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absorb: aborting if another operation is in progress...
absorb: aborting if another operation is in progress This increases safety of using absorb by both aborting when another operation is in progress (since the absorption could confuse any other command a lot) and holding the locks throughout the reading of the working directory (for which changes to absorb) and the reading of the repo (for which changes to absorb into). Differential Revision: https://phab.mercurial-scm.org/D6237

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extutil.py
66 lines | 1.9 KiB | text/x-python | PythonLexer
# 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)