Bug 693242 – sys-apps/portage: backtracking terminates prematurely

• Product: Portage Development
• Status: RESOLVED FIXED

[Description Zac Medico 2019-09-01 00:18:56 UTC]

When investigating this test failure triggered by the fix for bug 692746:

> ======================================================================
> FAIL: testSonameSkipUpdate (portage.tests.resolver.soname.test_skip_update.SonameSkipUpdateTestCase)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "lib/portage/tests/__init__.py", line 211, in run
>     testMethod()
>   File "lib/portage/tests/resolver/soname/test_skip_update.py", line 82, in testSonameSkipUpdate
>     test_case.fail_msg)
> AssertionError: False != True : atoms: (@world), key: success, expected: True, got: False
> atoms: (@world), key: mergelist, expected: [], got: ['[binary]dev-libs/B-1', '[binary]dev-libs/B-2', '[binary]app-misc/A-1']
> atoms: (@world), key: slot_collision_solutions, expected: None, got: []

I found that backtracking terminates prematurely, and this fixes the problem:

> diff --git a/lib/_emerge/depgraph.py b/lib/_emerge/depgraph.py
> index 3e99ac077..08240af67 100644
> --- a/lib/_emerge/depgraph.py
> +++ b/lib/_emerge/depgraph.py
> @@ -9794,8 +9794,8 @@ def _backtrack_depgraph(settings, trees, myopts, myparams, myaction, myfiles, sp
>                 elif mydepgraph.need_restart():
>                         backtracked += 1
>                         backtracker.feedback(mydepgraph.get_backtrack_infos())
> -               else:
> -                       break
> +               elif backtracker:
> +                       backtracked += 1
>  
>         if not (success or mydepgraph.need_config_change()) and backtracked:

This change greatly increases the probability of backtracking success.

[Comment 1 Larry the Git Cow 2019-09-01 01:09:26 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/proj/portage.git/commit/?id=bb0bb4104b0d6cab16abce9cd6e1683c0b6d5c8d

commit bb0bb4104b0d6cab16abce9cd6e1683c0b6d5c8d
Author:     Zac Medico <[e-mail]>
AuthorDate: 2019-09-01 00:24:43 +0000
Commit:     Zac Medico <[e-mail]>
CommitDate: 2019-09-01 00:30:04 +0000

    _backtrack_depgraph: fix premature backtracking termination (bug 693242)
    
    Make backtracking continue as long as the backtracker has remaining
    nodes to explore. This fixes a case where it would terminate prematurely
    when the depgraph.need_restart() method returned False, even though the
    backtracker had remaining nodes to explore.
    
    Bug: https://bugs.gentoo.org/693242
    Signed-off-by: Zac Medico <[e-mail]>

 lib/_emerge/depgraph.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

[Comment 2 Larry the Git Cow 2019-09-01 21:20:51 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=fc1ee19f135a3446d16deac8f783472b464e3a2e

commit fc1ee19f135a3446d16deac8f783472b464e3a2e
Author:     Zac Medico <[e-mail]>
AuthorDate: 2019-09-01 21:12:24 +0000
Commit:     Zac Medico <[e-mail]>
CommitDate: 2019-09-01 21:20:36 +0000

    sys-apps/portage: Bump to version 2.3.75
    
     #235970 glsa-check: add --reverse option
     #692134 glsa-check: fix truncated CVE ids in listmode
     #692746 missed virtual/libmysqlclient update
     #693242 premature backtracking termination
    
    Bug: https://bugs.gentoo.org/691278
    Bug: https://bugs.gentoo.org/235970
    Bug: https://bugs.gentoo.org/692134
    Bug: https://bugs.gentoo.org/692746
    Bug: https://bugs.gentoo.org/693242
    Package-Manager: Portage-2.3.75, Repoman-2.3.17
    Signed-off-by: Zac Medico <[e-mail]>

 sys-apps/portage/Manifest              |   1 +
 sys-apps/portage/portage-2.3.75.ebuild | 261 +++++++++++++++++++++++++++++++++
 2 files changed, 262 insertions(+)

[Comment 3 Larry the Git Cow 2019-09-12 19:05:46 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/proj/portage.git/commit/?id=54cab2dea3c55cbcd3a9bc2831c0ad25b12f12fa

commit 54cab2dea3c55cbcd3a9bc2831c0ad25b12f12fa
Author:     Zac Medico <[e-mail]>
AuthorDate: 2019-09-12 18:59:09 +0000
Commit:     Zac Medico <[e-mail]>
CommitDate: 2019-09-12 19:03:04 +0000

    SlotConflictMaskUpdateTestCase: remove todo flag (bug 693242)
    
    This test passes since the fix premature backtracking termination in
    commit bb0bb4104b0d6cab16abce9cd6e1683c0b6d5c8d.
    
    Bug: https://bugs.gentoo.org/693242
    Signed-off-by: Zac Medico <[e-mail]>

 lib/portage/tests/resolver/test_slot_conflict_mask_update.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)