view tests/test-excessive-merge.t @ 42486:35d674a3d5db

copies: don't filter out copy targets created on other side of merge commit

If file X is copied to Y on one side of merge and the other side
creates Y (no copy), we would not mark that as copy. In the
changeset-centric pathcopies() version, that was done by checking if
the copy target existed on the other branch. Even though merge commits
are pretty uncommon, it still turned out to be too expensive to load
the manifest of the parents of merge commits. In a repo of
mozilla-unified converted to storing copies in changesets, about 2m30s
of `hg debugpathcopies FIREFOX_BETA_59_END FIREFOX_BETA_60_BASE` is
spent on this check of merge commits.

I tried to think of a way of storing more information in the
changesets in order to cheaply detect these cases, but I couldn't
think of a solution. So this patch simply removes those checks.

For reference, these extra copies are reported from the aforementioned
command after this patch:

  browser/base/content/sanitize.js -> browser/modules/Sanitizer.jsm
  testing/mozbase/mozprocess/tests/process_normal_finish_python.ini -> testing/mozbase/mozprocess/tests/process_normal_finish.ini
  testing/mozbase/mozprocess/tests/process_waittimeout_python.ini -> testing/mozbase/mozprocess/tests/process_waittimeout.ini
  testing/mozbase/mozprocess/tests/process_waittimeout_10s_python.ini -> testing/mozbase/mozprocess/tests/process_waittimeout_10s.ini

Since these copies were created on one side of some merge, it still
seems reasonable to include them, so I'm not even sure it's worse than
filelog pathcopies(), just different.

Differential Revision: https://phab.mercurial-scm.org/D6420

  $ hg init

  $ echo foo > a
  $ echo foo > b
  $ hg add a b

  $ hg ci -m "test"

  $ echo blah > a

  $ hg ci -m "branch a"

  $ hg co 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ echo blah > b

  $ hg ci -m "branch b"
  created new head
  $ HGMERGE=true hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg ci -m "merge b/a -> blah"

  $ hg co 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ HGMERGE=true hg merge 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m "merge a/b -> blah"
  created new head

  $ hg log
  changeset:   4:2ee31f665a86
  tag:         tip
  parent:      1:96155394af80
  parent:      2:92cc4c306b19
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     merge a/b -> blah
  
  changeset:   3:e16a66a37edd
  parent:      2:92cc4c306b19
  parent:      1:96155394af80
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     merge b/a -> blah
  
  changeset:   2:92cc4c306b19
  parent:      0:5e0375449e74
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     branch b
  
  changeset:   1:96155394af80
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     branch a
  
  changeset:   0:5e0375449e74
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     test
  
  $ hg debugindex --changelog
     rev linkrev nodeid       p1           p2
       0       0 5e0375449e74 000000000000 000000000000
       1       1 96155394af80 5e0375449e74 000000000000
       2       2 92cc4c306b19 5e0375449e74 000000000000
       3       3 e16a66a37edd 92cc4c306b19 96155394af80
       4       4 2ee31f665a86 96155394af80 92cc4c306b19

revision 1
  $ hg manifest --debug 1
  79d7492df40aa0fa093ec4209be78043c181f094 644   a
  2ed2a3912a0b24502043eae84ee4b279c18b90dd 644   b
revision 2
  $ hg manifest --debug 2
  2ed2a3912a0b24502043eae84ee4b279c18b90dd 644   a
  79d7492df40aa0fa093ec4209be78043c181f094 644   b
revision 3
  $ hg manifest --debug 3
  79d7492df40aa0fa093ec4209be78043c181f094 644   a
  79d7492df40aa0fa093ec4209be78043c181f094 644   b
revision 4
  $ hg manifest --debug 4
  79d7492df40aa0fa093ec4209be78043c181f094 644   a
  79d7492df40aa0fa093ec4209be78043c181f094 644   b

  $ hg debugindex a
     rev linkrev nodeid       p1           p2
       0       0 2ed2a3912a0b 000000000000 000000000000
       1       1 79d7492df40a 2ed2a3912a0b 000000000000

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 4 changes to 2 files