mercurial/lock.py
author Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
Mon, 18 Nov 2019 20:10:38 -0800
changeset 43709 039fbd14d4e2
parent 43708 cd822413b9aa
child 43778 888bd39ed555
permissions -rw-r--r--
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
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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# lock.py - simple advisory locking scheme for mercurial
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#
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# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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from __future__ import absolute_import
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import contextlib
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import errno
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import os
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import signal
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import socket
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import time
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import warnings
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from .i18n import _
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from .pycompat import getattr
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from . import (
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    encoding,
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    error,
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    pycompat,
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    util,
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)
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from .utils import procutil
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def _getlockprefix():
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    """Return a string which is used to differentiate pid namespaces
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    It's useful to detect "dead" processes and remove stale locks with
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    confidence. Typically it's just hostname. On modern linux, we include an
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    extra Linux-specific pid namespace identifier.
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    """
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    result = encoding.strtolocal(socket.gethostname())
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    if pycompat.sysplatform.startswith(b'linux'):
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        try:
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            result += b'/%x' % os.stat(b'/proc/self/ns/pid').st_ino
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        except OSError as ex:
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            if ex.errno not in (errno.ENOENT, errno.EACCES, errno.ENOTDIR):
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                raise
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    return result
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@contextlib.contextmanager
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def _delayedinterrupt():
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    """Block signal interrupt while doing something critical
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    This makes sure that the code block wrapped by this context manager won't
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    be interrupted.
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    For Windows developers: It appears not possible to guard time.sleep()
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    from CTRL_C_EVENT, so please don't use time.sleep() to test if this is
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    working.
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    """
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    assertedsigs = []
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    blocked = False
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    orighandlers = {}
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    def raiseinterrupt(num):
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        if num == getattr(signal, 'SIGINT', None) or num == getattr(
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            signal, 'CTRL_C_EVENT', None
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        ):
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            raise KeyboardInterrupt
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        else:
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            raise error.SignalInterrupt
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    def catchterm(num, frame):
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        if blocked:
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            assertedsigs.append(num)
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        else:
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            raiseinterrupt(num)
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    try:
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        # save handlers first so they can be restored even if a setup is
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        # interrupted between signal.signal() and orighandlers[] =.
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        for name in [
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            b'CTRL_C_EVENT',
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            b'SIGINT',
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            b'SIGBREAK',
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            b'SIGHUP',
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            b'SIGTERM',
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        ]:
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            num = getattr(signal, name, None)
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            if num and num not in orighandlers:
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                orighandlers[num] = signal.getsignal(num)
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        try:
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            for num in orighandlers:
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                signal.signal(num, catchterm)
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        except ValueError:
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            pass  # in a thread? no luck
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        blocked = True
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        yield
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    finally:
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        # no simple way to reliably restore all signal handlers because
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        # any loops, recursive function calls, except blocks, etc. can be
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        # interrupted. so instead, make catchterm() raise interrupt.
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        blocked = False
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        try:
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            for num, handler in orighandlers.items():
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                signal.signal(num, handler)
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        except ValueError:
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            pass  # in a thread?
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    # re-raise interrupt exception if any, which may be shadowed by a new
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    # interrupt occurred while re-raising the first one
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    if assertedsigs:
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        raiseinterrupt(assertedsigs[0])
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def trylock(ui, vfs, lockname, timeout, warntimeout, *args, **kwargs):
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    """return an acquired lock or raise an a LockHeld exception
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    This function is responsible to issue warnings and or debug messages about
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    the held lock while trying to acquires it."""
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    def printwarning(printer, locker):
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        """issue the usual "waiting on lock" message through any channel"""
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        # show more details for new-style locks
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        if b':' in locker:
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            host, pid = locker.split(b":", 1)
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            msg = _(
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                b"waiting for lock on %s held by process %r on host %r\n"
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            ) % (
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                pycompat.bytestr(l.desc),
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                pycompat.bytestr(pid),
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                pycompat.bytestr(host),
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            )
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        else:
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            msg = _(b"waiting for lock on %s held by %r\n") % (
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                l.desc,
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                pycompat.bytestr(locker),
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            )
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        printer(msg)
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    l = lock(vfs, lockname, 0, *args, dolock=False, **kwargs)
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    debugidx = 0 if (warntimeout and timeout) else -1
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    warningidx = 0
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    if not timeout:
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        warningidx = -1
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    elif warntimeout:
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        warningidx = warntimeout
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    delay = 0
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    while True:
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        try:
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            l._trylock()
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            break
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        except error.LockHeld as inst:
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            if delay == debugidx:
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                printwarning(ui.debug, inst.locker)
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            if delay == warningidx:
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                printwarning(ui.warn, inst.locker)
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            if timeout <= delay:
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                raise error.LockHeld(
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                    errno.ETIMEDOUT, inst.filename, l.desc, inst.locker
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                )
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            time.sleep(1)
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            delay += 1
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    l.delay = delay
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    if l.delay:
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        if 0 <= warningidx <= l.delay:
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            ui.warn(_(b"got lock after %d seconds\n") % l.delay)
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        else:
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            ui.debug(b"got lock after %d seconds\n" % l.delay)
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    if l.acquirefn:
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        l.acquirefn()
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    return l
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class lock(object):
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    '''An advisory lock held by one process to control access to a set
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    of files.  Non-cooperating processes or incorrectly written scripts
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    can ignore Mercurial's locking scheme and stomp all over the
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    repository, so don't do that.
