:"
			else:
				msg = "The following package has " + \
					"failed to build or install:"
			prefix = bad(" * ")
			writemsg(prefix + "\n", noiselevel=-1)
			from textwrap import wrap
			for line in wrap(msg, 72):
				writemsg("%s%s\n" % (prefix, line), noiselevel=-1)
			writemsg(prefix + "\n", noiselevel=-1)
			for failed_pkg in self._failed_pkgs_all:
				writemsg("%s\t%s\n" % (prefix,
					colorize("INFORM", str(failed_pkg.pkg))),
					noiselevel=-1)
			writemsg(prefix + "\n", noiselevel=-1)

		return rval

	def _elog_listener(self, mysettings, key, logentries, fulltext):
		errors = portage.elog.filter_loglevels(logentries, ["ERROR"])
		if errors:
			self._failed_pkgs_die_msgs.append(
				(mysettings, key, errors))

	def _locate_failure_log(self, failed_pkg):

		build_dir = failed_pkg.build_dir
		log_file = None

		log_paths = [failed_pkg.build_log]

		for log_path in log_paths:
			if not log_path:
				continue

			try:
				log_size = os.stat(log_path).st_size
			except OSError:
				continue

			if log_size == 0:
				continue

			return log_path

		return None

	def _add_packages(self):
		pkg_queue = self._pkg_queue
		for pkg in self._mergelist:
			if isinstance(pkg, Package):
				pkg_queue.append(pkg)
			elif isinstance(pkg, Blocker):
				pass

	def _system_merge_started(self, merge):
		"""
		Add any unsatisfied runtime deps to self._unsatisfied_system_deps.
		"""
		graph = self._digraph
		if graph is None:
			return
		pkg = merge.merge.pkg

		# Skip this if $ROOT != / since it shouldn't matter if there
		# are unsatisfied system runtime deps in this case.
		if pkg.root != '/':
			return

		completed_tasks = self._completed_tasks
		unsatisfied = self._unsatisfied_system_deps

		def ignore_non_runtime_or_satisfied(priority):
			"""
			Ignore non-runtime and satisfied runtime priorities.
			"""
			if isinstance(priority, DepPriority) and \
				not priority.satisfied and \
				(priority.runtime or priority.runtime_post):
				return False
			return True

		# When checking for unsatisfied runtime deps, only check
		# direct deps since indirect deps are checked when the
		# corresponding parent is merged.
		for child in graph.child_nodes(pkg,
			ignore_priority=ignore_non_runtime_or_satisfied):
			if not isinstance(child, Package) or \
				child.operation == 'uninstall':
				continue
			if child is pkg:
				continue
			if child.operation == 'merge' and \
				child not in completed_tasks:
				unsatisfied.add(child)

	def _merge_wait_exit_handler(self, task):
		self._merge_wait_scheduled.remove(task)
		self._merge_exit(task)

	def _merge_exit(self, merge):
		self._do_merge_exit(merge)
		self._deallocate_config(merge.merge.settings)
		if merge.returncode == os.EX_OK and \
			not merge.merge.pkg.installed:
			self._status_display.curval += 1
		self._status_display.merges = len(self._task_queues.merge)
		self._schedule()

	def _do_merge_exit(self, merge):
		pkg = merge.merge.pkg
		if merge.returncode != os.EX_OK:
			settings = merge.merge.settings
			build_dir = settings.get("PORTAGE_BUILDDIR")
			build_log = settings.get("PORTAGE_LOG_FILE")

			self._failed_pkgs.append(self._failed_pkg(
				build_dir=build_dir, build_log=build_log,
				pkg=pkg,
				returncode=merge.returncode))
			self._failed_pkg_msg(self._failed_pkgs[-1], "install", "to")

			self._status_display.failed = len(self._failed_pkgs)
			return

		self._task_complete(pkg)
		pkg_to_replace = merge.merge.pkg_to_replace
		if pkg_to_replace is not None:
			# When a package is replaced, mark it's uninstall
			# task complete (if any).
			uninst_hash_key = \
				("installed", pkg.root, pkg_to_replace.cpv, "uninstall")
			self._task_complete(uninst_hash_key)

		if pkg.installed:
			return

		self._restart_if_necessary(pkg)

		# Call mtimedb.commit() after each merge so that
		# --resume still works after being interrupted
		# by reboot, sigkill or similar.
		mtimedb = self._mtimedb
		mtimedb["resume"]["mergelist"].remove(list(pkg))
		if not mtimedb["resume"]["mergelist"]:
			del mtimedb["resume"]
		mtimedb.commit()

	def _build_exit(self, build):
		if build.returncode == os.EX_OK:
			self.curval += 1
			merge = PackageMerge(merge=build)
			if not build.build_opts.buildpkgonly and \
				build.pkg in self._deep_system_deps:
				# Since dependencies on system packages are frequently
				# unspecified, merge them only when no builds are executing.
				self._merge_wait_queue.append(merge)
				merge.addStartListener(self._system_merge_started)
			else:
				merge.addExitListener(self._merge_exit)
				self._task_queues.merge.add(merge)
				self._status_display.merges = len(self._task_queues.merge)
		else:
			settings = build.settings
			build_dir = settings.get("PORTAGE_BUILDDIR")
			build_log = settings.get("PORTAGE_LOG_FILE")

			self._failed_pkgs.append(self._failed_pkg(
				build_dir=build_dir, build_log=build_log,
				pkg=build.pkg,
				returncode=build.returncode))
			self._failed_pkg_msg(self._failed_pkgs[-1], "emerge", "for")

			self._status_display.failed = len(self._failed_pkgs)
			self._deallocate_config(build.settings)
		self._jobs -= 1
		self._status_display.running = self._jobs
		self._schedule()

	def _extract_exit(self, build):
		self._build_exit(build)

	def _task_complete(self, pkg):
		self._completed_tasks.add(pkg)
		self._unsatisfied_system_deps.discard(pkg)
		self._choose_pkg_return_early = False

	def _merge(self):

		self._add_prefetchers()
		self._add_packages()
		pkg_queue = self._pkg_queue
		failed_pkgs = self._failed_pkgs
		portage.locks._quiet = self._background
		portage.elog._emerge_elog_listener = self._elog_listener
		rval = os.EX_OK

		try:
			self._main_loop()
		finally:
			self._main_loop_cleanup()
			portage.locks._quiet = False
			portage.elog._emerge_elog_listener = None
			if failed_pkgs:
				rval = failed_pkgs[-1].returncode

		return rval

	def _main_loop_cleanup(self):
		del self._pkg_queue[:]
		self._completed_tasks.clear()
		self._deep_system_deps.clear()
		self._unsatisfied_system_deps.clear()
		self._choose_pkg_return_early = False
		self._status_display.reset()
		self._digraph = None
		self._task_queues.fetch.clear()

	def _choose_pkg(self):
		"""
		Choose a task that has all it's dependencies satisfied.
		"""

		if self._choose_pkg_return_early:
			return None

		if self._digraph is None:
			if (self._jobs or self._task_queues.merge) and \
				not ("--nodeps" in self.myopts and \
				(self._max_jobs is True or self._max_jobs > 1)):
				self._choose_pkg_return_early = True
				return None
			return self._pkg_queue.pop(0)

		if not (self._jobs or self._task_queues.merge):
			return self._pkg_queue.pop(0)

		self._prune_digraph()

		chosen_pkg = None
		later = set(self._pkg_queue)
		for pkg in self._pkg_queue:
			later.remove(pkg)
			if not self._dependent_on_scheduled_merges(pkg, later):
				chosen_pkg = pkg
				break

		if chosen_pkg is not None:
			self._pkg_queue.remove(chosen_pkg)

		if chosen_pkg is None:
			# There's no point in searching for a package to
			# choose until at least one of the existing jobs
			# completes.
			self._choose_pkg_return_early = True

		return chosen_pkg

	def _dependent_on_scheduled_merges(self, pkg, later):
		"""
		Traverse the subgraph of the given packages deep dependencies
		to see if it contains any scheduled merges.
		@param pkg: a package to check dependencies for
		@type pkg: Package
		@param later: packages for which dependence should be ignored
			since they will be merged later than pkg anyway and therefore
			delaying the merge of pkg will not result in a more optimal
			merge order
		@type later: set
		@rtype: bool
		@returns: True if the package is dependent, False otherwise.
		"""

		graph = self._digraph
		completed_tasks = self._completed_tasks

		dependent = False
		traversed_nodes = set([pkg])
		direct_deps = graph.child_nodes(pkg)
		node_stack = direct_deps
		direct_deps = frozenset(direct_deps)
		while node_stack:
			node = node_stack.pop()
			if node in traversed_nodes:
				continue
			traversed_nodes.add(node)
			if not ((node.installed and node.operation == "nomerge") or \
				(node.operation == "uninstall" and \
				node not in direct_deps) or \
				node in completed_tasks or \
				node in later):
				dependent = True
				break
			node_stack.extend(graph.child_nodes(node))

		return dependent

	def _allocate_config(self, root):
		"""
		Allocate a unique config instance for a task in order
		to prevent interference between parallel tasks.
		"""
		if self._config_pool[root]:
			temp_settings = self._config_pool[root].pop()
		else:
			temp_settings = portage.config(clone=self.pkgsettings[root])
		# Since config.setcpv() isn't guaranteed to call config.reset() due to
		# performance reasons, call it here to make sure all settings from the
		# previous package get flushed out (such as PORTAGE_LOG_FILE).
		temp_settings.reload()
		temp_settings.reset()
		return temp_settings

	def _deallocate_config(self, settings):
		self._config_pool[settings["ROOT"]].append(settings)

	def _main_loop(self):

		# Only allow 1 job max if a restart is scheduled
		# due to portage update.
		if self._is_restart_scheduled() or \
			self._opts_no_background.intersection(self.myopts):
			self._set_max_jobs(1)

		merge_queue = self._task_queues.merge

		while self._schedule():
			if self._poll_event_handlers:
				self._poll_loop()

		while True:
			self._schedule()
			if not (self._jobs or merge_queue):
				break
			if self._poll_event_handlers:
				self._poll_loop()

	def _keep_scheduling(self):
		return bool(self._pkg_queue and \
			not (self._failed_pkgs and not self._build_opts.fetchonly))

	def _schedule_tasks(self):

		# When the number of jobs drops to zero, process all waiting merges.
		if not self._jobs and self._merge_wait_queue:
			for task in self._merge_wait_queue:
				task.addExitListener(self._merge_wait_exit_handler)
				self._task_queues.merge.add(task)
			self._status_display.merges = len(self._task_queues.merge)
			self._merge_wait_scheduled.extend(self._merge_wait_queue)
			del self._merge_wait_queue[:]

		self._schedule_tasks_imp()
		self._status_display.display()

		state_change = 0
		for q in self._task_queues.values():
			if q.schedule():
				state_change += 1

		# Cancel prefetchers if they're the only reason
		# the main poll loop is still running.
		if self._failed_pkgs and not self._build_opts.fetchonly and \
			not (self._jobs or self._task_queues.merge) and \
			self._task_queues.fetch:
			self._task_queues.fetch.clear()
			state_change += 1

		if state_change:
			self._schedule_tasks_imp()
			self._status_display.display()

		return self._keep_scheduling()

	def _job_delay(self):
		"""
		@rtype: bool
		@returns: True if job scheduling should be delayed, False otherwise.
		"""

		if self._jobs and self._max_load is not None:

			current_time = time.time()

			delay = self._job_delay_factor * self._jobs ** self._job_delay_exp
			if delay > self._job_delay_max:
				delay = self._job_delay_max
			if (current_time - self._previous_job_start_time) < delay:
				return True

		return False

	def _schedule_tasks_imp(self):
		"""
		@rtype: bool
		@returns: True if state changed, False otherwise.
		"""

		state_change = 0

		while True:

			if not self._keep_scheduling():
				return bool(state_change)

			if self._choose_pkg_return_early or \
				self._merge_wait_scheduled or \
				(self._jobs and self._unsatisfied_system_deps) or \
				not self._can_add_job() or \
				self._job_delay():
				return bool(state_change)

			pkg = self._choose_pkg()
			if pkg is None:
				return bool(state_change)

			state_change += 1

			if not pkg.installed:
				self._pkg_count.curval += 1

			task = self._task(pkg)

			if pkg.installed:
				merge = PackageMerge(merge=task)
				merge.addExitListener(self._merge_exit)
				self._task_queues.merge.add(merge)

			elif pkg.built:
				self._jobs += 1
				self._previous_job_start_time = time.time()
				self._status_display.running = self._jobs
				task.addExitListener(self._extract_exit)
				self._task_queues.jobs.add(task)

			else:
				self._jobs += 1
				self._previous_job_start_time = time.time()
				self._status_display.running = self._jobs
				task.addExitListener(self._build_exit)
				self._task_queues.jobs.add(task)

		return bool(state_change)

	def _task(self, pkg):

		pkg_to_replace = None
		if pkg.operation != "uninstall":
			vardb = pkg.root_config.trees["vartree"].dbapi
			previous_cpv = vardb.match(pkg.slot_atom)
			if previous_cpv:
				previous_cpv = previous_cpv.pop()
				pkg_to_replace = self._pkg(previous_cpv,
					"installed", pkg.root_config, installed=True)

		task = MergeListItem(args_set=self._args_set,
			background=self._background, binpkg_opts=self._binpkg_opts,
			build_opts=self._build_opts,
			config_pool=self._ConfigPool(pkg.root,
			self._allocate_config, self._deallocate_config),
			emerge_opts=self.myopts,
			find_blockers=self._find_blockers(pkg), logger=self._logger,
			mtimedb=self._mtimedb, pkg=pkg, pkg_count=self._pkg_count.copy(),
			pkg_to_replace=pkg_to_replace,
			prefetcher=self._prefetchers.get(pkg),
			scheduler=self._sched_iface,
			settings=self._allocate_config(pkg.root),
			statusMessage=self._status_msg,
			world_atom=self._world_atom)

		return task

	def _failed_pkg_msg(self, failed_pkg, action, preposition):
		pkg = failed_pkg.pkg
		msg = "%s to %s %s" % \
			(bad("Failed"), action, colorize("INFORM", pkg.cpv))
		if pkg.root != "/":
			msg += " %s %s" % (preposition, pkg.root)

		log_path = self._locate_failure_log(failed_pkg)
		if log_path is not None:
			msg += ", Log file:"
		self._status_msg(msg)

		if log_path is not None:
			self._status_msg(" '%s'" % (colorize("INFORM", log_path),))

	def _status_msg(self, msg):
		"""
		Display a brief status message (no newlines) in the status display.
		This is called by tasks to provide feedback to the user. This
		delegates the resposibility of generating \r and \n control characters,
		to guarantee that lines are created or erased when necessary and
		appropriate.

		@type msg: str
		@param msg: a brief status message (no newlines allowed)
		"""
		if not self._background:
			writemsg_level("\n")
		self._status_display.displayMessage(msg)

	def _save_resume_list(self):
		"""
		Do this before verifying the ebuild Manifests since it might
		be possible for the user to use --resume --skipfirst get past
		a non-essential package with a broken digest.
		"""
		mtimedb = self._mtimedb
		mtimedb["resume"]["mergelist"] = [list(x) \
			for x in self._mergelist \
			if isinstance(x, Package) and x.operation == "merge"]

		mtimedb.commit()

	def _calc_resume_list(self):
		"""
		Use the current resume list to calculate a new one,
		dropping any packages with unsatisfied deps.
		@rtype: bool
		@returns: True if successful, False otherwise.
		"""
		print colorize("GOOD", "*** Resuming merge...")

		if self._show_list():
			if "--tree" in self.myopts:
				portage.writemsg_stdout("\n" + \
					darkgreen("These are the packages that " + \
					"would be merged, in reverse order:\n\n"))

			else:
				portage.writemsg_stdout("\n" + \
					darkgreen("These are the packages that " + \
					"would be merged, in order:\n\n"))

		show_spinner = "--quiet" not in self.myopts and \
			"--nodeps" not in self.myopts

		if show_spinner:
			print "Calculating dependencies  ",

		myparams = create_depgraph_params(self.myopts, None)
		success = False
		e = None
		try:
			success, mydepgraph, dropped_tasks = resume_depgraph(
				self.settings, self.trees, self._mtimedb, self.myopts,
				myparams, self._spinner)
		except depgraph.UnsatisfiedResumeDep, exc:
			# rename variable to avoid python-3.0 error:
			# SyntaxError: can not delete variable 'e' referenced in nested
			#              scope
			e = exc
			mydepgraph = e.depgraph
			dropped_tasks = set()

		if show_spinner:
			print "\b\b... done!"

		if e is not None:
			def unsatisfied_resume_dep_msg():
				mydepgraph.display_problems()
				out = portage.output.EOutput()
				out.eerror("One or more packages are either masked or " + \
					"have missing dependencies:")
				out.eerror("")
				indent = "  "
				show_parents = set()
				for dep in e.value:
					if dep.parent in show_parents:
						continue
					show_parents.add(dep.parent)
					if dep.atom is None:
						out.eerror(indent + "Masked package:")
						out.eerror(2 * indent + str(dep.parent))
						out.eerror("")
					else:
						out.eerror(indent + str(dep.atom) + " pulled in by:")
						out.eerror(2 * indent + str(dep.parent))
						out.eerror("")
				msg = "The resume list contains packages " + \
					"that are either masked or have " + \
					"unsatisfied dependencies. " + \
					"Please restart/continue " + \
					"the operation manually, or use --skipfirst " + \
					"to skip the first package in the list and " + \
					"any other packages that may be " + \
					"masked or have missing dependencies."
				for line in textwrap.wrap(msg, 72):
					out.eerror(line)
			self._post_mod_echo_msgs.append(unsatisfied_resume_dep_msg)
			return False

		if success and self._show_list():
			mylist = mydepgraph.altlist()
			if mylist:
				if "--tree" in self.myopts:
					mylist.reverse()
				mydepgraph.display(mylist, favorites=self._favorites)

		if not success:
			self._post_mod_echo_msgs.append(mydepgraph.display_problems)
			return False
		mydepgraph.display_problems()

		mylist = mydepgraph.altlist()
		mydepgraph.break_refs(mylist)
		mydepgraph.break_refs(dropped_tasks)
		self._mergelist = mylist
		self._set_digraph(mydepgraph.schedulerGraph())

		msg_width = 75
		for task in dropped_tasks:
			if not (isinstance(task, Package) and task.operation == "merge"):
				continue
			pkg = task
			msg = "emerge --keep-going:" + \
				" %s" % (pkg.cpv,)
			if pkg.root != "/":
				msg += " for %s" % (pkg.root,)
			msg += " dropped due to unsatisfied dependency."
			for line in textwrap.wrap(msg, msg_width):
				eerror(line, phase="other", key=pkg.cpv)
			settings = self.pkgsettings[pkg.root]
			# Ensure that log collection from $T is disabled inside
			# elog_process(), since any logs that might exist are
			# not valid here.
			settings.pop("T", None)
			portage.elog.elog_process(pkg.cpv, settings)
			self._failed_pkgs_all.append(self._failed_pkg(pkg=pkg))

		return True

	def _show_list(self):
		myopts = self.myopts
		if "--quiet" not in myopts and \
			("--ask" in myopts or "--tree" in myopts or \
			"--verbose" in myopts):
			return True
		return False

	def _world_atom(self, pkg):
		"""
		Add the package to the world file, but only if
		it's supposed to be added. Otherwise, do nothing.
		"""

		if set(("--buildpkgonly", "--fetchonly",
			"--fetch-all-uri",
			"--oneshot", "--onlydeps",
			"--pretend")).intersection(self.myopts):
			return

		if pkg.root != self.target_root:
			return

		args_set = self._args_set
		if not args_set.findAtomForPackage(pkg):
			return

		logger = self._logger
		pkg_count = self._pkg_count
		root_config = pkg.root_config
		world_set = root_config.sets["world"]
		world_locked = False
		if hasattr(world_set, "lock"):
			world_set.lock()
			world_locked = True

		try:
			if hasattr(world_set, "load"):
				world_set.load() # maybe it's changed on disk

			atom = create_world_atom(pkg, args_set, root_config)
			if atom:
				if hasattr(world_set, "add"):
					self._status_msg(('Recording %s in "world" ' + \
						'favorites file...') % atom)
					logger.log(" === (%s of %s) Updating world file (%s)" % \
						(pkg_count.curval, pkg_count.maxval, pkg.cpv))
					world_set.add(atom)
				else:
					writemsg_level('\n!!! Unable to record %s in "world"\n' % \
						(atom,), level=logging.WARN, noiselevel=-1)
		finally:
			if world_locked:
				world_set.unlock()

	def _pkg(self, cpv, type_name, root_config, installed=False):
		"""
		Get a package instance from the cache, or create a new
		one if necessary. Raises KeyError from aux_get if it
		failures for some reason (package does not exist or is
		corrupt).
		"""
		operation = "merge"
		if installed:
			operation = "nomerge"

		if self._digraph is not None:
			# Reuse existing instance when available.
			pkg = self._digraph.get(
				(type_name, root_config.root, cpv, operation))
			if pkg is not None:
				return pkg

		tree_type = depgraph.pkg_tree_map[type_name]
		db = root_config.trees[tree_type].dbapi
		db_keys = list(self.trees[root_config.root][
			tree_type].dbapi._aux_cache_keys)
		metadata = izip(db_keys, db.aux_get(cpv, db_keys))
		pkg = Package(cpv=cpv, metadata=metadata,
			root_config=root_config, installed=installed)
		if type_name == "ebuild":
			settings = self.pkgsettings[root_config.root]
			settings.setcpv(pkg)
			pkg.metadata["USE"] = settings["PORTAGE_USE"]
			pkg.metadata['CHOST'] = settings.get('CHOST', '')

		return pkg

def chk_updated_info_files(root, infodirs, prev_mtimes, retval):

	if os.path.exists("/usr/bin/install-info"):

		print "Use " + colorize("GOOD", "emerge @preserved-rebuild") + " to rebuild packages using these libraries"


def _flush_elog_mod_echo():
	"""
	Dump the mod_echo output now so that our other
	notifications are shown last.
	@rtype: bool
	@returns: True if messages were shown, False otherwise.
	"""
	messages_shown = False
	try:
		from portage.elog import mod_echo
	except ImportError:
		pass # happens during downgrade to a version without the module
	else:
		messages_shown = bool(mod_echo._items)
		mod_echo.finalize()
	return messages_shown

def post_emerge(root_config, myopts, mtimedb, retval):
	"""
	Misc. things to run at the end of a merge session.

	manager = NewsManager(portdb, vardb, NEWS_PATH, UNREAD_PATH)
	return manager.getUnreadItems( repo_id, update=update )

def insert_category_into_atom(atom, category):
	alphanum = re.search(r'\w', atom)
	if alphanum:
		ret = atom[:alphanum.start()] + "%s/" % category + \
			atom[alphanum.start():]
	else:
		ret = None
	return ret

def is_valid_package_atom(x):
	if "/" not in x:
		alphanum = re.search(r'\w', x)
		if alphanum:
			x = x[:alphanum.start()] + "cat/" + x[alphanum.start():]
	return portage.isvalidatom(x)

def show_blocker_docs_link():
	print
	print "For more information about " + bad("Blocked Packages") + ", please refer to the following"
	print "section of the Gentoo Linux x86 Handbook (architecture is irrelevant):"
	print
	print "http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked"
	print

def show_mask_docs():
	print "For more information, see the MASKED PACKAGES section in the emerge"
	print "man page or refer to the Gentoo Handbook."

def action_sync(settings, trees, mtimedb, myopts, myaction):
	xterm_titles = "notitles" not in settings.features
	emergelog(xterm_titles, " === sync")

	else:
		print "Number removed:       "+str(len(cleanlist))

def resume_depgraph(settings, trees, mtimedb, myopts, myparams, spinner):
	"""
	Construct a depgraph for the given resume list. This will raise
	PackageNotFound or depgraph.UnsatisfiedResumeDep when necessary.
	@rtype: tuple
	@returns: (success, depgraph, dropped_tasks)
	"""
	skip_masked = True
	skip_unsatisfied = True
	mergelist = mtimedb["resume"]["mergelist"]
	dropped_tasks = set()
	while True:
		mydepgraph = depgraph(settings, trees,
			myopts, myparams, spinner)
		try:
			success = mydepgraph.loadResumeCommand(mtimedb["resume"],
				skip_masked=skip_masked)
		except depgraph.UnsatisfiedResumeDep, e:
			if not skip_unsatisfied:
				raise

			graph = mydepgraph.digraph
			unsatisfied_parents = dict((dep.parent, dep.parent) \
				for dep in e.value)
			traversed_nodes = set()
			unsatisfied_stack = list(unsatisfied_parents)
			while unsatisfied_stack:
				pkg = unsatisfied_stack.pop()
				if pkg in traversed_nodes:
					continue
				traversed_nodes.add(pkg)

				# If this package was pulled in by a parent
				# package scheduled for merge, removing this
				# package may cause the the parent package's
				# dependency to become unsatisfied.
				for parent_node in graph.parent_nodes(pkg):
					if not isinstance(parent_node, Package) \
						or parent_node.operation not in ("merge", "nomerge"):
						continue
					unsatisfied = \
						graph.child_nodes(parent_node,
						ignore_priority=DepPrioritySatisfiedRange.ignore_soft)
					if pkg in unsatisfied:
						unsatisfied_parents[parent_node] = parent_node
						unsatisfied_stack.append(parent_node)

			pruned_mergelist = []
			for x in mergelist:
				if isinstance(x, list) and \
					tuple(x) not in unsatisfied_parents:
					pruned_mergelist.append(x)

			# If the mergelist doesn't shrink then this loop is infinite.
			if len(pruned_mergelist) == len(mergelist):
				# This happens if a package can't be dropped because
				# it's already installed, but it has unsatisfied PDEPEND.
				raise
			mergelist[:] = pruned_mergelist

			# Exclude installed packages that have been removed from the graph due
			# to failure to build/install runtime dependencies after the dependent
			# package has already been installed.
			dropped_tasks.update(pkg for pkg in \
				unsatisfied_parents if pkg.operation != "nomerge")
			mydepgraph.break_refs(unsatisfied_parents)

			del e, graph, traversed_nodes, \
				unsatisfied_parents, unsatisfied_stack
			continue
		else:
			break
	return (success, mydepgraph, dropped_tasks)

def action_build(settings, trees, mtimedb,
	myopts, myaction, myfiles, spinner):


		settings = trees[myroot]["vartree"].settings
		settings.validate()

def clear_caches(trees):
	for d in trees.itervalues():
		d["porttree"].dbapi.melt()
		d["porttree"].dbapi._aux_cache.clear()
		d["bintree"].dbapi._aux_cache.clear()
		d["bintree"].dbapi._clear_cache()
		d["vartree"].dbapi.linkmap._clear_cache()
	portage.dircache.clear()
	gc.collect()

def load_emerge_config(trees=None):
	kwargs = {}
	for k, envvar in (("config_root", "PORTAGE_CONFIGROOT"), ("target_root", "ROOT")):

				msg += " for '%s'" % root
			writemsg_level(msg, level=logging.WARN, noiselevel=-1)

def ambiguous_package_name(arg, atoms, root_config, spinner, myopts):

	if "--quiet" in myopts:
		print "!!! The short ebuild name \"%s\" is ambiguous. Please specify" % arg
		print "!!! one of the following fully-qualified ebuild names instead:\n"
		for cp in sorted(set(portage.dep_getkey(atom) for atom in atoms)):
			print "    " + colorize("INFORM", cp)
		return

	s = search(root_config, spinner, "--searchdesc" in myopts,
		"--quiet" not in myopts, "--usepkg" in myopts,
		"--usepkgonly" in myopts)
	null_cp = portage.dep_getkey(insert_category_into_atom(
		arg, "null"))
	cat, atom_pn = portage.catsplit(null_cp)
	s.searchkey = atom_pn
	for cp in sorted(set(portage.dep_getkey(atom) for atom in atoms)):
		s.addCP(cp)
	s.output()
	print "!!! The short ebuild name \"%s\" is ambiguous. Please specify" % arg
	print "!!! one of the above fully-qualified ebuild names instead.\n"

def profile_check(trees, myaction, myopts):
	if myaction in ("info", "sync"):
		return os.EX_OK




import logging
import os
import sys
import textwrap
import time
import weakref
from itertools import izip

try:
	import portage
except ImportError:
	from os import path as osp
	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	import portage

from portage.cache.mappings import slot_dict_class
from portage.elog.messages import eerror
from portage.output import colorize, create_color_func, darkgreen, red
bad = create_color_func("BAD")
from portage.sets.base import InternalPackageSet
from portage.util import writemsg, writemsg_level

from _emerge.BinpkgPrefetcher import BinpkgPrefetcher
from _emerge.Blocker import Blocker
from _emerge.BlockerDB import BlockerDB
from _emerge.clear_caches import clear_caches
from _emerge.create_depgraph_params import create_depgraph_params
from _emerge.create_world_atom import create_world_atom
from _emerge.DepPriority import DepPriority
from _emerge.EbuildFetcher import EbuildFetcher
from _emerge.EbuildPhase import EbuildPhase
from _emerge.emergelog import emergelog, _emerge_log_dir
from _emerge._find_deep_system_runtime_deps import _find_deep_system_runtime_deps
from _emerge._flush_elog_mod_echo import _flush_elog_mod_echo
from _emerge.JobStatusDisplay import JobStatusDisplay
from _emerge.MergeListItem import MergeListItem
from _emerge.Package import Package
from _emerge.PackageMerge import PackageMerge
from _emerge.PollScheduler import PollScheduler
from _emerge.RootConfig import RootConfig
from _emerge.SlotObject import SlotObject
from _emerge.SequentialTaskQueue import SequentialTaskQueue
from _emerge.show_invalid_depstring_notice import show_invalid_depstring_notice

import portage.proxy.lazyimport
import portage.proxy as proxy
proxy.lazyimport.lazyimport(globals(),
	'_emerge.depgraph:depgraph',
)

class Scheduler(PollScheduler):

	_opts_ignore_blockers = \
		frozenset(["--buildpkgonly",
		"--fetchonly", "--fetch-all-uri",
		"--nodeps", "--pretend"])

	_opts_no_background = \
		frozenset(["--pretend",
		"--fetchonly", "--fetch-all-uri"])

	_opts_no_restart = frozenset(["--buildpkgonly",
		"--fetchonly", "--fetch-all-uri", "--pretend"])

	_bad_resume_opts = set(["--ask", "--changelog",
		"--resume", "--skipfirst"])

	_fetch_log = os.path.join(_emerge_log_dir, 'emerge-fetch.log')

	class _iface_class(SlotObject):
		__slots__ = ("dblinkEbuildPhase", "dblinkDisplayMerge",
			"dblinkElog", "dblinkEmergeLog", "fetch", "register", "schedule",
			"scheduleSetup", "scheduleUnpack", "scheduleYield",
			"unregister")

	class _fetch_iface_class(SlotObject):
		__slots__ = ("log_file", "schedule")

	_task_queues_class = slot_dict_class(
		("merge", "jobs", "fetch", "unpack"), prefix="")

	class _build_opts_class(SlotObject):
		__slots__ = ("buildpkg", "buildpkgonly",
			"fetch_all_uri", "fetchonly", "pretend")

	class _binpkg_opts_class(SlotObject):
		__slots__ = ("fetchonly", "getbinpkg", "pretend")

	class _pkg_count_class(SlotObject):
		__slots__ = ("curval", "maxval")

	class _emerge_log_class(SlotObject):
		__slots__ = ("xterm_titles",)

		def log(self, *pargs, **kwargs):
			if not self.xterm_titles:
				# Avoid interference with the scheduler's status display.
				kwargs.pop("short_msg", None)
			emergelog(self.xterm_titles, *pargs, **kwargs)

	class _failed_pkg(SlotObject):
		__slots__ = ("build_dir", "build_log", "pkg", "returncode")

	class _ConfigPool(object):
		"""Interface for a task to temporarily allocate a config
		instance from a pool. This allows a task to be constructed
		long before the config instance actually becomes needed, like
		when prefetchers are constructed for the whole merge list."""
		__slots__ = ("_root", "_allocate", "_deallocate")
		def __init__(self, root, allocate, deallocate):
			self._root = root
			self._allocate = allocate
			self._deallocate = deallocate
		def allocate(self):
			return self._allocate(self._root)
		def deallocate(self, settings):
			self._deallocate(settings)

	class _unknown_internal_error(portage.exception.PortageException):
		"""
		Used internally to terminate scheduling. The specific reason for
		the failure should have been dumped to stderr.
		"""
		def __init__(self, value=""):
			portage.exception.PortageException.__init__(self, value)

	def __init__(self, settings, trees, mtimedb, myopts,
		spinner, mergelist, favorites, digraph):
		PollScheduler.__init__(self)
		self.settings = settings
		self.target_root = settings["ROOT"]
		self.trees = trees
		self.myopts = myopts
		self._spinner = spinner
		self._mtimedb = mtimedb
		self._mergelist = mergelist
		self._favorites = favorites
		self._args_set = InternalPackageSet(favorites)
		self._build_opts = self._build_opts_class()
		for k in self._build_opts.__slots__:
			setattr(self._build_opts, k, "--" + k.replace("_", "-") in myopts)
		self._binpkg_opts = self._binpkg_opts_class()
		for k in self._binpkg_opts.__slots__:
			setattr(self._binpkg_opts, k, "--" + k.replace("_", "-") in myopts)

		self.curval = 0
		self._logger = self._emerge_log_class()
		self._task_queues = self._task_queues_class()
		for k in self._task_queues.allowed_keys:
			setattr(self._task_queues, k,
				SequentialTaskQueue())

