vfs: copy if EPERM to avoid file stat ambiguity forcibly at closing
Now, files (to be truncated) are opened with checkambig=True, only if
localrepository caches it.
Therefore, straightforward "copy if EPERM" is always reasonable to
avoid file stat ambiguity at closing.
This patch makes checkambigatclosing close wrapper copy the target
file, and advance mtime on it after renaming, if EPERM. This can avoid
file stat ambiguity, even if the target file is owned by another (see
issue5418 and
issue5584 for detail).
This patch factors main logic out instead of changing
checkambigatclosing._checkambig() directly, in order to reuse it.
transaction: apply checkambig=True only on limited files for similarity
Now, transaction can determine whether avoidance of file stat
ambiguity is needed for each files, by blacklist "checkambigfiles".
For similarity to truncation in _playback(), this patch apply
checkambig=True only on limited files in code paths below.
- restoring files by util.copyfile(), in _playback()
(checkambigfiles itself is examined at first, because it as a
keyword argument might be None)
- writing files at finalization of transaction, in _generatefiles()
This patch reduces cost of checking stat at writing out and restoring
files, which aren't filecache-ed.
transaction: avoid file stat ambiguity only for files in blacklist
Advancing mtime by os.utime() fails for EPERM, if the target file is
owned by another.
bff5ccbe5ead and related changes made some code
paths give advancing mtime up in such case, to fix
issue5418.
This causes file stat ambiguity (again), if it is owned by another.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
To avoid file stat ambiguity in such case, especially for
.hg/dirstate,
ed66ec39933f made vfs.rename() copy the target file, and
advance mtime of renamed one again, if EPERM (see
issue5584 for detail).
But straightforward "copy if EPERM" isn't reasonable for truncation of
append-only files at rollbacking, because rollbacking might cost much
for truncation of many filelogs, even though filelogs aren't
filecache-ed.
Therefore, this patch introduces blacklist "checkambigfiles", and
avoids file stat ambiguity only for files specified in this blacklist.
This patch consists of two parts below, which should be applied at
once in order to avoid regression.
- specify 'checkambig=True' at vfs.open(mode='a') in _playback()
according to checkambigfiles
- invoke _playback() with checkambigfiles
- add transaction.__init__() checkambigfiles argument, for _abort()
- make localrepo instantiate transaction with _cachedfiles
- add rollback() checkambigfiles argument, for "hg rollback/recover"
- make localrepo invoke rollback() with _cachedfiles
After this patch, straightforward "copy if EPERM" will be reasonable
at closing the file opened with checkambig=True, because this policy
is applied only on files, which are listed in blacklist
"checkambigfiles".
localrepo: store path and vfs location of cached properties
This information is used to make transaction handle these files
specially, in order to avoid file stat ambiguity of them.
Gathering information about cached files via annotation classes can
avoid overlooking properties newly introduced in the future.
template: add successors template
Add a 'successorssets' template that returns the list of all closest known
sucessorssets for a changectx. The elements of the list are changesets.
The "closest successors" are the first locally known revisions encountered
while, walking successors markers. It uses successorsets previously modified
to support the closest argument.
This logic respect repository filtering. So hidden revision will be skipped by
this logic unless --hidden is specified. Since we only display the visible
predecessors, this template will not display anything in most case. It makes a
good candidate for inclusion in the default log output.
I updated the test-obsmarker-template.t test file introduced with the
predecessors template to test successorssets template.
template: add tests for more complex cases
We add new tests for improving the coverage of existing obs-markers related
template (predecessors) and the new one we are introducing (successorssets).