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    Typically used via localrepository.lock() to lock the repository
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    store (.hg/store/) or localrepository.wlock() to lock everything
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    else under .hg/.'''
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   186
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    # lock is symlink on platforms that support it, file on others.
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    # symlink is used because create of directory entry and contents
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    # are atomic even over nfs.
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    # old-style lock: symlink to pid
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    # new-style lock: symlink to hostname:pid
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    _host = None
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   196
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    def __init__(
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        self,
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        vfs,
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        fname,
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        timeout=-1,
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        releasefn=None,
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        acquirefn=None,
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        desc=None,
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        inheritchecker=None,
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        parentlock=None,
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        signalsafe=True,
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        dolock=True,
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    ):
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   210
        self.vfs = vfs
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        self.f = fname
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        self.held = 0
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        self.timeout = timeout
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        self.releasefn = releasefn
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        self.acquirefn = acquirefn
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        self.desc = desc
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        self._inheritchecker = inheritchecker
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        self.parentlock = parentlock
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        self._parentheld = False
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        self._inherited = False
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        if signalsafe:
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            self._maybedelayedinterrupt = _delayedinterrupt
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        else:
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            self._maybedelayedinterrupt = util.nullcontextmanager
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        self.postrelease = []
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        self.pid = self._getpid()
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        if dolock:
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            self.delay = self.lock()
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            if self.acquirefn:
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                self.acquirefn()
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    def __enter__(self):
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        return self
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    def __exit__(self, exc_type, exc_value, exc_tb):
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   236
        self.release()
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   237
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    def __del__(self):
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        if self.held:
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            warnings.warn(
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                "use lock.release instead of del lock",
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                category=DeprecationWarning,
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                stacklevel=2,
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            )
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   245
8108
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            # ensure the lock will be removed
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            # even if recursive locking did occur
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            self.held = 1
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   249
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        self.release()
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   251
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    def _getpid(self):
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        # wrapper around procutil.getpid() to make testing easier
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        return procutil.getpid()
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161
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parents:
diff changeset
   256
    def lock(self):
1787
e431344e604c add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 1753
diff changeset
   257
        timeout = self.timeout
14494
1ffeeb91c55d check-code: flag 0/1 used as constant Boolean expression
Martin Geisler <mg@lazybytes.net>
parents: 13281
diff changeset
   258
        while True:
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   259
            try:
26082
b188f60bd955 lock: make trylock private
Matt Mackall <mpm@selenic.com>
parents: 26081
diff changeset
   260
                self._trylock()
20380
c697b70f295f localrepo: give a sigh of relief when getting lock after waiting for it
Mads Kiilerich <madski@unity3d.com>
parents: 20091
diff changeset
   261
                return self.timeout - timeout
25660
328739ea70c3 global: mass rewrite to use modern exception syntax
Gregory Szorc <gregory.szorc@gmail.com>
parents: 23032
diff changeset
   262
            except error.LockHeld as inst:
1787
e431344e604c add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 1753
diff changeset
   263
                if timeout != 0:
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   264
                    time.sleep(1)
1787
e431344e604c add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 1753
diff changeset
   265
                    if timeout > 0:
e431344e604c add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 1753
diff changeset
   266
                        timeout -= 1