		# Holds merges that will wait to be executed when no builds are
		# executing. This is useful for system packages since dependencies
		# on system packages are frequently unspecified.
		self._merge_wait_queue = []
		# Holds merges that have been transfered from the merge_wait_queue to
		# the actual merge queue. They are removed from this list upon
		# completion. Other packages can start building only when this list is
		# empty.
		self._merge_wait_scheduled = []

		# Holds system packages and their deep runtime dependencies. Before
		# being merged, these packages go to merge_wait_queue, to be merged
		# when no other packages are building.
		self._deep_system_deps = set()

		# Holds packages to merge which will satisfy currently unsatisfied
		# deep runtime dependencies of system packages. If this is not empty
		# then no parallel builds will be spawned until it is empty. This
		# minimizes the possibility that a build will fail due to the system
		# being in a fragile state. For example, see bug #259954.
		self._unsatisfied_system_deps = set()

		self._status_display = JobStatusDisplay(
			xterm_titles=('notitles' not in settings.features))
		self._max_load = myopts.get("--load-average")
		max_jobs = myopts.get("--jobs")
		if max_jobs is None:
			max_jobs = 1
		self._set_max_jobs(max_jobs)

		# The root where the currently running
		# portage instance is installed.
		self._running_root = trees["/"]["root_config"]
		self.edebug = 0
		if settings.get("PORTAGE_DEBUG", "") == "1":
			self.edebug = 1
		self.pkgsettings = {}
		self._config_pool = {}
		self._blocker_db = {}
		for root in trees:
			self._config_pool[root] = []
			self._blocker_db[root] = BlockerDB(trees[root]["root_config"])

		fetch_iface = self._fetch_iface_class(log_file=self._fetch_log,
			schedule=self._schedule_fetch)
		self._sched_iface = self._iface_class(
			dblinkEbuildPhase=self._dblink_ebuild_phase,
			dblinkDisplayMerge=self._dblink_display_merge,
			dblinkElog=self._dblink_elog,
			dblinkEmergeLog=self._dblink_emerge_log,
			fetch=fetch_iface, register=self._register,
			schedule=self._schedule_wait,
			scheduleSetup=self._schedule_setup,
			scheduleUnpack=self._schedule_unpack,
			scheduleYield=self._schedule_yield,
			unregister=self._unregister)

		self._prefetchers = weakref.WeakValueDictionary()
		self._pkg_queue = []
		self._completed_tasks = set()

		self._failed_pkgs = []
		self._failed_pkgs_all = []
		self._failed_pkgs_die_msgs = []
		self._post_mod_echo_msgs = []
		self._parallel_fetch = False
		merge_count = len([x for x in mergelist \
			if isinstance(x, Package) and x.operation == "merge"])
		self._pkg_count = self._pkg_count_class(
			curval=0, maxval=merge_count)
		self._status_display.maxval = self._pkg_count.maxval

		# The load average takes some time to respond when new
		# jobs are added, so we need to limit the rate of adding
		# new jobs.
		self._job_delay_max = 10
		self._job_delay_factor = 1.0
		self._job_delay_exp = 1.5
		self._previous_job_start_time = None

		self._set_digraph(digraph)

		# This is used to memoize the _choose_pkg() result when
		# no packages can be chosen until one of the existing
		# jobs completes.
		self._choose_pkg_return_early = False

		features = self.settings.features
		if "parallel-fetch" in features and \
			not ("--pretend" in self.myopts or \
			"--fetch-all-uri" in self.myopts or \
			"--fetchonly" in self.myopts):
			if "distlocks" not in features:
				portage.writemsg(red("!!!")+"\n", noiselevel=-1)
				portage.writemsg(red("!!!")+" parallel-fetching " + \
					"requires the distlocks feature enabled"+"\n",
					noiselevel=-1)
				portage.writemsg(red("!!!")+" you have it disabled, " + \
					"thus parallel-fetching is being disabled"+"\n",
					noiselevel=-1)
				portage.writemsg(red("!!!")+"\n", noiselevel=-1)
			elif len(mergelist) > 1:
				self._parallel_fetch = True

		if self._parallel_fetch:
				# clear out existing fetch log if it exists
				try:
					open(self._fetch_log, 'w')
				except EnvironmentError:
					pass

		self._running_portage = None
		portage_match = self._running_root.trees["vartree"].dbapi.match(
			portage.const.PORTAGE_PACKAGE_ATOM)
		if portage_match:
			cpv = portage_match.pop()
			self._running_portage = self._pkg(cpv, "installed",
				self._running_root, installed=True)

	def _poll(self, timeout=None):
		self._schedule()
		PollScheduler._poll(self, timeout=timeout)

	def _set_max_jobs(self, max_jobs):
		self._max_jobs = max_jobs
		self._task_queues.jobs.max_jobs = max_jobs

	def _background_mode(self):
		"""
		Check if background mode is enabled and adjust states as necessary.

		@rtype: bool
		@returns: True if background mode is enabled, False otherwise.
		"""
		background = (self._max_jobs is True or \
			self._max_jobs > 1 or "--quiet" in self.myopts) and \
			not bool(self._opts_no_background.intersection(self.myopts))

		if background:
			interactive_tasks = self._get_interactive_tasks()
			if interactive_tasks:
				background = False
				writemsg_level(">>> Sending package output to stdio due " + \
					"to interactive package(s):\n",
					level=logging.INFO, noiselevel=-1)
				msg = [""]
				for pkg in interactive_tasks:
					pkg_str = "  " + colorize("INFORM", str(pkg.cpv))
					if pkg.root != "/":
						pkg_str += " for " + pkg.root
					msg.append(pkg_str)
				msg.append("")
				writemsg_level("".join("%s\n" % (l,) for l in msg),
					level=logging.INFO, noiselevel=-1)
				if self._max_jobs is True or self._max_jobs > 1:
					self._set_max_jobs(1)
					writemsg_level(">>> Setting --jobs=1 due " + \
						"to the above interactive package(s)\n",
						level=logging.INFO, noiselevel=-1)

		self._status_display.quiet = \
			not background or \
			("--quiet" in self.myopts and \
			"--verbose" not in self.myopts)

		self._logger.xterm_titles = \
			"notitles" not in self.settings.features and \
			self._status_display.quiet

		return background

	def _get_interactive_tasks(self):
		from portage import flatten
		from portage.dep import use_reduce, paren_reduce
		interactive_tasks = []
		for task in self._mergelist:
			if not (isinstance(task, Package) and \
				task.operation == "merge"):
				continue
			try:
				properties = flatten(use_reduce(paren_reduce(
					task.metadata["PROPERTIES"]), uselist=task.use.enabled))
			except portage.exception.InvalidDependString, e:
				show_invalid_depstring_notice(task,
					task.metadata["PROPERTIES"], str(e))
				raise self._unknown_internal_error()
			if "interactive" in properties:
				interactive_tasks.append(task)
		return interactive_tasks

	def _set_digraph(self, digraph):
		if "--nodeps" in self.myopts or \
			(self._max_jobs is not True and self._max_jobs < 2):
			# save some memory
			self._digraph = None
			return

		self._digraph = digraph
		self._find_system_deps()
		self._prune_digraph()
		self._prevent_builddir_collisions()

	def _find_system_deps(self):
		"""
		Find system packages and their deep runtime dependencies. Before being
		merged, these packages go to merge_wait_queue, to be merged when no
		other packages are building.
		"""
		deep_system_deps = self._deep_system_deps
		deep_system_deps.clear()
		deep_system_deps.update(
			_find_deep_system_runtime_deps(self._digraph))
		deep_system_deps.difference_update([pkg for pkg in \
			deep_system_deps if pkg.operation != "merge"])

	def _prune_digraph(self):
		"""
		Prune any root nodes that are irrelevant.
		"""

		graph = self._digraph
		completed_tasks = self._completed_tasks
		removed_nodes = set()
		while True:
			for node in graph.root_nodes():
				if not isinstance(node, Package) or \
					(node.installed and node.operation == "nomerge") or \
					node.onlydeps or \
					node in completed_tasks:
					removed_nodes.add(node)
			if removed_nodes:
				graph.difference_update(removed_nodes)
			if not removed_nodes:
				break
			removed_nodes.clear()

	def _prevent_builddir_collisions(self):
		"""
		When building stages, sometimes the same exact cpv needs to be merged
		to both $ROOTs. Add edges to the digraph in order to avoid collisions
		in the builddir. Currently, normal file locks would be inappropriate
		for this purpose since emerge holds all of it's build dir locks from
		the main process.
		"""
		cpv_map = {}
		for pkg in self._mergelist:
			if not isinstance(pkg, Package):
				# a satisfied blocker
				continue
			if pkg.installed:
				continue
			if pkg.cpv not in cpv_map:
				cpv_map[pkg.cpv] = [pkg]
				continue
			for earlier_pkg in cpv_map[pkg.cpv]:
				self._digraph.add(earlier_pkg, pkg,
					priority=DepPriority(buildtime=True))
			cpv_map[pkg.cpv].append(pkg)

	class _pkg_failure(portage.exception.PortageException):
		"""
		An instance of this class is raised by unmerge() when
		an uninstallation fails.
		"""
		status = 1
		def __init__(self, *pargs):
			portage.exception.PortageException.__init__(self, pargs)
			if pargs:
				self.status = pargs[0]

	def _schedule_fetch(self, fetcher):
		"""
		Schedule a fetcher on the fetch queue, in order to
		serialize access to the fetch log.
		"""
		self._task_queues.fetch.addFront(fetcher)

	def _schedule_setup(self, setup_phase):
		"""
		Schedule a setup phase on the merge queue, in order to
		serialize unsandboxed access to the live filesystem.
		"""
		self._task_queues.merge.addFront(setup_phase)
		self._schedule()

	def _schedule_unpack(self, unpack_phase):
		"""
		Schedule an unpack phase on the unpack queue, in order
		to serialize $DISTDIR access for live ebuilds.
		"""
		self._task_queues.unpack.add(unpack_phase)

	def _find_blockers(self, new_pkg):
		"""
		Returns a callable which should be called only when
		the vdb lock has been acquired.
		"""
		def get_blockers():
			return self._find_blockers_with_lock(new_pkg, acquire_lock=0)
		return get_blockers

	def _find_blockers_with_lock(self, new_pkg, acquire_lock=0):
		if self._opts_ignore_blockers.intersection(self.myopts):
			return None

		# Call gc.collect() here to avoid heap overflow that
		# triggers 'Cannot allocate memory' errors (reported
		# with python-2.5).
		import gc
		gc.collect()

		blocker_db = self._blocker_db[new_pkg.root]

		blocker_dblinks = []
		for blocking_pkg in blocker_db.findInstalledBlockers(
			new_pkg, acquire_lock=acquire_lock):
			if new_pkg.slot_atom == blocking_pkg.slot_atom:
				continue
			if new_pkg.cpv == blocking_pkg.cpv:
				continue
			blocker_dblinks.append(portage.dblink(
				blocking_pkg.category, blocking_pkg.pf, blocking_pkg.root,
				self.pkgsettings[blocking_pkg.root], treetype="vartree",
				vartree=self.trees[blocking_pkg.root]["vartree"]))

		gc.collect()

		return blocker_dblinks

	def _dblink_pkg(self, pkg_dblink):
		cpv = pkg_dblink.mycpv
		type_name = RootConfig.tree_pkg_map[pkg_dblink.treetype]
		root_config = self.trees[pkg_dblink.myroot]["root_config"]
		installed = type_name == "installed"
		return self._pkg(cpv, type_name, root_config, installed=installed)

	def _append_to_log_path(self, log_path, msg):
		f = open(log_path, 'a')
		try:
			f.write(msg)
		finally:
			f.close()

	def _dblink_elog(self, pkg_dblink, phase, func, msgs):

		log_path = pkg_dblink.settings.get("PORTAGE_LOG_FILE")
		log_file = None
		out = sys.stdout
		background = self._background

		if background and log_path is not None:
			log_file = open(log_path, 'a')
			out = log_file

		try:
			for msg in msgs:
				func(msg, phase=phase, key=pkg_dblink.mycpv, out=out)
		finally:
			if log_file is not None:
				log_file.close()

	def _dblink_emerge_log(self, msg):
		self._logger.log(msg)

	def _dblink_display_merge(self, pkg_dblink, msg, level=0, noiselevel=0):
		log_path = pkg_dblink.settings.get("PORTAGE_LOG_FILE")
		background = self._background

		if log_path is None:
			if not (background and level < logging.WARN):
				portage.util.writemsg_level(msg,
					level=level, noiselevel=noiselevel)
		else:
			if not background:
				portage.util.writemsg_level(msg,
					level=level, noiselevel=noiselevel)
			self._append_to_log_path(log_path, msg)

	def _dblink_ebuild_phase(self,
		pkg_dblink, pkg_dbapi, ebuild_path, phase):
		"""
		Using this callback for merge phases allows the scheduler
		to run while these phases execute asynchronously, and allows
		the scheduler control output handling.
		"""

		scheduler = self._sched_iface
		settings = pkg_dblink.settings
		pkg = self._dblink_pkg(pkg_dblink)
		background = self._background
		log_path = settings.get("PORTAGE_LOG_FILE")

		ebuild_phase = EbuildPhase(background=background,
			pkg=pkg, phase=phase, scheduler=scheduler,
			settings=settings, tree=pkg_dblink.treetype)
		ebuild_phase.start()
		ebuild_phase.wait()

		return ebuild_phase.returncode

	def _generate_digests(self):
		"""
		Generate digests if necessary for --digests or FEATURES=digest.
		In order to avoid interference, this must done before parallel
		tasks are started.
		"""

		if '--fetchonly' in self.myopts:
			return os.EX_OK

		digest = '--digest' in self.myopts
		if not digest:
			for pkgsettings in self.pkgsettings.itervalues():
				if 'digest' in pkgsettings.features:
					digest = True
					break

		if not digest:
			return os.EX_OK

		for x in self._mergelist:
			if not isinstance(x, Package) or \
				x.type_name != 'ebuild' or \
				x.operation != 'merge':
				continue
			pkgsettings = self.pkgsettings[x.root]
			if '--digest' not in self.myopts and \
				'digest' not in pkgsettings.features:
				continue
			portdb = x.root_config.trees['porttree'].dbapi
			ebuild_path = portdb.findname(x.cpv)
			if not ebuild_path:
				writemsg_level(
					"!!! Could not locate ebuild for '%s'.\n" \
					% x.cpv, level=logging.ERROR, noiselevel=-1)
				return 1
			pkgsettings['O'] = os.path.dirname(ebuild_path)
			if not portage.digestgen([], pkgsettings, myportdb=portdb):
				writemsg_level(
					"!!! Unable to generate manifest for '%s'.\n" \
					% x.cpv, level=logging.ERROR, noiselevel=-1)
				return 1

		return os.EX_OK

	def _check_manifests(self):
		# Verify all the manifests now so that the user is notified of failure
		# as soon as possible.
		if "strict" not in self.settings.features or \
			"--fetchonly" in self.myopts or \
			"--fetch-all-uri" in self.myopts:
			return os.EX_OK

		shown_verifying_msg = False
		quiet_settings = {}
		for myroot, pkgsettings in self.pkgsettings.iteritems():
			quiet_config = portage.config(clone=pkgsettings)
			quiet_config["PORTAGE_QUIET"] = "1"
			quiet_config.backup_changes("PORTAGE_QUIET")
			quiet_settings[myroot] = quiet_config
			del quiet_config

		for x in self._mergelist:
			if not isinstance(x, Package) or \
				x.type_name != "ebuild":
				continue

			if not shown_verifying_msg:
				shown_verifying_msg = True
				self._status_msg("Verifying ebuild manifests")

			root_config = x.root_config
			portdb = root_config.trees["porttree"].dbapi
			quiet_config = quiet_settings[root_config.root]
			quiet_config["O"] = os.path.dirname(portdb.findname(x.cpv))
			if not portage.digestcheck([], quiet_config, strict=True):
				return 1

		return os.EX_OK

	def _add_prefetchers(self):

		if not self._parallel_fetch:
			return

		if self._parallel_fetch:
			self._status_msg("Starting parallel fetch")

			prefetchers = self._prefetchers
			getbinpkg = "--getbinpkg" in self.myopts

			# In order to avoid "waiting for lock" messages
			# at the beginning, which annoy users, never
			# spawn a prefetcher for the first package.
			for pkg in self._mergelist[1:]:
				prefetcher = self._create_prefetcher(pkg)
				if prefetcher is not None:
					self._task_queues.fetch.add(prefetcher)
					prefetchers[pkg] = prefetcher

	def _create_prefetcher(self, pkg):
		"""
		@return: a prefetcher, or None if not applicable
		"""
		prefetcher = None

		if not isinstance(pkg, Package):
			pass

		elif pkg.type_name == "ebuild":

			prefetcher = EbuildFetcher(background=True,
				config_pool=self._ConfigPool(pkg.root,
				self._allocate_config, self._deallocate_config),
				fetchonly=1, logfile=self._fetch_log,
				pkg=pkg, prefetch=True, scheduler=self._sched_iface)

		elif pkg.type_name == "binary" and \
			"--getbinpkg" in self.myopts and \
			pkg.root_config.trees["bintree"].isremote(pkg.cpv):

			prefetcher = BinpkgPrefetcher(background=True,
				pkg=pkg, scheduler=self._sched_iface)

		return prefetcher

	def _is_restart_scheduled(self):
		"""
		Check if the merge list contains a replacement
		for the current running instance, that will result
		in restart after merge.
		@rtype: bool
		@returns: True if a restart is scheduled, False otherwise.
		"""
		if self._opts_no_restart.intersection(self.myopts):
			return False

		mergelist = self._mergelist

		for i, pkg in enumerate(mergelist):
			if self._is_restart_necessary(pkg) and \
				i != len(mergelist) - 1:
				return True

		return False

	def _is_restart_necessary(self, pkg):
		"""
		@return: True if merging the given package
			requires restart, False otherwise.
		"""

		# Figure out if we need a restart.
		if pkg.root == self._running_root.root and \
			portage.match_from_list(
			portage.const.PORTAGE_PACKAGE_ATOM, [pkg]):
			if self._running_portage:
				return pkg.cpv != self._running_portage.cpv
			return True
		return False

	def _restart_if_necessary(self, pkg):
		"""
		Use execv() to restart emerge. This happens
		if portage upgrades itself and there are
		remaining packages in the list.
		"""

		if self._opts_no_restart.intersection(self.myopts):
			return

		if not self._is_restart_necessary(pkg):
			return

		if pkg == self._mergelist[-1]:
			return

		self._main_loop_cleanup()

		logger = self._logger
		pkg_count = self._pkg_count
		mtimedb = self._mtimedb
		bad_resume_opts = self._bad_resume_opts

		logger.log(" ::: completed emerge (%s of %s) %s to %s" % \
			(pkg_count.curval, pkg_count.maxval, pkg.cpv, pkg.root))

		logger.log(" *** RESTARTING " + \
			"emerge via exec() after change of " + \
			"portage version.")

		mtimedb["resume"]["mergelist"].remove(list(pkg))
		mtimedb.commit()
		portage.run_exitfuncs()
		mynewargv = [sys.argv[0], "--resume"]
		resume_opts = self.myopts.copy()
		# For automatic resume, we need to prevent
		# any of bad_resume_opts from leaking in
		# via EMERGE_DEFAULT_OPTS.
		resume_opts["--ignore-default-opts"] = True
		for myopt, myarg in resume_opts.iteritems():
			if myopt not in bad_resume_opts:
				if myarg is True:
					mynewargv.append(myopt)
				else:
					mynewargv.append(myopt +"="+ str(myarg))
		# priority only needs to be adjusted on the first run
		os.environ["PORTAGE_NICENESS"] = "0"
		os.execv(mynewargv[0], mynewargv)

	def merge(self):

		if "--resume" in self.myopts:
			# We're resuming.
			portage.writemsg_stdout(
				colorize("GOOD", "*** Resuming merge...\n"), noiselevel=-1)
			self._logger.log(" *** Resuming merge...")

		self._save_resume_list()

		try:
			self._background = self._background_mode()
		except self._unknown_internal_error:
			return 1

		for root in self.trees:
			root_config = self.trees[root]["root_config"]

			# Even for --pretend --fetch mode, PORTAGE_TMPDIR is required
			# since it might spawn pkg_nofetch which requires PORTAGE_BUILDDIR
			# for ensuring sane $PWD (bug #239560) and storing elog messages.
			tmpdir = root_config.settings.get("PORTAGE_TMPDIR", "")
			if not tmpdir or not os.path.isdir(tmpdir):
				msg = "The directory specified in your " + \
					"PORTAGE_TMPDIR variable, '%s', " % tmpdir + \
				"does not exist. Please create this " + \
				"directory or correct your PORTAGE_TMPDIR setting."
				msg = textwrap.wrap(msg, 70)
				out = portage.output.EOutput()
				for l in msg:
					out.eerror(l)
				return 1

			if self._background:
				root_config.settings.unlock()
				root_config.settings["PORTAGE_BACKGROUND"] = "1"
				root_config.settings.backup_changes("PORTAGE_BACKGROUND")
				root_config.settings.lock()

			self.pkgsettings[root] = portage.config(
				clone=root_config.settings)

		rval = self._generate_digests()
		if rval != os.EX_OK:
			return rval

		rval = self._check_manifests()
		if rval != os.EX_OK:
			return rval

		keep_going = "--keep-going" in self.myopts
		fetchonly = self._build_opts.fetchonly
		mtimedb = self._mtimedb
		failed_pkgs = self._failed_pkgs

		while True:
			rval = self._merge()
			if rval == os.EX_OK or fetchonly or not keep_going:
				break
			if "resume" not in mtimedb:
				break
			mergelist = self._mtimedb["resume"].get("mergelist")
			if not mergelist:
				break

			if not failed_pkgs:
				break

			for failed_pkg in failed_pkgs:
				mergelist.remove(list(failed_pkg.pkg))

			self._failed_pkgs_all.extend(failed_pkgs)
			del failed_pkgs[:]

			if not mergelist:
				break

			if not self._calc_resume_list():
				break

			clear_caches(self.trees)
			if not self._mergelist:
				break

			self._save_resume_list()
			self._pkg_count.curval = 0
			self._pkg_count.maxval = len([x for x in self._mergelist \
				if isinstance(x, Package) and x.operation == "merge"])
			self._status_display.maxval = self._pkg_count.maxval

		self._logger.log(" *** Finished. Cleaning up...")

		if failed_pkgs:
			self._failed_pkgs_all.extend(failed_pkgs)
			del failed_pkgs[:]

		background = self._background
		failure_log_shown = False
		if background and len(self._failed_pkgs_all) == 1:
			# If only one package failed then just show it's
			# whole log for easy viewing.
			failed_pkg = self._failed_pkgs_all[-1]
			build_dir = failed_pkg.build_dir
			log_file = None

			log_paths = [failed_pkg.build_log]

			log_path = self._locate_failure_log(failed_pkg)
			if log_path is not None:
				try:
					log_file = open(log_path)
				except IOError:
					pass

			if log_file is not None:
				try:
					for line in log_file:
						writemsg_level(line, noiselevel=-1)
				finally:
					log_file.close()
				failure_log_shown = True

		# Dump mod_echo output now since it tends to flood the terminal.
		# This allows us to avoid having more important output, generated
		# later, from being swept away by the mod_echo output.
		mod_echo_output =  _flush_elog_mod_echo()

		if background and not failure_log_shown and \
			self._failed_pkgs_all and \
			self._failed_pkgs_die_msgs and \
			not mod_echo_output:

			printer = portage.output.EOutput()
			for mysettings, key, logentries in self._failed_pkgs_die_msgs:
				root_msg = ""
				if mysettings["ROOT"] != "/":
					root_msg = " merged to %s" % mysettings["ROOT"]
				print
				printer.einfo("Error messages for package %s%s:" % \
					(colorize("INFORM", key), root_msg))
				print
				for phase in portage.const.EBUILD_PHASES:
					if phase not in logentries:
						continue
					for msgtype, msgcontent in logentries[phase]:
						if isinstance(msgcontent, basestring):
							msgcontent = [msgcontent]
						for line in msgcontent:
							printer.eerror(line.strip("\n"))

		if self._post_mod_echo_msgs:
			for msg in self._post_mod_echo_msgs:
				msg()

		if len(self._failed_pkgs_all) > 1 or \
			(self._failed_pkgs_all and "--keep-going" in self.myopts):
			if len(self._failed_pkgs_all) > 1:
				msg = "The following %d packages have " % \
					len(self._failed_pkgs_all) + \
					"failed to build or install:"
			else:
				msg = "The following package has " + \
					"failed to build or install:"
			prefix = bad(" * ")
			writemsg(prefix + "\n", noiselevel=-1)
			from textwrap import wrap
			for line in wrap(msg, 72):
				writemsg("%s%s\n" % (prefix, line), noiselevel=-1)
			writemsg(prefix + "\n", noiselevel=-1)
			for failed_pkg in self._failed_pkgs_all:
				writemsg("%s\t%s\n" % (prefix,
					colorize("INFORM", str(failed_pkg.pkg))),
					noiselevel=-1)
			writemsg(prefix + "\n", noiselevel=-1)

		return rval

	def _elog_listener(self, mysettings, key, logentries, fulltext):
		errors = portage.elog.filter_loglevels(logentries, ["ERROR"])
		if errors:
			self._failed_pkgs_die_msgs.append(
				(mysettings, key, errors))

	def _locate_failure_log(self, failed_pkg):

		build_dir = failed_pkg.build_dir
		log_file = None

		log_paths = [failed_pkg.build_log]

		for log_path in log_paths:
			if not log_path:
				continue

			try:
				log_size = os.stat(log_path).st_size
			except OSError:
				continue

			if log_size == 0:
				continue

			return log_path

		return None

	def _add_packages(self):
		pkg_queue = self._pkg_queue
		for pkg in self._mergelist:
			if isinstance(pkg, Package):
				pkg_queue.append(pkg)
			elif isinstance(pkg, Blocker):
				pass

	def _system_merge_started(self, merge):
		"""
		Add any unsatisfied runtime deps to self._unsatisfied_system_deps.
		"""
		graph = self._digraph
		if graph is None:
			return
		pkg = merge.merge.pkg

		# Skip this if $ROOT != / since it shouldn't matter if there
		# are unsatisfied system runtime deps in this case.
		if pkg.root != '/':
			return

		completed_tasks = self._completed_tasks
		unsatisfied = self._unsatisfied_system_deps

		def ignore_non_runtime_or_satisfied(priority):
			"""
			Ignore non-runtime and satisfied runtime priorities.
			"""
			if isinstance(priority, DepPriority) and \
				not priority.satisfied and \
				(priority.runtime or priority.runtime_post):
				return False
			return True

		# When checking for unsatisfied runtime deps, only check
		# direct deps since indirect deps are checked when the
		# corresponding parent is merged.
		for child in graph.child_nodes(pkg,
			ignore_priority=ignore_non_runtime_or_satisfied):
			if not isinstance(child, Package) or \
				child.operation == 'uninstall':
				continue
			if child is pkg:
				continue
			if child.operation == 'merge' and \
				child not in completed_tasks:
				unsatisfied.add(child)

	def _merge_wait_exit_handler(self, task):
		self._merge_wait_scheduled.remove(task)
		self._merge_exit(task)

	def _merge_exit(self, merge):
		self._do_merge_exit(merge)
		self._deallocate_config(merge.merge.settings)
		if merge.returncode == os.EX_OK and \
			not merge.merge.pkg.installed:
			self._status_display.curval += 1
		self._status_display.merges = len(self._task_queues.merge)
		self._schedule()

	def _do_merge_exit(self, merge):
		pkg = merge.merge.pkg
		if merge.returncode != os.EX_OK:
			settings = merge.merge.settings
			build_dir = settings.get("PORTAGE_BUILDDIR")
			build_log = settings.get("PORTAGE_LOG_FILE")

			self._failed_pkgs.append(self._failed_pkg(
				build_dir=build_dir, build_log=build_log,
				pkg=pkg,
				returncode=merge.returncode))
			self._failed_pkg_msg(self._failed_pkgs[-1], "install", "to")

			self._status_display.failed = len(self._failed_pkgs)
			return

		self._task_complete(pkg)
		pkg_to_replace = merge.merge.pkg_to_replace
		if pkg_to_replace is not None:
			# When a package is replaced, mark it's uninstall
			# task complete (if any).
			uninst_hash_key = \
				("installed", pkg.root, pkg_to_replace.cpv, "uninstall")
			self._task_complete(uninst_hash_key)

		if pkg.installed:
			return

		self._restart_if_necessary(pkg)

		# Call mtimedb.commit() after each merge so that
		# --resume still works after being interrupted
		# by reboot, sigkill or similar.
		mtimedb = self._mtimedb
		mtimedb["resume"]["mergelist"].remove(list(pkg))
		if not mtimedb["resume"]["mergelist"]:
			del mtimedb["resume"]
		mtimedb.commit()

	def _build_exit(self, build):
		if build.returncode == os.EX_OK:
			self.curval += 1
			merge = PackageMerge(merge=build)
			if not build.build_opts.buildpkgonly and \
				build.pkg in self._deep_system_deps:
				# Since dependencies on system packages are frequently
				# unspecified, merge them only when no builds are executing.
				self._merge_wait_queue.append(merge)
				merge.addStartListener(self._system_merge_started)
			else:
				merge.addExitListener(self._merge_exit)
				self._task_queues.merge.add(merge)
				self._status_display.merges = len(self._task_queues.merge)
		else:
			settings = build.settings
			build_dir = settings.get("PORTAGE_BUILDDIR")
			build_log = settings.get("PORTAGE_LOG_FILE")

			self._failed_pkgs.append(self._failed_pkg(
				build_dir=build_dir, build_log=build_log,
				pkg=build.pkg,
				returncode=build.returncode))
			self._failed_pkg_msg(self._failed_pkgs[-1], "emerge", "for")

			self._status_display.failed = len(self._failed_pkgs)
			self._deallocate_config(build.settings)
		self._jobs -= 1
		self._status_display.running = self._jobs
		self._schedule()

	def _extract_exit(self, build):
		self._build_exit(build)

	def _task_complete(self, pkg):
		self._completed_tasks.add(pkg)
		self._unsatisfied_system_deps.discard(pkg)
		self._choose_pkg_return_early = False

	def _merge(self):

		self._add_prefetchers()
		self._add_packages()
		pkg_queue = self._pkg_queue
		failed_pkgs = self._failed_pkgs
		portage.locks._quiet = self._background
		portage.elog._emerge_elog_listener = self._elog_listener
		rval = os.EX_OK

		try:
			self._main_loop()
		finally:
			self._main_loop_cleanup()
			portage.locks._quiet = False
			portage.elog._emerge_elog_listener = None
			if failed_pkgs:
				rval = failed_pkgs[-1].returncode

		return rval

	def _main_loop_cleanup(self):
		del self._pkg_queue[:]
		self._completed_tasks.clear()
		self._deep_system_deps.clear()
		self._unsatisfied_system_deps.clear()
		self._choose_pkg_return_early = False
		self._status_display.reset()
		self._digraph = None
		self._task_queues.fetch.clear()

	def _choose_pkg(self):
		"""
		Choose a task that has all it's dependencies satisfied.
		"""

		if self._choose_pkg_return_early:
			return None

		if self._digraph is None:
			if (self._jobs or self._task_queues.merge) and \
				not ("--nodeps" in self.myopts and \
				(self._max_jobs is True or self._max_jobs > 1)):
				self._choose_pkg_return_early = True
				return None
			return self._pkg_queue.pop(0)

		if not (self._jobs or self._task_queues.merge):
			return self._pkg_queue.pop(0)

		self._prune_digraph()

		chosen_pkg = None
		later = set(self._pkg_queue)
		for pkg in self._pkg_queue:
			later.remove(pkg)
			if not self._dependent_on_scheduled_merges(pkg, later):
				chosen_pkg = pkg
				break

		if chosen_pkg is not None:
			self._pkg_queue.remove(chosen_pkg)

		if chosen_pkg is None:
			# There's no point in searching for a package to
			# choose until at least one of the existing jobs
			# completes.
			self._choose_pkg_return_early = True

		return chosen_pkg

	def _dependent_on_scheduled_merges(self, pkg, later):
		"""
		Traverse the subgraph of the given packages deep dependencies
		to see if it contains any scheduled merges.
		@param pkg: a package to check dependencies for
		@type pkg: Package
		@param later: packages for which dependence should be ignored
			since they will be merged later than pkg anyway and therefore
			delaying the merge of pkg will not result in a more optimal
			merge order
		@type later: set
		@rtype: bool
		@returns: True if the package is dependent, False otherwise.
		"""

		graph = self._digraph
		completed_tasks = self._completed_tasks

		dependent = False
		traversed_nodes = set([pkg])
		direct_deps = graph.child_nodes(pkg)
		node_stack = direct_deps
		direct_deps = frozenset(direct_deps)
		while node_stack:
			node = node_stack.pop()
			if node in traversed_nodes:
				continue
			traversed_nodes.add(node)
			if not ((node.installed and node.operation == "nomerge") or \
				(node.operation == "uninstall" and \
				node not in direct_deps) or \
				node in completed_tasks or \
				node in later):
				dependent = True
				break
			node_stack.extend(graph.child_nodes(node))

		return dependent

	def _allocate_config(self, root):
		"""
		Allocate a unique config instance for a task in order
		to prevent interference between parallel tasks.
		"""
		if self._config_pool[root]:
			temp_settings = self._config_pool[root].pop()
		else:
			temp_settings = portage.config(clone=self.pkgsettings[root])
		# Since config.setcpv() isn't guaranteed to call config.reset() due to
		# performance reasons, call it here to make sure all settings from the
		# previous package get flushed out (such as PORTAGE_LOG_FILE).
		temp_settings.reload()
		temp_settings.reset()
		return temp_settings

	def _deallocate_config(self, settings):
		self._config_pool[settings["ROOT"]].append(settings)

	def _main_loop(self):

