##// 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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scmposix.py
97 lines | 2.6 KiB | text/x-python | PythonLexer
Gregory Szorc
scmposix: use absolute_import
r27483 from __future__ import absolute_import
Yuya Nishihara
scmutil: narrow ImportError handling in termwidth()...
r30311 import array
Yuya Nishihara
scmutil: move util.termwidth()...
r30309 import errno
import fcntl
Gregory Szorc
scmposix: use absolute_import
r27483 import os
import sys
Gregory Szorc
py3: manually import getattr where it is needed...
r43359 from .pycompat import getattr
Gregory Szorc
scmposix: use absolute_import
r27483 from . import (
Pulkit Goyal
py3: make scmposix.userrcpath() return bytes...
r30276 encoding,
Pulkit Goyal
py3: use pycompat.sysargv in scmposix.systemrcpath()...
r30467 pycompat,
Yuya Nishihara
osutil: proxy through util (and platform) modules (API)...
r32203 util,
Gregory Szorc
scmposix: use absolute_import
r27483 )
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690
Yuya Nishihara
pager: use less as a fallback on Unix...
r32078 # BSD 'more' escapes ANSI color sequences by default. This can be disabled by
# $MORE variable, but there's no compatible option with Linux 'more'. Given
# OS X is widely used and most modern Unix systems would have 'less', setting
# 'less' as the default seems reasonable.
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 fallbackpager = b'less'
Yuya Nishihara
pager: use less as a fallback on Unix...
r32078
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 def _rcfiles(path):
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 rcs = [os.path.join(path, b'hgrc')]
rcdir = os.path.join(path, b'hgrc.d')
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 try:
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345 rcs.extend(
[
os.path.join(rcdir, f)
for f, kind in util.listdir(rcdir)
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 if f.endswith(b".rc")
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345 ]
)
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 except OSError:
pass
return rcs
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 def systemrcpath():
path = []
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 if pycompat.sysplatform == b'plan9':
root = b'lib/mercurial'
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 else:
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 root = b'etc/mercurial'
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 # old mod_python does not set sys.argv
if len(getattr(sys, 'argv', [])) > 0:
Pulkit Goyal
py3: use pycompat.sysargv in scmposix.systemrcpath()...
r30467 p = os.path.dirname(os.path.dirname(pycompat.sysargv[0]))
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 if p != b'/':
Mads Kiilerich
config: don't read the same config file twice...
r22583 path.extend(_rcfiles(os.path.join(p, root)))
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 path.extend(_rcfiles(b'/' + root))
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 return path
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 def userrcpath():
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 if pycompat.sysplatform == b'plan9':
return [encoding.environ[b'home'] + b'/lib/hgrc']
Jun Wu
codemod: use pycompat.isdarwin...
r34648 elif pycompat.isdarwin:
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 return [os.path.expanduser(b'~/.hgrc')]
Kevin Bullock
scmutil: split platform-specific bits into their own modules...
r18690 else:
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 confighome = encoding.environ.get(b'XDG_CONFIG_HOME')
David Demelier
hg: allow usage of XDG_CONFIG_HOME/hg/hgrc...
r30941 if confighome is None or not os.path.isabs(confighome):
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 confighome = os.path.expanduser(b'~/.config')
David Demelier
hg: allow usage of XDG_CONFIG_HOME/hg/hgrc...
r30941
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345 return [
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 os.path.expanduser(b'~/.hgrc'),
os.path.join(confighome, b'hg', b'hgrc'),
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345 ]
Yuya Nishihara
scmutil: move util.termwidth()...
r30309
Yuya Nishihara
scmutil: extend termwidth() to return terminal height, renamed to termsize()...
r30314 def termsize(ui):
Yuya Nishihara
scmutil: move util.termwidth()...
r30309 try:
import termios
Augie Fackler
style: run a patched black on a subset of mercurial...
r43345
Yuya Nishihara
scmutil: narrow ImportError handling in termwidth()...
r30311 TIOCGWINSZ = termios.TIOCGWINSZ # unavailable on IRIX (issue3449)
except (AttributeError, ImportError):
Yuya Nishihara
scmutil: extend termwidth() to return terminal height, renamed to termsize()...
r30314 return 80, 24
Yuya Nishihara
scmutil: remove superfluous indent from termwidth()
r30312
for dev in (ui.ferr, ui.fout, ui.fin):
try:
Yuya Nishihara
scmutil: move util.termwidth()...
r30309 try:
Yuya Nishihara
scmutil: remove superfluous indent from termwidth()
r30312 fd = dev.fileno()
except AttributeError:
continue
if not os.isatty(fd):
continue
Augie Fackler
formatting: byteify all mercurial/ and hgext/ string literals...
r43347 arri = fcntl.ioctl(fd, TIOCGWINSZ, b'\0' * 8)
Augie Fackler
cleanup: remove pointless r-prefixes on single-quoted strings...
r43906 height, width = array.array('h', arri)[:2]
Yuya Nishihara
scmutil: extend termwidth() to return terminal height, renamed to termsize()...
r30314 if width > 0 and height > 0:
return width, height
Yuya Nishihara
scmutil: remove superfluous indent from termwidth()
r30312 except ValueError:
pass
except IOError as e:
Augie Fackler
scmposix: another suppression on IOError subscripting...
r43781 if e[0] == errno.EINVAL: # pytype: disable=unsupported-operands
Yuya Nishihara
scmutil: move util.termwidth()...
r30309 pass
Yuya Nishihara
scmutil: remove superfluous indent from termwidth()
r30312 else:
raise
Yuya Nishihara
scmutil: extend termwidth() to return terminal height, renamed to termsize()...
r30314 return 80, 24