python-3.x - UDP 服务器内的 asyncio.sleep 不起作用

Question

我正在玩 asyncio UDP server example并希望有一个sleep来自datagram_received内方法。

import asyncio

class EchoServerProtocol:
    def connection_made(self, transport):
        self.transport = transport

    def datagram_received(self, data, addr):
        message = data.decode()
        print('Received %r from %s' % (message, addr))
        # Sleep
        await asyncio.sleep(1)
        print('Send %r to %s' % (message, addr))
        self.transport.sendto(data, addr)

loop = asyncio.get_event_loop()
print("Starting UDP server")
# One protocol instance will be created to serve all client requests
listen = loop.create_datagram_endpoint(EchoServerProtocol,
                                       local_addr=('127.0.0.1', 9999))
transport, protocol = loop.run_until_complete(listen)

try:
    loop.run_forever()
except KeyboardInterrupt:
    pass

transport.close()
loop.close()

此操作失败并显示 SyntaxError在 sleep 线上(Python 3.5.1)。使用time.sleep显然不起作用，因为它阻止接收任何其他数据报。关于如何解决这个问题有任何提示吗？

目标是取代这个 sleep具有真正的非阻塞 I/O 调用。

Answer 1

似乎 await 必须存在于 async def (协程)中。为此，您必须通过 asyncio.ensure_future 触发调用。

def datagram_received(self, data, addr):
    asyncio.ensure_future(self.reply(data, addr))

async def reply(self, data, addr):
    await asyncio.sleep(1)
    self.transport.sendto(data, addr)