On Thu, Jan 27, 2011 at 12:03, Daniel da Silva <ddas...@umd.edu> wrote:
> We have a threading.Timer class which executes after a given delay and then> terminates. I was thinking about a pre-made class that would execute, wait> an interval, and then repeat. It would cut down on the logic people need to> implement themselves, and make simple scripts faster.>> Here are some use cases:>> # Send a ping message to all connected clients every 120 seconds> from server import ping_all_clients> pinger = threading.RepeatTimer(120, ping_all_clients)> pinger.start()>> # Check for updates every 3 hours> from mymodule import check_for_updates> update_checker = threading.RepeatTimer(60*60*3, check_for_updates)> update_checker.start()>>> I was thinking of the class having an initializer signature as follows:>> class threading.RepeatTimer(interval, function, args=[], kwargs={},> limit=None)> Create a timer that will run function with args and kwargs and repeat> every interval secods. If limit is> an integer, limits repetitions to that many calls.>> cancel()> Stop the repeat timer. If in the middle of a call, the call is> allowed to finish.>> Daniel
I'm not sure this is a good fit in the standard library. There's too much
that the implementer might want to customize for their repeating needs. For
your pinger, what if a ping fails? Keep pinging while it fails? Timeout for
a bit and try again? Increasing timeouts? Just exit? I don't think there's a
general enough use case that a repetitive timer has in order to be included.
The following will likely do what you want.
import threading
class RepeatTimer(threading.Thread):
def __init__(self, interval, callable, *args, **kwargs):
threading.Thread.__init__(self)
self.interval = interval
self.callable = callable
self.args = args
self.kwargs = kwargs
self.event = threading.Event()
self.event.set()
def run(self):
while self.event.is_set():
t = threading.Timer(self.interval, self.callable,
self.args, self.kwargs)
t.start()
t.join()
def cancel(self):
self.event.clear()
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