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   267
                    continue
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   268
                raise error.LockHeld(
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   269
                    errno.ETIMEDOUT, inst.filename, self.desc, inst.locker
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   270
                )
515
03f27b1381f9 Whitespace cleanups
mpm@selenic.com
parents: 503
diff changeset
   271
26082
b188f60bd955 lock: make trylock private
Matt Mackall <mpm@selenic.com>
parents: 26081
diff changeset
   272
    def _trylock(self):
8108
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   273
        if self.held:
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   274
            self.held += 1
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   275
            return
4947
3e25a6eb5c9a lock.py: cache hostname, but not pid, in case we fork
Bryan O'Sullivan <bos@serpentine.com>
parents: 3877
diff changeset
   276
        if lock._host is None:
30920
dc9f086c7691 lock: move lock._host calculation to a function
Jun Wu <quark@fb.com>
parents: 28959
diff changeset
   277
            lock._host = _getlockprefix()
43077
687b865b95ad formatting: byteify all mercurial/ and hgext/ string literals
Augie Fackler <augie@google.com>
parents: 43076
diff changeset
   278
        lockname = b'%s:%d' % (lock._host, self.pid)
26081
3b6e5914edd8 lock: loop a finite number of times in trylock (issue4787)
Matt Mackall <mpm@selenic.com>
parents: 25956
diff changeset
   279
        retry = 5
3b6e5914edd8 lock: loop a finite number of times in trylock (issue4787)
Matt Mackall <mpm@selenic.com>
parents: 25956
diff changeset
   280
        while not self.held and retry:
3b6e5914edd8 lock: loop a finite number of times in trylock (issue4787)
Matt Mackall <mpm@selenic.com>
parents: 25956
diff changeset
   281
            retry -= 1
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   282
            try:
38038
8c828beb7543 lock: add internal config to not replace signal handlers while locking
Yuya Nishihara <yuya@tcha.org>
parents: 37659
diff changeset
   283
                with self._maybedelayedinterrupt():
36701
d77c3b023393 lock: block signal interrupt while making a lock file
Yuya Nishihara <yuya@tcha.org>
parents: 36657
diff changeset
   284
                    self.vfs.makelock(lockname, self.f)
d77c3b023393 lock: block signal interrupt while making a lock file
Yuya Nishihara <yuya@tcha.org>
parents: 36657
diff changeset
   285
                    self.held = 1
25660
328739ea70c3 global: mass rewrite to use modern exception syntax
Gregory Szorc <gregory.szorc@gmail.com>
parents: 23032
diff changeset
   286
            except (OSError, IOError) as why:
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   287
                if why.errno == errno.EEXIST:
26387
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   288
                    locker = self._readlock()
32087
e1938d6051da lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 31378
diff changeset
   289
                    if locker is None:
e1938d6051da lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 31378
diff changeset
   290
                        continue
e1938d6051da lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 31378
diff changeset
   291
26387
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   292
                    # special case where a parent process holds the lock -- this
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   293
                    # is different from the pid being different because we do
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   294
                    # want the unlock and postrelease functions to be called,
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   295
                    # but the lockfile to not be removed.
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   296
                    if locker == self.parentlock:
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   297
                        self._parentheld = True
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   298
                        self.held = 1
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   299
                        return
e16f80f89a29 lock: recognize parent locks while acquiring
Siddharth Agarwal <sid0@fb.com>
parents: 26383
diff changeset
   300
                    locker = self._testlock(locker)
3686
4308f4cdc07b Don't step into an endless loop when lock file is empty.
Thomas Arendsen Hein <thomas@intevation.de>
parents: 2859
diff changeset
   301
                    if locker is not None:
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   302
                        raise error.LockHeld(
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   303
                            errno.EAGAIN,
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   304
                            self.vfs.join(self.f),
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   305
                            self.desc,
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   306
                            locker,
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   307
                        )
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   308
                else:
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   309
                    raise error.LockUnavailable(
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   310
                        why.errno, why.strerror, why.filename, self.desc
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   311
                    )
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   312
32088
0d892d820a51 lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 32087
diff changeset
   313
        if not self.held:
0d892d820a51 lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 32087
diff changeset
   314
            # use empty locker to mean "busy for frequent lock/unlock
0d892d820a51 lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 32087
diff changeset
   315
            # by many processes"
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   316
            raise error.LockHeld(
43077
687b865b95ad formatting: byteify all mercurial/ and hgext/ string literals
Augie Fackler <augie@google.com>
parents: 43076
diff changeset
   317
                errno.EAGAIN, self.vfs.join(self.f), self.desc, b""
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   318
            )
32088
0d892d820a51 lock: avoid unintentional lock acquisition at failure of readlock
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents: 32087
diff changeset
   319
26290
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   320
    def _readlock(self):
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   321
        """read lock and return its value
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   322
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   323
        Returns None if no lock exists, pid for old-style locks, and host:pid
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   324
        for new-style locks.
