A Python repeatable threading.Timer class

gfoster — Wed, 18 Mar 2009 19:20:00 +0000

I had a function that I wanted to be called repeatedly every x seconds but couldn't find a nice way of doing this. The python threading module has a Timer class which will wait for the given number of seconds and then execute the passed in callable object. Unfortunately, once it has executed that code it is no longer useable. So based upon that class I whipped up the following RepeatableTimer. It's not "hard real-time" or anything since it doesn't account for the time taken to execute the given function, but it's good enough for what I needed. Feel free to use it however you see fit as I'm distributing it under the MIT license.

Usage:

Create a new RepeatTimer object passing it required arguments and any optional ones.

Required Arguments:

interval -- floating point number specifying the number of seconds to wait before executing function
function -- the function (or callable object) to be executed

Optional Arguments:

iterations -- integer specifying the number of iterations to perform
args -- list of positional arguments passed to function
kwargs -- dictionary of keyword arguments passed to function

Examples:

Execute the hello function every 5 seconds:

def hello():
	print "Hello World!"
 
r = RepeatTimer(5.0, hello)
r.start()

Execute the hello function every 5 seconds but terminate when it has executed 10 times:

def hello():
	print "Hello World!"
 
r = RepeatTimer(5.0, hello, 10)
r.start()

# Copyright (c) 2009 Geoffrey Foster
# 
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
 
from threading import Event, Thread
 
class RepeatTimer(Thread):
    def __init__(self, interval, function, iterations=0, args=[], kwargs={}):
        Thread.__init__(self)
        self.interval = interval
        self.function = function
        self.iterations = iterations
        self.args = args
        self.kwargs = kwargs
        self.finished = Event()
 
    def run(self):
        count = 0
        while not self.finished.is_set() and (self.iterations <= 0 or count < self.iterations):
            self.finished.wait(self.interval)
            if not self.finished.is_set():
                self.function(*self.args, **self.kwargs)
                count += 1
 
    def cancel(self):
        self.finished.set()

Updated Oct 29, 2009: Removed extra unneeded Event object.

g-Off.net | Geoffrey Foster » threading

A Python repeatable threading.Timer class

Usage:

Required Arguments:

Optional Arguments:

Examples: