在python中编写socket服务端模块（二）：使用poll或epoll

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 Queue



server_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 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 socket

import select

import Queue



server_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 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。