Created attachment 456552 [details, diff] Sort dictionary before writing to disc I have my configuration files under version control. Among the tracked files is portage's /var/lib/portage/config (if that's a good idea to track is a different story, but currently I do). Over the time I noticed that the file is changed by portage in a non deterministic way, e.g. emerging openssl and then reemering it yielded different /var/lib/portage/config files. The reason is that the file /var/lib/portage/config is just a python dictionary written to disc and dictionaries are unordered (pym/portage/util/__init__.py, line 577) def writedict(mydict, myfilename, writekey=True): """Writes out a dict to a file; writekey=0 mode doesn't write out the key and assumes all values are strings, not lists.""" lines = [] if not writekey: for v in mydict.values(): lines.append(v + "\n") else: for k, v in mydict.items(): lines.append("%s %s\n" % (k, " ".join(v))) write_atomic(myfilename, "".join(lines)) I propose to change the implementation to write out the dictionary in alphabetical order (of the key if writekey=True, or the value otherwise). This makes the implementation more deterministic over different runs. This is a small change, just inserting sorted() in each of the two for-loops (patch also attached), e.g. [...] if not writekey: for v in sorted(mydict.values()): lines.append(v + "\n") else: for k, v in sorted(mydict.items()): lines.append("%s %s\n" % (k, " ".join(v))) [...]
Sorting this file is a waste of cpu time, and really we should take every opportunity that we can to conserve resources. I think we can eliminate /var/lib/portage/config entirely, and instead rely upon the md5 digest of the config file installed by the previous instance the package (the md5 digests are available in /var/db/pkg/*/*/CONTENTS).
(In reply to Zac Medico from comment #1) > I think we can eliminate /var/lib/portage/config entirely, and instead rely > upon the md5 digest of the config file installed by the previous instance > the package (the md5 digests are available in /var/db/pkg/*/*/CONTENTS). Since file collisions are allowed for files under CONFIG_PROTECT, it's possible for multiple packages to "own" a particular config file, so /var/lib/portage/config currently provides disambiguation in this case.
