cdist/cdist/flock.py

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# -*- coding: utf-8 -*-
#
# 2017 Darko Poljak (darko.poljak at gmail.com)
#
# This file is part of cdist.
#
# cdist is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# cdist is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with cdist. If not, see <http://www.gnu.org/licenses/>.
#
#
import fcntl
import logging
import os
log = logging.getLogger('cdist-flock')
class Flock():
def __init__(self, path):
self.path = path
self.lockfd = None
def flock(self):
log.debug('Acquiring lock on %s', self.path)
self.lockfd = open(self.path, 'w+')
fcntl.flock(self.lockfd, fcntl.LOCK_EX)
log.debug('Acquired lock on %s', self.path)
def funlock(self):
log.debug('Releasing lock on %s', self.path)
fcntl.flock(self.lockfd, fcntl.LOCK_UN)
self.lockfd.close()
self.lockfd = None
try:
os.remove(self.path)
except FileNotFoundError:
pass
log.debug('Released lock on %s', self.path)
def __enter__(self):
self.flock()
return self
def __exit__(self, *args):
self.funlock()
return False