		# Only allow 1 job max if a restart is scheduled
		# due to portage update.
		if self._is_restart_scheduled() or \
			self._opts_no_background.intersection(self.myopts):
			self._set_max_jobs(1)

		merge_queue = self._task_queues.merge

		while self._schedule():
			if self._poll_event_handlers:
				self._poll_loop()

		while True:
			self._schedule()
			if not (self._jobs or merge_queue):
				break
			if self._poll_event_handlers:
				self._poll_loop()

	def _keep_scheduling(self):
		return bool(self._pkg_queue and \
			not (self._failed_pkgs and not self._build_opts.fetchonly))

	def _schedule_tasks(self):

		# When the number of jobs drops to zero, process all waiting merges.
		if not self._jobs and self._merge_wait_queue:
			for task in self._merge_wait_queue:
				task.addExitListener(self._merge_wait_exit_handler)
				self._task_queues.merge.add(task)
			self._status_display.merges = len(self._task_queues.merge)
			self._merge_wait_scheduled.extend(self._merge_wait_queue)
			del self._merge_wait_queue[:]

		self._schedule_tasks_imp()
		self._status_display.display()

		state_change = 0
		for q in self._task_queues.values():
			if q.schedule():
				state_change += 1

		# Cancel prefetchers if they're the only reason
		# the main poll loop is still running.
		if self._failed_pkgs and not self._build_opts.fetchonly and \
			not (self._jobs or self._task_queues.merge) and \
			self._task_queues.fetch:
			self._task_queues.fetch.clear()
			state_change += 1

		if state_change:
			self._schedule_tasks_imp()
			self._status_display.display()

		return self._keep_scheduling()

	def _job_delay(self):
		"""
		@rtype: bool
		@returns: True if job scheduling should be delayed, False otherwise.
		"""

		if self._jobs and self._max_load is not None:

			current_time = time.time()

			delay = self._job_delay_factor * self._jobs ** self._job_delay_exp
			if delay > self._job_delay_max:
				delay = self._job_delay_max
			if (current_time - self._previous_job_start_time) < delay:
				return True

		return False

	def _schedule_tasks_imp(self):
		"""
		@rtype: bool
		@returns: True if state changed, False otherwise.
		"""

		state_change = 0

		while True:

			if not self._keep_scheduling():
				return bool(state_change)

			if self._choose_pkg_return_early or \
				self._merge_wait_scheduled or \
				(self._jobs and self._unsatisfied_system_deps) or \
				not self._can_add_job() or \
				self._job_delay():
				return bool(state_change)

			pkg = self._choose_pkg()
			if pkg is None:
				return bool(state_change)

			state_change += 1

			if not pkg.installed:
				self._pkg_count.curval += 1

			task = self._task(pkg)

			if pkg.installed:
				merge = PackageMerge(merge=task)
				merge.addExitListener(self._merge_exit)
				self._task_queues.merge.add(merge)

			elif pkg.built:
				self._jobs += 1
				self._previous_job_start_time = time.time()
				self._status_display.running = self._jobs
				task.addExitListener(self._extract_exit)
				self._task_queues.jobs.add(task)

			else:
				self._jobs += 1
				self._previous_job_start_time = time.time()
				self._status_display.running = self._jobs
				task.addExitListener(self._build_exit)
				self._task_queues.jobs.add(task)

		return bool(state_change)

	def _task(self, pkg):

		pkg_to_replace = None
		if pkg.operation != "uninstall":
			vardb = pkg.root_config.trees["vartree"].dbapi
			previous_cpv = vardb.match(pkg.slot_atom)
			if previous_cpv:
				previous_cpv = previous_cpv.pop()
				pkg_to_replace = self._pkg(previous_cpv,
					"installed", pkg.root_config, installed=True)

		task = MergeListItem(args_set=self._args_set,
			background=self._background, binpkg_opts=self._binpkg_opts,
			build_opts=self._build_opts,
			config_pool=self._ConfigPool(pkg.root,
			self._allocate_config, self._deallocate_config),
			emerge_opts=self.myopts,
			find_blockers=self._find_blockers(pkg), logger=self._logger,
			mtimedb=self._mtimedb, pkg=pkg, pkg_count=self._pkg_count.copy(),
			pkg_to_replace=pkg_to_replace,
			prefetcher=self._prefetchers.get(pkg),
			scheduler=self._sched_iface,
			settings=self._allocate_config(pkg.root),
			statusMessage=self._status_msg,
			world_atom=self._world_atom)

		return task

	def _failed_pkg_msg(self, failed_pkg, action, preposition):
		pkg = failed_pkg.pkg
		msg = "%s to %s %s" % \
			(bad("Failed"), action, colorize("INFORM", pkg.cpv))
		if pkg.root != "/":
			msg += " %s %s" % (preposition, pkg.root)

		log_path = self._locate_failure_log(failed_pkg)
		if log_path is not None:
			msg += ", Log file:"
		self._status_msg(msg)

		if log_path is not None:
			self._status_msg(" '%s'" % (colorize("INFORM", log_path),))

	def _status_msg(self, msg):
		"""
		Display a brief status message (no newlines) in the status display.
		This is called by tasks to provide feedback to the user. This
		delegates the resposibility of generating \r and \n control characters,
		to guarantee that lines are created or erased when necessary and
		appropriate.

		@type msg: str
		@param msg: a brief status message (no newlines allowed)
		"""
		if not self._background:
			writemsg_level("\n")
		self._status_display.displayMessage(msg)

	def _save_resume_list(self):
		"""
		Do this before verifying the ebuild Manifests since it might
		be possible for the user to use --resume --skipfirst get past
		a non-essential package with a broken digest.
		"""
		mtimedb = self._mtimedb
		mtimedb["resume"]["mergelist"] = [list(x) \
			for x in self._mergelist \
			if isinstance(x, Package) and x.operation == "merge"]

		mtimedb.commit()

	def _calc_resume_list(self):
		"""
		Use the current resume list to calculate a new one,
		dropping any packages with unsatisfied deps.
		@rtype: bool
		@returns: True if successful, False otherwise.
		"""
		print colorize("GOOD", "*** Resuming merge...")

		if self._show_list():
			if "--tree" in self.myopts:
				portage.writemsg_stdout("\n" + \
					darkgreen("These are the packages that " + \
					"would be merged, in reverse order:\n\n"))

			else:
				portage.writemsg_stdout("\n" + \
					darkgreen("These are the packages that " + \
					"would be merged, in order:\n\n"))

		show_spinner = "--quiet" not in self.myopts and \
			"--nodeps" not in self.myopts

		if show_spinner:
			print "Calculating dependencies  ",

		myparams = create_depgraph_params(self.myopts, None)
		success = False
		e = None
		try:
			success, mydepgraph, dropped_tasks = resume_depgraph(
				self.settings, self.trees, self._mtimedb, self.myopts,
				myparams, self._spinner)
		except depgraph.UnsatisfiedResumeDep, exc:
			# rename variable to avoid python-3.0 error:
			# SyntaxError: can not delete variable 'e' referenced in nested
			#              scope
			e = exc
			mydepgraph = e.depgraph
			dropped_tasks = set()

		if show_spinner:
			print "\b\b... done!"

		if e is not None:
			def unsatisfied_resume_dep_msg():
				mydepgraph.display_problems()
				out = portage.output.EOutput()
				out.eerror("One or more packages are either masked or " + \
					"have missing dependencies:")
				out.eerror("")
				indent = "  "
				show_parents = set()
				for dep in e.value:
					if dep.parent in show_parents:
						continue
					show_parents.add(dep.parent)
					if dep.atom is None:
						out.eerror(indent + "Masked package:")
						out.eerror(2 * indent + str(dep.parent))
						out.eerror("")
					else:
						out.eerror(indent + str(dep.atom) + " pulled in by:")
						out.eerror(2 * indent + str(dep.parent))
						out.eerror("")
				msg = "The resume list contains packages " + \
					"that are either masked or have " + \
					"unsatisfied dependencies. " + \
					"Please restart/continue " + \
					"the operation manually, or use --skipfirst " + \
					"to skip the first package in the list and " + \
					"any other packages that may be " + \
					"masked or have missing dependencies."
				for line in textwrap.wrap(msg, 72):
					out.eerror(line)
			self._post_mod_echo_msgs.append(unsatisfied_resume_dep_msg)
			return False

		if success and self._show_list():
			mylist = mydepgraph.altlist()
			if mylist:
				if "--tree" in self.myopts:
					mylist.reverse()
				mydepgraph.display(mylist, favorites=self._favorites)

		if not success:
			self._post_mod_echo_msgs.append(mydepgraph.display_problems)
			return False
		mydepgraph.display_problems()

		mylist = mydepgraph.altlist()
		mydepgraph.break_refs(mylist)
		mydepgraph.break_refs(dropped_tasks)
		self._mergelist = mylist
		self._set_digraph(mydepgraph.schedulerGraph())

		msg_width = 75
		for task in dropped_tasks:
			if not (isinstance(task, Package) and task.operation == "merge"):
				continue
			pkg = task
			msg = "emerge --keep-going:" + \
				" %s" % (pkg.cpv,)
			if pkg.root != "/":
				msg += " for %s" % (pkg.root,)
			msg += " dropped due to unsatisfied dependency."
			for line in textwrap.wrap(msg, msg_width):
				eerror(line, phase="other", key=pkg.cpv)
			settings = self.pkgsettings[pkg.root]
			# Ensure that log collection from $T is disabled inside
			# elog_process(), since any logs that might exist are
			# not valid here.
			settings.pop("T", None)
			portage.elog.elog_process(pkg.cpv, settings)
			self._failed_pkgs_all.append(self._failed_pkg(pkg=pkg))

		return True

	def _show_list(self):
		myopts = self.myopts
		if "--quiet" not in myopts and \
			("--ask" in myopts or "--tree" in myopts or \
			"--verbose" in myopts):
			return True
		return False

	def _world_atom(self, pkg):
		"""
		Add the package to the world file, but only if
		it's supposed to be added. Otherwise, do nothing.
		"""

		if set(("--buildpkgonly", "--fetchonly",
			"--fetch-all-uri",
			"--oneshot", "--onlydeps",
			"--pretend")).intersection(self.myopts):
			return

		if pkg.root != self.target_root:
			return

		args_set = self._args_set
		if not args_set.findAtomForPackage(pkg):
			return

		logger = self._logger
		pkg_count = self._pkg_count
		root_config = pkg.root_config
		world_set = root_config.sets["world"]
		world_locked = False
		if hasattr(world_set, "lock"):
			world_set.lock()
			world_locked = True

		try:
			if hasattr(world_set, "load"):
				world_set.load() # maybe it's changed on disk

			atom = create_world_atom(pkg, args_set, root_config)
			if atom:
				if hasattr(world_set, "add"):
					self._status_msg(('Recording %s in "world" ' + \
						'favorites file...') % atom)
					logger.log(" === (%s of %s) Updating world file (%s)" % \
						(pkg_count.curval, pkg_count.maxval, pkg.cpv))
					world_set.add(atom)
				else:
					writemsg_level('\n!!! Unable to record %s in "world"\n' % \
						(atom,), level=logging.WARN, noiselevel=-1)
		finally:
			if world_locked:
				world_set.unlock()

	def _pkg(self, cpv, type_name, root_config, installed=False):
		"""
		Get a package instance from the cache, or create a new
		one if necessary. Raises KeyError from aux_get if it
		failures for some reason (package does not exist or is
		corrupt).
		"""
		operation = "merge"
		if installed:
			operation = "nomerge"

		if self._digraph is not None:
			# Reuse existing instance when available.
			pkg = self._digraph.get(
				(type_name, root_config.root, cpv, operation))
			if pkg is not None:
				return pkg

		tree_type = depgraph.pkg_tree_map[type_name]
		db = root_config.trees[tree_type].dbapi
		db_keys = list(self.trees[root_config.root][
			tree_type].dbapi._aux_cache_keys)
		metadata = izip(db_keys, db.aux_get(cpv, db_keys))
		pkg = Package(cpv=cpv, metadata=metadata,
			root_config=root_config, installed=installed)
		if type_name == "ebuild":
			settings = self.pkgsettings[root_config.root]
			settings.setcpv(pkg)
			pkg.metadata["USE"] = settings["PORTAGE_USE"]
			pkg.metadata['CHOST'] = settings.get('CHOST', '')

		return pkg




import gc

try:
	import portage
except ImportError:
	from os import path as osp
	import sys
	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	import portage

def clear_caches(trees):
	for d in trees.itervalues():
		d["porttree"].dbapi.melt()
		d["porttree"].dbapi._aux_cache.clear()
		d["bintree"].dbapi._aux_cache.clear()
		d["bintree"].dbapi._clear_cache()
		d["vartree"].dbapi.linkmap._clear_cache()
	portage.dircache.clear()
	gc.collect()




def _flush_elog_mod_echo():
	"""
	Dump the mod_echo output now so that our other
	notifications are shown last.
	@rtype: bool
	@returns: True if messages were shown, False otherwise.
	"""
	messages_shown = False
	try:
		from portage.elog import mod_echo
	except ImportError:
		pass # happens during downgrade to a version without the module
	else:
		messages_shown = bool(mod_echo._items)
		mod_echo.finalize()
	return messages_shown





import gc
import os
import re
import sys
import textwrap
from itertools import chain, izip

try:
	import portage
except ImportError:
	from os import path as osp
	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	import portage

from portage import digraph
from portage.output import bold, blue, colorize, create_color_func, darkblue, \
	darkgreen, green, nc_len, red, teal, turquoise, yellow
bad = create_color_func("BAD")
from portage.sets import SETPREFIX
from portage.sets.base import InternalPackageSet
from portage.util import cmp_sort_key, writemsg

from _emerge.AtomArg import AtomArg
from _emerge.Blocker import Blocker
from _emerge.BlockerCache import BlockerCache
from _emerge.BlockerDepPriority import BlockerDepPriority
from _emerge.countdown import countdown
from _emerge.create_world_atom import create_world_atom
from _emerge.Dependency import Dependency
from _emerge.DependencyArg import DependencyArg
from _emerge.DepPriority import DepPriority
from _emerge.DepPriorityNormalRange import DepPriorityNormalRange
from _emerge.DepPrioritySatisfiedRange import DepPrioritySatisfiedRange
from _emerge.FakeVartree import FakeVartree
from _emerge._find_deep_system_runtime_deps import _find_deep_system_runtime_deps
from _emerge.format_size import format_size
from _emerge.is_valid_package_atom import is_valid_package_atom
from _emerge.Package import Package
from _emerge.PackageArg import PackageArg
from _emerge.PackageCounters import PackageCounters
from _emerge.PackageVirtualDbapi import PackageVirtualDbapi
from _emerge.RepoDisplay import RepoDisplay
from _emerge.RootConfig import RootConfig
from _emerge.search import search
from _emerge.SetArg import SetArg
from _emerge.show_invalid_depstring_notice import show_invalid_depstring_notice
from _emerge.UnmergeDepPriority import UnmergeDepPriority
from _emerge.visible import visible

import portage.proxy.lazyimport
import portage.proxy as proxy
proxy.lazyimport.lazyimport(globals(),
	'_emerge.Scheduler:Scheduler',
)
#from _emerge.Scheduler import Scheduler
class depgraph(object):

	pkg_tree_map = RootConfig.pkg_tree_map

	_dep_keys = ["DEPEND", "RDEPEND", "PDEPEND"]

	def __init__(self, settings, trees, myopts, myparams, spinner):
		self.settings = settings
		self.target_root = settings["ROOT"]
		self.myopts = myopts
		self.myparams = myparams
		self.edebug = 0
		if settings.get("PORTAGE_DEBUG", "") == "1":
			self.edebug = 1
		self.spinner = spinner
		self._running_root = trees["/"]["root_config"]
		self._opts_no_restart = Scheduler._opts_no_restart
		self.pkgsettings = {}
		# Maps slot atom to package for each Package added to the graph.
		self._slot_pkg_map = {}
		# Maps nodes to the reasons they were selected for reinstallation.
		self._reinstall_nodes = {}
		self.mydbapi = {}
		self.trees = {}
		self._trees_orig = trees
		self.roots = {}
		# Contains a filtered view of preferred packages that are selected
		# from available repositories.
		self._filtered_trees = {}
		# Contains installed packages and new packages that have been added
		# to the graph.
		self._graph_trees = {}
		# All Package instances
		self._pkg_cache = {}
		for myroot in trees:
			self.trees[myroot] = {}
			# Create a RootConfig instance that references
			# the FakeVartree instead of the real one.
			self.roots[myroot] = RootConfig(
				trees[myroot]["vartree"].settings,
				self.trees[myroot],
				trees[myroot]["root_config"].setconfig)
			for tree in ("porttree", "bintree"):
				self.trees[myroot][tree] = trees[myroot][tree]
			self.trees[myroot]["vartree"] = \
				FakeVartree(trees[myroot]["root_config"],
					pkg_cache=self._pkg_cache)
			self.pkgsettings[myroot] = portage.config(
				clone=self.trees[myroot]["vartree"].settings)
			self._slot_pkg_map[myroot] = {}
			vardb = self.trees[myroot]["vartree"].dbapi
			preload_installed_pkgs = "--nodeps" not in self.myopts and \
				"--buildpkgonly" not in self.myopts
			# This fakedbapi instance will model the state that the vdb will
			# have after new packages have been installed.
			fakedb = PackageVirtualDbapi(vardb.settings)
			if preload_installed_pkgs:
				for pkg in vardb:
					self.spinner.update()
					# This triggers metadata updates via FakeVartree.
					vardb.aux_get(pkg.cpv, [])
					fakedb.cpv_inject(pkg)

			# Now that the vardb state is cached in our FakeVartree,
			# we won't be needing the real vartree cache for awhile.
			# To make some room on the heap, clear the vardbapi
			# caches.
			trees[myroot]["vartree"].dbapi._clear_cache()
			gc.collect()

			self.mydbapi[myroot] = fakedb
			def graph_tree():
				pass
			graph_tree.dbapi = fakedb
			self._graph_trees[myroot] = {}
			self._filtered_trees[myroot] = {}
			# Substitute the graph tree for the vartree in dep_check() since we
			# want atom selections to be consistent with package selections
			# have already been made.
			self._graph_trees[myroot]["porttree"]   = graph_tree
			self._graph_trees[myroot]["vartree"]    = graph_tree
			def filtered_tree():
				pass
			filtered_tree.dbapi = self._dep_check_composite_db(self, myroot)
			self._filtered_trees[myroot]["porttree"] = filtered_tree

			# Passing in graph_tree as the vartree here could lead to better
			# atom selections in some cases by causing atoms for packages that
			# have been added to the graph to be preferred over other choices.
			# However, it can trigger atom selections that result in
			# unresolvable direct circular dependencies. For example, this
			# happens with gwydion-dylan which depends on either itself or
			# gwydion-dylan-bin. In case gwydion-dylan is not yet installed,
			# gwydion-dylan-bin needs to be selected in order to avoid a
			# an unresolvable direct circular dependency.
			#
			# To solve the problem described above, pass in "graph_db" so that
			# packages that have been added to the graph are distinguishable
			# from other available packages and installed packages. Also, pass
			# the parent package into self._select_atoms() calls so that
			# unresolvable direct circular dependencies can be detected and
			# avoided when possible.
			self._filtered_trees[myroot]["graph_db"] = graph_tree.dbapi
			self._filtered_trees[myroot]["vartree"] = self.trees[myroot]["vartree"]

			dbs = []
			portdb = self.trees[myroot]["porttree"].dbapi
			bindb  = self.trees[myroot]["bintree"].dbapi
			vardb  = self.trees[myroot]["vartree"].dbapi
			#               (db, pkg_type, built, installed, db_keys)
			if "--usepkgonly" not in self.myopts:
				db_keys = list(portdb._aux_cache_keys)
				dbs.append((portdb, "ebuild", False, False, db_keys))
			if "--usepkg" in self.myopts:
				db_keys = list(bindb._aux_cache_keys)
				dbs.append((bindb,  "binary", True, False, db_keys))
			db_keys = list(trees[myroot]["vartree"].dbapi._aux_cache_keys)
			dbs.append((vardb, "installed", True, True, db_keys))
			self._filtered_trees[myroot]["dbs"] = dbs
			if "--usepkg" in self.myopts:
				self.trees[myroot]["bintree"].populate(
					"--getbinpkg" in self.myopts,
					"--getbinpkgonly" in self.myopts)
		del trees

		self.digraph=portage.digraph()
		# contains all sets added to the graph
		self._sets = {}
		# contains atoms given as arguments
		self._sets["args"] = InternalPackageSet()
		# contains all atoms from all sets added to the graph, including
		# atoms given as arguments
		self._set_atoms = InternalPackageSet()
		self._atom_arg_map = {}
		# contains all nodes pulled in by self._set_atoms
		self._set_nodes = set()
		# Contains only Blocker -> Uninstall edges
		self._blocker_uninstalls = digraph()
		# Contains only Package -> Blocker edges
		self._blocker_parents = digraph()
		# Contains only irrelevant Package -> Blocker edges
		self._irrelevant_blockers = digraph()
		# Contains only unsolvable Package -> Blocker edges
		self._unsolvable_blockers = digraph()
		# Contains all Blocker -> Blocked Package edges
		self._blocked_pkgs = digraph()
		# Contains world packages that have been protected from
		# uninstallation but may not have been added to the graph
		# if the graph is not complete yet.
		self._blocked_world_pkgs = {}
		self._slot_collision_info = {}
		# Slot collision nodes are not allowed to block other packages since
		# blocker validation is only able to account for one package per slot.
		self._slot_collision_nodes = set()
		self._parent_atoms = {}
		self._slot_conflict_parent_atoms = set()
		self._serialized_tasks_cache = None
		self._scheduler_graph = None
		self._displayed_list = None
		self._pprovided_args = []
		self._missing_args = []
		self._masked_installed = set()
		self._unsatisfied_deps_for_display = []
		self._unsatisfied_blockers_for_display = None
		self._circular_deps_for_display = None
		self._dep_stack = []
		self._dep_disjunctive_stack = []
		self._unsatisfied_deps = []
		self._initially_unsatisfied_deps = []
		self._ignored_deps = []
		self._required_set_names = set(["system", "world"])
		self._select_atoms = self._select_atoms_highest_available
		self._select_package = self._select_pkg_highest_available
		self._highest_pkg_cache = {}

	def _show_slot_collision_notice(self):
		"""Show an informational message advising the user to mask one of the
		the packages. In some cases it may be possible to resolve this
		automatically, but support for backtracking (removal nodes that have
		already been selected) will be required in order to handle all possible
		cases.
		"""

		if not self._slot_collision_info:
			return

		self._show_merge_list()

		msg = []
		msg.append("\n!!! Multiple package instances within a single " + \
			"package slot have been pulled\n")
		msg.append("!!! into the dependency graph, resulting" + \
			" in a slot conflict:\n\n")
		indent = "  "
		# Max number of parents shown, to avoid flooding the display.
		max_parents = 3
		explanation_columns = 70
		explanations = 0
		for (slot_atom, root), slot_nodes \
			in self._slot_collision_info.iteritems():
			msg.append(str(slot_atom))
			msg.append("\n\n")

			for node in slot_nodes:
				msg.append(indent)
				msg.append(str(node))
				parent_atoms = self._parent_atoms.get(node)
				if parent_atoms:
					pruned_list = set()
					# Prefer conflict atoms over others.
					for parent_atom in parent_atoms:
						if len(pruned_list) >= max_parents:
							break
						if parent_atom in self._slot_conflict_parent_atoms:
							pruned_list.add(parent_atom)

					# If this package was pulled in by conflict atoms then
					# show those alone since those are the most interesting.
					if not pruned_list:
						# When generating the pruned list, prefer instances
						# of DependencyArg over instances of Package.
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							parent, atom = parent_atom
							if isinstance(parent, DependencyArg):
								pruned_list.add(parent_atom)
						# Prefer Packages instances that themselves have been
						# pulled into collision slots.
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							parent, atom = parent_atom
							if isinstance(parent, Package) and \
								(parent.slot_atom, parent.root) \
								in self._slot_collision_info:
								pruned_list.add(parent_atom)
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							pruned_list.add(parent_atom)
					omitted_parents = len(parent_atoms) - len(pruned_list)
					parent_atoms = pruned_list
					msg.append(" pulled in by\n")
					for parent_atom in parent_atoms:
						parent, atom = parent_atom
						msg.append(2*indent)
						if isinstance(parent,
							(PackageArg, AtomArg)):
							# For PackageArg and AtomArg types, it's
							# redundant to display the atom attribute.
							msg.append(str(parent))
						else:
							# Display the specific atom from SetArg or
							# Package types.
							msg.append("%s required by %s" % (atom, parent))
						msg.append("\n")
					if omitted_parents:
						msg.append(2*indent)
						msg.append("(and %d more)\n" % omitted_parents)
				else:
					msg.append(" (no parents)\n")
				msg.append("\n")
			explanation = self._slot_conflict_explanation(slot_nodes)
			if explanation:
				explanations += 1
				msg.append(indent + "Explanation:\n\n")
				for line in textwrap.wrap(explanation, explanation_columns):
					msg.append(2*indent + line + "\n")
				msg.append("\n")
		msg.append("\n")
		sys.stderr.write("".join(msg))
		sys.stderr.flush()

		explanations_for_all = explanations == len(self._slot_collision_info)

		if explanations_for_all or "--quiet" in self.myopts:
			return

		msg = []
		msg.append("It may be possible to solve this problem ")
		msg.append("by using package.mask to prevent one of ")
		msg.append("those packages from being selected. ")
		msg.append("However, it is also possible that conflicting ")
		msg.append("dependencies exist such that they are impossible to ")
		msg.append("satisfy simultaneously.  If such a conflict exists in ")
		msg.append("the dependencies of two different packages, then those ")
		msg.append("packages can not be installed simultaneously.")

		from formatter import AbstractFormatter, DumbWriter
		f = AbstractFormatter(DumbWriter(sys.stderr, maxcol=72))
		for x in msg:
			f.add_flowing_data(x)
		f.end_paragraph(1)

		msg = []
		msg.append("For more information, see MASKED PACKAGES ")
		msg.append("section in the emerge man page or refer ")
		msg.append("to the Gentoo Handbook.")
		for x in msg:
			f.add_flowing_data(x)
		f.end_paragraph(1)
		f.writer.flush()

	def _slot_conflict_explanation(self, slot_nodes):
		"""
		When a slot conflict occurs due to USE deps, there are a few
		different cases to consider:

		1) New USE are correctly set but --newuse wasn't requested so an
		   installed package with incorrect USE happened to get pulled
		   into graph before the new one.

		2) New USE are incorrectly set but an installed package has correct
		   USE so it got pulled into the graph, and a new instance also got
		   pulled in due to --newuse or an upgrade.

		3) Multiple USE deps exist that can't be satisfied simultaneously,
		   and multiple package instances got pulled into the same slot to
		   satisfy the conflicting deps.

		Currently, explanations and suggested courses of action are generated
		for cases 1 and 2. Case 3 is too complex to give a useful suggestion.
		"""

		if len(slot_nodes) != 2:
			# Suggestions are only implemented for
			# conflicts between two packages.
			return None

		all_conflict_atoms = self._slot_conflict_parent_atoms
		matched_node = None
		matched_atoms = None
		unmatched_node = None
		for node in slot_nodes:
			parent_atoms = self._parent_atoms.get(node)
			if not parent_atoms:
				# Normally, there are always parent atoms. If there are
				# none then something unexpected is happening and there's
				# currently no suggestion for this case.
				return None
			conflict_atoms = all_conflict_atoms.intersection(parent_atoms)
			for parent_atom in conflict_atoms:
				parent, atom = parent_atom
				if not atom.use:
					# Suggestions are currently only implemented for cases
					# in which all conflict atoms have USE deps.
					return None
			if conflict_atoms:
				if matched_node is not None:
					# If conflict atoms match multiple nodes
					# then there's no suggestion.
					return None
				matched_node = node
				matched_atoms = conflict_atoms
			else:
				if unmatched_node is not None:
					# Neither node is matched by conflict atoms, and
					# there is no suggestion for this case.
					return None
				unmatched_node = node

		if matched_node is None or unmatched_node is None:
			# This shouldn't happen.
			return None

		if unmatched_node.installed and not matched_node.installed and \
			unmatched_node.cpv == matched_node.cpv:
			# If the conflicting packages are the same version then
			# --newuse should be all that's needed. If they are different
			# versions then there's some other problem.
			return "New USE are correctly set, but --newuse wasn't" + \
				" requested, so an installed package with incorrect USE " + \
				"happened to get pulled into the dependency graph. " + \
				"In order to solve " + \
				"this, either specify the --newuse option or explicitly " + \
				" reinstall '%s'." % matched_node.slot_atom

		if matched_node.installed and not unmatched_node.installed:
			atoms = sorted(set(atom for parent, atom in matched_atoms))
			explanation = ("New USE for '%s' are incorrectly set. " + \
				"In order to solve this, adjust USE to satisfy '%s'") % \
				(matched_node.slot_atom, atoms[0])
			if len(atoms) > 1:
				for atom in atoms[1:-1]:
					explanation += ", '%s'" % (atom,)
				if len(atoms) > 2:
					explanation += ","
				explanation += " and '%s'" % (atoms[-1],)
			explanation += "."
			return explanation

		return None

	def _process_slot_conflicts(self):
		"""
		Process slot conflict data to identify specific atoms which
		lead to conflict. These atoms only match a subset of the
		packages that have been pulled into a given slot.
		"""
		for (slot_atom, root), slot_nodes \
			in self._slot_collision_info.iteritems():

			all_parent_atoms = set()
			for pkg in slot_nodes:
				parent_atoms = self._parent_atoms.get(pkg)
				if not parent_atoms:
					continue
				all_parent_atoms.update(parent_atoms)

			for pkg in slot_nodes:
				parent_atoms = self._parent_atoms.get(pkg)
				if parent_atoms is None:
					parent_atoms = set()
					self._parent_atoms[pkg] = parent_atoms
				for parent_atom in all_parent_atoms:
					if parent_atom in parent_atoms:
						continue
					# Use package set for matching since it will match via
					# PROVIDE when necessary, while match_from_list does not.
					parent, atom = parent_atom
					atom_set = InternalPackageSet(
						initial_atoms=(atom,))
					if atom_set.findAtomForPackage(pkg):
						parent_atoms.add(parent_atom)
					else:
						self._slot_conflict_parent_atoms.add(parent_atom)

	def _reinstall_for_flags(self, forced_flags,
		orig_use, orig_iuse, cur_use, cur_iuse):
		"""Return a set of flags that trigger reinstallation, or None if there
		are no such flags."""
		if "--newuse" in self.myopts:
			flags = set(orig_iuse.symmetric_difference(
				cur_iuse).difference(forced_flags))
			flags.update(orig_iuse.intersection(orig_use).symmetric_difference(
				cur_iuse.intersection(cur_use)))
			if flags:
				return flags
		elif "changed-use" == self.myopts.get("--reinstall"):
			flags = orig_iuse.intersection(orig_use).symmetric_difference(
				cur_iuse.intersection(cur_use))
			if flags:
				return flags
		return None

	def _create_graph(self, allow_unsatisfied=False):
		dep_stack = self._dep_stack
		dep_disjunctive_stack = self._dep_disjunctive_stack
		while dep_stack or dep_disjunctive_stack:
			self.spinner.update()
			while dep_stack:
				dep = dep_stack.pop()
				if isinstance(dep, Package):
					if not self._add_pkg_deps(dep,
						allow_unsatisfied=allow_unsatisfied):
						return 0
					continue
				if not self._add_dep(dep, allow_unsatisfied=allow_unsatisfied):
					return 0
			if dep_disjunctive_stack:
				if not self._pop_disjunction(allow_unsatisfied):
					return 0
		return 1

	def _add_dep(self, dep, allow_unsatisfied=False):
		debug = "--debug" in self.myopts
		buildpkgonly = "--buildpkgonly" in self.myopts
		nodeps = "--nodeps" in self.myopts
		empty = "empty" in self.myparams
		deep = "deep" in self.myparams
		update = "--update" in self.myopts and dep.depth <= 1
		if dep.blocker:
			if not buildpkgonly and \
				not nodeps and \
				dep.parent not in self._slot_collision_nodes:
				if dep.parent.onlydeps:
					# It's safe to ignore blockers if the
					# parent is an --onlydeps node.
					return 1
				# The blocker applies to the root where
				# the parent is or will be installed.
				blocker = Blocker(atom=dep.atom,
					eapi=dep.parent.metadata["EAPI"],
					root=dep.parent.root)
				self._blocker_parents.add(blocker, dep.parent)
			return 1
		dep_pkg, existing_node = self._select_package(dep.root, dep.atom,
			onlydeps=dep.onlydeps)
		if not dep_pkg:
			if dep.priority.optional:
				# This could be an unecessary build-time dep
				# pulled in by --with-bdeps=y.
				return 1
			if allow_unsatisfied:
				self._unsatisfied_deps.append(dep)
				return 1
			self._unsatisfied_deps_for_display.append(
				((dep.root, dep.atom), {"myparent":dep.parent}))
			return 0
		# In some cases, dep_check will return deps that shouldn't
		# be proccessed any further, so they are identified and
		# discarded here. Try to discard as few as possible since
		# discarded dependencies reduce the amount of information
		# available for optimization of merge order.
		if dep.priority.satisfied and \
			not dep_pkg.installed and \
			not (existing_node or empty or deep or update):
			myarg = None
			if dep.root == self.target_root:
				try:
					myarg = self._iter_atoms_for_pkg(dep_pkg).next()
				except StopIteration:
					pass
				except portage.exception.InvalidDependString:
					if not dep_pkg.installed:
						# This shouldn't happen since the package
						# should have been masked.
						raise
			if not myarg:
				self._ignored_deps.append(dep)
				return 1

		if not self._add_pkg(dep_pkg, dep):
			return 0
		return 1

	def _add_pkg(self, pkg, dep):
		myparent = None
		priority = None
		depth = 0
		if dep is None:
			dep = Dependency()
		else:
			myparent = dep.parent
			priority = dep.priority
			depth = dep.depth
		if priority is None:
			priority = DepPriority()
		"""
		Fills the digraph with nodes comprised of packages to merge.
		mybigkey is the package spec of the package to merge.
		myparent is the package depending on mybigkey ( or None )
		addme = Should we add this package to the digraph or are we just looking at it's deps?
			Think --onlydeps, we need to ignore packages in that case.
		#stuff to add:
		#SLOT-aware emerge
		#IUSE-aware emerge -> USE DEP aware depgraph
		#"no downgrade" emerge
		"""
		# Ensure that the dependencies of the same package
		# are never processed more than once.
		previously_added = pkg in self.digraph

