基于python select.select模块通信的实例讲解

readable, writable, exceptional = select.select(inputs, outputs, inputs)

# coding: utf-8import selectimport socketimport Queuefrom time import sleep# Create a TCP/IPserver = socket.socket(socket.AF_INET, socket.SOCK_STREAM)server.setblocking(False)# Bind the socket to the portserver_address = ('localhost', 8090)print ('starting up on %s port %s' % server_address)server.bind(server_address)# Listen for incoming connectionsserver.listen(5)# Sockets from which we expect to readinputs = [server]# Sockets to which we expect to write# 处理要发送的消息outputs = []# Outgoing message queues (socket: Queue)message_queues = {}while inputs:  # Wait for at least one of the sockets to be ready for processing  print ('waiting for the next event')  # 开始select 监听, 对input_list 中的服务器端server 进行监听  # 一旦调用socket的send, recv函数，将会再次调用此模块  readable, writable, exceptional = select.select(inputs, outputs, inputs)  # Handle inputs  # 循环判断是否有客户端连接进来, 当有客户端连接进来时select 将触发  for s in readable:    # 判断当前触发的是不是服务端对象, 当触发的对象是服务端对象时,说明有新客户端连接进来了    # 表示有新用户来连接    if s is server:      # A "readable" socket is ready to accept a connection      connection, client_address = s.accept()      print ('connection from', client_address)      # this is connection not server      connection.setblocking(0)      # 将客户端对象也加入到监听的列表中, 当客户端发送消息时 select 将触发      inputs.append(connection)      # Give the connection a queue for data we want to send      # 为连接的客户端单独创建一个消息队列，用来保存客户端发送的消息      message_queues[connection] = Queue.Queue()    else:      # 有老用户发消息, 处理接受      # 由于客户端连接进来时服务端接收客户端连接请求，将客户端加入到了监听列表中(input_list), 客户端发送消息将触发      # 所以判断是否是客户端对象触发      data = s.recv(1024)      # 客户端未断开      if data != '':        # A readable client socket has data        print ('received "%s" from %s' % (data, s.getpeername()))        # 将收到的消息放入到相对应的socket客户端的消息队列中        message_queues[s].put(data)        # Add output channel for response        # 将需要进行回复操作socket放到output 列表中, 让select监听        if s not in outputs:          outputs.append(s)      else:        # 客户端断开了连接, 将客户端的监听从input列表中移除        # Interpret empty result as closed connection        print ('closing', client_address)        # Stop listening for input on the connection        if s in outputs:          outputs.remove(s)        inputs.remove(s)        s.close()        # Remove message queue        # 移除对应socket客户端对象的消息队列        del message_queues[s]  # Handle outputs  # 如果现在没有客户端请求, 也没有客户端发送消息时, 开始对发送消息列表进行处理, 是否需要发送消息  # 存储哪个客户端发送过消息  for s in writable:    try:      # 如果消息队列中有消息,从消息队列中获取要发送的消息      message_queue = message_queues.get(s)      send_data = ''      if message_queue is not None:        send_data = message_queue.get_nowait()      else:        # 客户端连接断开了        print "has closed "    except Queue.Empty:      # 客户端连接断开了      print "%s" % (s.getpeername())      outputs.remove(s)    else:      # print "sending %s to %s " % (send_data, s.getpeername)      # print "send something"      if message_queue is not None:        s.send(send_data)      else:        print "has closed "      # del message_queues[s]      # writable.remove(s)      # print "Client %s disconnected" % (client_address)  # # Handle "exceptional conditions"  # 处理异常的情况  for s in exceptional:    print ('exception condition on', s.getpeername())    # Stop listening for input on the connection    inputs.remove(s)    if s in outputs:      outputs.remove(s)    s.close()    # Remove message queue    del message_queues[s]  sleep(1)

# coding: utf-8import socketmessages = ['This is the message ', 'It will be sent ', 'in parts ', ]server_address = ('localhost', 8090)# Create aTCP/IP socketsocks = [socket.socket(socket.AF_INET, socket.SOCK_STREAM), socket.socket(socket.AF_INET, socket.SOCK_STREAM), ]# Connect thesocket to the port where the server is listeningprint ('connecting to %s port %s' % server_address)# 连接到服务器for s in socks:  s.connect(server_address)for index, message in enumerate(messages):  # Send messages on both sockets  for s in socks:    print ('%s: sending "%s"' % (s.getsockname(), message + str(index)))    s.send(bytes(message + str(index)).decode('utf-8'))  # Read responses on both socketsfor s in socks:  data = s.recv(1024)  print ('%s: received "%s"' % (s.getsockname(), data))  if data != "":    print ('closingsocket', s.getsockname())    s.close()