Hi! I just jotted down a little mechanism for cleaning-up in Twisted, and I wanted to see if: 1. other people think it's needed 2. other people manage to use it What this does is enable one to define a __cleanup__ method which gets call either when the instance is deleted, or when the reactor shuts down. It can return a dereffed that delays the shutdown. The benefit is being able to define communication-related stuff in the cleanup method, which is not so useful to do in __del__. The current implementation uses pyDispatcher, but it could easily be rewritten without it. Feedback is welcomed! Joe. #---------------------------------------------------------------------------------------------------- from twisted.internet import reactor, defer, task from dispatch import dispatcher, robustapply #---------------------------------------------------------------------------------------------------- class CleanUpper: # our pydispatcher cleanup event ABOUT_TO_SHUTDOWN = "*about to shutdown*" def __init__(self): self._deferreds_to_wait_for_before_shutdown = [] # register with twisted a special callback that # fires a pydispatcher event. reactor.addSystemEventTrigger('before', 'shutdown', self._shutdown_handler) def _shutdown_handler(self): """this simply dispatches a pydispatcher event""" results = dispatcher.send( signal = self.ABOUT_TO_SHUTDOWN, sender = self) # any deferred registered by cleanup handlers should be waited for dl = defer.DeferredList([response for handler, response in results if isinstance(response, defer.Deferred)]) return dl # PUBLIC METHODS -------------------------------------------------------------------------- def register(self, functionToRunBeforeShutdown): """makes the given function get called prior to communication infrastructure shutdown""" # register the given function with pydispatcher dispatcher.connect( functionToRunBeforeShutdown, signal = self.ABOUT_TO_SHUTDOWN, sender = self) #---------------------------------------------------------------------------------------------------- # create an instance of CleanUpper # and make its register method global _c = CleanUpper() register = _c.register unregister = _c.unregister #---------------------------------------------------------------------------------------------------- class Cleanuppable: """ Inherit from this if you want to do your cleanup before Twisted shuts down and not (only) when you get deleted. If you inherit from this do not implement __del__, only __cleanup__! """ def __init__(self): self._cleanuppable_state = "normal" # normal, deleted, or cleanupped self._cleanuppable_deferred = None # register cleanup method register(self._cleanuppable_internal_cleanup_handler) def _cleanuppable_apply_cleanup(self): if hasattr(self, "__cleanup__"): # call user-defined cleanup method return robustapply.robustApply(self.__cleanup__) def _cleanuppable_internal_cleanup_handler(self): try: if self._cleanuppable_state == "normal": return self._cleanuppable_apply_cleanup() if self._cleanuppable_state == "deleted" and self._cleanuppable_deferred is not None: return self._cleanuppable_deferred finally: self._cleanuppable_state = "cleanupped" def __del__(self): if self._cleanuppable_state == "normal": self._cleanuppable_state = "deleted" response = self._cleanuppable_apply_cleanup() if isinstance(response, defer.Deferred): self._cleanuppable_deferred = response #---------------------------------------------------------------------------------------------------- __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com