		# select the correct /var database that we'll be checking against
		vardbapi = self.trees[pkg.root]["vartree"].dbapi
		pkgsettings = self.pkgsettings[pkg.root]

		arg_atoms = None
		if True:
			try:
				arg_atoms = list(self._iter_atoms_for_pkg(pkg))
			except portage.exception.InvalidDependString, e:
				if not pkg.installed:
					show_invalid_depstring_notice(
						pkg, pkg.metadata["PROVIDE"], str(e))
					return 0
				del e

		if not pkg.onlydeps:
			if not pkg.installed and \
				"empty" not in self.myparams and \
				vardbapi.match(pkg.slot_atom):
				# Increase the priority of dependencies on packages that
				# are being rebuilt. This optimizes merge order so that
				# dependencies are rebuilt/updated as soon as possible,
				# which is needed especially when emerge is called by
				# revdep-rebuild since dependencies may be affected by ABI
				# breakage that has rendered them useless. Don't adjust
				# priority here when in "empty" mode since all packages
				# are being merged in that case.
				priority.rebuild = True

			existing_node = self._slot_pkg_map[pkg.root].get(pkg.slot_atom)
			slot_collision = False
			if existing_node:
				existing_node_matches = pkg.cpv == existing_node.cpv
				if existing_node_matches and \
					pkg != existing_node and \
					dep.atom is not None:
					# Use package set for matching since it will match via
					# PROVIDE when necessary, while match_from_list does not.
					atom_set = InternalPackageSet(initial_atoms=[dep.atom])
					if not atom_set.findAtomForPackage(existing_node):
						existing_node_matches = False
				if existing_node_matches:
					# The existing node can be reused.
					if arg_atoms:
						for parent_atom in arg_atoms:
							parent, atom = parent_atom
							self.digraph.add(existing_node, parent,
								priority=priority)
							self._add_parent_atom(existing_node, parent_atom)
					# If a direct circular dependency is not an unsatisfied
					# buildtime dependency then drop it here since otherwise
					# it can skew the merge order calculation in an unwanted
					# way.
					if existing_node != myparent or \
						(priority.buildtime and not priority.satisfied):
						self.digraph.addnode(existing_node, myparent,
							priority=priority)
						if dep.atom is not None and dep.parent is not None:
							self._add_parent_atom(existing_node,
								(dep.parent, dep.atom))
					return 1
				else:

					# A slot collision has occurred.  Sometimes this coincides
					# with unresolvable blockers, so the slot collision will be
					# shown later if there are no unresolvable blockers.
					self._add_slot_conflict(pkg)
					slot_collision = True

			if slot_collision:
				# Now add this node to the graph so that self.display()
				# can show use flags and --tree portage.output.  This node is
				# only being partially added to the graph.  It must not be
				# allowed to interfere with the other nodes that have been
				# added.  Do not overwrite data for existing nodes in
				# self.mydbapi since that data will be used for blocker
				# validation.
				# Even though the graph is now invalid, continue to process
				# dependencies so that things like --fetchonly can still
				# function despite collisions.
				pass
			elif not previously_added:
				self._slot_pkg_map[pkg.root][pkg.slot_atom] = pkg
				self.mydbapi[pkg.root].cpv_inject(pkg)
				self._filtered_trees[pkg.root]["porttree"].dbapi._clear_cache()

			if not pkg.installed:
				# Allow this package to satisfy old-style virtuals in case it
				# doesn't already. Any pre-existing providers will be preferred
				# over this one.
				try:
					pkgsettings.setinst(pkg.cpv, pkg.metadata)
					# For consistency, also update the global virtuals.
					settings = self.roots[pkg.root].settings
					settings.unlock()
					settings.setinst(pkg.cpv, pkg.metadata)
					settings.lock()
				except portage.exception.InvalidDependString, e:
					show_invalid_depstring_notice(
						pkg, pkg.metadata["PROVIDE"], str(e))
					del e
					return 0

		if arg_atoms:
			self._set_nodes.add(pkg)

		# Do this even when addme is False (--onlydeps) so that the
		# parent/child relationship is always known in case
		# self._show_slot_collision_notice() needs to be called later.
		self.digraph.add(pkg, myparent, priority=priority)
		if dep.atom is not None and dep.parent is not None:
			self._add_parent_atom(pkg, (dep.parent, dep.atom))

		if arg_atoms:
			for parent_atom in arg_atoms:
				parent, atom = parent_atom
				self.digraph.add(pkg, parent, priority=priority)
				self._add_parent_atom(pkg, parent_atom)

		""" This section determines whether we go deeper into dependencies or not.
		    We want to go deeper on a few occasions:
		    Installing package A, we need to make sure package A's deps are met.
		    emerge --deep <pkgspec>; we need to recursively check dependencies of pkgspec
		    If we are in --nodeps (no recursion) mode, we obviously only check 1 level of dependencies.
		"""
		dep_stack = self._dep_stack
		if "recurse" not in self.myparams:
			return 1
		elif pkg.installed and \
			"deep" not in self.myparams:
			dep_stack = self._ignored_deps

		self.spinner.update()

		if arg_atoms:
			depth = 0
		pkg.depth = depth
		if not previously_added:
			dep_stack.append(pkg)
		return 1

	def _add_parent_atom(self, pkg, parent_atom):
		parent_atoms = self._parent_atoms.get(pkg)
		if parent_atoms is None:
			parent_atoms = set()
			self._parent_atoms[pkg] = parent_atoms
		parent_atoms.add(parent_atom)

	def _add_slot_conflict(self, pkg):
		self._slot_collision_nodes.add(pkg)
		slot_key = (pkg.slot_atom, pkg.root)
		slot_nodes = self._slot_collision_info.get(slot_key)
		if slot_nodes is None:
			slot_nodes = set()
			slot_nodes.add(self._slot_pkg_map[pkg.root][pkg.slot_atom])
			self._slot_collision_info[slot_key] = slot_nodes
		slot_nodes.add(pkg)

	def _add_pkg_deps(self, pkg, allow_unsatisfied=False):

		mytype = pkg.type_name
		myroot = pkg.root
		mykey = pkg.cpv
		metadata = pkg.metadata
		myuse = pkg.use.enabled
		jbigkey = pkg
		depth = pkg.depth + 1
		removal_action = "remove" in self.myparams

		edepend={}
		depkeys = ["DEPEND","RDEPEND","PDEPEND"]
		for k in depkeys:
			edepend[k] = metadata[k]

		if not pkg.built and \
			"--buildpkgonly" in self.myopts and \
			"deep" not in self.myparams and \
			"empty" not in self.myparams:
			edepend["RDEPEND"] = ""
			edepend["PDEPEND"] = ""
		bdeps_optional = False

		if pkg.built and not removal_action:
			if self.myopts.get("--with-bdeps", "n") == "y":
				# Pull in build time deps as requested, but marked them as
				# "optional" since they are not strictly required. This allows
				# more freedom in the merge order calculation for solving
				# circular dependencies. Don't convert to PDEPEND since that
				# could make --with-bdeps=y less effective if it is used to
				# adjust merge order to prevent built_with_use() calls from
				# failing.
				bdeps_optional = True
			else:
				# built packages do not have build time dependencies.
				edepend["DEPEND"] = ""

		if removal_action and self.myopts.get("--with-bdeps", "y") == "n":
			edepend["DEPEND"] = ""

		bdeps_root = "/"
		root_deps = self.myopts.get("--root-deps")
		if root_deps is not None:
			if root_deps is True:
				bdeps_root = myroot
			elif root_deps == "rdeps":
				edepend["DEPEND"] = ""

		deps = (
			(bdeps_root, edepend["DEPEND"],
				self._priority(buildtime=(not bdeps_optional),
				optional=bdeps_optional)),
			(myroot, edepend["RDEPEND"], self._priority(runtime=True)),
			(myroot, edepend["PDEPEND"], self._priority(runtime_post=True))
		)

		debug = "--debug" in self.myopts
		strict = mytype != "installed"
		try:
			if not strict:
				portage.dep._dep_check_strict = False

			for dep_root, dep_string, dep_priority in deps:
				if not dep_string:
					continue
				if debug:
					print
					print "Parent:   ", jbigkey
					print "Depstring:", dep_string
					print "Priority:", dep_priority

				try:

					dep_string = portage.dep.paren_normalize(
						portage.dep.use_reduce(
						portage.dep.paren_reduce(dep_string),
						uselist=pkg.use.enabled))

					dep_string = list(self._queue_disjunctive_deps(
						pkg, dep_root, dep_priority, dep_string))

				except portage.exception.InvalidDependString, e:
					if pkg.installed:
						del e
						continue
					show_invalid_depstring_notice(pkg, dep_string, str(e))
					return 0

				if not dep_string:
					continue

				dep_string = portage.dep.paren_enclose(dep_string)

				if not self._add_pkg_dep_string(
					pkg, dep_root, dep_priority, dep_string,
					allow_unsatisfied):
					return 0

		except portage.exception.AmbiguousPackageName, e:
			pkgs = e.args[0]
			portage.writemsg("\n\n!!! An atom in the dependencies " + \
				"is not fully-qualified. Multiple matches:\n\n", noiselevel=-1)
			for cpv in pkgs:
				portage.writemsg("    %s\n" % cpv, noiselevel=-1)
			portage.writemsg("\n", noiselevel=-1)
			if mytype == "binary":
				portage.writemsg(
					"!!! This binary package cannot be installed: '%s'\n" % \
					mykey, noiselevel=-1)
			elif mytype == "ebuild":
				portdb = self.roots[myroot].trees["porttree"].dbapi
				myebuild, mylocation = portdb.findname2(mykey)
				portage.writemsg("!!! This ebuild cannot be installed: " + \
					"'%s'\n" % myebuild, noiselevel=-1)
			portage.writemsg("!!! Please notify the package maintainer " + \
				"that atoms must be fully-qualified.\n", noiselevel=-1)
			return 0
		finally:
			portage.dep._dep_check_strict = True
		return 1

	def _add_pkg_dep_string(self, pkg, dep_root, dep_priority, dep_string,
		allow_unsatisfied):
		depth = pkg.depth + 1
		debug = "--debug" in self.myopts
		strict = pkg.type_name != "installed"

		if debug:
			print
			print "Parent:   ", pkg
			print "Depstring:", dep_string
			print "Priority:", dep_priority

		try:
			selected_atoms = self._select_atoms(dep_root,
				dep_string, myuse=pkg.use.enabled, parent=pkg,
				strict=strict, priority=dep_priority)
		except portage.exception.InvalidDependString, e:
			show_invalid_depstring_notice(pkg, dep_string, str(e))
			del e
			if pkg.installed:
				return 1
			return 0

		if debug:
			print "Candidates:", selected_atoms

		vardb = self.roots[dep_root].trees["vartree"].dbapi

		for atom in selected_atoms:
			try:

				atom = portage.dep.Atom(atom)

				mypriority = dep_priority.copy()
				if not atom.blocker and vardb.match(atom):
					mypriority.satisfied = True

				if not self._add_dep(Dependency(atom=atom,
					blocker=atom.blocker, depth=depth, parent=pkg,
					priority=mypriority, root=dep_root),
					allow_unsatisfied=allow_unsatisfied):
					return 0

			except portage.exception.InvalidAtom, e:
				show_invalid_depstring_notice(
					pkg, dep_string, str(e))
				del e
				if not pkg.installed:
					return 0

		if debug:
			print "Exiting...", pkg

		return 1

	def _queue_disjunctive_deps(self, pkg, dep_root, dep_priority, dep_struct):
		"""
		Queue disjunctive (virtual and ||) deps in self._dep_disjunctive_stack.
		Yields non-disjunctive deps. Raises InvalidDependString when 
		necessary.
		"""
		i = 0
		while i < len(dep_struct):
			x = dep_struct[i]
			if isinstance(x, list):
				for y in self._queue_disjunctive_deps(
					pkg, dep_root, dep_priority, x):
					yield y
			elif x == "||":
				self._queue_disjunction(pkg, dep_root, dep_priority,
					[ x, dep_struct[ i + 1 ] ] )
				i += 1
			else:
				try:
					x = portage.dep.Atom(x)
				except portage.exception.InvalidAtom:
					if not pkg.installed:
						raise portage.exception.InvalidDependString(
							"invalid atom: '%s'" % x)
				else:
					# Note: Eventually this will check for PROPERTIES=virtual
					# or whatever other metadata gets implemented for this
					# purpose.
					if x.cp.startswith('virtual/'):
						self._queue_disjunction( pkg, dep_root,
							dep_priority, [ str(x) ] )
					else:
						yield str(x)
			i += 1

	def _queue_disjunction(self, pkg, dep_root, dep_priority, dep_struct):
		self._dep_disjunctive_stack.append(
			(pkg, dep_root, dep_priority, dep_struct))

	def _pop_disjunction(self, allow_unsatisfied):
		"""
		Pop one disjunctive dep from self._dep_disjunctive_stack, and use it to
		populate self._dep_stack.
		"""
		pkg, dep_root, dep_priority, dep_struct = \
			self._dep_disjunctive_stack.pop()
		dep_string = portage.dep.paren_enclose(dep_struct)
		if not self._add_pkg_dep_string(
			pkg, dep_root, dep_priority, dep_string, allow_unsatisfied):
			return 0
		return 1

	def _priority(self, **kwargs):
		if "remove" in self.myparams:
			priority_constructor = UnmergeDepPriority
		else:
			priority_constructor = DepPriority
		return priority_constructor(**kwargs)

	def _dep_expand(self, root_config, atom_without_category):
		"""
		@param root_config: a root config instance
		@type root_config: RootConfig
		@param atom_without_category: an atom without a category component
		@type atom_without_category: String
		@rtype: list
		@returns: a list of atoms containing categories (possibly empty)
		"""
		null_cp = portage.dep_getkey(insert_category_into_atom(
			atom_without_category, "null"))
		cat, atom_pn = portage.catsplit(null_cp)

		dbs = self._filtered_trees[root_config.root]["dbs"]
		categories = set()
		for db, pkg_type, built, installed, db_keys in dbs:
			for cat in db.categories:
				if db.cp_list("%s/%s" % (cat, atom_pn)):
					categories.add(cat)

		deps = []
		for cat in categories:
			deps.append(insert_category_into_atom(
				atom_without_category, cat))
		return deps

	def _have_new_virt(self, root, atom_cp):
		ret = False
		for db, pkg_type, built, installed, db_keys in \
			self._filtered_trees[root]["dbs"]:
			if db.cp_list(atom_cp):
				ret = True
				break
		return ret

	def _iter_atoms_for_pkg(self, pkg):
		# TODO: add multiple $ROOT support
		if pkg.root != self.target_root:
			return
		atom_arg_map = self._atom_arg_map
		root_config = self.roots[pkg.root]
		for atom in self._set_atoms.iterAtomsForPackage(pkg):
			atom_cp = portage.dep_getkey(atom)
			if atom_cp != pkg.cp and \
				self._have_new_virt(pkg.root, atom_cp):
				continue
			visible_pkgs = root_config.visible_pkgs.match_pkgs(atom)
			visible_pkgs.reverse() # descending order
			higher_slot = None
			for visible_pkg in visible_pkgs:
				if visible_pkg.cp != atom_cp:
					continue
				if pkg >= visible_pkg:
					# This is descending order, and we're not
					# interested in any versions <= pkg given.
					break
				if pkg.slot_atom != visible_pkg.slot_atom:
					higher_slot = visible_pkg
					break
			if higher_slot is not None:
				continue
			for arg in atom_arg_map[(atom, pkg.root)]:
				if isinstance(arg, PackageArg) and \
					arg.package != pkg:
					continue
				yield arg, atom

	def select_files(self, myfiles):
		"""Given a list of .tbz2s, .ebuilds sets, and deps, create the
		appropriate depgraph and return a favorite list."""
		debug = "--debug" in self.myopts
		root_config = self.roots[self.target_root]
		sets = root_config.sets
		getSetAtoms = root_config.setconfig.getSetAtoms
		myfavorites=[]
		myroot = self.target_root
		dbs = self._filtered_trees[myroot]["dbs"]
		vardb = self.trees[myroot]["vartree"].dbapi
		real_vardb = self._trees_orig[myroot]["vartree"].dbapi
		portdb = self.trees[myroot]["porttree"].dbapi
		bindb = self.trees[myroot]["bintree"].dbapi
		pkgsettings = self.pkgsettings[myroot]
		args = []
		onlydeps = "--onlydeps" in self.myopts
		lookup_owners = []
		for x in myfiles:
			ext = os.path.splitext(x)[1]
			if ext==".tbz2":
				if not os.path.exists(x):
					if os.path.exists(
						os.path.join(pkgsettings["PKGDIR"], "All", x)):
						x = os.path.join(pkgsettings["PKGDIR"], "All", x)
					elif os.path.exists(
						os.path.join(pkgsettings["PKGDIR"], x)):
						x = os.path.join(pkgsettings["PKGDIR"], x)
					else:
						print "\n\n!!! Binary package '"+str(x)+"' does not exist."
						print "!!! Please ensure the tbz2 exists as specified.\n"
						return 0, myfavorites
				mytbz2=portage.xpak.tbz2(x)
				mykey=mytbz2.getelements("CATEGORY")[0]+"/"+os.path.splitext(os.path.basename(x))[0]
				if os.path.realpath(x) != \
					os.path.realpath(self.trees[myroot]["bintree"].getname(mykey)):
					print colorize("BAD", "\n*** You need to adjust PKGDIR to emerge this package.\n")
					return 0, myfavorites
				db_keys = list(bindb._aux_cache_keys)
				metadata = izip(db_keys, bindb.aux_get(mykey, db_keys))
				pkg = Package(type_name="binary", root_config=root_config,
					cpv=mykey, built=True, metadata=metadata,
					onlydeps=onlydeps)
				self._pkg_cache[pkg] = pkg
				args.append(PackageArg(arg=x, package=pkg,
					root_config=root_config))
			elif ext==".ebuild":
				ebuild_path = portage.util.normalize_path(os.path.abspath(x))
				pkgdir = os.path.dirname(ebuild_path)
				tree_root = os.path.dirname(os.path.dirname(pkgdir))
				cp = pkgdir[len(tree_root)+1:]
				e = portage.exception.PackageNotFound(
					("%s is not in a valid portage tree " + \
					"hierarchy or does not exist") % x)
				if not portage.isvalidatom(cp):
					raise e
				cat = portage.catsplit(cp)[0]
				mykey = cat + "/" + os.path.basename(ebuild_path[:-7])
				if not portage.isvalidatom("="+mykey):
					raise e
				ebuild_path = portdb.findname(mykey)
				if ebuild_path:
					if ebuild_path != os.path.join(os.path.realpath(tree_root),
						cp, os.path.basename(ebuild_path)):
						print colorize("BAD", "\n*** You need to adjust PORTDIR or PORTDIR_OVERLAY to emerge this package.\n")
						return 0, myfavorites
					if mykey not in portdb.xmatch(
						"match-visible", portage.dep_getkey(mykey)):
						print colorize("BAD", "\n*** You are emerging a masked package. It is MUCH better to use")
						print colorize("BAD", "*** /etc/portage/package.* to accomplish this. See portage(5) man")
						print colorize("BAD", "*** page for details.")
						countdown(int(self.settings["EMERGE_WARNING_DELAY"]),
							"Continuing...")
				else:
					raise portage.exception.PackageNotFound(
						"%s is not in a valid portage tree hierarchy or does not exist" % x)
				db_keys = list(portdb._aux_cache_keys)
				metadata = izip(db_keys, portdb.aux_get(mykey, db_keys))
				pkg = Package(type_name="ebuild", root_config=root_config,
					cpv=mykey, metadata=metadata, onlydeps=onlydeps)
				pkgsettings.setcpv(pkg)
				pkg.metadata["USE"] = pkgsettings["PORTAGE_USE"]
				pkg.metadata['CHOST'] = pkgsettings.get('CHOST', '')
				self._pkg_cache[pkg] = pkg
				args.append(PackageArg(arg=x, package=pkg,
					root_config=root_config))
			elif x.startswith(os.path.sep):
				if not x.startswith(myroot):
					portage.writemsg(("\n\n!!! '%s' does not start with" + \
						" $ROOT.\n") % x, noiselevel=-1)
					return 0, []
				# Queue these up since it's most efficient to handle
				# multiple files in a single iter_owners() call.
				lookup_owners.append(x)
			else:
				if x in ("system", "world"):
					x = SETPREFIX + x
				if x.startswith(SETPREFIX):
					s = x[len(SETPREFIX):]
					if s not in sets:
						raise portage.exception.PackageSetNotFound(s)
					if s in self._sets:
						continue
					# Recursively expand sets so that containment tests in
					# self._get_parent_sets() properly match atoms in nested
					# sets (like if world contains system).
					expanded_set = InternalPackageSet(
						initial_atoms=getSetAtoms(s))
					self._sets[s] = expanded_set
					args.append(SetArg(arg=x, set=expanded_set,
						root_config=root_config))
					continue
				if not is_valid_package_atom(x):
					portage.writemsg("\n\n!!! '%s' is not a valid package atom.\n" % x,
						noiselevel=-1)
					portage.writemsg("!!! Please check ebuild(5) for full details.\n")
					portage.writemsg("!!! (Did you specify a version but forget to prefix with '='?)\n")
					return (0,[])
				# Don't expand categories or old-style virtuals here unless
				# necessary. Expansion of old-style virtuals here causes at
				# least the following problems:
				#   1) It's more difficult to determine which set(s) an atom
				#      came from, if any.
				#   2) It takes away freedom from the resolver to choose other
				#      possible expansions when necessary.
				if "/" in x:
					args.append(AtomArg(arg=x, atom=x,
						root_config=root_config))
					continue
				expanded_atoms = self._dep_expand(root_config, x)
				installed_cp_set = set()
				for atom in expanded_atoms:
					atom_cp = portage.dep_getkey(atom)
					if vardb.cp_list(atom_cp):
						installed_cp_set.add(atom_cp)

				if len(installed_cp_set) > 1:
					non_virtual_cps = set()
					for atom_cp in installed_cp_set:
						if not atom_cp.startswith("virtual/"):
							non_virtual_cps.add(atom_cp)
					if len(non_virtual_cps) == 1:
						installed_cp_set = non_virtual_cps

				if len(expanded_atoms) > 1 and len(installed_cp_set) == 1:
					installed_cp = iter(installed_cp_set).next()
					expanded_atoms = [atom for atom in expanded_atoms \
						if portage.dep_getkey(atom) == installed_cp]

				if len(expanded_atoms) > 1:
					print
					print
					ambiguous_package_name(x, expanded_atoms, root_config,
						self.spinner, self.myopts)
					return False, myfavorites
				if expanded_atoms:
					atom = expanded_atoms[0]
				else:
					null_atom = insert_category_into_atom(x, "null")
					null_cp = portage.dep_getkey(null_atom)
					cat, atom_pn = portage.catsplit(null_cp)
					virts_p = root_config.settings.get_virts_p().get(atom_pn)
					if virts_p:
						# Allow the depgraph to choose which virtual.
						atom = insert_category_into_atom(x, "virtual")
					else:
						atom = insert_category_into_atom(x, "null")

				args.append(AtomArg(arg=x, atom=atom,
					root_config=root_config))

		if lookup_owners:
			relative_paths = []
			search_for_multiple = False
			if len(lookup_owners) > 1:
				search_for_multiple = True

			for x in lookup_owners:
				if not search_for_multiple and os.path.isdir(x):
					search_for_multiple = True
				relative_paths.append(x[len(myroot):])

			owners = set()
			for pkg, relative_path in \
				real_vardb._owners.iter_owners(relative_paths):
				owners.add(pkg.mycpv)
				if not search_for_multiple:
					break

			if not owners:
				portage.writemsg(("\n\n!!! '%s' is not claimed " + \
					"by any package.\n") % lookup_owners[0], noiselevel=-1)
				return 0, []

			for cpv in owners:
				slot = vardb.aux_get(cpv, ["SLOT"])[0]
				if not slot:
					# portage now masks packages with missing slot, but it's
					# possible that one was installed by an older version
					atom = portage.cpv_getkey(cpv)
				else:
					atom = "%s:%s" % (portage.cpv_getkey(cpv), slot)
				args.append(AtomArg(arg=atom, atom=atom,
					root_config=root_config))

		if "--update" in self.myopts:
			# In some cases, the greedy slots behavior can pull in a slot that
			# the user would want to uninstall due to it being blocked by a
			# newer version in a different slot. Therefore, it's necessary to
			# detect and discard any that should be uninstalled. Each time
			# that arguments are updated, package selections are repeated in
			# order to ensure consistency with the current arguments:
			#
			#  1) Initialize args
			#  2) Select packages and generate initial greedy atoms
			#  3) Update args with greedy atoms
			#  4) Select packages and generate greedy atoms again, while
			#     accounting for any blockers between selected packages
			#  5) Update args with revised greedy atoms

			self._set_args(args)
			greedy_args = []
			for arg in args:
				greedy_args.append(arg)
				if not isinstance(arg, AtomArg):
					continue
				for atom in self._greedy_slots(arg.root_config, arg.atom):
					greedy_args.append(
						AtomArg(arg=arg.arg, atom=atom,
							root_config=arg.root_config))

			self._set_args(greedy_args)
			del greedy_args

			# Revise greedy atoms, accounting for any blockers
			# between selected packages.
			revised_greedy_args = []
			for arg in args:
				revised_greedy_args.append(arg)
				if not isinstance(arg, AtomArg):
					continue
				for atom in self._greedy_slots(arg.root_config, arg.atom,
					blocker_lookahead=True):
					revised_greedy_args.append(
						AtomArg(arg=arg.arg, atom=atom,
							root_config=arg.root_config))
			args = revised_greedy_args
			del revised_greedy_args

		self._set_args(args)

		myfavorites = set(myfavorites)
		for arg in args:
			if isinstance(arg, (AtomArg, PackageArg)):
				myfavorites.add(arg.atom)
			elif isinstance(arg, SetArg):
				myfavorites.add(arg.arg)
		myfavorites = list(myfavorites)

		pprovideddict = pkgsettings.pprovideddict
		if debug:
			portage.writemsg("\n", noiselevel=-1)
		# Order needs to be preserved since a feature of --nodeps
		# is to allow the user to force a specific merge order.
		args.reverse()
		while args:
			arg = args.pop()
			for atom in arg.set:
				self.spinner.update()
				dep = Dependency(atom=atom, onlydeps=onlydeps,
					root=myroot, parent=arg)
				atom_cp = portage.dep_getkey(atom)
				try:
					pprovided = pprovideddict.get(portage.dep_getkey(atom))
					if pprovided and portage.match_from_list(atom, pprovided):
						# A provided package has been specified on the command line.
						self._pprovided_args.append((arg, atom))
						continue
					if isinstance(arg, PackageArg):
						if not self._add_pkg(arg.package, dep) or \
							not self._create_graph():
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s\n") % arg.arg)
							return 0, myfavorites
						continue
					if debug:
						portage.writemsg("      Arg: %s\n     Atom: %s\n" % \
							(arg, atom), noiselevel=-1)
					pkg, existing_node = self._select_package(
						myroot, atom, onlydeps=onlydeps)
					if not pkg:
						if not (isinstance(arg, SetArg) and \
							arg.name in ("system", "world")):
							self._unsatisfied_deps_for_display.append(
								((myroot, atom), {}))
							return 0, myfavorites
						self._missing_args.append((arg, atom))
						continue
					if atom_cp != pkg.cp:
						# For old-style virtuals, we need to repeat the
						# package.provided check against the selected package.
						expanded_atom = atom.replace(atom_cp, pkg.cp)
						pprovided = pprovideddict.get(pkg.cp)
						if pprovided and \
							portage.match_from_list(expanded_atom, pprovided):
							# A provided package has been
							# specified on the command line.
							self._pprovided_args.append((arg, atom))
							continue
					if pkg.installed and "selective" not in self.myparams:
						self._unsatisfied_deps_for_display.append(
							((myroot, atom), {}))
						# Previous behavior was to bail out in this case, but
						# since the dep is satisfied by the installed package,
						# it's more friendly to continue building the graph
						# and just show a warning message. Therefore, only bail
						# out here if the atom is not from either the system or
						# world set.
						if not (isinstance(arg, SetArg) and \
							arg.name in ("system", "world")):
							return 0, myfavorites

					# Add the selected package to the graph as soon as possible
					# so that later dep_check() calls can use it as feedback
					# for making more consistent atom selections.
					if not self._add_pkg(pkg, dep):
						if isinstance(arg, SetArg):
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s from %s\n") % \
								(atom, arg.arg))
						else:
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s\n") % atom)
						return 0, myfavorites

				except portage.exception.MissingSignature, e:
					portage.writemsg("\n\n!!! A missing gpg signature is preventing portage from calculating the\n")
					portage.writemsg("!!! required dependencies. This is a security feature enabled by the admin\n")
					portage.writemsg("!!! to aid in the detection of malicious intent.\n\n")
					portage.writemsg("!!! THIS IS A POSSIBLE INDICATION OF TAMPERED FILES -- CHECK CAREFULLY.\n")
					portage.writemsg("!!! Affected file: %s\n" % (e), noiselevel=-1)
					return 0, myfavorites
				except portage.exception.InvalidSignature, e:
					portage.writemsg("\n\n!!! An invalid gpg signature is preventing portage from calculating the\n")
					portage.writemsg("!!! required dependencies. This is a security feature enabled by the admin\n")
					portage.writemsg("!!! to aid in the detection of malicious intent.\n\n")
					portage.writemsg("!!! THIS IS A POSSIBLE INDICATION OF TAMPERED FILES -- CHECK CAREFULLY.\n")
					portage.writemsg("!!! Affected file: %s\n" % (e), noiselevel=-1)
					return 0, myfavorites
				except SystemExit, e:
					raise # Needed else can't exit
				except Exception, e:
					print >> sys.stderr, "\n\n!!! Problem in '%s' dependencies." % atom
					print >> sys.stderr, "!!!", str(e), getattr(e, "__module__", None)
					raise

		# Now that the root packages have been added to the graph,
		# process the dependencies.
		if not self._create_graph():
			return 0, myfavorites

		missing=0
		if "--usepkgonly" in self.myopts:
			for xs in self.digraph.all_nodes():
				if not isinstance(xs, Package):
					continue
				if len(xs) >= 4 and xs[0] != "binary" and xs[3] == "merge":
					if missing == 0:
						print
					missing += 1
					print "Missing binary for:",xs[2]

		try:
			self.altlist()
		except self._unknown_internal_error:
			return False, myfavorites

