Mercurial > hg
view tests/test-i18n.t @ 43709:039fbd14d4e2
lock: fix race in lock-breaking code
With low frequency, I see hg pulls fail with output like:
abort: no such file or directory: .hg/store/lock
I think what happens is, in lock.py, in:
def _testlock(self, locker):
if not self._lockshouldbebroken(locker):
return locker
# if locker dead, break lock. must do this with another lock
# held, or can race and break valid lock.
try:
with lock(self.vfs, self.f + b'.break', timeout=0):
self.vfs.unlink(self.f)
except error.LockError:
return locker
if a lock is breakable on disk, and two hg processes concurrently get
to the "if locker dead" comment, a possible interleaving is: process1
finishes executing the function and then process2 finishes executing
the function. If that happens, process2 will either get ENOENT in
self.vfs.unlink (resulting in the spurious failure above), or break a
valid lock and potentially cause repository corruption.
The fix is simple enough: make sure the lock is breakable _inside_ the
critical section, because only then can we know that no other process
can invalidate our knowledge on the lock on disk.
I don't think there are tests for this. I've tested this manually
with:
diff --git a/mercurial/lock.py b/mercurial/lock.py
--- a/mercurial/lock.py
+++ b/mercurial/lock.py
@@ -351,6 +351,8 @@ class lock(object):
if not self._lockshouldbebroken(locker):
return locker
+ import random
+ time.sleep(1. + random.random())
# if locker dead, break lock. must do this with another lock
# held, or can race and break valid lock.
try:
@@ -358,6 +360,7 @@ class lock(object):
self.vfs.unlink(self.f)
except error.LockError:
return locker
+ time.sleep(1)
def testlock(self):
"""return id of locker if lock is valid, else None.
and I see this change of behavior before/after this commit:
$ $hg init repo
$ cd repo
$ ln -s $HOSTNAME/effffffc:987654321 .hg/wlock
$ touch a
$ $hg commit -Am_ & $hg commit -Am _; wait
-abort: No such file or directory: '/tmp/repo/.hg/wlock'
adding a
+warning: ignoring unknown working parent 679a8959a8ca!
+nothing changed
Differential Revision: https://phab.mercurial-scm.org/D7199
author | Valentin Gatien-Baron <valentin.gatienbaron@gmail.com> |
---|---|
date | Mon, 18 Nov 2019 20:10:38 -0800 |
parents | 5abc47d4ca6b |
children | 95c4cca641f6 |
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(Translations are optional) #if gettext no-outer-repo Test that translations are compiled and installed correctly. Default encoding in tests is "ascii" and the translation is encoded using the "replace" error handler: $ LANGUAGE=pt_BR hg tip abortado: n?o foi encontrado um reposit?rio em '$TESTTMP' (.hg n?o encontrado)! [255] Using a more accommodating encoding: $ HGENCODING=UTF-8 LANGUAGE=pt_BR hg tip abortado: n\xc3\xa3o foi encontrado um reposit\xc3\xb3rio em '$TESTTMP' (.hg n\xc3\xa3o encontrado)! (esc) [255] Different encoding: $ HGENCODING=Latin-1 LANGUAGE=pt_BR hg tip abortado: n\xe3o foi encontrado um reposit\xf3rio em '$TESTTMP' (.hg n\xe3o encontrado)! (esc) [255] #endif #if gettext Test keyword search in translated help text: $ HGENCODING=UTF-8 LANGUAGE=de hg help -k Aktualisiert Themen: subrepos Unterarchive Befehle: pull Ruft \xc3\x84nderungen von der angegebenen Quelle ab (esc) update Aktualisiert das Arbeitsverzeichnis (oder wechselt die Version) #endif Check Mercurial specific translation problems in each *.po files, and tool itself by doctest $ cd "$TESTDIR"/../i18n $ "$PYTHON" check-translation.py *.po $ "$PYTHON" check-translation.py --doctest $ cd $TESTTMP #if gettext Check i18n cache isn't reused after encoding change: $ cat > $TESTTMP/encodingchange.py << EOF > from mercurial.i18n import _ > from mercurial import encoding, registrar > cmdtable = {} > command = registrar.command(cmdtable) > @command(b'encodingchange', norepo=True) > def encodingchange(ui): > for encode in (b'ascii', b'UTF-8', b'ascii', b'UTF-8'): > encoding.encoding = encode > ui.write(b'%s\n' % _(b'(EXPERIMENTAL)')) > EOF $ LANGUAGE=ja hg --config extensions.encodingchange=$TESTTMP/encodingchange.py encodingchange (?????) (\xe5\xae\x9f\xe9\xa8\x93\xe7\x9a\x84\xe5\xae\x9f\xe8\xa3\x85) (esc) (?????) (\xe5\xae\x9f\xe9\xa8\x93\xe7\x9a\x84\xe5\xae\x9f\xe8\xa3\x85) (esc) #endif