如何阻止和等待异步的，基于回调的Python函数调用 [英] How to block and wait for async, callback based Python function calls

问题描述

我有一个Python脚本发出了许多异步请求。我正在使用的API会进行回调。

I have a Python script makes many async requests. The API I'm using takes a callback.

main函数调用run，我希望它阻止执行直到所有请求都返回。

The main function calls run and I want it to block execution until all the requests have come back.

我可以在Python 2.7中使用什么来实现这一目标？

What could I use within Python 2.7 to achieve this?

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

推荐答案

我发现最简单，侵入性最小的方法是使用 threading.Event ，在2.7版中可用。

I found that the simplest, least invasive way is to use 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)

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