Twisted Sleep

Q: "How do I sleep() in the context of a twisted application without blocking the reactor?"

Here's a simple way:

def sleep(secs):
    d = Deferred()
    reactor.callLater(secs, d.callback, None)
    return d

And here's how you might use the sleep function:

@inlineCallbacks
def doSomeStuff(stuff, throttle):
   for thing in stuff:
      yield someThing.send(thing)
      yield sleep(throttle)

But it's better to just let the reactor schedule things for you:

def doSomeStuff(stuff, throttle):
    if not stuff:
        return defer.succeed(None)
    d = Deferred()
    work = list(stuff)
    def sendNext()
        if not work:
            loop.stop()
            d.callback(None)
        next = work.pop(0)
        return someThing.send(next)
    loop = LoopingCall(sendNext)
    loop.start(throttle)
    return d