python - Python Circuits 框架中的延迟/挂起+恢复事件(处理)

Question

在我的项目中，我使用 Worker进行一些与事件相关的文件处理并避免阻塞其他事件的处理。我需要的是能够在工作人员完成时将事件(需要文件处理)置于待命状态(其他组件不会进一步处理)，然后恢复处理序列。

当工作线程完成时，我无法发出新事件，因为这可能会导致其他组件多次重新处理“相同”事件。

有什么方法可以延迟(即暂停和恢复)事件传播来完成我需要的事情吗？有更好的方法来解决我的用例吗？

附加说明:我无法避免阻塞行为，因为我需要使用一些外部(阻塞)库调用。

编辑:源码示例:

from time import sleep
from circuits import Component, Debugger, handler, Event, Worker, task


class my_event(Event):
    pass


def heavy_task():
    print "heavy task"
    sleep(3)


class NextHandler(Component):
    @handler("my_event", priority=10)
    def my_event(self, event):
        print "Handler 2"


class Handler(Component):
    _worker = Worker()

    @handler("my_event", priority=20)
    def my_event(self, event):
        self.fire(task(heavy_task), self._worker)
        print "Handler 1"
        # how do I delay "event" until "heavy_task" is completed?


class App(Component):
    h1 = Handler()
    h2 = NextHandler()

    def started(self, component):
        print "Running"
        self.fire(my_event())


if __name__ == '__main__':
    (App() + Debugger()).run()

在这种情况下，我想延迟“Handler”事件，以便“NextHandler”在“heavy_task”完成工作之前不会收到它。

Answer 1

根据您更新的问题和编辑；这就是您“等待”事件完成的方式:

示例:

from time import sleep
from circuits import Component, Debugger, handler, Event, Worker, task


class my_event(Event):
    pass


def heavy_task():
    print "heavy task"
    sleep(3)


class NextHandler(Component):
    @handler("my_event", priority=10)
    def my_event(self, event):
        print "Handler 2"


class Handler(Component):
    _worker = Worker(process=True)

    @handler("my_event", priority=20)
    def my_event(self, event):
        # Fire and Wait for: task()
        # This happens asynchornously under the covers
        # but gives you a synchronous API. Effectively
        # turning my_event into a coroutine.
        yield self.call(task(heavy_task), self._worker)

        # This will only print after task() is complete.
        print "Handler 1"


class App(Component):
    h1 = Handler()
    h2 = NextHandler()

    def started(self, component):
        print "Running"
        self.fire(my_event())


if __name__ == '__main__':
    (App() + Debugger()).run()

输出:

$ python app.py 
<registered[worker] (<Worker/worker 5848:MainThread (queued=0) [S]>, <Handler/* 5848:MainThread (queued=0) [S]> )>
<registered[*] (<Handler/* 5848:MainThread (queued=0) [S]>, <App/* 5848:MainThread (queued=4) [R]> )>
<registered[*] (<NextHandler/* 5848:MainThread (queued=0) [S]>, <App/* 5848:MainThread (queued=3) [R]> )>
<registered[*] (<Debugger/* 5848:MainThread (queued=0) [S]>, <App/* 5848:MainThread (queued=2) [R]> )>
<started[*] (<App/* 5848:MainThread (queued=1) [R]> )>
Running
<my_event[*] ( )>
Handler 2
<task[<Worker/worker 5848:MainThread (queued=0) [S]>] (<function heavy_task at 0x7f359df6ade8> )>
heavy task
<task_done[<Worker/worker 5848:MainThread (queued=0) [S]>] (None )>
<task_success[<Worker/worker 5848:MainThread (queued=0) [S]>] (<task[<Worker/worker 5848:MainThread (queued=0) [S]>] (<function heavy_task at 0x7f359df6ade8> )>, None )>
Handler 1

请参阅上面的评论。