##// END OF EJS Templates
lock: fix race in lock-breaking code...
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

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diffutil.py
136 lines | 4.5 KiB | text/x-python | PythonLexer
# diffutil.py - utility functions related to diff and patch
#
# Copyright 2006 Brendan Cully <brendan@kublai.com>
# Copyright 2007 Chris Mason <chris.mason@oracle.com>
# Copyright 2018 Octobus <octobus@octobus.net>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
from .i18n import _
from . import (
mdiff,
pycompat,
)
def diffallopts(
ui, opts=None, untrusted=False, section=b'diff', configprefix=b''
):
'''return diffopts with all features supported and parsed'''
return difffeatureopts(
ui,
opts=opts,
untrusted=untrusted,
section=section,
git=True,
whitespace=True,
formatchanging=True,
configprefix=configprefix,
)
def difffeatureopts(
ui,
opts=None,
untrusted=False,
section=b'diff',
git=False,
whitespace=False,
formatchanging=False,
configprefix=b'',
):
'''return diffopts with only opted-in features parsed
Features:
- git: git-style diffs
- whitespace: whitespace options like ignoreblanklines and ignorews
- formatchanging: options that will likely break or cause correctness issues
with most diff parsers
'''
def get(key, name=None, getter=ui.configbool, forceplain=None):
if opts:
v = opts.get(key)
# diffopts flags are either None-default (which is passed
# through unchanged, so we can identify unset values), or
# some other falsey default (eg --unified, which defaults
# to an empty string). We only want to override the config
# entries from hgrc with command line values if they
# appear to have been set, which is any truthy value,
# True, or False.
if v or isinstance(v, bool):
return v
if forceplain is not None and ui.plain():
return forceplain
return getter(
section, configprefix + (name or key), untrusted=untrusted
)
# core options, expected to be understood by every diff parser
buildopts = {
b'nodates': get(b'nodates'),
b'showfunc': get(b'show_function', b'showfunc'),
b'context': get(b'unified', getter=ui.config),
}
buildopts[b'xdiff'] = ui.configbool(b'experimental', b'xdiff')
if git:
buildopts[b'git'] = get(b'git')
# since this is in the experimental section, we need to call
# ui.configbool directory
buildopts[b'showsimilarity'] = ui.configbool(
b'experimental', b'extendedheader.similarity'
)
# need to inspect the ui object instead of using get() since we want to
# test for an int
hconf = ui.config(b'experimental', b'extendedheader.index')
if hconf is not None:
hlen = None
try:
# the hash config could be an integer (for length of hash) or a
# word (e.g. short, full, none)
hlen = int(hconf)
if hlen < 0 or hlen > 40:
msg = _(b"invalid length for extendedheader.index: '%d'\n")
ui.warn(msg % hlen)
except ValueError:
# default value
if hconf == b'short' or hconf == b'':
hlen = 12
elif hconf == b'full':
hlen = 40
elif hconf != b'none':
msg = _(b"invalid value for extendedheader.index: '%s'\n")
ui.warn(msg % hconf)
finally:
buildopts[b'index'] = hlen
if whitespace:
buildopts[b'ignorews'] = get(b'ignore_all_space', b'ignorews')
buildopts[b'ignorewsamount'] = get(
b'ignore_space_change', b'ignorewsamount'
)
buildopts[b'ignoreblanklines'] = get(
b'ignore_blank_lines', b'ignoreblanklines'
)
buildopts[b'ignorewseol'] = get(b'ignore_space_at_eol', b'ignorewseol')
if formatchanging:
buildopts[b'text'] = opts and opts.get(b'text')
binary = None if opts is None else opts.get(b'binary')
buildopts[b'nobinary'] = (
not binary
if binary is not None
else get(b'nobinary', forceplain=False)
)
buildopts[b'noprefix'] = get(b'noprefix', forceplain=False)
buildopts[b'worddiff'] = get(
b'word_diff', b'word-diff', forceplain=False
)
return mdiff.diffopts(**pycompat.strkwargs(buildopts))