##// END OF EJS Templates
dirstate: avoid a race with multiple commits in the same process...
dirstate: avoid a race with multiple commits in the same process (issue2264, issue2516) The race happens when two commits in a row change the same file without changing its size, *if* those two commits happen in the same second in the same process while holding the same repo lock. For example: commit 1: M a M b commit 2: # same process, same second, same repo lock M b # modify b without changing its size M c This first manifested in transplant, which is the most common way to do multiple commits in the same process. But it can manifest in any script or extension that does multiple commits under the same repo lock. (Thus, the test script tests both transplant and a custom script.) The problem was that dirstate.status() failed to notice the change to b when localrepo is about to do the second commit, meaning that change gets left in the working directory. In the context of transplant, that means either a crash ("RuntimeError: nothing committed after transplant") or a silently inaccurate transplant, depending on whether any other files were modified by the second transplanted changeset. The fix is to make status() work a little harder when we have previously marked files as clean (state 'normal') in the same process. Specifically, dirstate.normal() adds files to self._lastnormal, and other state-changing methods remove them. Then dirstate.status() puts any files in self._lastnormal into state 'lookup', which will make localrepository.status() read file contents to see if it has really changed. So we pay a small performance penalty for the second (and subsequent) commits in the same process, without affecting the common case. Anything that does lots of status updates and checks in the same process could suffer a performance hit. Incidentally, there is a simpler fix: call dirstate.normallookup() on every file updated by commit() at the end of the commit. The trouble with that solution is that it imposes a performance penalty on the common case: it means the next status-dependent hg command after every "hg commit" will be a little bit slower. The patch here is more complex, but only affects performance for the uncommon case.

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test-commit-multiple.t
119 lines | 3.3 KiB | text/troff | Tads3Lexer
/ tests / test-commit-multiple.t
# reproduce issue2264, issue2516
create test repo
$ cat <<EOF >> $HGRCPATH
> [extensions]
> transplant =
> graphlog =
> EOF
$ hg init repo
$ cd repo
$ template="{rev} {desc|firstline} [{branch}]\n"
# we need to start out with two changesets on the default branch
# in order to avoid the cute little optimization where transplant
# pulls rather than transplants
add initial changesets
$ echo feature1 > file1
$ hg ci -Am"feature 1"
adding file1
$ echo feature2 >> file2
$ hg ci -Am"feature 2"
adding file2
# The changes to 'bugfix' are enough to show the bug: in fact, with only
# those changes, it's a very noisy crash ("RuntimeError: nothing
# committed after transplant"). But if we modify a second file in the
# transplanted changesets, the bug is much more subtle: transplant
# silently drops the second change to 'bugfix' on the floor, and we only
# see it when we run 'hg status' after transplanting. Subtle data loss
# bugs are worse than crashes, so reproduce the subtle case here.
commit bug fixes on bug fix branch
$ hg branch fixes
marked working directory as branch fixes
$ echo fix1 > bugfix
$ echo fix1 >> file1
$ hg ci -Am"fix 1"
adding bugfix
$ echo fix2 > bugfix
$ echo fix2 >> file1
$ hg ci -Am"fix 2"
$ hg glog --template="$template"
@ 3 fix 2 [fixes]
|
o 2 fix 1 [fixes]
|
o 1 feature 2 [default]
|
o 0 feature 1 [default]
transplant bug fixes onto release branch
$ hg update 0
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ hg branch release
marked working directory as branch release
$ hg transplant 2 3
applying [0-9a-f]{12} (re)
[0-9a-f]{12} transplanted to [0-9a-f]{12} (re)
applying [0-9a-f]{12} (re)
[0-9a-f]{12} transplanted to [0-9a-f]{12} (re)
$ hg glog --template="$template"
@ 5 fix 2 [release]
|
o 4 fix 1 [release]
|
| o 3 fix 2 [fixes]
| |
| o 2 fix 1 [fixes]
| |
| o 1 feature 2 [default]
|/
o 0 feature 1 [default]
$ hg status
$ hg status --rev 0:4
M file1
A bugfix
$ hg status --rev 4:5
M bugfix
M file1
now test that we fixed the bug for all scripts/extensions
$ cat > $TESTTMP/committwice.py <<__EOF__
> from mercurial import ui, hg, match, node
>
> def replacebyte(fn, b):
> f = open("file1", "rb+")
> f.seek(0, 0)
> f.write(b)
> f.close()
>
> repo = hg.repository(ui.ui(), '.')
> assert len(repo) == 6, \
> "initial: len(repo) == %d, expected 6" % len(repo)
> try:
> wlock = repo.wlock()
> lock = repo.lock()
> m = match.exact(repo.root, '', ['file1'])
> replacebyte("file1", "x")
> n = repo.commit(text="x", user="test", date=(0, 0), match=m)
> print "commit 1: len(repo) == %d" % len(repo)
> replacebyte("file1", "y")
> n = repo.commit(text="y", user="test", date=(0, 0), match=m)
> print "commit 2: len(repo) == %d" % len(repo)
> finally:
> lock.release()
> wlock.release()
> __EOF__
$ $PYTHON $TESTTMP/committwice.py
commit 1: len(repo) == 7
commit 2: len(repo) == 8
Do a size-preserving modification outside of that process
$ echo abcd > bugfix
$ hg status
M bugfix
$ hg log --template "{rev} {desc} {files}\n" -r5:
5 fix 2 bugfix file1
6 x file1
7 y file1