事件对象asyncio.Event是基于threading.Event来实现的。

事件可以一个信号触发多个协程同步工作，

例子如下：

import asyncioimport functools def set_event(event): print('setting event in callback') event.set() async def coro1(event): print('coro1 waiting for event') await event.wait() print('coro1 triggered') async def coro2(event): print('coro2 waiting for event') await event.wait() print('coro2 triggered') async def main(loop): # Create a shared event event = asyncio.Event() print('event start state: {}'.format(event.is_set())) loop.call_later( 0.1, functools.partial(set_event, event) ) await asyncio.wait([coro1(event), coro2(event)]) print('event end state: {}'.format(event.is_set())) event_loop = asyncio.get_event_loop()try: event_loop.run_until_complete(main(event_loop))finally: event_loop.close()

输出如下：

event start state: Falsecoro2 waiting for eventcoro1 waiting for eventsetting event in callbackcoro2 triggeredcoro1 triggeredevent end state: True

补充知识：python里使用协程来创建echo客户端

在这个例子里使用asyncio.Protocol来创建一个echo客户端，先导入库asyncio和logging。

接着定义发送的消息MESSAGES。

创建连接服务器的地址SERVER_ADDRESS，接着创建EchoClient类，它是继承asyncio.Protocol。

在这个类的构造函数里，接收两个参数messages和future，

messages是指定要发送的消息数据，future是用来通知socket接收数据完成或者服务器关闭socket的事件通知，以便事件循环知道这个协程已经完成了，就可以退出整个程序。

connection_made函数是当socket连接到服务器时调用，它就立即发送数据给服务器，数据发送完成之后发送了eof标记。

服务器收到数据和标志都回复客户端，客户端data_received函数接收数据，eof_received函数接收结束标记。

connection_lost函数收到服务器断开连接。

这行代码：

client_completed = asyncio.Future()

创建一个协程完成的触发事件。

由于event_loop.create_connection函数只能接收一个参数，需要使用functools.partial来进行多个参数包装成一个参数。

后面通过事件循环来运行协程。

import asyncioimport functoolsimport loggingimport sys MESSAGES = [ b'This is the message. ', b'It will be sent ', b'in parts.',]SERVER_ADDRESS = ('localhost', 10000) class EchoClient(asyncio.Protocol): def __init__(self, messages, future): super().__init__() self.messages = messages self.log = logging.getLogger('EchoClient') self.f = future def connection_made(self, transport): self.transport = transport self.address = transport.get_extra_info('peername') self.log.debug( 'connecting to {} port {}'.format(*self.address) ) # This could be transport.writelines() except that # would make it harder to show each part of the message # being sent. for msg in self.messages: transport.write(msg) self.log.debug('sending {!r}'.format(msg)) if transport.can_write_eof(): transport.write_eof() def data_received(self, data): self.log.debug('received {!r}'.format(data)) def eof_received(self): self.log.debug('received EOF') self.transport.close() if not self.f.done(): self.f.set_result(True) def connection_lost(self, exc): self.log.debug('server closed connection') self.transport.close() if not self.f.done(): self.f.set_result(True) super().connection_lost(exc) logging.basicConfig( level=logging.DEBUG, format='%(name)s: %(message)s', stream=sys.stderr,)log = logging.getLogger('main') event_loop = asyncio.get_event_loop() client_completed = asyncio.Future() client_factory = functools.partial( EchoClient, messages=MESSAGES, future=client_completed,)factory_coroutine = event_loop.create_connection( client_factory, *SERVER_ADDRESS,) log.debug('waiting for client to complete')try: event_loop.run_until_complete(factory_coroutine) event_loop.run_until_complete(client_completed)finally: log.debug('closing event loop') event_loop.close()

以上这篇python 使用事件对象asyncio.Event来同步协程的操作就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。