hgext/remotefilelog/extutil.py
author Ian Moody <moz-ian@perix.co.uk>
Tue, 16 Jul 2019 19:18:16 +0100
changeset 42618 c17e6a3e7356
parent 40497 3fbfbc8c9f82
permissions -rw-r--r--
phabricator: handle local:commits time being string or int When setting local:commits arcanist has different behaviour depending on whether the repo is git or hg. With hg it sets the time as a number, since it calls PHP's strtotime on the value, but with git it sets it as a string. Normally this wouldn't be an issue since phabread wouldn't be interacting with Phabricator Revisions for git repos, but Mozilla has a secondary workflow for git users that uses the git-cinnabar tool to interact with their hg repos. When a git-cinnabar user uses the moz-phab tool to submit patches for mozilla-central it makes use of Mozilla's fork of arcanist, which works with their local git version of m-c, and thus sets the local:commit time as a string, and then translates the commit hashes. Currently when encountering such DREVS phabread dies with "TypeError: %d format: a number is required, not str". phabsend also used to set it as a string but wouldn't have encountered the issue with its own DREVs since it would read hg:meta first. Differential Revision: https://phab.mercurial-scm.org/D6650

# 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)