view tests/test-merge-commit.t @ 42377:0546ead39a7e stable

manifest: avoid corruption by dropping removed files with pure (issue5801)

Previously, removed files would simply be marked by overwriting the first byte
with NUL and dropping their entry in `self.position`.  But no effort was made to
ignore them when compacting the dictionary into text form.  This allowed them to
slip into the manifest revision, since the code seems to be trying to minimize
the string operations by copying as large a chunk as possible.  As part of this,
compact() walks the existing text based on entries in the `positions` list, and
consumed everything up to the next position entry.   This typically resulted in
a ValueError complaining about unsorted manifest entries.

Sometimes it seems that files do get dropped in large repos- it seems to
correspond to there being a new entry that would take the same slot.  A much
more trivial problem is that if the only changes were removals, `_compact()`
didn't even run because `__delitem__` doesn't add anything to `self.extradata`.
Now there's an explicit variable to flag this, both to allow `_compact()` to
run, and to avoid searching the manifest in cases where there are no removals.

In practice, this behavior was mostly obscured by the check in fastdelta() which
takes a different path that explicitly drops removed files if there are fewer
than 1000 changes.  However, timeless has a repo where after rebasing tens of
commits, a totally different path[1] is taken that bypasses the change count
check and hits this problem.

[1] https://www.mercurial-scm.org/repo/hg/file/2338bdea4474/mercurial/manifest.py#l1511

Check that renames are correctly saved by a commit after a merge

Test with the merge on 3 having the rename on the local parent

  $ hg init a
  $ cd a

  $ echo line1 > foo
  $ hg add foo
  $ hg ci -m '0: add foo'

  $ echo line2 >> foo
  $ hg ci -m '1: change foo'

  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg mv foo bar
  $ rm bar
  $ echo line0 > bar
  $ echo line1 >> bar
  $ hg ci -m '2: mv foo bar; change bar'
  created new head

  $ hg merge 1
  merging bar and foo to bar
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line0
  line1
  line2

  $ hg ci -m '3: merge with local rename'

  $ hg debugindex bar
     rev linkrev nodeid       p1           p2
       0       2 d35118874825 000000000000 000000000000
       1       3 5345f5ab8abd 000000000000 d35118874825

  $ hg debugrename bar
  bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2

  $ hg debugindex foo
     rev linkrev nodeid       p1           p2
       0       0 690b295714ae 000000000000 000000000000
       1       1 9e25c27b8757 690b295714ae 000000000000


Revert the content change from rev 2:

  $ hg up -C 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm bar
  $ echo line1 > bar
  $ hg ci -m '4: revert content change from rev 2'
  created new head

  $ hg log --template '{rev}:{node|short} {parents}\n'
  4:2263c1be0967 2:0f2ff26688b9 
  3:0555950ead28 2:0f2ff26688b9 1:5cd961e4045d 
  2:0f2ff26688b9 0:2665aaee66e9 
  1:5cd961e4045d 
  0:2665aaee66e9 

This should use bar@rev2 as the ancestor:

  $ hg --debug merge 3
    searching for copies back to rev 1
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 0555950ead28
   preserving bar for resolve of bar
  starting 4 threads for background file closing (?)
   bar: versions differ -> m (premerge)
  picked tool ':merge' for bar (binary False symlink False changedelete False)
  merging bar
  my bar@2263c1be0967+ other bar@0555950ead28 ancestor bar@0f2ff26688b9
   premerge successful
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line1
  line2

  $ hg ci -m '5: merge'

  $ hg debugindex bar
     rev linkrev nodeid       p1           p2
       0       2 d35118874825 000000000000 000000000000
       1       3 5345f5ab8abd 000000000000 d35118874825
       2       4 ff4b45017382 d35118874825 000000000000
       3       5 3701b4893544 ff4b45017382 5345f5ab8abd


Same thing, but with the merge on 3 having the rename
on the remote parent:

  $ cd ..
  $ hg clone -U -r 1 -r 2 a b
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  new changesets 2665aaee66e9:0f2ff26688b9
  $ cd b

  $ hg up -C 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg merge 2
  merging foo and bar to bar
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line0
  line1
  line2

  $ hg ci -m '3: merge with remote rename'

  $ hg debugindex bar
     rev linkrev nodeid       p1           p2
       0       2 d35118874825 000000000000 000000000000
       1       3 5345f5ab8abd 000000000000 d35118874825

  $ hg debugrename bar
  bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2

  $ hg debugindex foo
     rev linkrev nodeid       p1           p2
       0       0 690b295714ae 000000000000 000000000000
       1       1 9e25c27b8757 690b295714ae 000000000000


Revert the content change from rev 2:

  $ hg up -C 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm bar
  $ echo line1 > bar
  $ hg ci -m '4: revert content change from rev 2'
  created new head

  $ hg log --template '{rev}:{node|short} {parents}\n'
  4:2263c1be0967 2:0f2ff26688b9 
  3:3ffa6b9e35f0 1:5cd961e4045d 2:0f2ff26688b9 
  2:0f2ff26688b9 0:2665aaee66e9 
  1:5cd961e4045d 
  0:2665aaee66e9 

This should use bar@rev2 as the ancestor:

  $ hg --debug merge 3
    searching for copies back to rev 1
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 3ffa6b9e35f0
   preserving bar for resolve of bar
  starting 4 threads for background file closing (?)
   bar: versions differ -> m (premerge)
  picked tool ':merge' for bar (binary False symlink False changedelete False)
  merging bar
  my bar@2263c1be0967+ other bar@3ffa6b9e35f0 ancestor bar@0f2ff26688b9
   premerge successful
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line1
  line2

  $ hg ci -m '5: merge'

  $ hg debugindex bar
     rev linkrev nodeid       p1           p2
       0       2 d35118874825 000000000000 000000000000
       1       3 5345f5ab8abd 000000000000 d35118874825
       2       4 ff4b45017382 d35118874825 000000000000
       3       5 3701b4893544 ff4b45017382 5345f5ab8abd

  $ cd ..