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   325
        """
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   326
        try:
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   327
            return self.vfs.readlock(self.f)
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   328
        except (OSError, IOError) as why:
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   329
            if why.errno == errno.ENOENT:
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   330
                return None
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   331
            raise
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   332
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   333
    def _lockshouldbebroken(self, locker):
26290
9664d32bd6cb lock: factor code to read lock into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26082
diff changeset
   334
        if locker is None:
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   335
            return False
2579
0875cda033fd use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 2016
diff changeset
   336
        try:
43077
687b865b95ad formatting: byteify all mercurial/ and hgext/ string literals
Augie Fackler <augie@google.com>
parents: 43076
diff changeset
   337
            host, pid = locker.split(b":", 1)
2579
0875cda033fd use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 2016
diff changeset
   338
        except ValueError:
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   339
            return False
4947
3e25a6eb5c9a lock.py: cache hostname, but not pid, in case we fork
Bryan O'Sullivan <bos@serpentine.com>
parents: 3877
diff changeset
   340
        if host != lock._host:
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   341
            return False
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   342
        try:
2579
0875cda033fd use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 2016
diff changeset
   343
            pid = int(pid)
9685
a820cd39d415 lock: catch specific exceptions
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 9680
diff changeset
   344
        except ValueError:
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   345
            return False
37120
a8a902d7176e procutil: bulk-replace function calls to point to new module
Yuya Nishihara <yuya@tcha.org>
parents: 36701
diff changeset
   346
        if procutil.testpid(pid):
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   347
            return False
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   348
        return True
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   349
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   350
    def _testlock(self, locker):
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   351
        if not self._lockshouldbebroken(locker):
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   352
            return locker
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   353
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   354
        # if locker dead, break lock.  must do this with another lock
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   355
        # held, or can race and break valid lock.
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   356
        try:
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   357
            with lock(self.vfs, self.f + b'.break', timeout=0):
43709
039fbd14d4e2 lock: fix race in lock-breaking code
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43708
diff changeset
   358
                locker = self._readlock()
039fbd14d4e2 lock: fix race in lock-breaking code
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43708
diff changeset
   359
                if not self._lockshouldbebroken(locker):
039fbd14d4e2 lock: fix race in lock-breaking code
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43708
diff changeset
   360
                    return locker
43708
cd822413b9aa lock: refactor in preparation for next commit
Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
parents: 43503
diff changeset
   361
                self.vfs.unlink(self.f)
7640
7197812e8d44 error: move lock errors
Matt Mackall <mpm@selenic.com>
parents: 4959
diff changeset
   362
        except error.LockError:
1877
d314a89fa4f1 change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents: 1836
diff changeset
   363
            return locker
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   364
26291
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   365
    def testlock(self):
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   366
        """return id of locker if lock is valid, else None.
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   367
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   368
        If old-style lock, we cannot tell what machine locker is on.
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   369
        with new-style lock, if locker is on this machine, we can
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   370
        see if locker is alive.  If locker is on this machine but
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   371
        not alive, we can safely break lock.
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   372
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   373
        The lock file is only deleted when None is returned.
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   374
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   375
        """
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   376
        locker = self._readlock()
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   377
        return self._testlock(locker)
1d33842c5b3e lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents: 26290
diff changeset
   378
26473
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   379
    @contextlib.contextmanager
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   380
    def inherit(self):
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   381
        """context for the lock to be inherited by a Mercurial subprocess.
26357
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   382
26473
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   383
        Yields a string that will be recognized by the lock in the subprocess.
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   384
        Communicating this string to the subprocess needs to be done separately
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   385
        -- typically by an environment variable.
