timeout_helper.py

from functools import wraps

from twisted.internet import defer, reactor
from twisted.python import failure


class DeferTimeoutError(Exception):
    pass


def with_timeout(secs):
    def inner(my_func):
        @wraps(my_func)
        def wrapper(*args, **kwargs):
            def defer_cancel(d):
                if not d.called:
                    d._suppressAlreadyCalled = True
                d.errback(
                    failure.Failure(
                        DeferTimeoutError(
                            "{} timeout after {} secs".format(my_func.__name__, secs)
                        )
                    )
                )

            def completed(passthru):
                if timeout_watcher.active():
                    timeout_watcher.cancel()
                return passthru

            d = my_func(*args, **kwargs)
            d._canceller = defer_cancel
            timeout_watcher = reactor.callLater(secs, d.cancel)
            d.addBoth(completed)
            return d

        return wrapper

    return inner

usage.py

import time
import sys

from timeout_helper import DeferTimeoutError, with_timeout
from twisted.internet import defer, reactor
from twisted.web.client import Agent


# Example with_timeout usage
@defer.inlineCallbacks
def my_client_function(fake_delay):
    agent = Agent(reactor, connectTimeout=5)
    requester = with_timeout(secs=5)(agent.request)
    response = yield requester(
        "GET", "https://httpbin.org/delay/{}".format(fake_delay)
    )
    defer.returnValue(response.code)


@defer.inlineCallbacks
def main(delay):
    start = time.time()

    try:
        result = yield my_client_function(delay)
        print("status_code: {}".format(result))
    except DeferTimeoutError:
        print("timedout :(")

    end = time.time()
    print("Exec time: {}s".format(end - start))
    reactor.stop()


if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("Example: python usage.py 10")
        sys.exit(1)
    delay = sys.argv[1]
    reactor.callLater(0, main, delay)
    reactor.run()

https://github.com/debian-python/txfixtures/blob/40d39a7e937ea499820c71b10e38fa5fbda099fa/txfixtures/_twisted/backports/defer.py - backport from 16.5 :D