在gatherResults完成后停止一个扭曲的反应堆

Question

新的扭曲,只是尝试一些延期的东西.我有以下代码组成100个延迟调用的列表 - 每个等待一个随机时间并返回一个值.该列表打印结果并最终终止反应器.

但是,我很确定我停止反应堆的方式可能......不太好.

__author__ = 'Charlie'

from twisted.internet import defer, reactor
import random

def getDummyData(x):
    """returns a deferred object that will have a value in some random seconds
    sets up a callLater on the reactor to trgger the callback of d"""
    d = defer.Deferred()
    pause = random.randint(1,10)
    reactor.callLater(pause, d.callback, (x, pause))
    return d


def printData(result):
    """prints whatever is passed to it"""
    print result


def main():
    """makes a collection of deffered calls and then fires them. Stops reactor at end"""
    deferred_calls = [getDummyData(r) for r in range(0,100)]
    d = defer.gatherResults(deferred_calls, consumeErrors = True)
    d.addCallback(printData)

    # this additional callback on d stops the reacor
    # it fires after all the delayed callbacks have printed their values
    # the lambda ignored: ractor.stop() is required as callback takes a function
    # that takes a parameter.
    d.addCallback(lambda ignored: reactor.stop())

    # start the reactor.
    reactor.run()

if __name__ == "__main__":
    main()

我假设通过添加回调:

d.addCallback(lambda ignored: reactor.stop())

对收集的结果实际上添加了所有延期项目的回调？

如果是这样,那么可能有更优雅/正确的方法吗？

干杯!

Answer 1

我假设通过添加回调:d.addCallback(lambda ignored:reactor.stop())到收集的结果实际上在所有延期项目上添加了回调？

事实并非如此. gatherResults返回一个新的 Deferred.就像Deferred你遇到的任何其他人一样.它的addCallback方法与平常一样:添加一个将在一个回调链中的一个点调用的函数.

在一切的原因很不错,经常和unspecial像这是一个gatherResults需要照顾所有必要的逻辑来只给有规律Deferred,它毕竟输入返回结果Deferred■找的结果.

因此,请随意使用gatherResults,就像您使用任何其他Deferred令人遗憾的API一样.这不是特别的!

也就是说,从Twisted 12.3开始,有一个方便的实用程序,你可能想要用于这种事情 - twisted.internet.task.react.以下是main您使用它时的功能:

def main(reactor):
    """makes a collection of deffered calls and then fires them. Stops reactor at end"""
    deferred_calls = [getDummyData(r) for r in range(0,100)]
    d = defer.gatherResults(deferred_calls, consumeErrors = True)
    d.addCallback(printData)
    return d

if __name__ == "__main__":
    from twisted.internet import task
    task.react(main, [])

请注意,您可以更改,getDummyData以便它不依赖于全局反应器:

def getDummyData(reactor, x):
    """returns a deferred object that will have a value in some random seconds
    sets up a callLater on the reactor to trgger the callback of d"""
    d = defer.Deferred()
    pause = random.randint(1,10)
    reactor.callLater(pause, d.callback, (x, pause))
    return d

def main(reactor):
    """makes a collection of deffered calls and then fires them. Stops reactor at end"""
    deferred_calls = [getDummyData(reactor, r) for r in range(0,100)]
    d = defer.gatherResults(deferred_calls, consumeErrors = True)
    d.addCallback(printData)
    return d

现在你的代码根本不需要任何twisted.internet.reactor导入.

您还可以使用twisted.internet.task.deferLaterin getDummyData来节省更多的输入:

def getDummyData(reactor, x):
    """returns a deferred object that will have a value in some random seconds
    sets up a callLater on the reactor to trgger the callback of d"""
    pause = random.randint(1,10)
    return deferLater(reactor, pause, lambda: (x, pause))