		# We're true here unless we are missing binaries.
		return (not missing,myfavorites)

	def _set_args(self, args):
		"""
		Create the "args" package set from atoms and packages given as
		arguments. This method can be called multiple times if necessary.
		The package selection cache is automatically invalidated, since
		arguments influence package selections.
		"""
		args_set = self._sets["args"]
		args_set.clear()
		for arg in args:
			if not isinstance(arg, (AtomArg, PackageArg)):
				continue
			atom = arg.atom
			if atom in args_set:
				continue
			args_set.add(atom)

		self._set_atoms.clear()
		self._set_atoms.update(chain(*self._sets.itervalues()))
		atom_arg_map = self._atom_arg_map
		atom_arg_map.clear()
		for arg in args:
			for atom in arg.set:
				atom_key = (atom, arg.root_config.root)
				refs = atom_arg_map.get(atom_key)
				if refs is None:
					refs = []
					atom_arg_map[atom_key] = refs
					if arg not in refs:
						refs.append(arg)

		# Invalidate the package selection cache, since
		# arguments influence package selections.
		self._highest_pkg_cache.clear()
		for trees in self._filtered_trees.itervalues():
			trees["porttree"].dbapi._clear_cache()

	def _greedy_slots(self, root_config, atom, blocker_lookahead=False):
		"""
		Return a list of slot atoms corresponding to installed slots that
		differ from the slot of the highest visible match. When
		blocker_lookahead is True, slot atoms that would trigger a blocker
		conflict are automatically discarded, potentially allowing automatic
		uninstallation of older slots when appropriate.
		"""
		highest_pkg, in_graph = self._select_package(root_config.root, atom)
		if highest_pkg is None:
			return []
		vardb = root_config.trees["vartree"].dbapi
		slots = set()
		for cpv in vardb.match(atom):
			# don't mix new virtuals with old virtuals
			if portage.cpv_getkey(cpv) == highest_pkg.cp:
				slots.add(vardb.aux_get(cpv, ["SLOT"])[0])

		slots.add(highest_pkg.metadata["SLOT"])
		if len(slots) == 1:
			return []
		greedy_pkgs = []
		slots.remove(highest_pkg.metadata["SLOT"])
		while slots:
			slot = slots.pop()
			slot_atom = portage.dep.Atom("%s:%s" % (highest_pkg.cp, slot))
			pkg, in_graph = self._select_package(root_config.root, slot_atom)
			if pkg is not None and \
				pkg.cp == highest_pkg.cp and pkg < highest_pkg:
				greedy_pkgs.append(pkg)
		if not greedy_pkgs:
			return []
		if not blocker_lookahead:
			return [pkg.slot_atom for pkg in greedy_pkgs]

		blockers = {}
		blocker_dep_keys = ["DEPEND", "PDEPEND", "RDEPEND"]
		for pkg in greedy_pkgs + [highest_pkg]:
			dep_str = " ".join(pkg.metadata[k] for k in blocker_dep_keys)
			try:
				atoms = self._select_atoms(
					pkg.root, dep_str, pkg.use.enabled,
					parent=pkg, strict=True)
			except portage.exception.InvalidDependString:
				continue
			blocker_atoms = (x for x in atoms if x.blocker)
			blockers[pkg] = InternalPackageSet(initial_atoms=blocker_atoms)

		if highest_pkg not in blockers:
			return []

		# filter packages with invalid deps
		greedy_pkgs = [pkg for pkg in greedy_pkgs if pkg in blockers]

		# filter packages that conflict with highest_pkg
		greedy_pkgs = [pkg for pkg in greedy_pkgs if not \
			(blockers[highest_pkg].findAtomForPackage(pkg) or \
			blockers[pkg].findAtomForPackage(highest_pkg))]

		if not greedy_pkgs:
			return []

		# If two packages conflict, discard the lower version.
		discard_pkgs = set()
		greedy_pkgs.sort(reverse=True)
		for i in xrange(len(greedy_pkgs) - 1):
			pkg1 = greedy_pkgs[i]
			if pkg1 in discard_pkgs:
				continue
			for j in xrange(i + 1, len(greedy_pkgs)):
				pkg2 = greedy_pkgs[j]
				if pkg2 in discard_pkgs:
					continue
				if blockers[pkg1].findAtomForPackage(pkg2) or \
					blockers[pkg2].findAtomForPackage(pkg1):
					# pkg1 > pkg2
					discard_pkgs.add(pkg2)

		return [pkg.slot_atom for pkg in greedy_pkgs \
			if pkg not in discard_pkgs]

	def _select_atoms_from_graph(self, *pargs, **kwargs):
		"""
		Prefer atoms matching packages that have already been
		added to the graph or those that are installed and have
		not been scheduled for replacement.
		"""
		kwargs["trees"] = self._graph_trees
		return self._select_atoms_highest_available(*pargs, **kwargs)

	def _select_atoms_highest_available(self, root, depstring,
		myuse=None, parent=None, strict=True, trees=None, priority=None):
		"""This will raise InvalidDependString if necessary. If trees is
		None then self._filtered_trees is used."""
		pkgsettings = self.pkgsettings[root]
		if trees is None:
			trees = self._filtered_trees
		if not getattr(priority, "buildtime", False):
			# The parent should only be passed to dep_check() for buildtime
			# dependencies since that's the only case when it's appropriate
			# to trigger the circular dependency avoidance code which uses it.
			# It's important not to trigger the same circular dependency
			# avoidance code for runtime dependencies since it's not needed
			# and it can promote an incorrect package choice.
			parent = None
		if True:
			try:
				if parent is not None:
					trees[root]["parent"] = parent
				if not strict:
					portage.dep._dep_check_strict = False
				mycheck = portage.dep_check(depstring, None,
					pkgsettings, myuse=myuse,
					myroot=root, trees=trees)
			finally:
				if parent is not None:
					trees[root].pop("parent")
				portage.dep._dep_check_strict = True
			if not mycheck[0]:
				raise portage.exception.InvalidDependString(mycheck[1])
			selected_atoms = mycheck[1]
		return selected_atoms

	def _show_unsatisfied_dep(self, root, atom, myparent=None, arg=None):
		atom = portage.dep.Atom(atom)
		atom_set = InternalPackageSet(initial_atoms=(atom,))
		atom_without_use = atom
		if atom.use:
			atom_without_use = portage.dep.remove_slot(atom)
			if atom.slot:
				atom_without_use += ":" + atom.slot
			atom_without_use = portage.dep.Atom(atom_without_use)
		xinfo = '"%s"' % atom
		if arg:
			xinfo='"%s"' % arg
		# Discard null/ from failed cpv_expand category expansion.
		xinfo = xinfo.replace("null/", "")
		masked_packages = []
		missing_use = []
		masked_pkg_instances = set()
		missing_licenses = []
		have_eapi_mask = False
		pkgsettings = self.pkgsettings[root]
		implicit_iuse = pkgsettings._get_implicit_iuse()
		root_config = self.roots[root]
		portdb = self.roots[root].trees["porttree"].dbapi
		dbs = self._filtered_trees[root]["dbs"]
		for db, pkg_type, built, installed, db_keys in dbs:
			if installed:
				continue
			match = db.match
			if hasattr(db, "xmatch"):
				cpv_list = db.xmatch("match-all", atom_without_use)
			else:
				cpv_list = db.match(atom_without_use)
			# descending order
			cpv_list.reverse()
			for cpv in cpv_list:
				metadata, mreasons  = get_mask_info(root_config, cpv,
					pkgsettings, db, pkg_type, built, installed, db_keys)
				if metadata is not None:
					pkg = Package(built=built, cpv=cpv,
						installed=installed, metadata=metadata,
						root_config=root_config)
					if pkg.cp != atom.cp:
						# A cpv can be returned from dbapi.match() as an
						# old-style virtual match even in cases when the
						# package does not actually PROVIDE the virtual.
						# Filter out any such false matches here.
						if not atom_set.findAtomForPackage(pkg):
							continue
					if mreasons:
						masked_pkg_instances.add(pkg)
					if atom.use:
						missing_use.append(pkg)
						if not mreasons:
							continue
				masked_packages.append(
					(root_config, pkgsettings, cpv, metadata, mreasons))

		missing_use_reasons = []
		missing_iuse_reasons = []
		for pkg in missing_use:
			use = pkg.use.enabled
			iuse = implicit_iuse.union(re.escape(x) for x in pkg.iuse.all)
			iuse_re = re.compile("^(%s)$" % "|".join(iuse))
			missing_iuse = []
			for x in atom.use.required:
				if iuse_re.match(x) is None:
					missing_iuse.append(x)
			mreasons = []
			if missing_iuse:
				mreasons.append("Missing IUSE: %s" % " ".join(missing_iuse))
				missing_iuse_reasons.append((pkg, mreasons))
			else:
				need_enable = sorted(atom.use.enabled.difference(use))
				need_disable = sorted(atom.use.disabled.intersection(use))
				if need_enable or need_disable:
					changes = []
					changes.extend(colorize("red", "+" + x) \
						for x in need_enable)
					changes.extend(colorize("blue", "-" + x) \
						for x in need_disable)
					mreasons.append("Change USE: %s" % " ".join(changes))
					missing_use_reasons.append((pkg, mreasons))

		unmasked_use_reasons = [(pkg, mreasons) for (pkg, mreasons) \
			in missing_use_reasons if pkg not in masked_pkg_instances]

		unmasked_iuse_reasons = [(pkg, mreasons) for (pkg, mreasons) \
			in missing_iuse_reasons if pkg not in masked_pkg_instances]

		show_missing_use = False
		if unmasked_use_reasons:
			# Only show the latest version.
			show_missing_use = unmasked_use_reasons[:1]
		elif unmasked_iuse_reasons:
			if missing_use_reasons:
				# All packages with required IUSE are masked,
				# so display a normal masking message.
				pass
			else:
				show_missing_use = unmasked_iuse_reasons

		if show_missing_use:
			print "\nemerge: there are no ebuilds built with USE flags to satisfy "+green(xinfo)+"."
			print "!!! One of the following packages is required to complete your request:"
			for pkg, mreasons in show_missing_use:
				print "- "+pkg.cpv+" ("+", ".join(mreasons)+")"

		elif masked_packages:
			print "\n!!! " + \
				colorize("BAD", "All ebuilds that could satisfy ") + \
				colorize("INFORM", xinfo) + \
				colorize("BAD", " have been masked.")
			print "!!! One of the following masked packages is required to complete your request:"
			have_eapi_mask = show_masked_packages(masked_packages)
			if have_eapi_mask:
				print
				msg = ("The current version of portage supports " + \
					"EAPI '%s'. You must upgrade to a newer version" + \
					" of portage before EAPI masked packages can" + \
					" be installed.") % portage.const.EAPI
				from textwrap import wrap
				for line in wrap(msg, 75):
					print line
			print
			show_mask_docs()
		else:
			print "\nemerge: there are no ebuilds to satisfy "+green(xinfo)+"."

		# Show parent nodes and the argument that pulled them in.
		traversed_nodes = set()
		node = myparent
		msg = []
		while node is not None:
			traversed_nodes.add(node)
			msg.append('(dependency required by "%s" [%s])' % \
				(colorize('INFORM', str(node.cpv)), node.type_name))
			# When traversing to parents, prefer arguments over packages
			# since arguments are root nodes. Never traverse the same
			# package twice, in order to prevent an infinite loop.
			selected_parent = None
			for parent in self.digraph.parent_nodes(node):
				if isinstance(parent, DependencyArg):
					msg.append('(dependency required by "%s" [argument])' % \
						(colorize('INFORM', str(parent))))
					selected_parent = None
					break
				if parent not in traversed_nodes:
					selected_parent = parent
			node = selected_parent
		for line in msg:
			print line

		print

	def _select_pkg_highest_available(self, root, atom, onlydeps=False):
		cache_key = (root, atom, onlydeps)
		ret = self._highest_pkg_cache.get(cache_key)
		if ret is not None:
			pkg, existing = ret
			if pkg and not existing:
				existing = self._slot_pkg_map[root].get(pkg.slot_atom)
				if existing and existing == pkg:
					# Update the cache to reflect that the
					# package has been added to the graph.
					ret = pkg, pkg
					self._highest_pkg_cache[cache_key] = ret
			return ret
		ret = self._select_pkg_highest_available_imp(root, atom, onlydeps=onlydeps)
		self._highest_pkg_cache[cache_key] = ret
		pkg, existing = ret
		if pkg is not None:
			settings = pkg.root_config.settings
			if visible(settings, pkg) and not (pkg.installed and \
				settings._getMissingKeywords(pkg.cpv, pkg.metadata)):
				pkg.root_config.visible_pkgs.cpv_inject(pkg)
		return ret

	def _select_pkg_highest_available_imp(self, root, atom, onlydeps=False):
		root_config = self.roots[root]
		pkgsettings = self.pkgsettings[root]
		dbs = self._filtered_trees[root]["dbs"]
		vardb = self.roots[root].trees["vartree"].dbapi
		portdb = self.roots[root].trees["porttree"].dbapi
		# List of acceptable packages, ordered by type preference.
		matched_packages = []
		highest_version = None
		if not isinstance(atom, portage.dep.Atom):
			atom = portage.dep.Atom(atom)
		atom_cp = atom.cp
		atom_set = InternalPackageSet(initial_atoms=(atom,))
		existing_node = None
		myeb = None
		usepkgonly = "--usepkgonly" in self.myopts
		empty = "empty" in self.myparams
		selective = "selective" in self.myparams
		reinstall = False
		noreplace = "--noreplace" in self.myopts
		# Behavior of the "selective" parameter depends on
		# whether or not a package matches an argument atom.
		# If an installed package provides an old-style
		# virtual that is no longer provided by an available
		# package, the installed package may match an argument
		# atom even though none of the available packages do.
		# Therefore, "selective" logic does not consider
		# whether or not an installed package matches an
		# argument atom. It only considers whether or not
		# available packages match argument atoms, which is
		# represented by the found_available_arg flag.
		found_available_arg = False
		for find_existing_node in True, False:
			if existing_node:
				break
			for db, pkg_type, built, installed, db_keys in dbs:
				if existing_node:
					break
				if installed and not find_existing_node:
					want_reinstall = reinstall or empty or \
						(found_available_arg and not selective)
					if want_reinstall and matched_packages:
						continue
				if hasattr(db, "xmatch"):
					cpv_list = db.xmatch("match-all", atom)
				else:
					cpv_list = db.match(atom)

				# USE=multislot can make an installed package appear as if
				# it doesn't satisfy a slot dependency. Rebuilding the ebuild
				# won't do any good as long as USE=multislot is enabled since
				# the newly built package still won't have the expected slot.
				# Therefore, assume that such SLOT dependencies are already
				# satisfied rather than forcing a rebuild.
				if installed and not cpv_list and atom.slot:
					for cpv in db.match(atom.cp):
						slot_available = False
						for other_db, other_type, other_built, \
							other_installed, other_keys in dbs:
							try:
								if atom.slot == \
									other_db.aux_get(cpv, ["SLOT"])[0]:
									slot_available = True
									break
							except KeyError:
								pass
						if not slot_available:
							continue
						inst_pkg = self._pkg(cpv, "installed",
							root_config, installed=installed)
						# Remove the slot from the atom and verify that
						# the package matches the resulting atom.
						atom_without_slot = portage.dep.remove_slot(atom)
						if atom.use:
							atom_without_slot += str(atom.use)
						atom_without_slot = portage.dep.Atom(atom_without_slot)
						if portage.match_from_list(
							atom_without_slot, [inst_pkg]):
							cpv_list = [inst_pkg.cpv]
						break

				if not cpv_list:
					continue
				pkg_status = "merge"
				if installed or onlydeps:
					pkg_status = "nomerge"
				# descending order
				cpv_list.reverse()
				for cpv in cpv_list:
					# Make --noreplace take precedence over --newuse.
					if not installed and noreplace and \
						cpv in vardb.match(atom):
						# If the installed version is masked, it may
						# be necessary to look at lower versions,
						# in case there is a visible downgrade.
						continue
					reinstall_for_flags = None
					cache_key = (pkg_type, root, cpv, pkg_status)
					calculated_use = True
					pkg = self._pkg_cache.get(cache_key)
					if pkg is None:
						calculated_use = False
						try:
							metadata = izip(db_keys, db.aux_get(cpv, db_keys))
						except KeyError:
							continue
						pkg = Package(built=built, cpv=cpv,
							installed=installed, metadata=metadata,
							onlydeps=onlydeps, root_config=root_config,
							type_name=pkg_type)
						metadata = pkg.metadata
						if not built:
							metadata['CHOST'] = pkgsettings.get('CHOST', '')
						if not built and ("?" in metadata["LICENSE"] or \
							"?" in metadata["PROVIDE"]):
							# This is avoided whenever possible because
							# it's expensive. It only needs to be done here
							# if it has an effect on visibility.
							pkgsettings.setcpv(pkg)
							metadata["USE"] = pkgsettings["PORTAGE_USE"]
							calculated_use = True
						self._pkg_cache[pkg] = pkg

					if not installed or (built and matched_packages):
						# Only enforce visibility on installed packages
						# if there is at least one other visible package
						# available. By filtering installed masked packages
						# here, packages that have been masked since they
						# were installed can be automatically downgraded
						# to an unmasked version.
						try:
							if not visible(pkgsettings, pkg):
								continue
						except portage.exception.InvalidDependString:
							if not installed:
								continue

						# Enable upgrade or downgrade to a version
						# with visible KEYWORDS when the installed
						# version is masked by KEYWORDS, but never
						# reinstall the same exact version only due
						# to a KEYWORDS mask.
						if built and matched_packages:

							different_version = None
							for avail_pkg in matched_packages:
								if not portage.dep.cpvequal(
									pkg.cpv, avail_pkg.cpv):
									different_version = avail_pkg
									break
							if different_version is not None:

								if installed and \
									pkgsettings._getMissingKeywords(
									pkg.cpv, pkg.metadata):
									continue

								# If the ebuild no longer exists or it's
								# keywords have been dropped, reject built
								# instances (installed or binary).
								# If --usepkgonly is enabled, assume that
								# the ebuild status should be ignored.
								if not usepkgonly:
									try:
										pkg_eb = self._pkg(
											pkg.cpv, "ebuild", root_config)
									except portage.exception.PackageNotFound:
										continue
									else:
										if not visible(pkgsettings, pkg_eb):
											continue

					if not pkg.built and not calculated_use:
						# This is avoided whenever possible because
						# it's expensive.
						pkgsettings.setcpv(pkg)
						pkg.metadata["USE"] = pkgsettings["PORTAGE_USE"]

					if pkg.cp != atom.cp:
						# A cpv can be returned from dbapi.match() as an
						# old-style virtual match even in cases when the
						# package does not actually PROVIDE the virtual.
						# Filter out any such false matches here.
						if not atom_set.findAtomForPackage(pkg):
							continue

					myarg = None
					if root == self.target_root:
						try:
							# Ebuild USE must have been calculated prior
							# to this point, in case atoms have USE deps.
							myarg = self._iter_atoms_for_pkg(pkg).next()
						except StopIteration:
							pass
						except portage.exception.InvalidDependString:
							if not installed:
								# masked by corruption
								continue
					if not installed and myarg:
						found_available_arg = True

					if atom.use and not pkg.built:
						use = pkg.use.enabled
						if atom.use.enabled.difference(use):
							continue
						if atom.use.disabled.intersection(use):
							continue
					if pkg.cp == atom_cp:
						if highest_version is None:
							highest_version = pkg
						elif pkg > highest_version:
							highest_version = pkg
					# At this point, we've found the highest visible
					# match from the current repo. Any lower versions
					# from this repo are ignored, so this so the loop
					# will always end with a break statement below
					# this point.
					if find_existing_node:
						e_pkg = self._slot_pkg_map[root].get(pkg.slot_atom)
						if not e_pkg:
							break
						if portage.dep.match_from_list(atom, [e_pkg]):
							if highest_version and \
								e_pkg.cp == atom_cp and \
								e_pkg < highest_version and \
								e_pkg.slot_atom != highest_version.slot_atom:
								# There is a higher version available in a
								# different slot, so this existing node is
								# irrelevant.
								pass
							else:
								matched_packages.append(e_pkg)
								existing_node = e_pkg
						break
					# Compare built package to current config and
					# reject the built package if necessary.
					if built and not installed and \
						("--newuse" in self.myopts or \
						"--reinstall" in self.myopts):
						iuses = pkg.iuse.all
						old_use = pkg.use.enabled
						if myeb:
							pkgsettings.setcpv(myeb)
						else:
							pkgsettings.setcpv(pkg)
						now_use = pkgsettings["PORTAGE_USE"].split()
						forced_flags = set()
						forced_flags.update(pkgsettings.useforce)
						forced_flags.update(pkgsettings.usemask)
						cur_iuse = iuses
						if myeb and not usepkgonly:
							cur_iuse = myeb.iuse.all
						if self._reinstall_for_flags(forced_flags,
							old_use, iuses,
							now_use, cur_iuse):
							break
					# Compare current config to installed package
					# and do not reinstall if possible.
					if not installed and \
						("--newuse" in self.myopts or \
						"--reinstall" in self.myopts) and \
						cpv in vardb.match(atom):
						pkgsettings.setcpv(pkg)
						forced_flags = set()
						forced_flags.update(pkgsettings.useforce)
						forced_flags.update(pkgsettings.usemask)
						old_use = vardb.aux_get(cpv, ["USE"])[0].split()
						old_iuse = set(filter_iuse_defaults(
							vardb.aux_get(cpv, ["IUSE"])[0].split()))
						cur_use = pkg.use.enabled
						cur_iuse = pkg.iuse.all
						reinstall_for_flags = \
							self._reinstall_for_flags(
							forced_flags, old_use, old_iuse,
							cur_use, cur_iuse)
						if reinstall_for_flags:
							reinstall = True
					if not built:
						myeb = pkg
					matched_packages.append(pkg)
					if reinstall_for_flags:
						self._reinstall_nodes[pkg] = \
							reinstall_for_flags
					break

		if not matched_packages:
			return None, None

		if "--debug" in self.myopts:
			for pkg in matched_packages:
				portage.writemsg("%s %s\n" % \
					((pkg.type_name + ":").rjust(10), pkg.cpv), noiselevel=-1)

		# Filter out any old-style virtual matches if they are
		# mixed with new-style virtual matches.
		cp = portage.dep_getkey(atom)
		if len(matched_packages) > 1 and \
			"virtual" == portage.catsplit(cp)[0]:
			for pkg in matched_packages:
				if pkg.cp != cp:
					continue
				# Got a new-style virtual, so filter
				# out any old-style virtuals.
				matched_packages = [pkg for pkg in matched_packages \
					if pkg.cp == cp]
				break

		if len(matched_packages) > 1:
			bestmatch = portage.best(
				[pkg.cpv for pkg in matched_packages])
			matched_packages = [pkg for pkg in matched_packages \
				if portage.dep.cpvequal(pkg.cpv, bestmatch)]

		# ordered by type preference ("ebuild" type is the last resort)
		return  matched_packages[-1], existing_node

	def _select_pkg_from_graph(self, root, atom, onlydeps=False):
		"""
		Select packages that have already been added to the graph or
		those that are installed and have not been scheduled for
		replacement.
		"""
		graph_db = self._graph_trees[root]["porttree"].dbapi
		matches = graph_db.match_pkgs(atom)
		if not matches:
			return None, None
		pkg = matches[-1] # highest match
		in_graph = self._slot_pkg_map[root].get(pkg.slot_atom)
		return pkg, in_graph

	def _complete_graph(self):
		"""
		Add any deep dependencies of required sets (args, system, world) that
		have not been pulled into the graph yet. This ensures that the graph
		is consistent such that initially satisfied deep dependencies are not
		broken in the new graph. Initially unsatisfied dependencies are
		irrelevant since we only want to avoid breaking dependencies that are
		intially satisfied.

		Since this method can consume enough time to disturb users, it is
		currently only enabled by the --complete-graph option.
		"""
		if "--buildpkgonly" in self.myopts or \
			"recurse" not in self.myparams:
			return 1

		if "complete" not in self.myparams:
			# Skip this to avoid consuming enough time to disturb users.
			return 1

		# Put the depgraph into a mode that causes it to only
		# select packages that have already been added to the
		# graph or those that are installed and have not been
		# scheduled for replacement. Also, toggle the "deep"
		# parameter so that all dependencies are traversed and
		# accounted for.
		self._select_atoms = self._select_atoms_from_graph
		self._select_package = self._select_pkg_from_graph
		already_deep = "deep" in self.myparams
		if not already_deep:
			self.myparams.add("deep")

		for root in self.roots:
			required_set_names = self._required_set_names.copy()
			if root == self.target_root and \
				(already_deep or "empty" in self.myparams):
				required_set_names.difference_update(self._sets)
			if not required_set_names and not self._ignored_deps:
				continue
			root_config = self.roots[root]
			setconfig = root_config.setconfig
			args = []
			# Reuse existing SetArg instances when available.
			for arg in self.digraph.root_nodes():
				if not isinstance(arg, SetArg):
					continue
				if arg.root_config != root_config:
					continue
				if arg.name in required_set_names:
					args.append(arg)
					required_set_names.remove(arg.name)
			# Create new SetArg instances only when necessary.
			for s in required_set_names:
				expanded_set = InternalPackageSet(
					initial_atoms=setconfig.getSetAtoms(s))
				atom = SETPREFIX + s
				args.append(SetArg(arg=atom, set=expanded_set,
					root_config=root_config))
			vardb = root_config.trees["vartree"].dbapi
			for arg in args:
				for atom in arg.set:
					self._dep_stack.append(
						Dependency(atom=atom, root=root, parent=arg))
			if self._ignored_deps:
				self._dep_stack.extend(self._ignored_deps)
				self._ignored_deps = []
			if not self._create_graph(allow_unsatisfied=True):
				return 0
			# Check the unsatisfied deps to see if any initially satisfied deps
			# will become unsatisfied due to an upgrade. Initially unsatisfied
			# deps are irrelevant since we only want to avoid breaking deps
			# that are initially satisfied.
			while self._unsatisfied_deps:
				dep = self._unsatisfied_deps.pop()
				matches = vardb.match_pkgs(dep.atom)
				if not matches:
					self._initially_unsatisfied_deps.append(dep)
					continue
				# An scheduled installation broke a deep dependency.
				# Add the installed package to the graph so that it
				# will be appropriately reported as a slot collision
				# (possibly solvable via backtracking).
				pkg = matches[-1] # highest match
				if not self._add_pkg(pkg, dep):
					return 0
				if not self._create_graph(allow_unsatisfied=True):
					return 0
		return 1

	def _pkg(self, cpv, type_name, root_config, installed=False):
		"""
		Get a package instance from the cache, or create a new
		one if necessary. Raises KeyError from aux_get if it
		failures for some reason (package does not exist or is
		corrupt).
		"""
		operation = "merge"
		if installed:
			operation = "nomerge"
		pkg = self._pkg_cache.get(
			(type_name, root_config.root, cpv, operation))
		if pkg is None:
			tree_type = self.pkg_tree_map[type_name]
			db = root_config.trees[tree_type].dbapi
			db_keys = list(self._trees_orig[root_config.root][
				tree_type].dbapi._aux_cache_keys)
			try:
				metadata = izip(db_keys, db.aux_get(cpv, db_keys))
			except KeyError:
				raise portage.exception.PackageNotFound(cpv)
			pkg = Package(cpv=cpv, metadata=metadata,
				root_config=root_config, installed=installed)
			if type_name == "ebuild":
				settings = self.pkgsettings[root_config.root]
				settings.setcpv(pkg)
				pkg.metadata["USE"] = settings["PORTAGE_USE"]
				pkg.metadata['CHOST'] = settings.get('CHOST', '')
			self._pkg_cache[pkg] = pkg
		return pkg

	def validate_blockers(self):
		"""Remove any blockers from the digraph that do not match any of the
		packages within the graph.  If necessary, create hard deps to ensure
		correct merge order such that mutually blocking packages are never
		installed simultaneously."""

		if "--buildpkgonly" in self.myopts or \
			"--nodeps" in self.myopts:
			return True

		#if "deep" in self.myparams:
		if True:
			# Pull in blockers from all installed packages that haven't already
			# been pulled into the depgraph.  This is not enabled by default
			# due to the performance penalty that is incurred by all the
			# additional dep_check calls that are required.

			dep_keys = ["DEPEND","RDEPEND","PDEPEND"]
			for myroot in self.trees:
				vardb = self.trees[myroot]["vartree"].dbapi
				portdb = self.trees[myroot]["porttree"].dbapi
				pkgsettings = self.pkgsettings[myroot]
				final_db = self.mydbapi[myroot]

				blocker_cache = BlockerCache(myroot, vardb)
				stale_cache = set(blocker_cache)
				for pkg in vardb:
					cpv = pkg.cpv
					stale_cache.discard(cpv)
					pkg_in_graph = self.digraph.contains(pkg)

					# Check for masked installed packages. Only warn about
					# packages that are in the graph in order to avoid warning
					# about those that will be automatically uninstalled during
					# the merge process or by --depclean.
					if pkg in final_db:
						if pkg_in_graph and not visible(pkgsettings, pkg):
							self._masked_installed.add(pkg)

					blocker_atoms = None
					blockers = None
					if pkg_in_graph:
						blockers = []
						try:
							blockers.extend(
								self._blocker_parents.child_nodes(pkg))
						except KeyError:
							pass
						try:
							blockers.extend(
								self._irrelevant_blockers.child_nodes(pkg))
						except KeyError:
							pass
					if blockers is not None:
						blockers = set(str(blocker.atom) \
							for blocker in blockers)

					# If this node has any blockers, create a "nomerge"
					# node for it so that they can be enforced.
					self.spinner.update()
					blocker_data = blocker_cache.get(cpv)
					if blocker_data is not None and \
						blocker_data.counter != long(pkg.metadata["COUNTER"]):
						blocker_data = None

					# If blocker data from the graph is available, use
					# it to validate the cache and update the cache if
					# it seems invalid.
					if blocker_data is not None and \
						blockers is not None:
						if not blockers.symmetric_difference(
							blocker_data.atoms):
							continue
						blocker_data = None

					if blocker_data is None and \
						blockers is not None:
						# Re-use the blockers from the graph.
						blocker_atoms = sorted(blockers)
						counter = long(pkg.metadata["COUNTER"])
						blocker_data = \
							blocker_cache.BlockerData(counter, blocker_atoms)
						blocker_cache[pkg.cpv] = blocker_data
						continue

					if blocker_data:
						blocker_atoms = blocker_data.atoms
					else:
						# Use aux_get() to trigger FakeVartree global
						# updates on *DEPEND when appropriate.
						depstr = " ".join(vardb.aux_get(pkg.cpv, dep_keys))
						# It is crucial to pass in final_db here in order to
						# optimize dep_check calls by eliminating atoms via
						# dep_wordreduce and dep_eval calls.
						try:
							portage.dep._dep_check_strict = False
							try:
								success, atoms = portage.dep_check(depstr,
									final_db, pkgsettings, myuse=pkg.use.enabled,
									trees=self._graph_trees, myroot=myroot)
							except Exception, e:
								if isinstance(e, SystemExit):
									raise
								# This is helpful, for example, if a ValueError
								# is thrown from cpv_expand due to multiple
								# matches (this can happen if an atom lacks a
								# category).
								show_invalid_depstring_notice(
									pkg, depstr, str(e))
								del e
								raise
						finally:
							portage.dep._dep_check_strict = True
						if not success:
							replacement_pkg = final_db.match_pkgs(pkg.slot_atom)
							if replacement_pkg and \
								replacement_pkg[0].operation == "merge":
								# This package is being replaced anyway, so
								# ignore invalid dependencies so as not to
								# annoy the user too much (otherwise they'd be
								# forced to manually unmerge it first).
								continue
							show_invalid_depstring_notice(pkg, depstr, atoms)
							return False
						blocker_atoms = [myatom for myatom in atoms \
							if myatom.startswith("!")]
						blocker_atoms.sort()
						counter = long(pkg.metadata["COUNTER"])
						blocker_cache[cpv] = \
							blocker_cache.BlockerData(counter, blocker_atoms)
					if blocker_atoms:
						try:
							for atom in blocker_atoms:
								blocker = Blocker(atom=portage.dep.Atom(atom),
									eapi=pkg.metadata["EAPI"], root=myroot)
								self._blocker_parents.add(blocker, pkg)
						except portage.exception.InvalidAtom, e:
							depstr = " ".join(vardb.aux_get(pkg.cpv, dep_keys))
							show_invalid_depstring_notice(
								pkg, depstr, "Invalid Atom: %s" % (e,))
							return False
				for cpv in stale_cache:
					del blocker_cache[cpv]
				blocker_cache.flush()
				del blocker_cache

