检查python中套接字中是否有数据可用

我想要一个功能来检查数据是否在读取之前在套接字中等待读取.这样的事情会有所帮助：

if (data available) then read data

else wait in blocking mode till data becomes available

我怎样才能在Python中实现这一点
最佳答案

while 1:
  socket_list = [sys.stdin,s]
  # Get the list sockets which are readable
  read_sockets,write_sockets,error_sockets = select.select(socket_list,[],[])
  for sock in read_sockets:
   #incoming message from remote server
   if sock == s:
      data = sock.recv(4096)
      if not data :
        print '\nDisconnected from server'
        sys.exit()
      else :
         #print data
         sys.stdout.write(data)


   #user entered a message
   else :
     msg = sys.stdin.readline()
     s.send(msg)