如何在asyncio上重新连接套接字？

Question

我想在app.py上创建两个带有asyncio的协议(TcpClient和UdpServer),其中TcpClient将与server.py和UdpServer作为UDP服务器建立持久连接:

我需要的是:
a)两种通信协议:相互调用方法.这只是在第一个连接上工作.如果TcpClient重新连接,则无法再次发送字符串"send to tcp".来自UdpServer.我检查print(self)并且TcpClient创建一个新实例,旧的仍然存在但没有连接,但我不知道如何重构.我认为我以错误的方式使用asyncio.
b)当TcpClient与server.py断开连接时,等待5s并再次尝试重新连接,依此类推.我试图使用call_later()asyncio,但我认为有一种本地方式来做到这一点,而不是一种技巧.
c)当我启动app.py并且如果TcpClient无法连接时,我想尝试在5s后重新连接,依此类推.我不知道该怎么做.

这是我的app.py server.py的示例测试.server.py仅用于测试 - 这将是另一种语言.

只是说我尝试了什么:
1)当我启动app.py并且server.py关闭时,app.py不会重试.
2)当app.py连接到server.py并且服务器关闭并快速启动时,TcpClient重新连接,但我无法在新实例上相互连接方法并发送字符串"send to tcp".到server.py,只是旧的,没有更多的连接.
3)如果我用asyncio.async(),而不是run_until_complete()我不能打电话相互协议的方法.

我把app.py和server.py放在这里,所以你可以复制并运行测试.

我ncat localhost 9000 -u -v用来发送字符串"send to tcp.".此字符串需要打印在UdpServer类上,并传递给TcpClient类上的方法send_data_to_tcp,此方法将字符串发送到server.py.< - 首次重新连接tcpClient后,这不起作用.

我正在使用Python 3.4.0.

非常感谢.

app.py:

import asyncio

#TCP client
class TcpClient(asyncio.Protocol):
    message = 'Testing'

    def connection_made(self, transport):
        self.transport = transport
        self.transport.write(self.message.encode())
        print('data sent: {}'.format(self.message))
        server_udp[1].tcp_client_connected()


    def data_received(self, data):
        self.data = format(data.decode())
        print('data received: {}'.format(data.decode()))
        if self.data == 'Testing':
            server_udp[1].send_data_to_udp(self.data)

    def send_data_to_tcp(self, data):
        self.transport.write(data.encode())

    def connection_lost(self, exc):
        msg = 'Connection lost with the server...'
        info = self.transport.get_extra_info('peername')
        server_udp[1].tcp_client_disconnected(msg, info)


#UDP Server
class UdpServer(asyncio.DatagramProtocol):

    CLIENT_TCP_TIMEOUT = 5.0

    def __init__(self):
        self.client_tcp_timeout = None

    def connection_made(self, transport):
        print('start', transport)
        self.transport = transport

    def datagram_received(self, data, addr):
        self.data = data.strip()
        self.data = self.data.decode()
        print('Data received:', self.data, addr)
        if self.data == 'send to tcp.':
            client_tcp[1].send_data_to_tcp(self.data)

    def connection_lost(self, exc):
        print('stop', exc)

    def send_data_to_udp(self, data):
        print('Receiving on UDPServer Class: ', (data))

    def connect_client_tcp(self):
        coro = loop.create_connection(TcpClient, 'localhost', 8000)
        #client_tcp = loop.run_until_complete(coro)
        client_tcp = asyncio.async(coro)

    def tcp_client_disconnected(self, data, info):
        print(data)
        self.client_tcp_info = info
        self.client_tcp_timeout = asyncio.get_event_loop().call_later(self.CLIENT_TCP_TIMEOUT, self.connect_client_tcp)

    def tcp_client_connected(self):
        if self.client_tcp_timeout:
            self.client_tcp_timeout.cancel()
            print('call_later cancel.')

loop = asyncio.get_event_loop()

#UDP Server
coro = loop.create_datagram_endpoint(UdpServer, local_addr=('localhost', 9000)) 
#server_udp = asyncio.Task(coro)
server_udp = loop.run_until_complete(coro)


#TCP client
coro = loop.create_connection(TcpClient, 'localhost', 8000)
#client_tcp = asyncio.async(coro)
client_tcp = loop.run_until_complete(coro)

loop.run_forever()

server.py:

import asyncio

class EchoServer(asyncio.Protocol):
    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        print('connection from {}'.format(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()

    #def connection_lost(self):
    #    print('server closed the connection')



loop = asyncio.get_event_loop()
coro = loop.create_server(EchoServer, 'localhost', 8000)
server = loop.run_until_complete(coro)
print(server)
print(dir(server))
print(dir(server.sockets))

print('serving on {}'.format(server.sockets[0].getsockname()))

try:
    loop.run_forever()
except KeyboardInterrupt:
    print("exit")
finally:
    server.close()
    loop.close()

