让asyncio服务器调用另一个服务器

Question

因此，我修改了asyncio客户端和服务器的示例（在此处找到：https://docs.python.org/3/library/asyncio-protocol.html#protocol-example-tcp-echo-server-and-client，而我想要的只是使client.py调用serverone.py，然后依次调用servertwo.py。

client.py

#!/usr/bin/env python3.4
import asyncio

class EchoClient(asyncio.Protocol):
    message = 'This is the Client'

    def connection_made(self, transport):
        transport.write(self.message.encode())

    def data_received(self, data):
        print('data received: {}'.format(data.decode()))

    def connection_lost(self, exc):
        asyncio.get_event_loop().stop()

loop = asyncio.get_event_loop()
coro = loop.create_connection(EchoClient, '127.0.0.1', 8888)
loop.run_until_complete(coro)
loop.run_forever()
loop.close()

serverone.py

#!/usr/bin/env python3.4

import asyncio

class EchoClient(asyncio.Protocol):
    message = 'Server One sending message'

    def connection_made(self, transport):
        transport.write(self.message.encode())

    def data_received(self, data):
        print('data received: {}'.format(data.decode()))

    def connection_lost(self, exc):
        asyncio.get_event_loop().stop()

class EchoServer(asyncio.Protocol):
    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        self.transport = transport

    def data_received(self, data):
        loop = asyncio.get_event_loop()
        coro = loop.create_connection(EchoClient, '127.0.0.1', 8889)
        loop.run_until_complete(coro)
        # close the socket
        self.transport.close()
        loop.close()

loop = asyncio.get_event_loop()
coro = loop.create_server(EchoServer, '127.0.0.1', 8888)
server = loop.run_until_complete(coro)
try:
    loop.run_forever()
except KeyboardInterrupt:
    print("exit")
finally:
    server.close()
    loop.close()

servertwo.py

#!/usr/bin/env python3.4

import asyncio

class EchoServer(asyncio.Protocol):
    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        self.transport = transport

    def data_received(self, data):
        print('data received: {}'.format(data.decode()))
        self.transport.write(data)
        # close the socket
        self.transport.close()

loop = asyncio.get_event_loop()
coro = loop.create_server(EchoServer, '127.0.0.1', 8889)
server = loop.run_until_complete(coro)
try:
    loop.run_forever()
except KeyboardInterrupt:
    print("exit")
finally:
    server.close()
    loop.close()

我在终端中启动servertwo.py和serverone.py，然后调用client.py。事情部分起作用；客户端确实调用了serverone，后者又调用了servertwo，但随后serverone失败，并显示以下错误：

Exception in callback <bound method _SelectorSocketTransport._read_ready of <asyncio.selector_events._SelectorSocketTransport object at 0x7fbf4453b048>>()
handle: Handle(<bound method _SelectorSocketTransport._read_ready of <asyncio.selector_events._SelectorSocketTransport object at 0x7fbf4453b048>>, ())
Traceback (most recent call last):
  File "/usr/lib64/python3.4/asyncio/events.py", line 39, in _run
    self._callback(*self._args)
  File "/usr/lib64/python3.4/asyncio/selector_events.py", line 458, in _read_ready
    self._protocol.data_received(data)
  File "./serverone.py", line 25, in data_received
    loop.run_until_complete(coro)
  File "/usr/lib64/python3.4/asyncio/base_events.py", line 203, in run_until_complete
    self.run_forever()
  File "/usr/lib64/python3.4/asyncio/base_events.py", line 179, in run_forever
    raise RuntimeError('Event loop is running.')
RuntimeError: Event loop is running.

该文档没有涵盖很多奇怪的用例，所以我有点受限制。我应该使用asyncio.async拨打电话吗？我可以正确解决问题吗？

如何解决或避免RuntimeError？

Answer 1

您可以使用asyncio.async安排由asyncio.async返回的协程由事件循环运行，然后使用create_connection的add_done_callback方法（更具体地说，是asyncio.Future） ]一旦协程完成，返回以关闭循环：

asyncio.Task

Answer 2

将asyncio.Task替换为async，它将与更新的答案一起运行。