26357
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   386
        """
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   387
        if not self.held:
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   388
            raise error.LockInheritanceContractViolation(
43077
687b865b95ad formatting: byteify all mercurial/ and hgext/ string literals
Augie Fackler <augie@google.com>
parents: 43076
diff changeset
   389
                b'inherit can only be called while lock is held'
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   390
            )
26357
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   391
        if self._inherited:
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   392
            raise error.LockInheritanceContractViolation(
43077
687b865b95ad formatting: byteify all mercurial/ and hgext/ string literals
Augie Fackler <augie@google.com>
parents: 43076
diff changeset
   393
                b'inherit cannot be called while lock is already inherited'
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   394
            )
26498
e8564e04382d lock: add a way to prevent locks from being inherited
Siddharth Agarwal <sid0@fb.com>
parents: 26474
diff changeset
   395
        if self._inheritchecker is not None:
e8564e04382d lock: add a way to prevent locks from being inherited
Siddharth Agarwal <sid0@fb.com>
parents: 26474
diff changeset
   396
            self._inheritchecker()
26357
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   397
        if self.releasefn:
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   398
            self.releasefn()
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   399
        if self._parentheld:
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   400
            lockname = self.parentlock
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   401
        else:
37658
34758397ad1b py3: use b"%d" instead of str() to convert integers to bytes
Pulkit Goyal <7895pulkit@gmail.com>
parents: 37120
diff changeset
   402
            lockname = b'%s:%d' % (lock._host, self.pid)
26357
6979a1369185 lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents: 26356
diff changeset
   403
        self._inherited = True
26473
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   404
        try:
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   405
            yield lockname
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   406
        finally:
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   407
            if self.acquirefn:
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   408
                self.acquirefn()
5f94e64f182c lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents: 26387
diff changeset
   409
            self._inherited = False
26358
de5a52e5eb9e lock: add a method to reacquire the lock after subprocesses exit
Siddharth Agarwal <sid0@fb.com>
parents: 26357
diff changeset
   410
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   411
    def release(self):
15583
926a06f7a353 lock: add mechanism to register post release callback
Pierre-Yves David <pierre-yves.david@ens-lyon.org>
parents: 14494
diff changeset
   412
        """release the lock and execute callback function if any
926a06f7a353 lock: add mechanism to register post release callback
Pierre-Yves David <pierre-yves.david@ens-lyon.org>
parents: 14494
diff changeset
   413
17537
31f32a96e1e3 Merge spelling fixes
Bryan O'Sullivan <bryano@fb.com>
parents: 17427 17510
diff changeset
   414
        If the lock has been acquired multiple times, the actual release is
17510
7c44b703657b spelling: release
timeless@mozdev.org
parents: 15589
diff changeset
   415
        delayed to the last release call."""
8108
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   416
        if self.held > 1:
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   417
            self.held -= 1
9680
8cea86d73887 lock: use '==' instead of 'is' for integer equality ('is' may not work)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents: 9309
diff changeset
   418
        elif self.held == 1:
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   419
            self.held = 0
26383
0fceb34806e1 lock: add a wrapper to os.getpid() to make testing easier
Siddharth Agarwal <sid0@fb.com>
parents: 26359
diff changeset
   420
            if self._getpid() != self.pid:
18907
af9fa8d4c939 lock: if we fork, ensure that only the parent releases
Bryan O'Sullivan <bryano@fb.com>
parents: 17683
diff changeset
   421
                # we forked, and are not the parent
af9fa8d4c939 lock: if we fork, ensure that only the parent releases
Bryan O'Sullivan <bryano@fb.com>
parents: 17683
diff changeset
   422
                return
503
c6a2e41c8c60 Fix troubles with clone and exception handling
mpm@selenic.com
parents: 429
diff changeset
   423
            try:
23032
f484be02bd35 lock: while releasing, unlink lockfile even if the release function throws
Siddharth Agarwal <sid0@fb.com>
parents: 20380
diff changeset
   424
                if self.releasefn:
f484be02bd35 lock: while releasing, unlink lockfile even if the release function throws
Siddharth Agarwal <sid0@fb.com>
parents: 20380
diff changeset
   425
                    self.releasefn()
f484be02bd35 lock: while releasing, unlink lockfile even if the release function throws
Siddharth Agarwal <sid0@fb.com>
parents: 20380
diff changeset
   426
            finally:
26359
c545d51c901e lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26358
diff changeset
   427
                if not self._parentheld:
c545d51c901e lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26358
diff changeset
   428
                    try:
c545d51c901e lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26358
diff changeset
   429
                        self.vfs.unlink(self.f)
c545d51c901e lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26358
diff changeset
   430
                    except OSError:
c545d51c901e lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26358
diff changeset
   431
                        pass
26474
431094a3b21f lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26473
diff changeset
   432
            # The postrelease functions typically assume the lock is not held
431094a3b21f lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26473
diff changeset
   433
            # at all.
431094a3b21f lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26473
diff changeset
   434
            if not self._parentheld:
431094a3b21f lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26473
diff changeset
   435
                for callback in self.postrelease:
431094a3b21f lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents: 26473
diff changeset
   436
                    callback()
28959
518c3e392f75 lock: clear postrelease hooks list after usage
Gregory Szorc <gregory.szorc@gmail.com>
parents: 28027
diff changeset
   437
                # Prevent double usage and help clear cycles.
518c3e392f75 lock: clear postrelease hooks list after usage
Gregory Szorc <gregory.szorc@gmail.com>
parents: 28027
diff changeset
   438
                self.postrelease = None
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
   439
43076
2372284d9457 formatting: blacken the codebase
Augie Fackler <augie@google.com>
parents: 38239
diff changeset
   440
8108
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   441
def release(*locks):
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   442
    for lock in locks:
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   443
        if lock is not None:
a26d33749bd8 made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents: 7640
diff changeset
   444
            lock.release()