Mercurial > kallithea
view rhodecode/lib/pidlock.py @ 3774:60335b702a00 beta
invalidation: don't create CacheInvalidation records on startup
Creating the records early gave an advantage before lightweight was introduced.
With lightweight it is no longer necessary.
The records will be created on demand anyway and there is no reason to create and
maintain them before they are used.
author | Mads Kiilerich <madski@unity3d.com> |
---|---|
date | Wed, 03 Apr 2013 15:56:12 +0200 |
parents | 29e999f26998 |
children | ffd45b185016 |
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import os import sys import time import errno from warnings import warn 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): 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: 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) dir_, file_ = os.path.split(pidfile) if not os.path.isdir(dir_): os.makedirs(dir_) pidfile = open(self.pidfile, "wb") pidfile.write(lockname) pidfile.close self.held = True