Added tag v4.14.1 for changeset a47eeac5dfa4
Added tag v4.14.1 for changeset a47eeac5dfa4

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pidlock.py
149 lines | 4.8 KiB | text/x-python | PythonLexer
# -*- coding: utf-8 -*-
# Copyright (C) 2010-2018 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), as published by the Free Software Foundation.
#
# This program 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 Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/
import os
import errno
from multiprocessing.util import Finalize
from rhodecode.lib.compat import kill
class LockHeld(Exception):
pass
class DaemonLock(object):
"""daemon locking
USAGE:
try:
l = DaemonLock(file_='/path/tolockfile',desc='test lock')
main()
l.release()
except LockHeld:
sys.exit(1)
"""
def __init__(self, file_=None, callbackfn=None,
desc='daemon lock', debug=False):
lock_name = os.path.join(os.path.dirname(__file__), 'running.lock')
self.pidfile = file_ if file_ else lock_name
self.callbackfn = callbackfn
self.desc = desc
self.debug = debug
self.held = False
#run the lock automatically !
self.lock()
self._finalize = Finalize(self, DaemonLock._on_finalize,
args=(self, debug), exitpriority=10)
@staticmethod
def _on_finalize(lock, debug):
if lock.held:
if debug:
print('leck held finilazing and running lock.release()')
lock.release()
def lock(self):
"""
locking function, if lock is present it
will raise LockHeld exception
"""
lockname = '%s' % (os.getpid())
if self.debug:
print('running lock')
self.trylock()
self.makelock(lockname, self.pidfile)
return True
def trylock(self):
running_pid = False
if self.debug:
print('checking for already running process')
try:
with open(self.pidfile, 'r') as f:
try:
running_pid = int(f.readline())
except ValueError:
running_pid = -1
if self.debug:
print('lock file present running_pid: %s, '
'checking for execution' % (running_pid,))
# Now we check the PID from lock file matches to the current
# process PID
if running_pid:
try:
kill(running_pid, 0)
except OSError as exc:
if exc.errno in (errno.ESRCH, errno.EPERM):
print("Lock File is there but"
" the program is not running")
print("Removing lock file for the: %s" % running_pid)
self.release()
else:
raise
else:
print("You already have an instance of the program running")
print("It is running as process %s" % running_pid)
raise LockHeld()
except IOError as e:
if e.errno != 2:
raise
def release(self):
"""releases the pid by removing the pidfile
"""
if self.debug:
print('trying to release the pidlock')
if self.callbackfn:
# execute callback function on release
if self.debug:
print('executing callback function %s' % self.callbackfn)
self.callbackfn()
try:
if self.debug:
print('removing pidfile %s' % self.pidfile)
os.remove(self.pidfile)
self.held = False
except OSError as e:
if self.debug:
print('removing pidfile failed %s' % e)
pass
def makelock(self, lockname, pidfile):
"""
this function will make an actual lock
:param lockname: acctual pid of file
:param pidfile: the file to write the pid in
"""
if self.debug:
print('creating a file %s and pid: %s' % (pidfile, lockname))
dir_, file_ = os.path.split(pidfile)
if not os.path.isdir(dir_):
os.makedirs(dir_)
with open(self.pidfile, 'wb') as f:
f.write(lockname)
self.held = True