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small fixes, and optimization for changelog graph
small fixes, and optimization for changelog graph

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pidlock.py
120 lines | 3.8 KiB | text/x-python | PythonLexer
import os, time
import sys
from warnings import warn
from multiprocessing.util import Finalize
import errno
class LockHeld(Exception):pass
class DaemonLock(object):
"""daemon locking
USAGE:
try:
l = DaemonLock(desc='test lock')
main()
l.release()
except LockHeld:
sys.exit(1)
"""
def __init__(self, file=None, callbackfn=None,
desc='daemon lock', debug=False):
self.pidfile = file if file else os.path.join(os.path.dirname(__file__),
'running.lock')
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:
pidfile = open(self.pidfile, "r")
pidfile.seek(0)
running_pid = int(pidfile.readline())
pidfile.close()
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:
os.kill(running_pid, 0)
except OSError, 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, 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, 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)
pidfile = open(self.pidfile, "wb")
pidfile.write(lockname)
pidfile.close
self.held = True