		# Discard any "uninstall" tasks scheduled by previous calls
		# to this method, since those tasks may not make sense given
		# the current graph state.
		previous_uninstall_tasks = self._blocker_uninstalls.leaf_nodes()
		if previous_uninstall_tasks:
			self._blocker_uninstalls = digraph()
			self.digraph.difference_update(previous_uninstall_tasks)

		for blocker in self._blocker_parents.leaf_nodes():
			self.spinner.update()
			root_config = self.roots[blocker.root]
			virtuals = root_config.settings.getvirtuals()
			myroot = blocker.root
			initial_db = self.trees[myroot]["vartree"].dbapi
			final_db = self.mydbapi[myroot]
			
			provider_virtual = False
			if blocker.cp in virtuals and \
				not self._have_new_virt(blocker.root, blocker.cp):
				provider_virtual = True

			# Use this to check PROVIDE for each matched package
			# when necessary.
			atom_set = InternalPackageSet(
				initial_atoms=[blocker.atom])

			if provider_virtual:
				atoms = []
				for provider_entry in virtuals[blocker.cp]:
					provider_cp = \
						portage.dep_getkey(provider_entry)
					atoms.append(blocker.atom.replace(
						blocker.cp, provider_cp))
			else:
				atoms = [blocker.atom]

			blocked_initial = set()
			for atom in atoms:
				for pkg in initial_db.match_pkgs(atom):
					if atom_set.findAtomForPackage(pkg):
						blocked_initial.add(pkg)

			blocked_final = set()
			for atom in atoms:
				for pkg in final_db.match_pkgs(atom):
					if atom_set.findAtomForPackage(pkg):
						blocked_final.add(pkg)

			if not blocked_initial and not blocked_final:
				parent_pkgs = self._blocker_parents.parent_nodes(blocker)
				self._blocker_parents.remove(blocker)
				# Discard any parents that don't have any more blockers.
				for pkg in parent_pkgs:
					self._irrelevant_blockers.add(blocker, pkg)
					if not self._blocker_parents.child_nodes(pkg):
						self._blocker_parents.remove(pkg)
				continue
			for parent in self._blocker_parents.parent_nodes(blocker):
				unresolved_blocks = False
				depends_on_order = set()
				for pkg in blocked_initial:
					if pkg.slot_atom == parent.slot_atom:
						# TODO: Support blocks within slots in cases where it
						# might make sense.  For example, a new version might
						# require that the old version be uninstalled at build
						# time.
						continue
					if parent.installed:
						# Two currently installed packages conflict with
						# eachother. Ignore this case since the damage
						# is already done and this would be likely to
						# confuse users if displayed like a normal blocker.
						continue

					self._blocked_pkgs.add(pkg, blocker)

					if parent.operation == "merge":
						# Maybe the blocked package can be replaced or simply
						# unmerged to resolve this block.
						depends_on_order.add((pkg, parent))
						continue
					# None of the above blocker resolutions techniques apply,
					# so apparently this one is unresolvable.
					unresolved_blocks = True
				for pkg in blocked_final:
					if pkg.slot_atom == parent.slot_atom:
						# TODO: Support blocks within slots.
						continue
					if parent.operation == "nomerge" and \
						pkg.operation == "nomerge":
						# This blocker will be handled the next time that a
						# merge of either package is triggered.
						continue

					self._blocked_pkgs.add(pkg, blocker)

					# Maybe the blocking package can be
					# unmerged to resolve this block.
					if parent.operation == "merge" and pkg.installed:
						depends_on_order.add((pkg, parent))
						continue
					elif parent.operation == "nomerge":
						depends_on_order.add((parent, pkg))
						continue
					# None of the above blocker resolutions techniques apply,
					# so apparently this one is unresolvable.
					unresolved_blocks = True

				# Make sure we don't unmerge any package that have been pulled
				# into the graph.
				if not unresolved_blocks and depends_on_order:
					for inst_pkg, inst_task in depends_on_order:
						if self.digraph.contains(inst_pkg) and \
							self.digraph.parent_nodes(inst_pkg):
							unresolved_blocks = True
							break

				if not unresolved_blocks and depends_on_order:
					for inst_pkg, inst_task in depends_on_order:
						uninst_task = Package(built=inst_pkg.built,
							cpv=inst_pkg.cpv, installed=inst_pkg.installed,
							metadata=inst_pkg.metadata,
							operation="uninstall",
							root_config=inst_pkg.root_config,
							type_name=inst_pkg.type_name)
						self._pkg_cache[uninst_task] = uninst_task
						# Enforce correct merge order with a hard dep.
						self.digraph.addnode(uninst_task, inst_task,
							priority=BlockerDepPriority.instance)
						# Count references to this blocker so that it can be
						# invalidated after nodes referencing it have been
						# merged.
						self._blocker_uninstalls.addnode(uninst_task, blocker)
				if not unresolved_blocks and not depends_on_order:
					self._irrelevant_blockers.add(blocker, parent)
					self._blocker_parents.remove_edge(blocker, parent)
					if not self._blocker_parents.parent_nodes(blocker):
						self._blocker_parents.remove(blocker)
					if not self._blocker_parents.child_nodes(parent):
						self._blocker_parents.remove(parent)
				if unresolved_blocks:
					self._unsolvable_blockers.add(blocker, parent)

		return True

	def _accept_blocker_conflicts(self):
		acceptable = False
		for x in ("--buildpkgonly", "--fetchonly",
			"--fetch-all-uri", "--nodeps"):
			if x in self.myopts:
				acceptable = True
				break
		return acceptable

	def _merge_order_bias(self, mygraph):
		"""
		For optimal leaf node selection, promote deep system runtime deps and
		order nodes from highest to lowest overall reference count.
		"""

		node_info = {}
		for node in mygraph.order:
			node_info[node] = len(mygraph.parent_nodes(node))
		deep_system_deps = _find_deep_system_runtime_deps(mygraph)

		def cmp_merge_preference(node1, node2):

			if node1.operation == 'uninstall':
				if node2.operation == 'uninstall':
					return 0
				return 1

			if node2.operation == 'uninstall':
				if node1.operation == 'uninstall':
					return 0
				return -1

			node1_sys = node1 in deep_system_deps
			node2_sys = node2 in deep_system_deps
			if node1_sys != node2_sys:
				if node1_sys:
					return -1
				return 1

			return node_info[node2] - node_info[node1]

		mygraph.order.sort(key=cmp_sort_key(cmp_merge_preference))

	def altlist(self, reversed=False):

		while self._serialized_tasks_cache is None:
			self._resolve_conflicts()
			try:
				self._serialized_tasks_cache, self._scheduler_graph = \
					self._serialize_tasks()
			except self._serialize_tasks_retry:
				pass

		retlist = self._serialized_tasks_cache[:]
		if reversed:
			retlist.reverse()
		return retlist

	def schedulerGraph(self):
		"""
		The scheduler graph is identical to the normal one except that
		uninstall edges are reversed in specific cases that require
		conflicting packages to be temporarily installed simultaneously.
		This is intended for use by the Scheduler in it's parallelization
		logic. It ensures that temporary simultaneous installation of
		conflicting packages is avoided when appropriate (especially for
		!!atom blockers), but allowed in specific cases that require it.

		Note that this method calls break_refs() which alters the state of
		internal Package instances such that this depgraph instance should
		not be used to perform any more calculations.
		"""
		if self._scheduler_graph is None:
			self.altlist()
		self.break_refs(self._scheduler_graph.order)
		return self._scheduler_graph

	def break_refs(self, nodes):
		"""
		Take a mergelist like that returned from self.altlist() and
		break any references that lead back to the depgraph. This is
		useful if you want to hold references to packages without
		also holding the depgraph on the heap.
		"""
		for node in nodes:
			if hasattr(node, "root_config"):
				# The FakeVartree references the _package_cache which
				# references the depgraph. So that Package instances don't
				# hold the depgraph and FakeVartree on the heap, replace
				# the RootConfig that references the FakeVartree with the
				# original RootConfig instance which references the actual
				# vartree.
				node.root_config = \
					self._trees_orig[node.root_config.root]["root_config"]

	def _resolve_conflicts(self):
		if not self._complete_graph():
			raise self._unknown_internal_error()

		if not self.validate_blockers():
			raise self._unknown_internal_error()

		if self._slot_collision_info:
			self._process_slot_conflicts()

	def _serialize_tasks(self):

		if "--debug" in self.myopts:
			writemsg("\ndigraph:\n\n", noiselevel=-1)
			self.digraph.debug_print()
			writemsg("\n", noiselevel=-1)

		scheduler_graph = self.digraph.copy()

		if '--nodeps' in self.myopts:
			# Preserve the package order given on the command line.
			return ([node for node in scheduler_graph \
				if isinstance(node, Package) \
				and node.operation == 'merge'], scheduler_graph)

		mygraph=self.digraph.copy()
		# Prune "nomerge" root nodes if nothing depends on them, since
		# otherwise they slow down merge order calculation. Don't remove
		# non-root nodes since they help optimize merge order in some cases
		# such as revdep-rebuild.
		removed_nodes = set()
		while True:
			for node in mygraph.root_nodes():
				if not isinstance(node, Package) or \
					node.installed or node.onlydeps:
					removed_nodes.add(node)
			if removed_nodes:
				self.spinner.update()
				mygraph.difference_update(removed_nodes)
			if not removed_nodes:
				break
			removed_nodes.clear()
		self._merge_order_bias(mygraph)
		def cmp_circular_bias(n1, n2):
			"""
			RDEPEND is stronger than PDEPEND and this function
			measures such a strength bias within a circular
			dependency relationship.
			"""
			n1_n2_medium = n2 in mygraph.child_nodes(n1,
				ignore_priority=priority_range.ignore_medium_soft)
			n2_n1_medium = n1 in mygraph.child_nodes(n2,
				ignore_priority=priority_range.ignore_medium_soft)
			if n1_n2_medium == n2_n1_medium:
				return 0
			elif n1_n2_medium:
				return 1
			return -1
		myblocker_uninstalls = self._blocker_uninstalls.copy()
		retlist=[]
		# Contains uninstall tasks that have been scheduled to
		# occur after overlapping blockers have been installed.
		scheduled_uninstalls = set()
		# Contains any Uninstall tasks that have been ignored
		# in order to avoid the circular deps code path. These
		# correspond to blocker conflicts that could not be
		# resolved.
		ignored_uninstall_tasks = set()
		have_uninstall_task = False
		complete = "complete" in self.myparams
		asap_nodes = []

		def get_nodes(**kwargs):
			"""
			Returns leaf nodes excluding Uninstall instances
			since those should be executed as late as possible.
			"""
			return [node for node in mygraph.leaf_nodes(**kwargs) \
				if isinstance(node, Package) and \
					(node.operation != "uninstall" or \
					node in scheduled_uninstalls)]

		# sys-apps/portage needs special treatment if ROOT="/"
		running_root = self._running_root.root
		from portage.const import PORTAGE_PACKAGE_ATOM
		runtime_deps = InternalPackageSet(
			initial_atoms=[PORTAGE_PACKAGE_ATOM])
		running_portage = self.trees[running_root]["vartree"].dbapi.match_pkgs(
			PORTAGE_PACKAGE_ATOM)
		replacement_portage = self.mydbapi[running_root].match_pkgs(
			PORTAGE_PACKAGE_ATOM)

		if running_portage:
			running_portage = running_portage[0]
		else:
			running_portage = None

		if replacement_portage:
			replacement_portage = replacement_portage[0]
		else:
			replacement_portage = None

		if replacement_portage == running_portage:
			replacement_portage = None

		if replacement_portage is not None:
			# update from running_portage to replacement_portage asap
			asap_nodes.append(replacement_portage)

		if running_portage is not None:
			try:
				portage_rdepend = self._select_atoms_highest_available(
					running_root, running_portage.metadata["RDEPEND"],
					myuse=running_portage.use.enabled,
					parent=running_portage, strict=False)
			except portage.exception.InvalidDependString, e:
				portage.writemsg("!!! Invalid RDEPEND in " + \
					"'%svar/db/pkg/%s/RDEPEND': %s\n" % \
					(running_root, running_portage.cpv, e), noiselevel=-1)
				del e
				portage_rdepend = []
			runtime_deps.update(atom for atom in portage_rdepend \
				if not atom.startswith("!"))

		def gather_deps(ignore_priority, mergeable_nodes,
			selected_nodes, node):
			"""
			Recursively gather a group of nodes that RDEPEND on
			eachother. This ensures that they are merged as a group
			and get their RDEPENDs satisfied as soon as possible.
			"""
			if node in selected_nodes:
				return True
			if node not in mergeable_nodes:
				return False
			if node == replacement_portage and \
				mygraph.child_nodes(node,
				ignore_priority=priority_range.ignore_medium_soft):
				# Make sure that portage always has all of it's
				# RDEPENDs installed first.
				return False
			selected_nodes.add(node)
			for child in mygraph.child_nodes(node,
				ignore_priority=ignore_priority):
				if not gather_deps(ignore_priority,
					mergeable_nodes, selected_nodes, child):
					return False
			return True

		def ignore_uninst_or_med(priority):
			if priority is BlockerDepPriority.instance:
				return True
			return priority_range.ignore_medium(priority)

		def ignore_uninst_or_med_soft(priority):
			if priority is BlockerDepPriority.instance:
				return True
			return priority_range.ignore_medium_soft(priority)

		tree_mode = "--tree" in self.myopts
		# Tracks whether or not the current iteration should prefer asap_nodes
		# if available.  This is set to False when the previous iteration
		# failed to select any nodes.  It is reset whenever nodes are
		# successfully selected.
		prefer_asap = True

		# Controls whether or not the current iteration should drop edges that
		# are "satisfied" by installed packages, in order to solve circular
		# dependencies. The deep runtime dependencies of installed packages are
		# not checked in this case (bug #199856), so it must be avoided
		# whenever possible.
		drop_satisfied = False

		# State of variables for successive iterations that loosen the
		# criteria for node selection.
		#
		# iteration   prefer_asap   drop_satisfied
		# 1           True          False
		# 2           False         False
		# 3           False         True
		#
		# If no nodes are selected on the last iteration, it is due to
		# unresolved blockers or circular dependencies.

		while not mygraph.empty():
			self.spinner.update()
			selected_nodes = None
			ignore_priority = None
			if drop_satisfied or (prefer_asap and asap_nodes):
				priority_range = DepPrioritySatisfiedRange
			else:
				priority_range = DepPriorityNormalRange
			if prefer_asap and asap_nodes:
				# ASAP nodes are merged before their soft deps. Go ahead and
				# select root nodes here if necessary, since it's typical for
				# the parent to have been removed from the graph already.
				asap_nodes = [node for node in asap_nodes \
					if mygraph.contains(node)]
				for node in asap_nodes:
					if not mygraph.child_nodes(node,
						ignore_priority=priority_range.ignore_soft):
						selected_nodes = [node]
						asap_nodes.remove(node)
						break
			if not selected_nodes and \
				not (prefer_asap and asap_nodes):
				for i in xrange(priority_range.NONE,
					priority_range.MEDIUM_SOFT + 1):
					ignore_priority = priority_range.ignore_priority[i]
					nodes = get_nodes(ignore_priority=ignore_priority)
					if nodes:
						# If there is a mix of uninstall nodes with other
						# types, save the uninstall nodes for later since
						# sometimes a merge node will render an uninstall
						# node unnecessary (due to occupying the same slot),
						# and we want to avoid executing a separate uninstall
						# task in that case.
						if len(nodes) > 1:
							good_uninstalls = []
							with_some_uninstalls_excluded = []
							for node in nodes:
								if node.operation == "uninstall":
									slot_node = self.mydbapi[node.root
										].match_pkgs(node.slot_atom)
									if slot_node and \
										slot_node[0].operation == "merge":
										continue
									good_uninstalls.append(node)
								with_some_uninstalls_excluded.append(node)
							if good_uninstalls:
								nodes = good_uninstalls
							elif with_some_uninstalls_excluded:
								nodes = with_some_uninstalls_excluded
							else:
								nodes = nodes

						if ignore_priority is None and not tree_mode:
							# Greedily pop all of these nodes since no
							# relationship has been ignored. This optimization
							# destroys --tree output, so it's disabled in tree
							# mode.
							selected_nodes = nodes
						else:
							# For optimal merge order:
							#  * Only pop one node.
							#  * Removing a root node (node without a parent)
							#    will not produce a leaf node, so avoid it.
							#  * It's normal for a selected uninstall to be a
							#    root node, so don't check them for parents.
							for node in nodes:
								if node.operation == "uninstall" or \
									mygraph.parent_nodes(node):
									selected_nodes = [node]
									break

						if selected_nodes:
							break

			if not selected_nodes:
				nodes = get_nodes(ignore_priority=priority_range.ignore_medium)
				if nodes:
					mergeable_nodes = set(nodes)
					if prefer_asap and asap_nodes:
						nodes = asap_nodes
					for i in xrange(priority_range.SOFT,
						priority_range.MEDIUM_SOFT + 1):
						ignore_priority = priority_range.ignore_priority[i]
						for node in nodes:
							if not mygraph.parent_nodes(node):
								continue
							selected_nodes = set()
							if gather_deps(ignore_priority,
								mergeable_nodes, selected_nodes, node):
								break
							else:
								selected_nodes = None
						if selected_nodes:
							break

					if prefer_asap and asap_nodes and not selected_nodes:
						# We failed to find any asap nodes to merge, so ignore
						# them for the next iteration.
						prefer_asap = False
						continue

			if selected_nodes and ignore_priority is not None:
				# Try to merge ignored medium_soft deps as soon as possible
				# if they're not satisfied by installed packages.
				for node in selected_nodes:
					children = set(mygraph.child_nodes(node))
					soft = children.difference(
						mygraph.child_nodes(node,
						ignore_priority=DepPrioritySatisfiedRange.ignore_soft))
					medium_soft = children.difference(
						mygraph.child_nodes(node,
							ignore_priority = \
							DepPrioritySatisfiedRange.ignore_medium_soft))
					medium_soft.difference_update(soft)
					for child in medium_soft:
						if child in selected_nodes:
							continue
						if child in asap_nodes:
							continue
						asap_nodes.append(child)

			if selected_nodes and len(selected_nodes) > 1:
				if not isinstance(selected_nodes, list):
					selected_nodes = list(selected_nodes)
				selected_nodes.sort(key=cmp_sort_key(cmp_circular_bias))

			if not selected_nodes and not myblocker_uninstalls.is_empty():
				# An Uninstall task needs to be executed in order to
				# avoid conflict if possible.

				if drop_satisfied:
					priority_range = DepPrioritySatisfiedRange
				else:
					priority_range = DepPriorityNormalRange

				mergeable_nodes = get_nodes(
					ignore_priority=ignore_uninst_or_med)

				min_parent_deps = None
				uninst_task = None
				for task in myblocker_uninstalls.leaf_nodes():
					# Do some sanity checks so that system or world packages
					# don't get uninstalled inappropriately here (only really
					# necessary when --complete-graph has not been enabled).

					if task in ignored_uninstall_tasks:
						continue

					if task in scheduled_uninstalls:
						# It's been scheduled but it hasn't
						# been executed yet due to dependence
						# on installation of blocking packages.
						continue

					root_config = self.roots[task.root]
					inst_pkg = self._pkg_cache[
						("installed", task.root, task.cpv, "nomerge")]

					if self.digraph.contains(inst_pkg):
						continue

					forbid_overlap = False
					heuristic_overlap = False
					for blocker in myblocker_uninstalls.parent_nodes(task):
						if blocker.eapi in ("0", "1"):
							heuristic_overlap = True
						elif blocker.atom.blocker.overlap.forbid:
							forbid_overlap = True
							break
					if forbid_overlap and running_root == task.root:
						continue

					if heuristic_overlap and running_root == task.root:
						# Never uninstall sys-apps/portage or it's essential
						# dependencies, except through replacement.
						try:
							runtime_dep_atoms = \
								list(runtime_deps.iterAtomsForPackage(task))
						except portage.exception.InvalidDependString, e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							continue

						# Don't uninstall a runtime dep if it appears
						# to be the only suitable one installed.
						skip = False
						vardb = root_config.trees["vartree"].dbapi
						for atom in runtime_dep_atoms:
							other_version = None
							for pkg in vardb.match_pkgs(atom):
								if pkg.cpv == task.cpv and \
									pkg.metadata["COUNTER"] == \
									task.metadata["COUNTER"]:
									continue
								other_version = pkg
								break
							if other_version is None:
								skip = True
								break
						if skip:
							continue

						# For packages in the system set, don't take
						# any chances. If the conflict can't be resolved
						# by a normal replacement operation then abort.
						skip = False
						try:
							for atom in root_config.sets[
								"system"].iterAtomsForPackage(task):
								skip = True
								break
						except portage.exception.InvalidDependString, e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							skip = True
						if skip:
							continue

					# Note that the world check isn't always
					# necessary since self._complete_graph() will
					# add all packages from the system and world sets to the
					# graph. This just allows unresolved conflicts to be
					# detected as early as possible, which makes it possible
					# to avoid calling self._complete_graph() when it is
					# unnecessary due to blockers triggering an abortion.
					if not complete:
						# For packages in the world set, go ahead an uninstall
						# when necessary, as long as the atom will be satisfied
						# in the final state.
						graph_db = self.mydbapi[task.root]
						skip = False
						try:
							for atom in root_config.sets[
								"world"].iterAtomsForPackage(task):
								satisfied = False
								for pkg in graph_db.match_pkgs(atom):
									if pkg == inst_pkg:
										continue
									satisfied = True
									break
								if not satisfied:
									skip = True
									self._blocked_world_pkgs[inst_pkg] = atom
									break
						except portage.exception.InvalidDependString, e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							skip = True
						if skip:
							continue

					# Check the deps of parent nodes to ensure that
					# the chosen task produces a leaf node. Maybe
					# this can be optimized some more to make the
					# best possible choice, but the current algorithm
					# is simple and should be near optimal for most
					# common cases.
					mergeable_parent = False
					parent_deps = set()
					for parent in mygraph.parent_nodes(task):
						parent_deps.update(mygraph.child_nodes(parent,
							ignore_priority=priority_range.ignore_medium_soft))
						if parent in mergeable_nodes and \
							gather_deps(ignore_uninst_or_med_soft,
							mergeable_nodes, set(), parent):
							mergeable_parent = True

					if not mergeable_parent:
						continue

					parent_deps.remove(task)
					if min_parent_deps is None or \
						len(parent_deps) < min_parent_deps:
						min_parent_deps = len(parent_deps)
						uninst_task = task

				if uninst_task is not None:
					# The uninstall is performed only after blocking
					# packages have been merged on top of it. File
					# collisions between blocking packages are detected
					# and removed from the list of files to be uninstalled.
					scheduled_uninstalls.add(uninst_task)
					parent_nodes = mygraph.parent_nodes(uninst_task)

					# Reverse the parent -> uninstall edges since we want
					# to do the uninstall after blocking packages have
					# been merged on top of it.
					mygraph.remove(uninst_task)
					for blocked_pkg in parent_nodes:
						mygraph.add(blocked_pkg, uninst_task,
							priority=BlockerDepPriority.instance)
						scheduler_graph.remove_edge(uninst_task, blocked_pkg)
						scheduler_graph.add(blocked_pkg, uninst_task,
							priority=BlockerDepPriority.instance)

					# Reset the state variables for leaf node selection and
					# continue trying to select leaf nodes.
					prefer_asap = True
					drop_satisfied = False
					continue

			if not selected_nodes:
				# Only select root nodes as a last resort. This case should
				# only trigger when the graph is nearly empty and the only
				# remaining nodes are isolated (no parents or children). Since
				# the nodes must be isolated, ignore_priority is not needed.
				selected_nodes = get_nodes()

			if not selected_nodes and not drop_satisfied:
				drop_satisfied = True
				continue

			if not selected_nodes and not myblocker_uninstalls.is_empty():
				# If possible, drop an uninstall task here in order to avoid
				# the circular deps code path. The corresponding blocker will
				# still be counted as an unresolved conflict.
				uninst_task = None
				for node in myblocker_uninstalls.leaf_nodes():
					try:
						mygraph.remove(node)
					except KeyError:
						pass
					else:
						uninst_task = node
						ignored_uninstall_tasks.add(node)
						break

				if uninst_task is not None:
					# Reset the state variables for leaf node selection and
					# continue trying to select leaf nodes.
					prefer_asap = True
					drop_satisfied = False
					continue

			if not selected_nodes:
				self._circular_deps_for_display = mygraph
				raise self._unknown_internal_error()

			# At this point, we've succeeded in selecting one or more nodes, so
			# reset state variables for leaf node selection.
			prefer_asap = True
			drop_satisfied = False

			mygraph.difference_update(selected_nodes)

			for node in selected_nodes:
				if isinstance(node, Package) and \
					node.operation == "nomerge":
					continue

				# Handle interactions between blockers
				# and uninstallation tasks.
				solved_blockers = set()
				uninst_task = None
				if isinstance(node, Package) and \
					"uninstall" == node.operation:
					have_uninstall_task = True
					uninst_task = node
				else:
					vardb = self.trees[node.root]["vartree"].dbapi
					previous_cpv = vardb.match(node.slot_atom)
					if previous_cpv:
						# The package will be replaced by this one, so remove
						# the corresponding Uninstall task if necessary.
						previous_cpv = previous_cpv[0]
						uninst_task = \
							("installed", node.root, previous_cpv, "uninstall")
						try:
							mygraph.remove(uninst_task)
						except KeyError:
							pass

				if uninst_task is not None and \
					uninst_task not in ignored_uninstall_tasks and \
					myblocker_uninstalls.contains(uninst_task):
					blocker_nodes = myblocker_uninstalls.parent_nodes(uninst_task)
					myblocker_uninstalls.remove(uninst_task)
					# Discard any blockers that this Uninstall solves.
					for blocker in blocker_nodes:
						if not myblocker_uninstalls.child_nodes(blocker):
							myblocker_uninstalls.remove(blocker)
							solved_blockers.add(blocker)

				retlist.append(node)

				if (isinstance(node, Package) and \
					"uninstall" == node.operation) or \
					(uninst_task is not None and \
					uninst_task in scheduled_uninstalls):
					# Include satisfied blockers in the merge list
					# since the user might be interested and also
					# it serves as an indicator that blocking packages
					# will be temporarily installed simultaneously.
					for blocker in solved_blockers:
						retlist.append(Blocker(atom=blocker.atom,
							root=blocker.root, eapi=blocker.eapi,
							satisfied=True))

		unsolvable_blockers = set(self._unsolvable_blockers.leaf_nodes())
		for node in myblocker_uninstalls.root_nodes():
			unsolvable_blockers.add(node)

		for blocker in unsolvable_blockers:
			retlist.append(blocker)

		# If any Uninstall tasks need to be executed in order
		# to avoid a conflict, complete the graph with any
		# dependencies that may have been initially
		# neglected (to ensure that unsafe Uninstall tasks
		# are properly identified and blocked from execution).
		if have_uninstall_task and \
			not complete and \
			not unsolvable_blockers:
			self.myparams.add("complete")
			raise self._serialize_tasks_retry("")

		if unsolvable_blockers and \
			not self._accept_blocker_conflicts():
			self._unsatisfied_blockers_for_display = unsolvable_blockers
			self._serialized_tasks_cache = retlist[:]
			self._scheduler_graph = scheduler_graph
			raise self._unknown_internal_error()

		if self._slot_collision_info and \
			not self._accept_blocker_conflicts():
			self._serialized_tasks_cache = retlist[:]
			self._scheduler_graph = scheduler_graph
			raise self._unknown_internal_error()

		return retlist, scheduler_graph

	def _show_circular_deps(self, mygraph):
		# No leaf nodes are available, so we have a circular
		# dependency panic situation.  Reduce the noise level to a
		# minimum via repeated elimination of root nodes since they
		# have no parents and thus can not be part of a cycle.
		while True:
			root_nodes = mygraph.root_nodes(
				ignore_priority=DepPrioritySatisfiedRange.ignore_medium_soft)
			if not root_nodes:
				break
			mygraph.difference_update(root_nodes)
		# Display the USE flags that are enabled on nodes that are part
		# of dependency cycles in case that helps the user decide to
		# disable some of them.
		display_order = []
		tempgraph = mygraph.copy()
		while not tempgraph.empty():
			nodes = tempgraph.leaf_nodes()
			if not nodes:
				node = tempgraph.order[0]
			else:
				node = nodes[0]
			display_order.append(node)
			tempgraph.remove(node)
		display_order.reverse()
		self.myopts.pop("--quiet", None)
		self.myopts.pop("--verbose", None)
		self.myopts["--tree"] = True
		portage.writemsg("\n\n", noiselevel=-1)
		self.display(display_order)
		prefix = colorize("BAD", " * ")
		portage.writemsg("\n", noiselevel=-1)
		portage.writemsg(prefix + "Error: circular dependencies:\n",
			noiselevel=-1)
		portage.writemsg("\n", noiselevel=-1)
		mygraph.debug_print()
		portage.writemsg("\n", noiselevel=-1)
		portage.writemsg(prefix + "Note that circular dependencies " + \
			"can often be avoided by temporarily\n", noiselevel=-1)
		portage.writemsg(prefix + "disabling USE flags that trigger " + \
			"optional dependencies.\n", noiselevel=-1)

	def _show_merge_list(self):
		if self._serialized_tasks_cache is not None and \
			not (self._displayed_list and \
			(self._displayed_list == self._serialized_tasks_cache or \
			self._displayed_list == \
				list(reversed(self._serialized_tasks_cache)))):
			display_list = self._serialized_tasks_cache[:]
			if "--tree" in self.myopts:
				display_list.reverse()
			self.display(display_list)

	def _show_unsatisfied_blockers(self, blockers):
		self._show_merge_list()
		msg = "Error: The above package list contains " + \
			"packages which cannot be installed " + \
			"at the same time on the same system."
		prefix = colorize("BAD", " * ")
		from textwrap import wrap
		portage.writemsg("\n", noiselevel=-1)
		for line in wrap(msg, 70):
			portage.writemsg(prefix + line + "\n", noiselevel=-1)

		# Display the conflicting packages along with the packages
		# that pulled them in. This is helpful for troubleshooting
		# cases in which blockers don't solve automatically and
		# the reasons are not apparent from the normal merge list
		# display.

		conflict_pkgs = {}
		for blocker in blockers:
			for pkg in chain(self._blocked_pkgs.child_nodes(blocker), \
				self._blocker_parents.parent_nodes(blocker)):
				parent_atoms = self._parent_atoms.get(pkg)
				if not parent_atoms:
					atom = self._blocked_world_pkgs.get(pkg)
					if atom is not None:
						parent_atoms = set([("@world", atom)])
				if parent_atoms:
					conflict_pkgs[pkg] = parent_atoms

		if conflict_pkgs:
			# Reduce noise by pruning packages that are only
			# pulled in by other conflict packages.
			pruned_pkgs = set()
			for pkg, parent_atoms in conflict_pkgs.iteritems():
				relevant_parent = False
				for parent, atom in parent_atoms:
					if parent not in conflict_pkgs:
						relevant_parent = True
						break
				if not relevant_parent:
					pruned_pkgs.add(pkg)
			for pkg in pruned_pkgs:
				del conflict_pkgs[pkg]

		if conflict_pkgs:
			msg = []
			msg.append("\n")
			indent = "  "
			# Max number of parents shown, to avoid flooding the display.
			max_parents = 3
			for pkg, parent_atoms in conflict_pkgs.iteritems():

				pruned_list = set()

				# Prefer packages that are not directly involved in a conflict.
				for parent_atom in parent_atoms:
					if len(pruned_list) >= max_parents:
						break
					parent, atom = parent_atom
					if parent not in conflict_pkgs:
						pruned_list.add(parent_atom)

				for parent_atom in parent_atoms:
					if len(pruned_list) >= max_parents:
						break
					pruned_list.add(parent_atom)

				omitted_parents = len(parent_atoms) - len(pruned_list)
				msg.append(indent + "%s pulled in by\n" % pkg)

				for parent_atom in pruned_list:
					parent, atom = parent_atom
					msg.append(2*indent)
					if isinstance(parent,
						(PackageArg, AtomArg)):
						# For PackageArg and AtomArg types, it's
						# redundant to display the atom attribute.
						msg.append(str(parent))
					else:
						# Display the specific atom from SetArg or
						# Package types.
						msg.append("%s required by %s" % (atom, parent))
					msg.append("\n")

				if omitted_parents:
					msg.append(2*indent)
					msg.append("(and %d more)\n" % omitted_parents)

				msg.append("\n")

			sys.stderr.write("".join(msg))
			sys.stderr.flush()

		if "--quiet" not in self.myopts:
			show_blocker_docs_link()

	def display(self, mylist, favorites=[], verbosity=None):

