view tests/test-merge-local.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

  $ hg init

Revision 0:

  $ echo "unchanged" > unchanged
  $ echo "remove me" > remove
  $ echo "copy me" > copy
  $ echo "move me" > move
  $ for i in 1 2 3 4 5 6 7 8 9; do
  >     echo "merge ok $i" >> zzz1_merge_ok
  > done
  $ echo "merge bad" > zzz2_merge_bad
  $ hg ci -Am "revision 0"
  adding copy
  adding move
  adding remove
  adding unchanged
  adding zzz1_merge_ok
  adding zzz2_merge_bad

Revision 1:

  $ hg rm remove
  $ hg mv move moved
  $ hg cp copy copied
  $ echo "added" > added
  $ hg add added
  $ echo "new first line" > zzz1_merge_ok
  $ hg cat zzz1_merge_ok >> zzz1_merge_ok
  $ echo "new last line" >> zzz2_merge_bad
  $ hg ci -m "revision 1"

Local changes to revision 0:

  $ hg co 0
  4 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ echo "new last line" >> zzz1_merge_ok
  $ echo "another last line" >> zzz2_merge_bad

  $ hg diff --nodates | grep "^[+-][^<>]"
  --- a/zzz1_merge_ok
  +++ b/zzz1_merge_ok
  +new last line
  --- a/zzz2_merge_bad
  +++ b/zzz2_merge_bad
  +another last line

  $ hg st
  M zzz1_merge_ok
  M zzz2_merge_bad

Local merge with bad merge tool:

  $ HGMERGE=false hg co
  merging zzz1_merge_ok
  merging zzz2_merge_bad
  merging zzz2_merge_bad failed!
  3 files updated, 1 files merged, 2 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]

  $ hg resolve -m
  (no more unresolved files)

  $ hg co 0
  merging zzz1_merge_ok
  merging zzz2_merge_bad
  warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
  2 files updated, 1 files merged, 3 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]

  $ hg diff --nodates | grep "^[+-][^<>]"
  --- a/zzz1_merge_ok
  +++ b/zzz1_merge_ok
  +new last line
  --- a/zzz2_merge_bad
  +++ b/zzz2_merge_bad
  +another last line
  +=======

  $ hg st
  M zzz1_merge_ok
  M zzz2_merge_bad
  ? zzz2_merge_bad.orig

Local merge with conflicts:

  $ hg resolve -m
  (no more unresolved files)

  $ hg co
  merging zzz1_merge_ok
  merging zzz2_merge_bad
  warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
  3 files updated, 1 files merged, 2 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]

  $ hg resolve -m
  (no more unresolved files)

  $ hg co 0 --config 'ui.origbackuppath=.hg/origbackups'
  merging zzz1_merge_ok
  merging zzz2_merge_bad
  warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
  2 files updated, 1 files merged, 3 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]

Are orig files from the last commit where we want them?
  $ ls .hg/origbackups
  zzz2_merge_bad

  $ hg diff --nodates | grep "^[+-][^<>]"
  --- a/zzz1_merge_ok
  +++ b/zzz1_merge_ok
  +new last line
  --- a/zzz2_merge_bad
  +++ b/zzz2_merge_bad
  +another last line
  +=======
  +=======
  +new last line
  +=======

  $ hg st
  M zzz1_merge_ok
  M zzz2_merge_bad
  ? zzz2_merge_bad.orig

Local merge without conflicts:

  $ hg revert zzz2_merge_bad

  $ hg resolve -m
  (no more unresolved files)

  $ hg co
  merging zzz1_merge_ok
  4 files updated, 1 files merged, 2 files removed, 0 files unresolved

  $ hg diff --nodates | grep "^[+-][^<>]"
  --- a/zzz1_merge_ok
  +++ b/zzz1_merge_ok
  +new last line

  $ hg st
  M zzz1_merge_ok
  ? zzz2_merge_bad.orig