comparison mercurial/lock.py @ 30921:1f151a33af8e

lock: include Linux pid namespace identifier in prefix

Previously, the lock only contains a hostname as an attempt to detect pid
namespace difference. However, that's not enough on modern Linux - a single
hostname could have different pid namespaces.

That means if people run hg inside different PID namespaces with a same UTS
namespae, the lock would be broken - an hg proccess in pid namespace A will
think the lock having a "random" pid in pid namespace B is "dead" and remove
it.

This patch solves the above issue by appending an PID namespace identifier of
the current process to the lock prefix ("hostname"). It depends on /proc
being mounted properly. But I don't think there is a better way to get pid
namespace identifier reliably.

30920:dc9f086c7691

from __future__ import absolute_import

import contextlib
import errno
import socket
import time
import warnings

from . import (
    error,
    util,
)

def _getlockprefix():
    """Return a string which is used to differentiate pid namespaces

    It's useful to detect "dead" processes and remove stale locks with
    confidence. Typically it's just hostname.
    """
    return socket.gethostname()

class lock(object):
    '''An advisory lock held by one process to control access to a set
    of files.  Non-cooperating processes or incorrectly written scripts
    can ignore Mercurial's locking scheme and stomp all over the

30921:1f151a33af8e

from __future__ import absolute_import

import contextlib
import errno
import os
import socket
import time
import warnings

from . import (
    error,
    pycompat,
    util,
)

def _getlockprefix():
    """Return a string which is used to differentiate pid namespaces

    It's useful to detect "dead" processes and remove stale locks with
    confidence. Typically it's just hostname. On modern linux, we include an
    extra Linux-specific pid namespace identifier.
    """
    result = socket.gethostname()
    if pycompat.sysplatform.startswith('linux'):
        try:
            result += '/%x' % os.stat('/proc/self/ns/pid').st_ino
        except OSError as ex:
            if ex.errno not in (errno.ENOENT, errno.EACCES, errno.ENOTDIR):
                raise
    return result

class lock(object):
    '''An advisory lock held by one process to control access to a set
    of files.  Non-cooperating processes or incorrectly written scripts
    can ignore Mercurial's locking scheme and stomp all over the