python - 如何阻止和等待异步、基于回调的 Python 函数调用

Question

我有一个 Python 脚本发出许多异步请求。我正在使用的 API 需要回调。

主函数调用运行，我希望它阻止执行，直到所有请求都返回。

我可以在 Python 2.7 中使用什么来实现这一点？

def run():
    for request in requests:
        client.send_request(request, callback)

def callback(error, response):
    # handle response
    pass

def main():
    run()

    # I want to block here

Answer 1

我发现最简单、侵入性最小的方法是使用threading.Event，available in 2.7 .

import threading
import functools

def run():
    events = []
    for request in requests:
        event = threading.Event()
        callback_with_event = functools.partial(callback, event)
        client.send_request(request, callback_with_event)
        events.append(event)

    return events

def callback(event, error, response):
    # handle response
    event.set()

def wait_for_events(events):
    for event in events:
        event.wait()

def main():
    events = run()
    wait_for_events(events)