Twisted Countdown Etude 4

# A solution to the Twisted tutorial exercise suggested in the comment at
# http://krondo.com/?p=1333&cpage=1#comment-20929

import time
from twisted.internet.task import LoopingCall

class TaskMonitor(object):

    def __init__(self):
        self.tasks = []
        self.finishedTasks = []
        reactor.callWhenRunning(self.start)

    def register(self, task):
        task.setCallback(lambda : self.taskFinished(task))
#        task.setCallback(lambda endTime: self.taskFinished(task, endTime))
        self.tasks.append(task)

    def start(self):
        if self.tasks:
            self.startTime = time.time()
        else:
            print 'Aborting: no tasks were registered'
            self.stop()

    def taskFinished(self, task):
        endTime = time.time()
        self.tasks.remove(task)
        self.finishedTasks.append((str(task), endTime - self.startTime))
        if not self.tasks:
            reactor.callLater(0, self.stop)

    def stop(self):
        for name, elapsed in self.finishedTasks:
            print 'Task {} finished in {:.3f} sec'.format(name,elapsed)
        reactor.callLater(0, reactor.stop)

class Countdown(object):

    def __init__(self, name, ticks, rate):
        self.name, self.counter, self.rate = name, ticks, rate
        self.callbacks = []
        self.looper = LoopingCall(self.count)
        reactor.callWhenRunning(self.start)

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

    def setCallback(self, clb):
        self.callbacks.append(clb)

    def __str__(self):
        return self.name

    def count(self):
        if self.counter == 0:
            self.looper.stop()
            print 'Counter {} complete!'.format(self.name)
            for clb in self.callbacks: clb()
        else:
            print '{}: {:>2} ticks left at {} sec/tick ...'.format(self.name, self.counter, self.rate)
            self.counter -= 1

from twisted.internet import reactor

monitor = TaskMonitor()

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

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