		# This is used to prevent display_problems() from
		# redundantly displaying this exact same merge list
		# again via _show_merge_list().
		self._displayed_list = mylist

		if verbosity is None:
			verbosity = ("--quiet" in self.myopts and 1 or \
				"--verbose" in self.myopts and 3 or 2)
		favorites_set = InternalPackageSet(favorites)
		oneshot = "--oneshot" in self.myopts or \
			"--onlydeps" in self.myopts
		columns = "--columns" in self.myopts
		changelogs=[]
		p=[]
		blockers = []

		counters = PackageCounters()

		if verbosity == 1 and "--verbose" not in self.myopts:
			def create_use_string(*args):
				return ""
		else:
			def create_use_string(name, cur_iuse, iuse_forced, cur_use,
				old_iuse, old_use,
				is_new, reinst_flags,
				all_flags=(verbosity == 3 or "--quiet" in self.myopts),
				alphabetical=("--alphabetical" in self.myopts)):
				enabled = []
				if alphabetical:
					disabled = enabled
					removed = enabled
				else:
					disabled = []
					removed = []
				cur_iuse = set(cur_iuse)
				enabled_flags = cur_iuse.intersection(cur_use)
				removed_iuse = set(old_iuse).difference(cur_iuse)
				any_iuse = cur_iuse.union(old_iuse)
				any_iuse = list(any_iuse)
				any_iuse.sort()
				for flag in any_iuse:
					flag_str = None
					isEnabled = False
					reinst_flag = reinst_flags and flag in reinst_flags
					if flag in enabled_flags:
						isEnabled = True
						if is_new or flag in old_use and \
							(all_flags or reinst_flag):
							flag_str = red(flag)
						elif flag not in old_iuse:
							flag_str = yellow(flag) + "%*"
						elif flag not in old_use:
							flag_str = green(flag) + "*"
					elif flag in removed_iuse:
						if all_flags or reinst_flag:
							flag_str = yellow("-" + flag) + "%"
							if flag in old_use:
								flag_str += "*"
							flag_str = "(" + flag_str + ")"
							removed.append(flag_str)
						continue
					else:
						if is_new or flag in old_iuse and \
							flag not in old_use and \
							(all_flags or reinst_flag):
							flag_str = blue("-" + flag)
						elif flag not in old_iuse:
							flag_str = yellow("-" + flag)
							if flag not in iuse_forced:
								flag_str += "%"
						elif flag in old_use:
							flag_str = green("-" + flag) + "*"
					if flag_str:
						if flag in iuse_forced:
							flag_str = "(" + flag_str + ")"
						if isEnabled:
							enabled.append(flag_str)
						else:
							disabled.append(flag_str)

				if alphabetical:
					ret = " ".join(enabled)
				else:
					ret = " ".join(enabled + disabled + removed)
				if ret:
					ret = '%s="%s" ' % (name, ret)
				return ret

		repo_display = RepoDisplay(self.roots)

		tree_nodes = []
		display_list = []
		mygraph = self.digraph.copy()

		# If there are any Uninstall instances, add the corresponding
		# blockers to the digraph (useful for --tree display).

		executed_uninstalls = set(node for node in mylist \
			if isinstance(node, Package) and node.operation == "unmerge")

		for uninstall in self._blocker_uninstalls.leaf_nodes():
			uninstall_parents = \
				self._blocker_uninstalls.parent_nodes(uninstall)
			if not uninstall_parents:
				continue

			# Remove the corresponding "nomerge" node and substitute
			# the Uninstall node.
			inst_pkg = self._pkg_cache[
				("installed", uninstall.root, uninstall.cpv, "nomerge")]
			try:
				mygraph.remove(inst_pkg)
			except KeyError:
				pass

			try:
				inst_pkg_blockers = self._blocker_parents.child_nodes(inst_pkg)
			except KeyError:
				inst_pkg_blockers = []

			# Break the Package -> Uninstall edges.
			mygraph.remove(uninstall)

			# Resolution of a package's blockers
			# depend on it's own uninstallation.
			for blocker in inst_pkg_blockers:
				mygraph.add(uninstall, blocker)

			# Expand Package -> Uninstall edges into
			# Package -> Blocker -> Uninstall edges.
			for blocker in uninstall_parents:
				mygraph.add(uninstall, blocker)
				for parent in self._blocker_parents.parent_nodes(blocker):
					if parent != inst_pkg:
						mygraph.add(blocker, parent)

			# If the uninstall task did not need to be executed because
			# of an upgrade, display Blocker -> Upgrade edges since the
			# corresponding Blocker -> Uninstall edges will not be shown.
			upgrade_node = \
				self._slot_pkg_map[uninstall.root].get(uninstall.slot_atom)
			if upgrade_node is not None and \
				uninstall not in executed_uninstalls:
				for blocker in uninstall_parents:
					mygraph.add(upgrade_node, blocker)

		unsatisfied_blockers = []
		i = 0
		depth = 0
		shown_edges = set()
		for x in mylist:
			if isinstance(x, Blocker) and not x.satisfied:
				unsatisfied_blockers.append(x)
				continue
			graph_key = x
			if "--tree" in self.myopts:
				depth = len(tree_nodes)
				while depth and graph_key not in \
					mygraph.child_nodes(tree_nodes[depth-1]):
						depth -= 1
				if depth:
					tree_nodes = tree_nodes[:depth]
					tree_nodes.append(graph_key)
					display_list.append((x, depth, True))
					shown_edges.add((graph_key, tree_nodes[depth-1]))
				else:
					traversed_nodes = set() # prevent endless circles
					traversed_nodes.add(graph_key)
					def add_parents(current_node, ordered):
						parent_nodes = None
						# Do not traverse to parents if this node is an
						# an argument or a direct member of a set that has
						# been specified as an argument (system or world).
						if current_node not in self._set_nodes:
							parent_nodes = mygraph.parent_nodes(current_node)
						if parent_nodes:
							child_nodes = set(mygraph.child_nodes(current_node))
							selected_parent = None
							# First, try to avoid a direct cycle.
							for node in parent_nodes:
								if not isinstance(node, (Blocker, Package)):
									continue
								if node not in traversed_nodes and \
									node not in child_nodes:
									edge = (current_node, node)
									if edge in shown_edges:
										continue
									selected_parent = node
									break
							if not selected_parent:
								# A direct cycle is unavoidable.
								for node in parent_nodes:
									if not isinstance(node, (Blocker, Package)):
										continue
									if node not in traversed_nodes:
										edge = (current_node, node)
										if edge in shown_edges:
											continue
										selected_parent = node
										break
							if selected_parent:
								shown_edges.add((current_node, selected_parent))
								traversed_nodes.add(selected_parent)
								add_parents(selected_parent, False)
						display_list.append((current_node,
							len(tree_nodes), ordered))
						tree_nodes.append(current_node)
					tree_nodes = []
					add_parents(graph_key, True)
			else:
				display_list.append((x, depth, True))
		mylist = display_list
		for x in unsatisfied_blockers:
			mylist.append((x, 0, True))

		last_merge_depth = 0
		for i in xrange(len(mylist)-1,-1,-1):
			graph_key, depth, ordered = mylist[i]
			if not ordered and depth == 0 and i > 0 \
				and graph_key == mylist[i-1][0] and \
				mylist[i-1][1] == 0:
				# An ordered node got a consecutive duplicate when the tree was
				# being filled in.
				del mylist[i]
				continue
			if ordered and graph_key[-1] != "nomerge":
				last_merge_depth = depth
				continue
			if depth >= last_merge_depth or \
				i < len(mylist) - 1 and \
				depth >= mylist[i+1][1]:
					del mylist[i]

		from portage import flatten
		from portage.dep import use_reduce, paren_reduce
		# files to fetch list - avoids counting a same file twice
		# in size display (verbose mode)
		myfetchlist=[]

		# Use this set to detect when all the "repoadd" strings are "[0]"
		# and disable the entire repo display in this case.
		repoadd_set = set()

		for mylist_index in xrange(len(mylist)):
			x, depth, ordered = mylist[mylist_index]
			pkg_type = x[0]
			myroot = x[1]
			pkg_key = x[2]
			portdb = self.trees[myroot]["porttree"].dbapi
			bindb  = self.trees[myroot]["bintree"].dbapi
			vardb = self.trees[myroot]["vartree"].dbapi
			vartree = self.trees[myroot]["vartree"]
			pkgsettings = self.pkgsettings[myroot]

			fetch=" "
			indent = " " * depth

			if isinstance(x, Blocker):
				if x.satisfied:
					blocker_style = "PKG_BLOCKER_SATISFIED"
					addl = "%s  %s  " % (colorize(blocker_style, "b"), fetch)
				else:
					blocker_style = "PKG_BLOCKER"
					addl = "%s  %s  " % (colorize(blocker_style, "B"), fetch)
				if ordered:
					counters.blocks += 1
					if x.satisfied:
						counters.blocks_satisfied += 1
				resolved = portage.key_expand(
					str(x.atom).lstrip("!"), mydb=vardb, settings=pkgsettings)
				if "--columns" in self.myopts and "--quiet" in self.myopts:
					addl += " " + colorize(blocker_style, resolved)
				else:
					addl = "[%s %s] %s%s" % \
						(colorize(blocker_style, "blocks"),
						addl, indent, colorize(blocker_style, resolved))
				block_parents = self._blocker_parents.parent_nodes(x)
				block_parents = set([pnode[2] for pnode in block_parents])
				block_parents = ", ".join(block_parents)
				if resolved!=x[2]:
					addl += colorize(blocker_style,
						" (\"%s\" is blocking %s)") % \
						(str(x.atom).lstrip("!"), block_parents)
				else:
					addl += colorize(blocker_style,
						" (is blocking %s)") % block_parents
				if isinstance(x, Blocker) and x.satisfied:
					if columns:
						continue
					p.append(addl)
				else:
					blockers.append(addl)
			else:
				pkg_status = x[3]
				pkg_merge = ordered and pkg_status == "merge"
				if not pkg_merge and pkg_status == "merge":
					pkg_status = "nomerge"
				built = pkg_type != "ebuild"
				installed = pkg_type == "installed"
				pkg = x
				metadata = pkg.metadata
				ebuild_path = None
				repo_name = metadata["repository"]
				if pkg_type == "ebuild":
					ebuild_path = portdb.findname(pkg_key)
					if not ebuild_path: # shouldn't happen
						raise portage.exception.PackageNotFound(pkg_key)
					repo_path_real = os.path.dirname(os.path.dirname(
						os.path.dirname(ebuild_path)))
				else:
					repo_path_real = portdb.getRepositoryPath(repo_name)
				pkg_use = list(pkg.use.enabled)
				try:
					restrict = flatten(use_reduce(paren_reduce(
						pkg.metadata["RESTRICT"]), uselist=pkg_use))
				except portage.exception.InvalidDependString, e:
					if not pkg.installed:
						show_invalid_depstring_notice(x,
							pkg.metadata["RESTRICT"], str(e))
						del e
						return 1
					restrict = []
				if "ebuild" == pkg_type and x[3] != "nomerge" and \
					"fetch" in restrict:
					fetch = red("F")
					if ordered:
						counters.restrict_fetch += 1
					if portdb.fetch_check(pkg_key, pkg_use):
						fetch = green("f")
						if ordered:
							counters.restrict_fetch_satisfied += 1

				#we need to use "--emptrytree" testing here rather than "empty" param testing because "empty"
				#param is used for -u, where you still *do* want to see when something is being upgraded.
				myoldbest = []
				myinslotlist = None
				installed_versions = vardb.match(portage.cpv_getkey(pkg_key))
				if vardb.cpv_exists(pkg_key):
					addl="  "+yellow("R")+fetch+"  "
					if ordered:
						if pkg_merge:
							counters.reinst += 1
						elif pkg_status == "uninstall":
							counters.uninst += 1
				# filter out old-style virtual matches
				elif installed_versions and \
					portage.cpv_getkey(installed_versions[0]) == \
					portage.cpv_getkey(pkg_key):
					myinslotlist = vardb.match(pkg.slot_atom)
					# If this is the first install of a new-style virtual, we
					# need to filter out old-style virtual matches.
					if myinslotlist and \
						portage.cpv_getkey(myinslotlist[0]) != \
						portage.cpv_getkey(pkg_key):
						myinslotlist = None
					if myinslotlist:
						myoldbest = myinslotlist[:]
						addl = "   " + fetch
						if not portage.dep.cpvequal(pkg_key,
							portage.best([pkg_key] + myoldbest)):
							# Downgrade in slot
							addl += turquoise("U")+blue("D")
							if ordered:
								counters.downgrades += 1
						else:
							# Update in slot
							addl += turquoise("U") + " "
							if ordered:
								counters.upgrades += 1
					else:
						# New slot, mark it new.
						addl = " " + green("NS") + fetch + "  "
						myoldbest = vardb.match(portage.cpv_getkey(pkg_key))
						if ordered:
							counters.newslot += 1

					if "--changelog" in self.myopts:
						inst_matches = vardb.match(pkg.slot_atom)
						if inst_matches:
							changelogs.extend(self.calc_changelog(
								portdb.findname(pkg_key),
								inst_matches[0], pkg_key))
				else:
					addl = " " + green("N") + " " + fetch + "  "
					if ordered:
						counters.new += 1

				verboseadd = ""
				repoadd = None

				if True:
					# USE flag display
					forced_flags = set()
					pkgsettings.setcpv(pkg) # for package.use.{mask,force}
					forced_flags.update(pkgsettings.useforce)
					forced_flags.update(pkgsettings.usemask)

					cur_use = [flag for flag in pkg.use.enabled \
						if flag in pkg.iuse.all]
					cur_iuse = sorted(pkg.iuse.all)

					if myoldbest and myinslotlist:
						previous_cpv = myoldbest[0]
					else:
						previous_cpv = pkg.cpv
					if vardb.cpv_exists(previous_cpv):
						old_iuse, old_use = vardb.aux_get(
								previous_cpv, ["IUSE", "USE"])
						old_iuse = list(set(
							filter_iuse_defaults(old_iuse.split())))
						old_iuse.sort()
						old_use = old_use.split()
						is_new = False
					else:
						old_iuse = []
						old_use = []
						is_new = True

					old_use = [flag for flag in old_use if flag in old_iuse]

					use_expand = pkgsettings["USE_EXPAND"].lower().split()
					use_expand.sort()
					use_expand.reverse()
					use_expand_hidden = \
						pkgsettings["USE_EXPAND_HIDDEN"].lower().split()

					def map_to_use_expand(myvals, forcedFlags=False,
						removeHidden=True):
						ret = {}
						forced = {}
						for exp in use_expand:
							ret[exp] = []
							forced[exp] = set()
							for val in myvals[:]:
								if val.startswith(exp.lower()+"_"):
									if val in forced_flags:
										forced[exp].add(val[len(exp)+1:])
									ret[exp].append(val[len(exp)+1:])
									myvals.remove(val)
						ret["USE"] = myvals
						forced["USE"] = [val for val in myvals \
							if val in forced_flags]
						if removeHidden:
							for exp in use_expand_hidden:
								ret.pop(exp, None)
						if forcedFlags:
							return ret, forced
						return ret

					# Prevent USE_EXPAND_HIDDEN flags from being hidden if they
					# are the only thing that triggered reinstallation.
					reinst_flags_map = {}
					reinstall_for_flags = self._reinstall_nodes.get(pkg)
					reinst_expand_map = None
					if reinstall_for_flags:
						reinst_flags_map = map_to_use_expand(
							list(reinstall_for_flags), removeHidden=False)
						for k in list(reinst_flags_map):
							if not reinst_flags_map[k]:
								del reinst_flags_map[k]
						if not reinst_flags_map.get("USE"):
							reinst_expand_map = reinst_flags_map.copy()
							reinst_expand_map.pop("USE", None)
					if reinst_expand_map and \
						not set(reinst_expand_map).difference(
						use_expand_hidden):
						use_expand_hidden = \
							set(use_expand_hidden).difference(
							reinst_expand_map)

					cur_iuse_map, iuse_forced = \
						map_to_use_expand(cur_iuse, forcedFlags=True)
					cur_use_map = map_to_use_expand(cur_use)
					old_iuse_map = map_to_use_expand(old_iuse)
					old_use_map = map_to_use_expand(old_use)

					use_expand.sort()
					use_expand.insert(0, "USE")
					
					for key in use_expand:
						if key in use_expand_hidden:
							continue
						verboseadd += create_use_string(key.upper(),
							cur_iuse_map[key], iuse_forced[key],
							cur_use_map[key], old_iuse_map[key],
							old_use_map[key], is_new,
							reinst_flags_map.get(key))

				if verbosity == 3:
					# size verbose
					mysize=0
					if pkg_type == "ebuild" and pkg_merge:
						try:
							myfilesdict = portdb.getfetchsizes(pkg_key,
								useflags=pkg_use, debug=self.edebug)
						except portage.exception.InvalidDependString, e:
							src_uri = portdb.aux_get(pkg_key, ["SRC_URI"])[0]
							show_invalid_depstring_notice(x, src_uri, str(e))
							del e
							return 1
						if myfilesdict is None:
							myfilesdict="[empty/missing/bad digest]"
						else:
							for myfetchfile in myfilesdict:
								if myfetchfile not in myfetchlist:
									mysize+=myfilesdict[myfetchfile]
									myfetchlist.append(myfetchfile)
							if ordered:
								counters.totalsize += mysize
						verboseadd += format_size(mysize)

					# overlay verbose
					# assign index for a previous version in the same slot
					has_previous = False
					repo_name_prev = None
					slot_atom = "%s:%s" % (portage.dep_getkey(pkg_key),
						metadata["SLOT"])
					slot_matches = vardb.match(slot_atom)
					if slot_matches:
						has_previous = True
						repo_name_prev = vardb.aux_get(slot_matches[0],
							["repository"])[0]

					# now use the data to generate output
					if pkg.installed or not has_previous:
						repoadd = repo_display.repoStr(repo_path_real)
					else:
						repo_path_prev = None
						if repo_name_prev:
							repo_path_prev = portdb.getRepositoryPath(
								repo_name_prev)
						if repo_path_prev == repo_path_real:
							repoadd = repo_display.repoStr(repo_path_real)
						else:
							repoadd = "%s=>%s" % (
								repo_display.repoStr(repo_path_prev),
								repo_display.repoStr(repo_path_real))
					if repoadd:
						repoadd_set.add(repoadd)

				xs = [portage.cpv_getkey(pkg_key)] + \
					list(portage.catpkgsplit(pkg_key)[2:])
				if xs[2] == "r0":
					xs[2] = ""
				else:
					xs[2] = "-" + xs[2]

				mywidth = 130
				if "COLUMNWIDTH" in self.settings:
					try:
						mywidth = int(self.settings["COLUMNWIDTH"])
					except ValueError, e:
						portage.writemsg("!!! %s\n" % str(e), noiselevel=-1)
						portage.writemsg(
							"!!! Unable to parse COLUMNWIDTH='%s'\n" % \
							self.settings["COLUMNWIDTH"], noiselevel=-1)
						del e
				oldlp = mywidth - 30
				newlp = oldlp - 30

				# Convert myoldbest from a list to a string.
				if not myoldbest:
					myoldbest = ""
				else:
					for pos, key in enumerate(myoldbest):
						key = portage.catpkgsplit(key)[2] + \
							"-" + portage.catpkgsplit(key)[3]
						if key[-3:] == "-r0":
							key = key[:-3]
						myoldbest[pos] = key
					myoldbest = blue("["+", ".join(myoldbest)+"]")

				pkg_cp = xs[0]
				root_config = self.roots[myroot]
				system_set = root_config.sets["system"]
				world_set  = root_config.sets["world"]

				pkg_system = False
				pkg_world = False
				try:
					pkg_system = system_set.findAtomForPackage(pkg)
					pkg_world  = world_set.findAtomForPackage(pkg)
					if not (oneshot or pkg_world) and \
						myroot == self.target_root and \
						favorites_set.findAtomForPackage(pkg):
						# Maybe it will be added to world now.
						if create_world_atom(pkg, favorites_set, root_config):
							pkg_world = True
				except portage.exception.InvalidDependString:
					# This is reported elsewhere if relevant.
					pass

				def pkgprint(pkg_str):
					if pkg_merge:
						if pkg_system:
							return colorize("PKG_MERGE_SYSTEM", pkg_str)
						elif pkg_world:
							return colorize("PKG_MERGE_WORLD", pkg_str)
						else:
							return colorize("PKG_MERGE", pkg_str)
					elif pkg_status == "uninstall":
						return colorize("PKG_UNINSTALL", pkg_str)
					else:
						if pkg_system:
							return colorize("PKG_NOMERGE_SYSTEM", pkg_str)
						elif pkg_world:
							return colorize("PKG_NOMERGE_WORLD", pkg_str)
						else:
							return colorize("PKG_NOMERGE", pkg_str)

				try:
					properties = flatten(use_reduce(paren_reduce(
						pkg.metadata["PROPERTIES"]), uselist=pkg.use.enabled))
				except portage.exception.InvalidDependString, e:
					if not pkg.installed:
						show_invalid_depstring_notice(pkg,
							pkg.metadata["PROPERTIES"], str(e))
						del e
						return 1
					properties = []
				interactive = "interactive" in properties
				if interactive and pkg.operation == "merge":
					addl = colorize("WARN", "I") + addl[1:]
					if ordered:
						counters.interactive += 1

				if x[1]!="/":
					if myoldbest:
						myoldbest +=" "
					if "--columns" in self.myopts:
						if "--quiet" in self.myopts:
							myprint=addl+" "+indent+pkgprint(pkg_cp)
							myprint=myprint+darkblue(" "+xs[1]+xs[2])+" "
							myprint=myprint+myoldbest
							myprint=myprint+darkgreen("to "+x[1])
							verboseadd = None
						else:
							if not pkg_merge:
								myprint = "[%s] %s%s" % \
									(pkgprint(pkg_status.ljust(13)),
									indent, pkgprint(pkg.cp))
							else:
								myprint = "[%s %s] %s%s" % \
									(pkgprint(pkg.type_name), addl,
									indent, pkgprint(pkg.cp))
							if (newlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(newlp-nc_len(myprint)))
							myprint=myprint+"["+darkblue(xs[1]+xs[2])+"] "
							if (oldlp-nc_len(myprint)) > 0:
								myprint=myprint+" "*(oldlp-nc_len(myprint))
							myprint=myprint+myoldbest
							myprint += darkgreen("to " + pkg.root)
					else:
						if not pkg_merge:
							myprint = "[%s] " % pkgprint(pkg_status.ljust(13))
						else:
							myprint = "[%s %s] " % (pkgprint(pkg_type), addl)
						myprint += indent + pkgprint(pkg_key) + " " + \
							myoldbest + darkgreen("to " + myroot)
				else:
					if "--columns" in self.myopts:
						if "--quiet" in self.myopts:
							myprint=addl+" "+indent+pkgprint(pkg_cp)
							myprint=myprint+" "+green(xs[1]+xs[2])+" "
							myprint=myprint+myoldbest
							verboseadd = None
						else:
							if not pkg_merge:
								myprint = "[%s] %s%s" % \
									(pkgprint(pkg_status.ljust(13)),
									indent, pkgprint(pkg.cp))
							else:
								myprint = "[%s %s] %s%s" % \
									(pkgprint(pkg.type_name), addl,
									indent, pkgprint(pkg.cp))
							if (newlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(newlp-nc_len(myprint)))
							myprint=myprint+green(" ["+xs[1]+xs[2]+"] ")
							if (oldlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(oldlp-nc_len(myprint)))
							myprint += myoldbest
					else:
						if not pkg_merge:
							myprint = "[%s] %s%s %s" % \
								(pkgprint(pkg_status.ljust(13)),
								indent, pkgprint(pkg.cpv),
								myoldbest)
						else:
							myprint = "[%s %s] %s%s %s" % \
								(pkgprint(pkg_type), addl, indent,
								pkgprint(pkg.cpv), myoldbest)

				if columns and pkg.operation == "uninstall":
					continue
				p.append((myprint, verboseadd, repoadd))

				if "--tree" not in self.myopts and \
					"--quiet" not in self.myopts and \
					not self._opts_no_restart.intersection(self.myopts) and \
					pkg.root == self._running_root.root and \
					portage.match_from_list(
					portage.const.PORTAGE_PACKAGE_ATOM, [pkg]) and \
					not vardb.cpv_exists(pkg.cpv) and \
					"--quiet" not in self.myopts:
						if mylist_index < len(mylist) - 1:
							p.append(colorize("WARN", "*** Portage will stop merging at this point and reload itself,"))
							p.append(colorize("WARN", "    then resume the merge."))

		out = sys.stdout
		show_repos = repoadd_set and repoadd_set != set(["0"])

		for x in p:
			if isinstance(x, basestring):
				out.write("%s\n" % (x,))
				continue

			myprint, verboseadd, repoadd = x

			if verboseadd:
				myprint += " " + verboseadd

			if show_repos and repoadd:
				myprint += " " + teal("[%s]" % repoadd)

			out.write("%s\n" % (myprint,))

		for x in blockers:
			print x

		if verbosity == 3:
			print
			print counters
			if show_repos:
				sys.stdout.write(str(repo_display))

		if "--changelog" in self.myopts:
			print
			for revision,text in changelogs:
				print bold('*'+revision)
				sys.stdout.write(text)

		sys.stdout.flush()
		return os.EX_OK

	def display_problems(self):
		"""
		Display problems with the dependency graph such as slot collisions.
		This is called internally by display() to show the problems _after_
		the merge list where it is most likely to be seen, but if display()
		is not going to be called then this method should be called explicitly
		to ensure that the user is notified of problems with the graph.

		All output goes to stderr, except for unsatisfied dependencies which
		go to stdout for parsing by programs such as autounmask.
		"""

		# Note that show_masked_packages() sends it's output to
		# stdout, and some programs such as autounmask parse the
		# output in cases when emerge bails out. However, when
		# show_masked_packages() is called for installed packages
		# here, the message is a warning that is more appropriate
		# to send to stderr, so temporarily redirect stdout to
		# stderr. TODO: Fix output code so there's a cleaner way
		# to redirect everything to stderr.
		sys.stdout.flush()
		sys.stderr.flush()
		stdout = sys.stdout
		try:
			sys.stdout = sys.stderr
			self._display_problems()
		finally:
			sys.stdout = stdout
			sys.stdout.flush()
			sys.stderr.flush()

		# This goes to stdout for parsing by programs like autounmask.
		for pargs, kwargs in self._unsatisfied_deps_for_display:
			self._show_unsatisfied_dep(*pargs, **kwargs)

	def _display_problems(self):
		if self._circular_deps_for_display is not None:
			self._show_circular_deps(
				self._circular_deps_for_display)

		# The user is only notified of a slot conflict if
		# there are no unresolvable blocker conflicts.
		if self._unsatisfied_blockers_for_display is not None:
			self._show_unsatisfied_blockers(
				self._unsatisfied_blockers_for_display)
		else:
			self._show_slot_collision_notice()

		# TODO: Add generic support for "set problem" handlers so that
		# the below warnings aren't special cases for world only.

		if self._missing_args:
			world_problems = False
			if "world" in self._sets:
				# Filter out indirect members of world (from nested sets)
				# since only direct members of world are desired here.
				world_set = self.roots[self.target_root].sets["world"]
				for arg, atom in self._missing_args:
					if arg.name == "world" and atom in world_set:
						world_problems = True
						break

			if world_problems:
				sys.stderr.write("\n!!! Problems have been " + \
					"detected with your world file\n")
				sys.stderr.write("!!! Please run " + \
					green("emaint --check world")+"\n\n")

		if self._missing_args:
			sys.stderr.write("\n" + colorize("BAD", "!!!") + \
				" Ebuilds for the following packages are either all\n")
			sys.stderr.write(colorize("BAD", "!!!") + \
				" masked or don't exist:\n")
			sys.stderr.write(" ".join(str(atom) for arg, atom in \
				self._missing_args) + "\n")

		if self._pprovided_args:
			arg_refs = {}
			for arg, atom in self._pprovided_args:
				if isinstance(arg, SetArg):
					parent = arg.name
					arg_atom = (atom, atom)
				else:
					parent = "args"
					arg_atom = (arg.arg, atom)
				refs = arg_refs.setdefault(arg_atom, [])
				if parent not in refs:
					refs.append(parent)
			msg = []
			msg.append(bad("\nWARNING: "))
			if len(self._pprovided_args) > 1:
				msg.append("Requested packages will not be " + \
					"merged because they are listed in\n")
			else:
				msg.append("A requested package will not be " + \
					"merged because it is listed in\n")
			msg.append("package.provided:\n\n")
			problems_sets = set()
			for (arg, atom), refs in arg_refs.iteritems():
				ref_string = ""
				if refs:
					problems_sets.update(refs)
					refs.sort()
					ref_string = ", ".join(["'%s'" % name for name in refs])
					ref_string = " pulled in by " + ref_string
				msg.append("  %s%s\n" % (colorize("INFORM", str(arg)), ref_string))
			msg.append("\n")
			if "world" in problems_sets:
				msg.append("This problem can be solved in one of the following ways:\n\n")
				msg.append("  A) Use emaint to clean offending packages from world (if not installed).\n")
				msg.append("  B) Uninstall offending packages (cleans them from world).\n")
				msg.append("  C) Remove offending entries from package.provided.\n\n")
				msg.append("The best course of action depends on the reason that an offending\n")
				msg.append("package.provided entry exists.\n\n")
			sys.stderr.write("".join(msg))

		masked_packages = []
		for pkg in self._masked_installed:
			root_config = pkg.root_config
			pkgsettings = self.pkgsettings[pkg.root]
			mreasons = get_masking_status(pkg, pkgsettings, root_config)
			masked_packages.append((root_config, pkgsettings,
				pkg.cpv, pkg.metadata, mreasons))
		if masked_packages:
			sys.stderr.write("\n" + colorize("BAD", "!!!") + \
				" The following installed packages are masked:\n")
			show_masked_packages(masked_packages)
			show_mask_docs()
			print

	def calc_changelog(self,ebuildpath,current,next):
		if ebuildpath == None or not os.path.exists(ebuildpath):
			return []
		current = '-'.join(portage.catpkgsplit(current)[1:])
		if current.endswith('-r0'):
			current = current[:-3]
		next = '-'.join(portage.catpkgsplit(next)[1:])
		if next.endswith('-r0'):
			next = next[:-3]
		changelogpath = os.path.join(os.path.split(ebuildpath)[0],'ChangeLog')
		try:
			changelog = open(changelogpath).read()
		except SystemExit, e:
			raise # Needed else can't exit
		except:
			return []
		divisions = self.find_changelog_tags(changelog)
		#print 'XX from',current,'to',next
		#for div,text in divisions: print 'XX',div
		# skip entries for all revisions above the one we are about to emerge
		for i in range(len(divisions)):
			if divisions[i][0]==next:
				divisions = divisions[i:]
				break
		# find out how many entries we are going to display
		for i in range(len(divisions)):
			if divisions[i][0]==current:
				divisions = divisions[:i]
				break
		else:
		    # couldnt find the current revision in the list. display nothing
			return []
		return divisions

	def find_changelog_tags(self,changelog):
		divs = []
		release = None
		while 1:
			match = re.search(r'^\*\ ?([-a-zA-Z0-9_.+]*)(?:\ .*)?\n',changelog,re.M)
			if match is None:
				if release is not None:
					divs.append((release,changelog))
				return divs
			if release is not None:
				divs.append((release,changelog[:match.start()]))
			changelog = changelog[match.end():]
			release = match.group(1)
			if release.endswith('.ebuild'):
				release = release[:-7]
			if release.endswith('-r0'):
				release = release[:-3]

	def saveNomergeFavorites(self):
		"""Find atoms in favorites that are not in the mergelist and add them
		to the world file if necessary."""
		for x in ("--buildpkgonly", "--fetchonly", "--fetch-all-uri",
			"--oneshot", "--onlydeps", "--pretend"):
			if x in self.myopts:
				return
		root_config = self.roots[self.target_root]
		world_set = root_config.sets["world"]

		world_locked = False
		if hasattr(world_set, "lock"):
			world_set.lock()
			world_locked = True

		if hasattr(world_set, "load"):
			world_set.load() # maybe it's changed on disk

		args_set = self._sets["args"]
		portdb = self.trees[self.target_root]["porttree"].dbapi
		added_favorites = set()
		for x in self._set_nodes:
			pkg_type, root, pkg_key, pkg_status = x
			if pkg_status != "nomerge":
				continue

			try:
				myfavkey = create_world_atom(x, args_set, root_config)
				if myfavkey:
					if myfavkey in added_favorites:
						continue
					added_favorites.add(myfavkey)
			except portage.exception.InvalidDependString, e:
				writemsg("\n\n!!! '%s' has invalid PROVIDE: %s\n" % \
					(pkg_key, str(e)), noiselevel=-1)
				writemsg("!!! see '%s'\n\n" % os.path.join(
					root, portage.VDB_PATH, pkg_key, "PROVIDE"), noiselevel=-1)
				del e
		all_added = []
		for k in self._sets:
			if k in ("args", "world") or not root_config.sets[k].world_candidate:
				continue
			s = SETPREFIX + k
			if s in world_set:
				continue
			all_added.append(SETPREFIX + k)
		all_added.extend(added_favorites)
		all_added.sort()
		for a in all_added:
			print ">>> Recording %s in \"world\" favorites file..." % \
				colorize("INFORM", str(a))
		if all_added:
			world_set.update(all_added)

		if world_locked:
			world_set.unlock()

	def loadResumeCommand(self, resume_data, skip_masked=True,
		skip_missing=True):
		"""
		Add a resume command to the graph and validate it in the process.  This
		will raise a PackageNotFound exception if a package is not available.
		"""

		if not isinstance(resume_data, dict):
			return False

		mergelist = resume_data.get("mergelist")
		if not isinstance(mergelist, list):
			mergelist = []

		fakedb = self.mydbapi
		trees = self.trees
		serialized_tasks = []
		masked_tasks = []
		for x in mergelist:
			if not (isinstance(x, list) and len(x) == 4):
				continue
			pkg_type, myroot, pkg_key, action = x
			if pkg_type not in self.pkg_tree_map:
				continue
			if action != "merge":
				continue
			tree_type = self.pkg_tree_map[pkg_type]
			mydb = trees[myroot][tree_type].dbapi
			db_keys = list(self._trees_orig[myroot][
				tree_type].dbapi._aux_cache_keys)
			try:
				metadata = izip(db_keys, mydb.aux_get(pkg_key, db_keys))
			except KeyError:
				# It does no exist or it is corrupt.
				if action == "uninstall":
					continue
				if skip_missing:
					# TODO: log these somewhere
					continue
				raise portage.exception.PackageNotFound(pkg_key)
			installed = action == "uninstall"
			built = pkg_type != "ebuild"
			root_config = self.roots[myroot]
			pkg = Package(built=built, cpv=pkg_key,
				installed=installed, metadata=metadata,
				operation=action, root_config=root_config,
				type_name=pkg_type)
			if pkg_type == "ebuild":
				pkgsettings = self.pkgsettings[myroot]
				pkgsettings.setcpv(pkg)
				pkg.metadata["USE"] = pkgsettings["PORTAGE_USE"]
				pkg.metadata['CHOST'] = pkgsettings.get('CHOST', '')
			self._pkg_cache[pkg] = pkg

			root_config = self.roots[pkg.root]
			if "merge" == pkg.operation and \
				not visible(root_config.settings, pkg):
				if skip_masked:
					masked_tasks.append(Dependency(root=pkg.root, parent=pkg))
				else:
					self._unsatisfied_deps_for_display.append(
						((pkg.root, "="+pkg.cpv), {"myparent":None}))

			fakedb[myroot].cpv_inject(pkg)
			serialized_tasks.append(pkg)
			self.spinner.update()

		if self._unsatisfied_deps_for_display:
			return False

		if not serialized_tasks or "--nodeps" in self.myopts:
			self._serialized_tasks_cache = serialized_tasks
			self._scheduler_graph = self.digraph
		else:
			self._select_package = self._select_pkg_from_graph
			self.myparams.add("selective")
			# Always traverse deep dependencies in order to account for
			# potentially unsatisfied dependencies of installed packages.
			# This is necessary for correct --keep-going or --resume operation
			# in case a package from a group of circularly dependent packages
			# fails. In this case, a package which has recently been installed
			# may have an unsatisfied circular dependency (pulled in by
			# PDEPEND, for example). So, even though a package is already
			# installed, it may not have all of it's dependencies satisfied, so
			# it may not be usable. If such a package is in the subgraph of
			# deep depenedencies of a scheduled build, that build needs to
			# be cancelled. In order for this type of situation to be
			# recognized, deep traversal of dependencies is required.
			self.myparams.add("deep")

			favorites = resume_data.get("favorites")
			args_set = self._sets["args"]
			if isinstance(favorites, list):
				args = self._load_favorites(favorites)
			else:
				args = []

			for task in serialized_tasks:
				if isinstance(task, Package) and \
					task.operation == "merge":
					if not self._add_pkg(task, None):
						return False

