如何处理TCP客户端套接字在python asyncio中自动重新连接？

Question

我正在使用python asyncio流连接到多个套接字服务器，但是当服务器关闭时，我的代码无法自动重新连接。

我需要的是，当服务器关闭时，我的脚本会尝试每5秒重新连接，直到连接并开始再次解析数据。

import asyncio 

server1 = {'host': '192.168.1.51', 'port': 11110} 
server2 = {'host': '192.168.1.52', 'port': 11110} 


async def tcp_client(host, port, loop): 
    print('connect to server {} {}'.format(host, str(port))) 
    reader, writer = await asyncio.open_connection(host, port, loop=loop) 

    while True: 
     data = await reader.read(100) 
     print('raw data received: {}'.format(data)) 

     await asyncio.sleep(0.1) 


loop = asyncio.get_event_loop() 
try: 
    for server in [server1, server2]: 
     loop.run_until_complete(tcp_client(server['host'], server['port'], loop)) 
     print('task added: connect to server {} {}'.format(server['host'], server['port'])) 
finally: 
    loop.close() 
    print('loop closed') 

Answer 1

你可以通过简单地在一个try/except声明循环处理重新连接。另外，asyncio.wait_for可用于设置读取操作的超时。

考虑这个工作的例子：

的所有代码将无法运行

import asyncio 

async def tcp_client(host, port): 
    reader, writer = await asyncio.open_connection(host, port) 
    try: 
     while not reader.at_eof(): 
      data = await asyncio.wait_for(reader.read(100), 3.0) 
      print('raw data received: {}'.format(data)) 
    finally: 
     writer.close() 

async def tcp_reconnect(host, port): 
    server = '{} {}'.format(host, port) 
    while True: 
     print('Connecting to server {} ...'.format(server)) 
     try: 
      await tcp_client(host, port) 
     except ConnectionRefusedError: 
      print('Connection to server {} failed!'.format(server)) 
     except asyncio.TimeoutError: 
      print('Connection to server {} timed out!'.format(server)) 
     else: 
      print('Connection to server {} is closed.'.format(server)) 
     await asyncio.sleep(2.0) 

async def main(): 
    servers = [('localhost', 8888), ('localhost', 9999)] 
    coros = [tcp_reconnect(host, port) for host, port in servers] 
    await asyncio.gather(*coros) 

if __name__ == '__main__': 
    loop = asyncio.get_event_loop() 
    loop.run_until_complete(main()) 
    loop.close()