异步select

server coding:

  1 #!/usr/bin/python
  2 # -*- coding: utf-8 -*-
  3
  4 import select
  5 import socket
  6 import sys
  7 import Queue
  8
  9 # Create a TCP/IP socket
 10 server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
 11 server.setblocking(False)
 12
 13 # Bind the socket to the port
 14 server_address = (‘localhost‘,1000)
 15 print >>sys.stderr, ‘starting up on %s port %s‘%server_address
 16 server.bind(server_address)
 17
 18 # Listen for incoming connections
 19 server.listen(5)
 20
 21 # Sockets from which we expect to read
 22 inputs = [server]
 23
 24 # Sockets to which we expect to write
 25 outputs = []
 26
 27 # Outgoing message queues (socket:Queue)
 28 message_queues = {}
 29
 30 while True:
 31     # Wait for at least one of the sockets to be ready for processing
 32     print >>sys.stderr, ‘\nwaiting for the next event‘
 33     #分别筛选出可接收消息的sockets、等待发送消息的sockets、和中途出错的sockets。
 34     #其中exceptional为了把所有可接收消息的sockets都遍历到，所以要从inputs列表中读取。
 35     readable, writable, exceptional = select.select(inputs,outputs,inputs)
 36
 37     # Handle inputs
 38     for s in readable:
 39         #第一种情况，创建一个待接收消息的socket放入inputs
 40         if s is server:
 41             # A "readable" server socket is ready to accept a connection
 42             connection, client_address = s.accept()
 43             print >>sys.stderr, ‘new connection from‘, client_address
 44             connection.setblocking(0)
 45             inputs.append(connection)
 46
 47             # Give the connection a queue for data we want to send
 48             message_queues[connection] = Queue.Queue()
 49
 50         #第二种情况，在后续循环中，已经添加到inputs中的sockets已经不是readable了，所以
 51         #要进行接收消息，消息存在message_queues中，并把该socket添加到outputs。
 52         else:
 53             data = s.recv(1024)
 54             if data:
 55                 # A readable client socket has data
 56                 print >>sys.stderr, ‘receieved "%s" from %s‘%(data.upper(),s.getpeername())
 57                 message_queues[s].put(data)
 58                 # Add output channel for response，添加到待发送消息列表
 59                 if s not in outputs:
 60                     outputs.append(s)
 61
 62             #第三种情况就是这个客户端已经断开了，
 63             #所以你再通过recv()接收到的数据就为空了，
 64             #所以这个时候你就可以把这个跟客户端的连接关闭了。
 65             else:
 66                 print >>sys.stderr, ‘closing‘,client_address,‘after reading no data‘
 67                 if s in outputs:
 68                     outputs.remove(s)#既然客户端都断开了，我就不用再给它返回数据了，所以这时候如果这个客户端的连接对象还在outputs列表中，就把它删掉
 69                 inputs.remove(s)#inputs中也删除掉
 70                 s.close()#把这个连接关闭掉
 71
 72                  # Remove message queue
 73                 del message_queues[s]
 74
 75     # Handle outputs
 76     for s2 in writable:
 77         try:
 78             next_msg = message_queues[s2].get_nowait()
 79         #没有消息了
 80         except Queue.Empty:
 81             # No messages waiting so stop checking for writability.
 82             print >>sys.stderr,‘output queue for‘,s2.getpeername(),‘is empty‘
 83             outputs.remove(s2)
 84         #发送消息
 85         else:
 86             print >>sys.stderr, ‘sending "%s" to %s‘%(next_msg,s2.getpeername())
 87             s2.send(next_msg)
 88
 89     # Handle "exceptional conditions"
 90     for s3 in exceptional:
 91         print >>sys.stderr, ‘handling exceptional condition for ‘,s3.getpeername()
 92         # Stop listening for input on the connection
 93         inputs.remove(s3)
 94         if s3 in outputs:
 95             outputs.remove(s3)
 96         s3.close()
 97
 98         #Remove message queue
 99         del message_queues[s3]
100
101
102             

client coding

 1 # -*- coding: utf-8 -*-
 2 """
 3 Created on Sun Oct 23 14:49:20 2016
 4
 5 @author: fuzzier
 6 """
 7
 8 import sys
 9 import socket
10
11 messages = [‘This is the message.‘,
12             ‘It will be sent‘,
13             ‘in parts.‘
14             ]
15 server_address = (‘localhost‘,1000)
16
17 # Create a TCP/IP socket，创建两个客户端
18 socks = [socket.socket(socket.AF_INET,socket.SOCK_STREAM),
19          socket.socket(socket.AF_INET,socket.SOCK_STREAM)
20          ]
21
22 # Connect the socket to the port where the server is listening
23 print >>sys.stderr, ‘connecting to %s port %s‘%server_address
24 for s in socks:
25     s.connect(server_address)
26
27 for message in messages:
28
29     # Send messages on both sockets
30     for s2 in socks:
31         print >>sys.stderr, ‘%s:sending "%s"‘%(s2.getsockname(),message)
32         s2.send(message)
33
34     #Read responses on both sockets
35     for s3 in socks:
36         data = s3.recv(1024)
37         print >>sys.stderr, ‘%s: received "%s"‘ % (s3.getsockname(), data.upper())
38         if not data:
39             print >>sys.stderr,‘closing socket‘,s3.getsockname()
40             s3.close()

原理图：

运行结果：