# HG changeset patch
# User FUJIWARA Katsunori <fo...@lares.dti.ne.jp>
# Date 1496981269 -32400
# Fri Jun 09 13:07:49 2017 +0900
# Node ID 664e3e012535c9d161f0ecb95c6dc0bfdfe9c672
# Parent 9b4ff10f9db00ae7d91a28067d6b50655f5f957d
context: avoid writing outdated dirstate out (issue5584)
Before this patch, workingctx.status() may cause writing outdated
dirstate out, if:
- .hg/dirstate is changed simultaneously after last loading it,
- there is any file, which should be dirstate.normal()-ed
Typical issue case is:
- the working directory is updated by "hg update"
- .hg/dirstate is updated in background (e.g. fsmonitor)
This patch compares identities of dirstate before and after
acquisition of wlock, and avoids writing outdated dirstate out, if
change of .hg/dirstate is detected.
diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -1763,19 +1763,30 @@ class workingctx(committablectx):
# update dirstate for files that are actually clean
if fixup:
try:
+ oldid = self._repo.dirstate.identity()
+
# updating the dirstate is optional
# so we don't wait on the lock
# wlock can invalidate the dirstate, so cache normal _after_
# taking the lock
with self._repo.wlock(False):
- normal = self._repo.dirstate.normal
- for f in fixup:
- normal(f)
- # write changes out explicitly, because nesting
- # wlock at runtime may prevent 'wlock.release()'
- # after this block from doing so for subsequent
- # changing files
- self._repo.dirstate.write(self._repo.currenttransaction())
+ if self._repo.dirstate.identity() == oldid:
+ normal = self._repo.dirstate.normal
+ for f in fixup:
+ normal(f)
+ # write changes out explicitly, because nesting
+ # wlock at runtime may prevent 'wlock.release()'
+ # after this block from doing so for subsequent
+ # changing files
+ tr = self._repo.currenttransaction()
+ self._repo.dirstate.write(tr)
+ else:
+ # in this case, writing changes out breaks
+ # consistency, because .hg/dirstate was
+ # already changed simultaneously after last
+ # caching (see also issue5584 for detail)
+ self._repo.ui.debug('skip updating dirstate: '
+ 'identity mismatch\n')
except error.LockError:
pass
return modified, deleted, fixup
diff --git a/tests/test-dirstate-race.t b/tests/test-dirstate-race.t
--- a/tests/test-dirstate-race.t
+++ b/tests/test-dirstate-race.t
@@ -95,3 +95,65 @@ anyway.
! d
! dir1/c
! e
+
+ $ rmdir d e
+ $ hg update -C -q .
+
+Test that dirstate changes aren't written out at the end of "hg
+status", if .hg/dirstate is already changed simultaneously before
+acquisition of wlock in workingctx._checklookup().
+
+This avoidance is important to keep consistency of dirstate in race
+condition (see issue5584 for detail).
+
+ $ hg parents -q
+ 1:* (glob)
+
+ $ hg debugrebuilddirstate
+ $ hg debugdirstate
+ n 0 -1 unset a
+ n 0 -1 unset b
+ n 0 -1 unset d
+ n 0 -1 unset dir1/c
+ n 0 -1 unset e
+
+ $ cat > $TESTTMP/dirstaterace.sh <<EOF
+ > # This script assumes timetable of typical issue5584 case below:
+ > #
+ > # 1. "hg status" loads .hg/dirstate
+ > # 2. "hg status" confirms clean-ness of FILE
+ > # 3. "hg update -C 0" updates the working directory simultaneously
+ > # (FILE is removed, and FILE is dropped from .hg/dirstate)
+ > # 4. "hg status" acquires wlock
+ > # (.hg/dirstate is re-loaded = no FILE entry in dirstate)
+ > # 5. "hg status" marks FILE in dirstate as clean
+ > # (FILE entry is added to in-memory dirstate)
+ > # 6. "hg status" writes dirstate changes into .hg/dirstate
+ > # (FILE entry is written into .hg/dirstate)
+ > #
+ > # To reproduce similar situation easily and certainly, #2 and #3
+ > # are swapped. "hg cat" below ensures #2 on "hg status" side.
+ >
+ > hg update -q -C 0
+ > hg cat -r 1 b > b
+ > EOF
+
+"hg status" below should excludes "e", of which exec flag is set, for
+portability of test scenario, because unsure but missing "e" is
+treated differently in _checklookup() according to runtime platform.
+
+- "missing(!)" on POSIX, "pctx[f].cmp(self[f])" raises ENOENT
+- "modified(M)" on Windows, "self.flags(f) != pctx.flags(f)" is True
+
+ $ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py
--debug -X path:e
+ skip updating dirstate: identity mismatch
+ M a
+ ! d
+ ! dir1/c
+
+ $ hg parents -q
+ 0:* (glob)
+ $ hg files
+ a
+ $ hg debugdirstate
+ n * * * a (glob)
_______________________________________________
Mercurial-devel mailing list
Mercurial-devel@mercurial-scm.org
https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
