twisted - 通过KeyboardInterrupt中断回调

Question

我正在使用Twisted在回调中的for循环中重复一个任务,但是如果用户通过Ctrl-C发出KeyboardInterrupt,则希望反应器在回调中打破循环(一).根据我测试的结果,反应器仅在回调结束时停止或处理中断.

有没有办法在回调运行过程中向回调或错误处理程序发送KeyboardInterrupt？

干杯,

克里斯

#!/usr/bin/env python

from twisted.internet import reactor, defer


def one(result):
    print "Start one()"
    for i in xrange(10000):
        print i
    print "End one()"
    reactor.stop()


def oneErrorHandler(failure):
    print failure
    print "INTERRUPTING one()"
    reactor.stop()    


if __name__ == '__main__':

    d = defer.Deferred()
    d.addCallback(one)
    d.addErrback(oneErrorHandler)
    reactor.callLater(1, d.callback, 'result')

    print "STARTING REACTOR..."
    try:
        reactor.run()
    except KeyboardInterrupt:
        print "Interrupted by keyboard. Exiting."
        reactor.stop()

Answer 1

我得到了这个工作花花公子.烧制SIGINT设置一个标志运行在我的代码的任何正在运行的任务,并且还要求reactor.callFromThread(reactor.stop)停止任何扭曲运行的代码:

#!/usr/bin/env python

import sys
import twisted
import re
from twisted.internet import reactor, defer, task
import signal


def one(result, token):
    print "Start one()"
    for i in xrange(1000):
        print i
        if token.running is False:
            raise KeyboardInterrupt()
            #reactor.callFromThread(reactor.stop) # this doesn't work
    print "End one()"

def oneErrorHandler(failure):
    print "INTERRUPTING one(): Unkown Exception"
    import traceback
    print traceback.format_exc()
    reactor.stop()

def oneKeyboardInterruptHandler(failure):
    failure.trap(KeyboardInterrupt)
    print "INTERRUPTING one(): KeyboardInterrupt"
    reactor.stop()

def repeatingTask(token):
    d = defer.Deferred()
    d.addCallback(one, token)
    d.addErrback(oneKeyboardInterruptHandler)
    d.addErrback(oneErrorHandler)
    d.callback('result')

class Token(object):
    def __init__(self):
        self.running = True

def sayBye():
    print "bye bye."


if __name__ == '__main__':

    token = Token()

    def customHandler(signum, stackframe):
        print "Got signal: %s" % signum
        token.running = False                # to stop my code
        reactor.callFromThread(reactor.stop) # to stop twisted code when in the reactor loop
    signal.signal(signal.SIGINT, customHandler)

    t2 = task.LoopingCall(reactor.callLater, 0, repeatingTask, token)
    t2.start(5) 

    reactor.addSystemEventTrigger('during', 'shutdown', sayBye)

    print "STARTING REACTOR..."
    reactor.run()

Answer 2

这是为了避免(半)抢占,因为Twisted是一个合作的多任务系统.Ctrl-C在Python中处理,启动时由解释器安装SIGINT处理程序.处理程序在调用时设置标志.执行每个字节代码后,解释器检查该标志.如果已设置,则在此时引发KeyboardInterrupt.

reactor安装自己的SIGINT处理程序.这取代了解释器处理程序的行为.反应堆的处理程序启动反应堆关闭.由于它不会引发异常,因此不会中断正在运行的代码.循环(或其他)完成,当控制返回到反应堆时,停止继续.

如果你宁愿让Ctrl-C(即SIGINT)引发KeyboardInterrupt,那么你可以使用信号模块恢复Python的SIGINT处理程序:

signal.signal(signal.SIGINT, signal.default_int_handler)

但请注意,如果在Twisted的代码运行时发送SIGINT而不是您自己的应用程序代码,则行为未定义,因为Twisted不期望被KeyboardInterrupt中断.