twisted 的新手，只是尝试一些延迟的东西。我有以下代码构成了 100 个延迟调用的列表 - 每个等待随机时间并返回一个值。该列表打印结果并最终终止 react 器。
但是，我很确定我停止 react 堆的方式可能...不是很好。
__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())
收集的结果实际上是在所有延迟的项目上添加回调？
如果是这样，那么可能有更优雅/更正确的方法来做到这一点？
干杯!
请您参考如下方法:
I'm assuming that by adding a callback: d.addCallback(lambda ignored: reactor.stop()) to the gathered results actually adds that callback on all the deferred items?
事实并非如此。 gatherResults 返回一个新 Deferred。它就像您可能遇到的任何其他 Deferred 一样。它的 addCallback 方法与往常一样做同样的事情:添加一个将在一个回调链中的某一点调用的函数。
之所以一切都像这样很好、规则且不特别，是因为 gatherResults 处理所有必要的逻辑，只给常规的 Deferred 它在所有输入 Deferred 都有结果后返回一个结果。
因此，请随意使用 gatherResults，就像使用任何其他 Deferred 返回 API 一样。没什么特别的!
也就是说，从 Twisted 12.3 开始，您可能想使用一个方便的实用程序来完成此类事情 - twisted.internet.task.react。如果您使用它，您的 main 函数将如下所示:
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，使其不依赖于全局 react 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
现在您的代码根本不需要任何 twisted.internet.reactor 导入。
您还可以在 getDummyData 中使用 twisted.internet.task.deferLater 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))