			# Packages for argument atoms need to be explicitly
			# added via _add_pkg() so that they are included in the
			# digraph (needed at least for --tree display).
			for arg in args:
				for atom in arg.set:
					pkg, existing_node = self._select_package(
						arg.root_config.root, atom)
					if existing_node is None and \
						pkg is not None:
						if not self._add_pkg(pkg, Dependency(atom=atom,
							root=pkg.root, parent=arg)):
							return False

			# Allow unsatisfied deps here to avoid showing a masking
			# message for an unsatisfied dep that isn't necessarily
			# masked.
			if not self._create_graph(allow_unsatisfied=True):
				return False

			unsatisfied_deps = []
			for dep in self._unsatisfied_deps:
				if not isinstance(dep.parent, Package):
					continue
				if dep.parent.operation == "merge":
					unsatisfied_deps.append(dep)
					continue

				# For unsatisfied deps of installed packages, only account for
				# them if they are in the subgraph of dependencies of a package
				# which is scheduled to be installed.
				unsatisfied_install = False
				traversed = set()
				dep_stack = self.digraph.parent_nodes(dep.parent)
				while dep_stack:
					node = dep_stack.pop()
					if not isinstance(node, Package):
						continue
					if node.operation == "merge":
						unsatisfied_install = True
						break
					if node in traversed:
						continue
					traversed.add(node)
					dep_stack.extend(self.digraph.parent_nodes(node))

				if unsatisfied_install:
					unsatisfied_deps.append(dep)

			if masked_tasks or unsatisfied_deps:
				# This probably means that a required package
				# was dropped via --skipfirst. It makes the
				# resume list invalid, so convert it to a
				# UnsatisfiedResumeDep exception.
				raise self.UnsatisfiedResumeDep(self,
					masked_tasks + unsatisfied_deps)
			self._serialized_tasks_cache = None
			try:
				self.altlist()
			except self._unknown_internal_error:
				return False

		return True

	def _load_favorites(self, favorites):
		"""
		Use a list of favorites to resume state from a
		previous select_files() call. This creates similar
		DependencyArg instances to those that would have
		been created by the original select_files() call.
		This allows Package instances to be matched with
		DependencyArg instances during graph creation.
		"""
		root_config = self.roots[self.target_root]
		getSetAtoms = root_config.setconfig.getSetAtoms
		sets = root_config.sets
		args = []
		for x in favorites:
			if not isinstance(x, basestring):
				continue
			if x in ("system", "world"):
				x = SETPREFIX + x
			if x.startswith(SETPREFIX):
				s = x[len(SETPREFIX):]
				if s not in sets:
					continue
				if s in self._sets:
					continue
				# Recursively expand sets so that containment tests in
				# self._get_parent_sets() properly match atoms in nested
				# sets (like if world contains system).
				expanded_set = InternalPackageSet(
					initial_atoms=getSetAtoms(s))
				self._sets[s] = expanded_set
				args.append(SetArg(arg=x, set=expanded_set,
					root_config=root_config))
			else:
				if not portage.isvalidatom(x):
					continue
				args.append(AtomArg(arg=x, atom=x,
					root_config=root_config))

		self._set_args(args)
		return args

	class UnsatisfiedResumeDep(portage.exception.PortageException):
		"""
		A dependency of a resume list is not installed. This
		can occur when a required package is dropped from the
		merge list via --skipfirst.
		"""
		def __init__(self, depgraph, value):
			portage.exception.PortageException.__init__(self, value)
			self.depgraph = depgraph

	class _internal_exception(portage.exception.PortageException):
		def __init__(self, value=""):
			portage.exception.PortageException.__init__(self, value)

	class _unknown_internal_error(_internal_exception):
		"""
		Used by the depgraph internally to terminate graph creation.
		The specific reason for the failure should have been dumped
		to stderr, unfortunately, the exact reason for the failure
		may not be known.
		"""

	class _serialize_tasks_retry(_internal_exception):
		"""
		This is raised by the _serialize_tasks() method when it needs to
		be called again for some reason. The only case that it's currently
		used for is when neglected dependencies need to be added to the
		graph in order to avoid making a potentially unsafe decision.
		"""

	class _dep_check_composite_db(portage.dbapi):
		"""
		A dbapi-like interface that is optimized for use in dep_check() calls.
		This is built on top of the existing depgraph package selection logic.
		Some packages that have been added to the graph may be masked from this
		view in order to influence the atom preference selection that occurs
		via dep_check().
		"""
		def __init__(self, depgraph, root):
			portage.dbapi.__init__(self)
			self._depgraph = depgraph
			self._root = root
			self._match_cache = {}
			self._cpv_pkg_map = {}

		def _clear_cache(self):
			self._match_cache.clear()
			self._cpv_pkg_map.clear()

		def match(self, atom):
			ret = self._match_cache.get(atom)
			if ret is not None:
				return ret[:]
			orig_atom = atom
			if "/" not in atom:
				atom = self._dep_expand(atom)
			pkg, existing = self._depgraph._select_package(self._root, atom)
			if not pkg:
				ret = []
			else:
				# Return the highest available from select_package() as well as
				# any matching slots in the graph db.
				slots = set()
				slots.add(pkg.metadata["SLOT"])
				atom_cp = portage.dep_getkey(atom)
				if pkg.cp.startswith("virtual/"):
					# For new-style virtual lookahead that occurs inside
					# dep_check(), examine all slots. This is needed
					# so that newer slots will not unnecessarily be pulled in
					# when a satisfying lower slot is already installed. For
					# example, if virtual/jdk-1.4 is satisfied via kaffe then
					# there's no need to pull in a newer slot to satisfy a
					# virtual/jdk dependency.
					for db, pkg_type, built, installed, db_keys in \
						self._depgraph._filtered_trees[self._root]["dbs"]:
						for cpv in db.match(atom):
							if portage.cpv_getkey(cpv) != pkg.cp:
								continue
							slots.add(db.aux_get(cpv, ["SLOT"])[0])
				ret = []
				if self._visible(pkg):
					self._cpv_pkg_map[pkg.cpv] = pkg
					ret.append(pkg.cpv)
				slots.remove(pkg.metadata["SLOT"])
				while slots:
					slot_atom = "%s:%s" % (atom_cp, slots.pop())
					pkg, existing = self._depgraph._select_package(
						self._root, slot_atom)
					if not pkg:
						continue
					if not self._visible(pkg):
						continue
					self._cpv_pkg_map[pkg.cpv] = pkg
					ret.append(pkg.cpv)
				if ret:
					self._cpv_sort_ascending(ret)
			self._match_cache[orig_atom] = ret
			return ret[:]

		def _visible(self, pkg):
			if pkg.installed and "selective" not in self._depgraph.myparams:
				try:
					arg = self._depgraph._iter_atoms_for_pkg(pkg).next()
				except (StopIteration, portage.exception.InvalidDependString):
					arg = None
				if arg:
					return False
			if pkg.installed:
				try:
					if not visible(
						self._depgraph.pkgsettings[pkg.root], pkg):
						return False
				except portage.exception.InvalidDependString:
					pass
			in_graph = self._depgraph._slot_pkg_map[
				self._root].get(pkg.slot_atom)
			if in_graph is None:
				# Mask choices for packages which are not the highest visible
				# version within their slot (since they usually trigger slot
				# conflicts).
				highest_visible, in_graph = self._depgraph._select_package(
					self._root, pkg.slot_atom)
				if pkg != highest_visible:
					return False
			elif in_graph != pkg:
				# Mask choices for packages that would trigger a slot
				# conflict with a previously selected package.
				return False
			return True

		def _dep_expand(self, atom):
			"""
			This is only needed for old installed packages that may
			contain atoms that are not fully qualified with a specific
			category. Emulate the cpv_expand() function that's used by
			dbapi.match() in cases like this. If there are multiple
			matches, it's often due to a new-style virtual that has
			been added, so try to filter those out to avoid raising
			a ValueError.
			"""
			root_config = self._depgraph.roots[self._root]
			orig_atom = atom
			expanded_atoms = self._depgraph._dep_expand(root_config, atom)
			if len(expanded_atoms) > 1:
				non_virtual_atoms = []
				for x in expanded_atoms:
					if not portage.dep_getkey(x).startswith("virtual/"):
						non_virtual_atoms.append(x)
				if len(non_virtual_atoms) == 1:
					expanded_atoms = non_virtual_atoms
			if len(expanded_atoms) > 1:
				# compatible with portage.cpv_expand()
				raise portage.exception.AmbiguousPackageName(
					[portage.dep_getkey(x) for x in expanded_atoms])
			if expanded_atoms:
				atom = expanded_atoms[0]
			else:
				null_atom = insert_category_into_atom(atom, "null")
				null_cp = portage.dep_getkey(null_atom)
				cat, atom_pn = portage.catsplit(null_cp)
				virts_p = root_config.settings.get_virts_p().get(atom_pn)
				if virts_p:
					# Allow the resolver to choose which virtual.
					atom = insert_category_into_atom(atom, "virtual")
				else:
					atom = insert_category_into_atom(atom, "null")
			return atom

		def aux_get(self, cpv, wants):
			metadata = self._cpv_pkg_map[cpv].metadata
			return [metadata.get(x, "") for x in wants]


def ambiguous_package_name(arg, atoms, root_config, spinner, myopts):

	if "--quiet" in myopts:
		print "!!! The short ebuild name \"%s\" is ambiguous. Please specify" % arg
		print "!!! one of the following fully-qualified ebuild names instead:\n"
		for cp in sorted(set(portage.dep_getkey(atom) for atom in atoms)):
			print "    " + colorize("INFORM", cp)
		return

	s = search(root_config, spinner, "--searchdesc" in myopts,
		"--quiet" not in myopts, "--usepkg" in myopts,
		"--usepkgonly" in myopts)
	null_cp = portage.dep_getkey(insert_category_into_atom(
		arg, "null"))
	cat, atom_pn = portage.catsplit(null_cp)
	s.searchkey = atom_pn
	for cp in sorted(set(portage.dep_getkey(atom) for atom in atoms)):
		s.addCP(cp)
	s.output()
	print "!!! The short ebuild name \"%s\" is ambiguous. Please specify" % arg
	print "!!! one of the above fully-qualified ebuild names instead.\n"

def insert_category_into_atom(atom, category):
	alphanum = re.search(r'\w', atom)
	if alphanum:
		ret = atom[:alphanum.start()] + "%s/" % category + \
			atom[alphanum.start():]
	else:
		ret = None
	return ret

def resume_depgraph(settings, trees, mtimedb, myopts, myparams, spinner):
	"""
	Construct a depgraph for the given resume list. This will raise
	PackageNotFound or depgraph.UnsatisfiedResumeDep when necessary.
	@rtype: tuple
	@returns: (success, depgraph, dropped_tasks)
	"""
	skip_masked = True
	skip_unsatisfied = True
	mergelist = mtimedb["resume"]["mergelist"]
	dropped_tasks = set()
	while True:
		mydepgraph = depgraph(settings, trees,
			myopts, myparams, spinner)
		try:
			success = mydepgraph.loadResumeCommand(mtimedb["resume"],
				skip_masked=skip_masked)
		except depgraph.UnsatisfiedResumeDep, e:
			if not skip_unsatisfied:
				raise

			graph = mydepgraph.digraph
			unsatisfied_parents = dict((dep.parent, dep.parent) \
				for dep in e.value)
			traversed_nodes = set()
			unsatisfied_stack = list(unsatisfied_parents)
			while unsatisfied_stack:
				pkg = unsatisfied_stack.pop()
				if pkg in traversed_nodes:
					continue
				traversed_nodes.add(pkg)

				# If this package was pulled in by a parent
				# package scheduled for merge, removing this
				# package may cause the the parent package's
				# dependency to become unsatisfied.
				for parent_node in graph.parent_nodes(pkg):
					if not isinstance(parent_node, Package) \
						or parent_node.operation not in ("merge", "nomerge"):
						continue
					unsatisfied = \
						graph.child_nodes(parent_node,
						ignore_priority=DepPrioritySatisfiedRange.ignore_soft)
					if pkg in unsatisfied:
						unsatisfied_parents[parent_node] = parent_node
						unsatisfied_stack.append(parent_node)

			pruned_mergelist = []
			for x in mergelist:
				if isinstance(x, list) and \
					tuple(x) not in unsatisfied_parents:
					pruned_mergelist.append(x)

			# If the mergelist doesn't shrink then this loop is infinite.
			if len(pruned_mergelist) == len(mergelist):
				# This happens if a package can't be dropped because
				# it's already installed, but it has unsatisfied PDEPEND.
				raise
			mergelist[:] = pruned_mergelist

			# Exclude installed packages that have been removed from the graph due
			# to failure to build/install runtime dependencies after the dependent
			# package has already been installed.
			dropped_tasks.update(pkg for pkg in \
				unsatisfied_parents if pkg.operation != "nomerge")
			mydepgraph.break_refs(unsatisfied_parents)

			del e, graph, traversed_nodes, \
				unsatisfied_parents, unsatisfied_stack
			continue
		else:
			break
	return (success, mydepgraph, dropped_tasks)

def get_mask_info(root_config, cpv, pkgsettings,
	db, pkg_type, built, installed, db_keys):
	eapi_masked = False
	try:
		metadata = dict(izip(db_keys,
			db.aux_get(cpv, db_keys)))
	except KeyError:
		metadata = None
	if metadata and not built:
		pkgsettings.setcpv(cpv, mydb=metadata)
		metadata["USE"] = pkgsettings["PORTAGE_USE"]
		metadata['CHOST'] = pkgsettings.get('CHOST', '')
	if metadata is None:
		mreasons = ["corruption"]
	else:
		eapi = metadata['EAPI']
		if eapi[:1] == '-':
			eapi = eapi[1:]
		if not portage.eapi_is_supported(eapi):
			mreasons = ['EAPI %s' % eapi]
		else:
			pkg = Package(type_name=pkg_type, root_config=root_config,
				cpv=cpv, built=built, installed=installed, metadata=metadata)
			mreasons = get_masking_status(pkg, pkgsettings, root_config)
	return metadata, mreasons

def show_masked_packages(masked_packages):
	shown_licenses = set()
	shown_comments = set()
	# Maybe there is both an ebuild and a binary. Only
	# show one of them to avoid redundant appearance.
	shown_cpvs = set()
	have_eapi_mask = False
	for (root_config, pkgsettings, cpv,
		metadata, mreasons) in masked_packages:
		if cpv in shown_cpvs:
			continue
		shown_cpvs.add(cpv)
		comment, filename = None, None
		if "package.mask" in mreasons:
			comment, filename = \
				portage.getmaskingreason(
				cpv, metadata=metadata,
				settings=pkgsettings,
				portdb=root_config.trees["porttree"].dbapi,
				return_location=True)
		missing_licenses = []
		if metadata:
			if not portage.eapi_is_supported(metadata["EAPI"]):
				have_eapi_mask = True
			try:
				missing_licenses = \
					pkgsettings._getMissingLicenses(
						cpv, metadata)
			except portage.exception.InvalidDependString:
				# This will have already been reported
				# above via mreasons.
				pass

		print "- "+cpv+" (masked by: "+", ".join(mreasons)+")"
		if comment and comment not in shown_comments:
			print filename+":"
			print comment
			shown_comments.add(comment)
		portdb = root_config.trees["porttree"].dbapi
		for l in missing_licenses:
			l_path = portdb.findLicensePath(l)
			if l in shown_licenses:
				continue
			msg = ("A copy of the '%s' license" + \
			" is located at '%s'.") % (l, l_path)
			print msg
			print
			shown_licenses.add(l)
	return have_eapi_mask

def show_mask_docs():
	print "For more information, see the MASKED PACKAGES section in the emerge"
	print "man page or refer to the Gentoo Handbook."

def filter_iuse_defaults(iuse):
	for flag in iuse:
		if flag.startswith("+") or flag.startswith("-"):
			yield flag[1:]
		else:
			yield flag

def show_blocker_docs_link():
	print
	print "For more information about " + bad("Blocked Packages") + ", please refer to the following"
	print "section of the Gentoo Linux x86 Handbook (architecture is irrelevant):"
	print
	print "http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked"
	print

def get_masking_status(pkg, pkgsettings, root_config):

	mreasons = portage.getmaskingstatus(
		pkg, settings=pkgsettings,
		portdb=root_config.trees["porttree"].dbapi)

	if not pkg.installed:
		if not pkgsettings._accept_chost(pkg.cpv, pkg.metadata):
			mreasons.append("CHOST: %s" % \
				pkg.metadata["CHOST"])

	if not pkg.metadata["SLOT"]:
		mreasons.append("invalid: SLOT is undefined")

	return mreasons




def create_depgraph_params(myopts, myaction):
	#configure emerge engine parameters
	#
	# self:      include _this_ package regardless of if it is merged.
	# selective: exclude the package if it is merged
	# recurse:   go into the dependencies
	# deep:      go into the dependencies of already merged packages
	# empty:     pretend nothing is merged
	# complete:  completely account for all known dependencies
	# remove:    build graph for use in removing packages
	myparams = set(["recurse"])

	if myaction == "remove":
		myparams.add("remove")
		myparams.add("complete")
		return myparams

	if "--update" in myopts or \
		"--newuse" in myopts or \
		"--reinstall" in myopts or \
		"--noreplace" in myopts:
		myparams.add("selective")
	if "--emptytree" in myopts:
		myparams.add("empty")
		myparams.discard("selective")
	if "--nodeps" in myopts:
		myparams.discard("recurse")
	if "--deep" in myopts:
		myparams.add("deep")
	if "--complete-graph" in myopts:
		myparams.add("complete")
	return myparams





import re

try:
	import portage
except ImportError:
	from os import path as osp
	import sys
	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	import portage

def is_valid_package_atom(x):
	if "/" not in x:
		alphanum = re.search(r'\w', x)
		if alphanum:
			x = x[:alphanum.start()] + "cat/" + x[alphanum.start():]
	return portage.isvalidatom(x)




try:
	import portage
except ImportError:
	from os import path as osp
	import sys
	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	import portage

def create_world_atom(pkg, args_set, root_config):
	"""Create a new atom for the world file if one does not exist.  If the
	argument atom is precise enough to identify a specific slot then a slot
	atom will be returned. Atoms that are in the system set may also be stored
	in world since system atoms can only match one slot while world atoms can
	be greedy with respect to slots.  Unslotted system packages will not be
	stored in world."""

	arg_atom = args_set.findAtomForPackage(pkg)
	if not arg_atom:
		return None
	cp = portage.dep_getkey(arg_atom)
	new_world_atom = cp
	sets = root_config.sets
	portdb = root_config.trees["porttree"].dbapi
	vardb = root_config.trees["vartree"].dbapi
	available_slots = set(portdb.aux_get(cpv, ["SLOT"])[0] \
		for cpv in portdb.match(cp))
	slotted = len(available_slots) > 1 or \
		(len(available_slots) == 1 and "0" not in available_slots)
	if not slotted:
		# check the vdb in case this is multislot
		available_slots = set(vardb.aux_get(cpv, ["SLOT"])[0] \
			for cpv in vardb.match(cp))
		slotted = len(available_slots) > 1 or \
			(len(available_slots) == 1 and "0" not in available_slots)
	if slotted and arg_atom != cp:
		# If the user gave a specific atom, store it as a
		# slot atom in the world file.
		slot_atom = pkg.slot_atom

		# For USE=multislot, there are a couple of cases to
		# handle here:
		#
		# 1) SLOT="0", but the real SLOT spontaneously changed to some
		#    unknown value, so just record an unslotted atom.
		#
		# 2) SLOT comes from an installed package and there is no
		#    matching SLOT in the portage tree.
		#
		# Make sure that the slot atom is available in either the
		# portdb or the vardb, since otherwise the user certainly
		# doesn't want the SLOT atom recorded in the world file
		# (case 1 above).  If it's only available in the vardb,
		# the user may be trying to prevent a USE=multislot
		# package from being removed by --depclean (case 2 above).

		mydb = portdb
		if not portdb.match(slot_atom):
			# SLOT seems to come from an installed multislot package
			mydb = vardb
		# If there is no installed package matching the SLOT atom,
		# it probably changed SLOT spontaneously due to USE=multislot,
		# so just record an unslotted atom.
		if vardb.match(slot_atom):
			# Now verify that the argument is precise
			# enough to identify a specific slot.
			matches = mydb.match(arg_atom)
			matched_slots = set()
			for cpv in matches:
				matched_slots.add(mydb.aux_get(cpv, ["SLOT"])[0])
			if len(matched_slots) == 1:
				new_world_atom = slot_atom

	if new_world_atom == sets["world"].findAtomForPackage(pkg):
		# Both atoms would be identical, so there's nothing to add.
		return None
	if not slotted:
		# Unlike world atoms, system atoms are not greedy for slots, so they
		# can't be safely excluded from world if they are slotted.
		system_atom = sets["system"].findAtomForPackage(pkg)
		if system_atom:
			if not portage.dep_getkey(system_atom).startswith("virtual/"):
				return None
			# System virtuals aren't safe to exclude from world since they can
			# match multiple old-style virtuals but only one of them will be
			# pulled in by update or depclean.
			providers = portdb.mysettings.getvirtuals().get(
				portage.dep_getkey(system_atom))
			if providers and len(providers) == 1 and providers[0] == cp:
				return None
	return new_world_atom





from _emerge.DepPriority import DepPriority
from _emerge.Package import Package

def _find_deep_system_runtime_deps(graph):
	deep_system_deps = set()
	node_stack = []
	for node in graph:
		if not isinstance(node, Package) or \
			node.operation == 'uninstall':
			continue
		if node.root_config.sets['system'].findAtomForPackage(node):
			node_stack.append(node)

	def ignore_priority(priority):
		"""
		Ignore non-runtime priorities.
		"""
		if isinstance(priority, DepPriority) and \
			(priority.runtime or priority.runtime_post):
			return False
		return True

	while node_stack:
		node = node_stack.pop()
		if node in deep_system_deps:
			continue
		deep_system_deps.add(node)
		for child in graph.child_nodes(node, ignore_priority=ignore_priority):
			if not isinstance(child, Package) or \
				child.operation == 'uninstall':
				continue
			node_stack.append(child)

	return deep_system_deps


Return to bug 275047

Line 0 Link Here

(-)clear_caches.py (+19 lines)
	1	import gc
	2
	3	try:
	4	import portage
	5	except ImportError:
	6	from os import path as osp
	7	import sys
	8	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	9	import portage
	10
	11	def clear_caches(trees):
	12	for d in trees.itervalues():
	13	d["porttree"].dbapi.melt()
	14	d["porttree"].dbapi._aux_cache.clear()
	15	d["bintree"].dbapi._aux_cache.clear()
	16	d["bintree"].dbapi._clear_cache()
	17	d["vartree"].dbapi.linkmap._clear_cache()
	18	portage.dircache.clear()
	19	gc.collect()

Line 0 Link Here

(-)_flush_elog_mod_echo.py (+17 lines)
	1	def _flush_elog_mod_echo():
	2	"""
	3	Dump the mod_echo output now so that our other
	4	notifications are shown last.
	5	@rtype: bool
	6	@returns: True if messages were shown, False otherwise.
	7	"""
	8	messages_shown = False
	9	try:
	10	from portage.elog import mod_echo
	11	except ImportError:
	12	pass # happens during downgrade to a version without the module
	13	else:
	14	messages_shown = bool(mod_echo._items)
	15	mod_echo.finalize()
	16	return messages_shown
	17

Line 0 Link Here

(-)create_depgraph_params.py (+33 lines)
	1	def create_depgraph_params(myopts, myaction):
	2	#configure emerge engine parameters
	3	#
	4	# self: include _this_ package regardless of if it is merged.
	5	# selective: exclude the package if it is merged
	6	# recurse: go into the dependencies
	7	# deep: go into the dependencies of already merged packages
	8	# empty: pretend nothing is merged
	9	# complete: completely account for all known dependencies
	10	# remove: build graph for use in removing packages
	11	myparams = set(["recurse"])
	12
	13	if myaction == "remove":
	14	myparams.add("remove")
	15	myparams.add("complete")
	16	return myparams
	17
	18	if "--update" in myopts or \
	19	"--newuse" in myopts or \
	20	"--reinstall" in myopts or \
	21	"--noreplace" in myopts:
	22	myparams.add("selective")
	23	if "--emptytree" in myopts:
	24	myparams.add("empty")
	25	myparams.discard("selective")
	26	if "--nodeps" in myopts:
	27	myparams.discard("recurse")
	28	if "--deep" in myopts:
	29	myparams.add("deep")
	30	if "--complete-graph" in myopts:
	31	myparams.add("complete")
	32	return myparams
	33

Line 0 Link Here

(-)is_valid_package_atom.py (+16 lines)
	1	import re
	2
	3	try:
	4	import portage
	5	except ImportError:
	6	from os import path as osp
	7	import sys
	8	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
	9	import portage
	10
	11	def is_valid_package_atom(x):
	12	if "/" not in x:
	13	alphanum = re.search(r'\w', x)
	14	if alphanum:
	15	x = x[:alphanum.start()] + "cat/" + x[alphanum.start():]
	16	return portage.isvalidatom(x)

Line 0 Link Here

(-)create_world_atom.py (+91 lines)
		1	try:
		2	import portage
		3	except ImportError:
		4	from os import path as osp
		5	import sys
		6	sys.path.insert(0, osp.join(osp.dirname(osp.dirname(osp.realpath(__file__))), "pym"))
		7	import portage
		8
		9	def create_world_atom(pkg, args_set, root_config):
		10	"""Create a new atom for the world file if one does not exist. If the
		11	argument atom is precise enough to identify a specific slot then a slot
		12	atom will be returned. Atoms that are in the system set may also be stored
		13	in world since system atoms can only match one slot while world atoms can
		14	be greedy with respect to slots. Unslotted system packages will not be
		15	stored in world."""
		16
		17	arg_atom = args_set.findAtomForPackage(pkg)
		18	if not arg_atom:
		19	return None
		20	cp = portage.dep_getkey(arg_atom)
		21	new_world_atom = cp
		22	sets = root_config.sets
		23	portdb = root_config.trees["porttree"].dbapi
		24	vardb = root_config.trees["vartree"].dbapi
		25	available_slots = set(portdb.aux_get(cpv, ["SLOT"])[0] \
		26	for cpv in portdb.match(cp))
		27	slotted = len(available_slots) > 1 or \
		28	(len(available_slots) == 1 and "0" not in available_slots)
		29	if not slotted:
		30	# check the vdb in case this is multislot
		31	available_slots = set(vardb.aux_get(cpv, ["SLOT"])[0] \
		32	for cpv in vardb.match(cp))
		33	slotted = len(available_slots) > 1 or \
		34	(len(available_slots) == 1 and "0" not in available_slots)
		35	if slotted and arg_atom != cp:
		36	# If the user gave a specific atom, store it as a
		37	# slot atom in the world file.
		38	slot_atom = pkg.slot_atom
		39
		40	# For USE=multislot, there are a couple of cases to
		41	# handle here:
		42	#
		43	# 1) SLOT="0", but the real SLOT spontaneously changed to some
		44	# unknown value, so just record an unslotted atom.
		45	#
		46	# 2) SLOT comes from an installed package and there is no
		47	# matching SLOT in the portage tree.
		48	#
		49	# Make sure that the slot atom is available in either the
		50	# portdb or the vardb, since otherwise the user certainly
		51	# doesn't want the SLOT atom recorded in the world file
		52	# (case 1 above). If it's only available in the vardb,
		53	# the user may be trying to prevent a USE=multislot
		54	# package from being removed by --depclean (case 2 above).
		55
		56	mydb = portdb
		57	if not portdb.match(slot_atom):
		58	# SLOT seems to come from an installed multislot package
		59	mydb = vardb
		60	# If there is no installed package matching the SLOT atom,
		61	# it probably changed SLOT spontaneously due to USE=multislot,
		62	# so just record an unslotted atom.
		63	if vardb.match(slot_atom):
		64	# Now verify that the argument is precise
65	# enough to identify a specific slot.
66	matches = mydb.match(arg_atom)
67	matched_slots = set()
68	for cpv in matches:
69	matched_slots.add(mydb.aux_get(cpv, ["SLOT"])[0])
70	if len(matched_slots) == 1:
71	new_world_atom = slot_atom
72
73	if new_world_atom == sets["world"].findAtomForPackage(pkg):
74	# Both atoms would be identical, so there's nothing to add.
75	return None
76	if not slotted:
77	# Unlike world atoms, system atoms are not greedy for slots, so they
78	# can't be safely excluded from world if they are slotted.
79	system_atom = sets["system"].findAtomForPackage(pkg)
80	if system_atom:
81	if not portage.dep_getkey(system_atom).startswith("virtual/"):
82	return None
83	# System virtuals aren't safe to exclude from world since they can
84	# match multiple old-style virtuals but only one of them will be
85	# pulled in by update or depclean.
86	providers = portdb.mysettings.getvirtuals().get(
87	portage.dep_getkey(system_atom))
88	if providers and len(providers) == 1 and providers[0] == cp:
89	return None
90	return new_world_atom
91

Line 0 Link Here

(-)_find_deep_system_runtime_deps.py (+35 lines)
	1	from _emerge.DepPriority import DepPriority
	2	from _emerge.Package import Package
	3
	4	def _find_deep_system_runtime_deps(graph):
	5	deep_system_deps = set()
	6	node_stack = []
	7	for node in graph:
	8	if not isinstance(node, Package) or \
	9	node.operation == 'uninstall':
	10	continue
	11	if node.root_config.sets['system'].findAtomForPackage(node):
	12	node_stack.append(node)
	13
	14	def ignore_priority(priority):
	15	"""
	16	Ignore non-runtime priorities.
	17	"""
	18	if isinstance(priority, DepPriority) and \
	19	(priority.runtime or priority.runtime_post):
	20	return False
	21	return True
	22
	23	while node_stack:
	24	node = node_stack.pop()
	25	if node in deep_system_deps:
	26	continue
	27	deep_system_deps.add(node)
	28	for child in graph.child_nodes(node, ignore_priority=ignore_priority):
	29	if not isinstance(child, Package) or \
	30	child.operation == 'uninstall':
	31	continue
	32	node_stack.append(child)
	33
	34	return deep_system_deps
	35