Answer 1

你真的只需要一些小修正.首先,我写了一个协程来处理连接重试:

@asyncio.coroutine
def do_connect():
    global tcp_server  # Make sure we use the global tcp_server
    while True:
        try:
            tcp_server = yield from loop.create_connection(TcpClient, 
                                                           'localhost', 8000)
        except OSError:
            print("Server not up retrying in 5 seconds...")
            yield from asyncio.sleep(5)
        else:
            break

然后我们用它来启动所有事情:

loop = asyncio.get_event_loop()

#UDP Server
coro = loop.create_datagram_endpoint(UdpServer, local_addr=('localhost', 9000)) 
server_udp = loop.run_until_complete(coro)

#TCP client
loop.run_until_complete(do_connect())

loop.run_forever()

接下来的部分是在app.py启动后处理服务器关闭/返回.我们需要修复tcp_client_disconnected并connect_client_tcp妥善处理:

def connect_client_tcp(self):
    global client_tcp
    task = asyncio.async(do_connect())
    def cb(result):
        client_tcp = result
    task.add_done_callback(cb)

def tcp_client_disconnected(self, data, info):
    print(data)
    self.client_tcp_info = info
    self.client_tcp_timeout = loop.call_later(self.CLIENT_TCP_TIMEOUT, self.connect_client_tcp)

有趣的是connect_client_tcp.您的原始版本有两个问题:

1. 您client_tcp直接分配给结果asyncio.async(coro),这意味着client_tcp分配给了asyncio.Task.那不是你想要的; 你想client_tcp被分配到完成的结果asyncio.Task.我们实现了通过使用task.add_done_callback分配client_tcp到的结果Task,一旦它完成.

2. 你忘记global client_tcp了方法的顶部.没有它,你只是创建了一个名为的局部变量client_tcp,它在最后被抛弃了connect_client_tcp.

一旦这些问题都是固定的,我能够运行app.py,启动/停止serv.py,每当我想要的,但总能看到来自正确发送的所有邮件ncat到serv.py时所有的三个组件一起运行.

这是完整的app.py,便于复制/粘贴:

import asyncio

#TCP client
class TcpClient(asyncio.Protocol):
    message = 'Testing'

    def connection_made(self, transport):
        self.transport = transport
        self.transport.write(self.message.encode())
        print('data sent: {}'.format(self.message))
        server_udp[1].tcp_client_connected()


    def data_received(self, data):
        self.data = format(data.decode())
        print('data received: {}'.format(data.decode()))
        if self.data == 'Testing':
            server_udp[1].send_data_to_udp(self.data)

    def send_data_to_tcp(self, data):
        self.transport.write(data.encode())

    def connection_lost(self, exc):
        msg = 'Connection lost with the server...'
        info = self.transport.get_extra_info('peername')
        server_udp[1].tcp_client_disconnected(msg, info)


#UDP Server
class UdpServer(asyncio.DatagramProtocol):

    CLIENT_TCP_TIMEOUT = 5.0

    def __init__(self):
        self.client_tcp_timeout = None

    def connection_made(self, transport):
        print('start', transport)
        self.transport = transport

    def datagram_received(self, data, addr):
        self.data = data.strip()
        self.data = self.data.decode()
        print('Data received:', self.data, addr)
        if self.data == 'send to tcp.':
            client_tcp[1].send_data_to_tcp(self.data)

    def connection_lost(self, exc):
        print('stop', exc)

    def send_data_to_udp(self, data):
        print('Receiving on UDPServer Class: ', (data))

    def connect_client_tcp(self):
        global client_tcp
        coro = loop.create_connection(TcpClient, 'localhost', 8000)
        task = asyncio.async(do_connect())
        def cb(result):
            client_tcp = result
        task.add_done_callback(cb)

    def tcp_client_disconnected(self, data, info):
        print(data)
        self.client_tcp_info = info
        self.client_tcp_timeout = loop.call_later(self.CLIENT_TCP_TIMEOUT, self.connect_client_tcp)

    def tcp_client_connected(self):
        if self.client_tcp_timeout:
            self.client_tcp_timeout.cancel()
            print('call_later cancel.')

@asyncio.coroutine
def do_connect():
    global client_tcp
    while True:
        try:
            client_tcp = yield from loop.create_connection(TcpClient, 'localhost', 8000)
        except OSError:
            print("Server not up retrying in 5 seconds...")
            yield from asyncio.sleep(1)
        else:
            break

loop = asyncio.get_event_loop()

#UDP Server
coro = loop.create_datagram_endpoint(UdpServer, local_addr=('localhost', 9000))
server_udp = loop.run_until_complete(coro)

#TCP client
loop.run_until_complete(do_connect())

loop.run_forever()