在linux上编写socket服务端程序一般可以用select、poll、epoll三种方式，本文主要介绍使用poll和epoll编写socket服务端模块。

使用poll方式的服务器端程序代码：

import socket
import select
import Queueserver_address=('10.0.2.15',21345)
server=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
server.setblocking(False)
server.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
server.bind(server_address)
server.listen(5)message_queues={}
#poll时间单位是毫秒
timeout = 1000# Create a limit for the event
READ_ONLY = ( select.POLLIN | select.POLLPRI | select.POLLHUP | select.POLLERR)
READ_WRITE = (READ_ONLY|select.POLLOUT)# Set up the poller
poller = select.poll()
poller.register(server,READ_ONLY)
#Map file descriptors to socket objects
#server.fileno()是获得server这个socket的文件描述符，是int类型
fd_to_socket = {server.fileno():server,}while True:events = poller.poll(timeout)#fd是描述符，flag是event状态，都是int类型for fd ,flag in  events:# Retrieve the actual socket from its file descriptor#s为当前的socket对象s = fd_to_socket[fd]if flag & (select.POLLIN | select.POLLPRI) :if s is server :# A readable socket is ready to accept a connectionconnection , client_address = s.accept()print " Connection " , client_addressconnection.setblocking(False)fd_to_socket[connection.fileno()] = connectionpoller.register(connection,READ_ONLY)#Give the connection a queue to send datamessage_queues[connection]  = Queue.Queue()else :data = s.recv(1024)if data:# A readable client socket has dataprint "  received %s from %s " % (data, s.getpeername())message_queues[s].put(data)poller.modify(s,READ_WRITE)else :# Close the connectionprint "  closing" , s.getpeername()# Stop listening for input on the connectionpoller.unregister(s)s.close()del message_queues[s]elif flag & select.POLLHUP :#A client that "hang up" , to be closed.print " Closing ", s.getpeername() ,"(HUP)"poller.unregister(s)s.close()elif flag & select.POLLOUT :#Socket is ready to send data , if there is any to sendtry:next_msg = message_queues[s].get_nowait()except Queue.Empty:# No messages waiting so stop checkingprint s.getpeername() , " queue empty"poller.modify(s,READ_ONLY)else :print " sending %s to %s" % (next_msg , s.getpeername())s.send(next_msg)elif flag & select.POLLERR:#Any events with POLLERR cause the server to close the socketprint "  exception on" , s.getpeername()poller.unregister(s)s.close()del message_queues[s]

使用epoll方式的服务器端程序代码跟poll方式类似，具体代码如下：

import socket
import select
import Queueserver_address=('10.0.2.15',21345)
server=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
server.setblocking(False)
server.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
server.bind(server_address)
server.listen(5)message_queues={}
#poll时间单位是毫秒
timeout = 1000# Create a limit for the event
READ_ONLY = ( select.EPOLLIN | select.EPOLLPRI | select.EPOLLHUP | select.EPOLLERR)
READ_WRITE = (READ_ONLY|select.EPOLLOUT)# Set up the poller
epoller = select.epoll()
epoller.register(server,READ_ONLY)
#Map file descriptors to socket objects
#server.fileno()是获得server这个socket的文件描述符，是int类型
fd_to_socket = {server.fileno():server,}while True:print "Waiting for the next event"events = epoller.poll(timeout)print events#fd是描述符，flag是event状态for fd ,flag in  events:# Retrieve the actual socket from its file descriptors = fd_to_socket[fd]if flag & (select.EPOLLIN | select.EPOLLPRI) :if s is server :# A readable socket is ready to accept a connectionconnection , client_address = s.accept()print " Connection " , client_addressconnection.setblocking(False)fd_to_socket[connection.fileno()] = connectionepoller.register(connection,READ_ONLY)#Give the connection a queue to send datamessage_queues[connection]  = Queue.Queue()else :data = s.recv(1024)if data:# A readable client socket has dataprint "  received %s from %s " % (data, s.getpeername())message_queues[s].put(data)epoller.modify(s,READ_WRITE)else :# Close the connectionprint "  closing" , s.getpeername()# Stop listening for input on the connectionepoller.unregister(s)s.close()del message_queues[s]elif flag & select.EPOLLHUP :#A client that "hang up" , to be closed.print " Closing ", s.getpeername() ,"(HUP)"epoller.unregister(s)s.close()elif flag & select.POLLOUT :#Socket is ready to send data , if there is any to sendtry:next_msg = message_queues[s].get_nowait()except Queue.Empty:# No messages waiting so stop checkingprint s.getpeername() , " queue empty"epoller.modify(s,READ_ONLY)else :print " sending %s to %s" % (next_msg , s.getpeername())s.send(next_msg)elif flag & select.EPOLLERR:#Any events with POLLERR cause the server to close the socketprint "  exception on" , s.getpeername()epoller.unregister(s)s.close()del message_queues[s]

客户端程序代码与上一篇博文中的相同。