[PATCH 3 of 5] branchmap: acquires lock before writting the rev branch cache
Pierre-Yves David
pierre-yves.david at ens-lyon.org
Fri Aug 5 19:02:55 EDT 2016
# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at ens-lyon.org>
# Date 1470401836 -7200
# Fri Aug 05 14:57:16 2016 +0200
# Node ID 84885aeec2e442d18dcb70fcce2d65dd9fafbf91
# Parent fa3f05a4219c4ea6b9bc9682f258e4418b36c265
# EXP-Topic vfsward
branchmap: acquires lock before writting the rev branch cache
We now attempt to acquire a lock and write the branch cache within that lock.
This would prevent cache corruption when multiple processes try to write the cache
at the same time.
diff -r fa3f05a4219c -r 84885aeec2e4 mercurial/branchmap.py
--- a/mercurial/branchmap.py Fri Aug 05 14:54:46 2016 +0200
+++ b/mercurial/branchmap.py Fri Aug 05 14:57:16 2016 +0200
@@ -470,8 +470,10 @@ class revbranchcache(object):
def write(self, tr=None):
"""Save branch cache if it is dirty."""
repo = self._repo
- if True:
+ wlock = None
+ try:
if self._rbcnamescount < len(self._names):
+ wlock = repo.wlock(wait=False)
try:
if self._rbcnamescount != 0:
f = repo.vfs.open(_rbcnames, 'ab')
@@ -501,6 +503,7 @@ class revbranchcache(object):
start = self._rbcrevslen * _rbcrecsize
if start != len(self._rbcrevs):
+ wlock = repo.wlock(wait=False)
revs = min(len(repo.changelog),
len(self._rbcrevs) // _rbcrecsize)
try:
@@ -521,3 +524,8 @@ class revbranchcache(object):
inst)
return
self._rbcrevslen = revs
+ except error.LockHeld as inst:
+ repo.ui.debug("couldn't write revision branch cache: %s\n" % inst)
+ finally:
+ if wlock is not None:
+ wlock.release()
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