Twisted Countdown Etude 2

# A solution to exercise 2 of the Twisted tutorial at http://krondo.com/?p=1333

import time
from twisted.internet.task import LoopingCall

class CountdownMonitor(object):

    def __init__(self):
        self.countdowns = []

    def register(self, *args):
        self.countdowns.extend(args)

    def start(self):
        self.startTime = time.time()

    def timeElapsed(self):
        return time.time() - self.startTime

    def finalize(self, ctdn):
        self.countdowns.remove(ctdn)
        if not self.countdowns:
            reactor.callLater(0, reactor.stop)

class Countdown(object):

    def __init__(self, name, ticks, rate, monitor):
        self.name, self.counter, self.rate, self.monitor = \
            name, ticks, rate, monitor
        self.looper = LoopingCall(self.count)
        monitor.register(self)

    def start(self):
        self.looper.start(self.rate)

    def count(self):
        if self.counter == 0:
            self.looper.stop()
            print 'Counter {} complete! ({:.3f} sec)'.format(self.name, monitor.timeElapsed())
            self.monitor.finalize(self)
        else:
            print '{}: {:>2} ticks left at {} sec/tick ...'.format(self.name, self.counter, self.rate)
            self.counter -= 1

from twisted.internet import reactor

monitor = CountdownMonitor()
reactor.callWhenRunning(monitor.start)

data = [['one', 5, 1.0], ['two', 13, .3], ['tri', 8, .8]]
for name, ticks, rate in data:
    reactor.callWhenRunning(Countdown(name, ticks, rate, monitor).start)

print 'Start!'
reactor.run()
print 'Stop!'


#### Output ####

Start!
one:  5 ticks left at 1.0 sec/tick ...
two: 13 ticks left at 0.3 sec/tick ...
tri:  8 ticks left at 0.8 sec/tick ...
two: 12 ticks left at 0.3 sec/tick ...
two: 11 ticks left at 0.3 sec/tick ...
tri:  7 ticks left at 0.8 sec/tick ...
two: 10 ticks left at 0.3 sec/tick ...
one:  4 ticks left at 1.0 sec/tick ...
two:  9 ticks left at 0.3 sec/tick ...
two:  8 ticks left at 0.3 sec/tick ...
tri:  6 ticks left at 0.8 sec/tick ...
two:  7 ticks left at 0.3 sec/tick ...
one:  3 ticks left at 1.0 sec/tick ...
two:  6 ticks left at 0.3 sec/tick ...
two:  5 ticks left at 0.3 sec/tick ...
tri:  5 ticks left at 0.8 sec/tick ...
two:  4 ticks left at 0.3 sec/tick ...
one:  2 ticks left at 1.0 sec/tick ...
two:  3 ticks left at 0.3 sec/tick ...
tri:  4 ticks left at 0.8 sec/tick ...
two:  2 ticks left at 0.3 sec/tick ...
two:  1 ticks left at 0.3 sec/tick ...
Counter two complete! (3.900 sec)
one:  1 ticks left at 1.0 sec/tick ...
tri:  3 ticks left at 0.8 sec/tick ...
tri:  2 ticks left at 0.8 sec/tick ...
Counter one complete! (5.000 sec)
tri:  1 ticks left at 0.8 sec/tick ...
Counter tri complete! (6.400 sec)
Stop!