feedrss-toot/feed2toot/lock.py

64 lines
2.5 KiB
Python

# vim:ts=4:sw=4:ft=python:fileencoding=utf-8
# Copyright © 2015-2019 Carl Chenet <carl.chenet@ohmytux.com>
# This program 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
# any later version.
#
# 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 General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>
'''Manage a lock file'''
# standard libraires imports
import datetime
import logging
import os
import os.path
import sys
class LockFile:
'''LockFile object'''
def __init__(self, lockfile, locktimeout):
'''check the lockfile and the locktimeout'''
self.lockfile = lockfile
ltimeout = datetime.timedelta(seconds=locktimeout)
self.lfdateformat = '%Y-%m-%d_%H-%M-%S'
# if a lock file exists
if os.path.exists(self.lockfile):
if os.path.isfile(self.lockfile):
with open(self.lockfile, 'r') as lf:
lfcontent = lf.read().rstrip()
# lfcontent should be a datetime
logging.debug('Check if lock file is older than timeout ({timeout} secs)'.format(timeout=locktimeout))
locktime = datetime.datetime.strptime(lfcontent, self.lfdateformat)
if locktime < (datetime.datetime.now() - ltimeout):
# remove the lock file
logging.debug('Found an expired lock file')
self.release()
self.create_lock()
else:
# quit because another feed2toot process is running
logging.debug('Found a valid lock file. Exiting immediately.')
sys.exit(0)
else:
# no lock file. Creating one
self.create_lock()
def create_lock(self):
'''Create a lock file'''
with open(self.lockfile, 'w') as lf:
currentdatestring = datetime.datetime.now().strftime(self.lfdateformat)
lf.write(currentdatestring)
logging.debug('lockfile {lockfile} created.'.format(lockfile=self.lockfile))
def release(self):
'''Release the lockfile'''
os.remove(self.lockfile)
logging.debug('Removed lock file.')