view hgext/remotefilelog/extutil.py @ 41192:2338eab5f8b7

remotefilelog: fix {file_copies} template keyword remotefilelog overrides templatekw.getrenamedfn(). I changed the return type of that function in ec37df9042f9 (templatekw: make getrenamed() return only filename, not nodeid, 2018-03-26). So we need to change remotefilelog too. The function is used by the {file_copies} template keyword and by `hg log --copies`. Differential Revision: https://phab.mercurial-scm.org/D5576
author Martin von Zweigbergk <martinvonz@google.com>
date Fri, 11 Jan 2019 14:07:35 -0800
parents 3fbfbc8c9f82
children
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# extutil.py - useful utility methods for extensions
#
# Copyright 2016 Facebook
#
# 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

import contextlib
import errno
import os
import time

from mercurial import (
    error,
    lock as lockmod,
    util,
    vfs as vfsmod,
)

@contextlib.contextmanager
def flock(lockpath, description, timeout=-1):
    """A flock based lock object. Currently it is always non-blocking.

    Note that since it is flock based, you can accidentally take it multiple
    times within one process and the first one to be released will release all
    of them. So the caller needs to be careful to not create more than one
    instance per lock.
    """

    # best effort lightweight lock
    try:
        import fcntl
        fcntl.flock
    except ImportError:
        # fallback to Mercurial lock
        vfs = vfsmod.vfs(os.path.dirname(lockpath))
        with lockmod.lock(vfs, os.path.basename(lockpath), timeout=timeout):
            yield
        return
    # make sure lock file exists
    util.makedirs(os.path.dirname(lockpath))
    with open(lockpath, 'a'):
        pass
    lockfd = os.open(lockpath, os.O_RDONLY, 0o664)
    start = time.time()
    while True:
        try:
            fcntl.flock(lockfd, fcntl.LOCK_EX | fcntl.LOCK_NB)
            break
        except IOError as ex:
            if ex.errno == errno.EAGAIN:
                if timeout != -1 and time.time() - start > timeout:
                    raise error.LockHeld(errno.EAGAIN, lockpath, description,
                                         '')
                else:
                    time.sleep(0.05)
                    continue
            raise

    try:
        yield
    finally:
        fcntl.flock(lockfd, fcntl.LOCK_UN)
        os.close(lockfd)