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 socketimport selectimport 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 eventREAD_ONLY = ( select.POLLIN | select.POLLPRI | select.POLLHUP | select.POLLERR)READ_WRITE = (READ_ONLY|select.POLLOUT)# Set up the pollerpoller = 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 connection                connection , client_address = s.accept()                print " Connection " , client_address                connection.setblocking(False)                                 fd_to_socket[connection.fileno()] = connection                poller.register(connection,READ_ONLY)                                 #Give the connection a queue to send data                message_queues[connection]  = Queue.Queue()            else :                data = s.recv(1024)                if data:                    # A readable client socket has data                    print "  received %s from %s " % (data, s.getpeername())                    message_queues[s].put(data)                    poller.modify(s,READ_WRITE)                else :                    # Close the connection                    print "  closing" , s.getpeername()                    # Stop listening for input on the connection                    poller.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 send            try:                next_msg = message_queues[s].get_nowait()            except Queue.Empty:                # No messages waiting so stop checking                print 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 socket            print "  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 socketimport selectimport 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 eventREAD_ONLY = ( select.EPOLLIN | select.EPOLLPRI | select.EPOLLHUP | select.EPOLLERR)READ_WRITE = (READ_ONLY|select.EPOLLOUT)# Set up the pollerepoller = 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 descriptor        s = fd_to_socket[fd]                if flag & (select.EPOLLIN | select.EPOLLPRI) :            if s is server :                # A readable socket is ready to accept a connection                connection , client_address = s.accept()                print " Connection " , client_address                connection.setblocking(False)                                 fd_to_socket[connection.fileno()] = connection                epoller.register(connection,READ_ONLY)                                 #Give the connection a queue to send data                message_queues[connection]  = Queue.Queue()            else :                data = s.recv(1024)                if data:                    # A readable client socket has data                    print "  received %s from %s " % (data, s.getpeername())                    message_queues[s].put(data)                    epoller.modify(s,READ_WRITE)                else :                    # Close the connection                    print "  closing" , s.getpeername()                    # Stop listening for input on the connection                    epoller.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 send            try:                next_msg = message_queues[s].get_nowait()            except Queue.Empty:                # No messages waiting so stop checking                print 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 socket            print "  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。