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上一篇对twisted大致做了介绍以及一些基本的概念。
这一篇从一个python epoll/soket聊天程序开始。
我们要实现的很简单，就是利用epoll实现一个服务端/客户端间的聊天，服务端和客户端可以接收消息的同时，可以利用raw_input，在命令行输入。
我们将socket fd设置为非阻塞的，但是我们知道标准的输入输出io都是阻塞的，我们就开辟一个线程专门处理输入，在主线程进行消息的收发。这样当我们没有输入的时候，raw_input就会阻塞，由我们的主线程进行监听和处理。代码如下：
server.py
1 #!/usr/local/bin/python 2 3 import socket 4 import select 5 import errno 6 import os 7 import sys 8 import time 9 import threading 10 import traceback 11 import signal 12 13 # global varables define here 14 # 15 IS_RUNNING = 0 16 SERVER_INPUT = "" 17 CONNTCTION_FD = 0 18 19 # class define here 20 # 21 class ServerInput(threading.Thread): 22 ‘‘‘ thread to handle write event ‘‘‘ 23 def __init__(self): 24 threading.Thread.__init__(self) 25 def run(self): 26 global SERVER_INPUT 27 global CONNECTION_FD 28 global IS_RUNNING 29 IS_RUNNING = 1 30 while IS_RUNNING: 31 SERVER_INPUT = raw_input("(192.168.56.101): ") 32 content = SERVER_INPUT 33 if len(content) > 0 : 34 send_len = 0 35 while True: 36 try: 37 global connections 38 send_len += CONNECTION_FD.send(content) 39 except Exception, e: 40 print "error happen" 41 traceback.print_exc() 42 print e 43 else: 44 if(send_len == len(content)): 45 break 46 content = "" 47 SERVER_INPUT = "" 48 def stop(self): 49 global IS_RUNNING 50 IS_RUNNING = 0 51 52 # globla function here 53 def signal_handle(signum, frame): 54 print "detect a signal" + str(signum) 55 global IS_RUNNING 56 IS_RUNNING = 0 57 server_input_thread.stop() 58 59 60 # main function 61 # 62 if __name__ == "__main__": 63 server_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM,0) 64 server_fd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 65 server_fd.bind(("0.0.0.0", 2003)) 66 server_fd.listen(10) 67 epoll_fd = select.epoll() 68 epoll_fd.register(server_fd.fileno(), select.EPOLLIN|select.EPOLLOUT) 69 connections = {} 70 addresses = {} 71 datalist = {} 72 client_addr = "" 73 server_content = "" 74 75 signal.signal(signal.SIGINT, signal_handle) 76 # a new thread to handle output event 77 # 78 server_input_thread = ServerInput() 79 try: 80 server_input_thread.start() 81 except Exception, e: 82 print e 83 else: 84 IS_RUNNING = 1 85 86 # just use EPOLLIN to listen read event 87 # 88 while IS_RUNNING: 89 epoll_list = epoll_fd.poll() 90 for fd, events in epoll_list: 91 if fd == server_fd.fileno(): 92 conn, addr = server_fd.accept() 93 conn.setblocking(0) 94 epoll_fd.register(conn.fileno(), select.EPOLLIN | select.EPOLLET) 95 connections[conn.fileno()] = conn 96 addresses[conn.fileno()] = addr 97 client_addr = addr 98 print " Welcome our new guest: " + str(client_addr) 99 CONNECTION_FD = conn 100 elif select.EPOLLIN & events: 101 datas = ‘‘ 102 while True: 103 try: 104 data = connections[fd].recv(10) 105 if not data and not datas: 106 epoll_fd.unregister(fd) 107 connections[fd].close() 108 break 109 else: 110 datas += data 111 except socket.error, msg: 112 if msg.errno == errno.EAGAIN: 113 datalist[fd] = datas 114 break 115 else: 116 print "connecting error" 117 epoll_fd.unregister(fd) 118 connections[fd].close() 119 break 120 print "\n" + str(client_addr) + " : " + datas 121 elif select.EPOLLHUP & events: 122 print "unknown connect" 123 epoll_fd.unregister(fd) 124 connections[fd].close() 125 else: 126 continue 127 else: 128 for fd in connections: 129 epoll_fd.unregister(fd) 130 connections[fd].close() # close all connection
client.py
1 #!/usr/local/bin/python 2 3 import socket 4 import time 5 import threading 6 import signal 7 8 # global variables define here 9 # 10 INPUT_CONTENT = "" 11 IS_RUNNING = 0 12 13 # class define here 14 # 15 class MyinputThread(threading.Thread): 16 ‘‘‘ a new thread to handle user input ‘‘‘ 17 def __init__(self): 18 threading.Thread.__init__(self) 19 def run(self): 20 global INPUT_CONTENT 21 global IS_RUNNING 22 IS_RUNNING = 1 23 while IS_RUNNING: 24 print "\n" 25 INPUT_CONTENT = raw_input("(192.168.56.102):") 26 def stop(self): 27 global IS_RUNNING 28 IS_RUNNING = 0 29 30 # global function define here 31 # 32 def signal_handle(signum, frame): 33 global IS_RUNNING 34 IS_RUNNING = 0 35 myInputThread.stop() 36 37 # main function 38 # 39 if __name__ == "__main__": 40 IS_RUNNING = 1 41 signal.signal(signal.SIGINT, signal_handle) 42 43 connFd = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) 44 connFd.connect(("192.168.56.101", 2003)) 45 connFd.settimeout(0.1) 46 47 myInputThread = MyinputThread() 48 myInputThread.start() 49 50 while IS_RUNNING: 51 client_content = INPUT_CONTENT 52 if len(client_content) > 0 and connFd.send(client_content) != len(client_content): 53 print "connection lost" 54 break 55 INPUT_CONTENT = "" 56 try: 57 readData = connFd.recv(1024) 58 except socket.timeout,e: 59 err = e.args[0] 60 if err == ‘time out‘: 61 print "time out" 62 readData = "time out" 63 else: 64 print "\n" + "(192.168.56.101): " + readData 65 connFd.close()
运行的结果如下：
server side:
1 (192.168.1.103): Welcome our new guest: (‘192.168.1.104‘, 35226) 2 3 (192.168.1.103): hello,this‘s server 4 (192.168.1.103): 5 (‘192.168.1.104‘, 35226) : hello,i‘m 6 7 (‘192.168.1.104‘, 35226) : hello,i‘m client 8 9 (192.168.1.103): bye
client side:
1 (192.168.1.104): 2 (192.168.56.101): hello,this‘s server 3 (192.168.1.104):hello,i‘m client 4 (192.168.1.104): 5 (192.168.56.101): bye 6 (192.168.1.104):bye
以上代码仅仅作为例子，处理的也仅仅是one server,one client的情况。 python epoll怎么使用就不再赘述，通过这个例子我们看到一个典型的python epoll程序，server端需要创建socket,绑定，监听，注册epoll，轮询处理读写事件。客户端需要创建socket，连接，处理读写io。 twisted框架是基于select/epoll的，它也是同样的一套流程，被封装好，方便我们调用。我在后面的twisted源码中会涉及到具体的内容。
从上述代码还可以看到：
twisted是跨平台的；如果我们要处理标准输入输出，其中有封装好的stdio.StandardIO可以很方便的使用，除了twisted已经封装好的tcp,udp,ssl,http,ftp等协议，我们可以定义自己的protocal，只需要简单的调用就可以实现。我们可以把服务端做成一个service在后台执行，等等。
下一篇详细分析一下select/epoll的源码,这是网络编程的基础，而且无论是面试问它们的区别还是学习，它们都很重要，相信看过源码分析后，所有的异同都会了如指掌。
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原文地址：http://www.cnblogs.com/wy-wangyan/p/5289821.html
