python select.select模块通信全过程解析

# 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()