async.py

import types, time, functools

from twisted.internet import reactor, protocol, threads


# ---


def async(func):
    def wrapper(*args, **kwargs):
        async_continue(func(*args, **kwargs))

    functools.update_wrapper(wrapper, func)
    return wrapper


def async_continue(func_generator, prev_result = None):
    try:
        func = func_generator.send(prev_result)
    except StopIteration:
        return

    deferred = threads.deferToThread(func)
    callback = lambda result: async_continue(func_generator, result)

    deferred.addCallback(callback)


def fake_async(func):
    def wrapper(*args, **kwargs):
        generator = func(*args, **kwargs)

        try:
            subfunc = generator.next()

            while True:
                subfunc = generator.send(subfunc())

        except StopIteration:
            return

    return wrapper


# ---


class Listing(protocol.Protocol):

    @async
    def connectionMade(self):
        print 'before'
        yield lambda: time.sleep(1) # every blocking call must instead yield lambda
        print 'after'
        self.transport.loseConnection()


def main():
    factory = protocol.ServerFactory()
    factory.protocol = Listing

    reactor.listenTCP(8000, factory)
    reactor.run()


if __name__ == '__main__':
    main()