SOCKET编程进阶之Overlapped I/O完成例程模型

SOCKET编程进阶之Overlapped I/O完成例程模型

原文地址:http://blog.youkuaiyun.com/echoff/archive/2007/09/23/1797319.aspx

完成例程模型相比与事件通知模型有个很大的优点就是不再受64个消息的限制，一个线程可以同时管理成百上千个socket连接，且保持较高的性能。 

完成例程相比与完成端口较为逊色，因为它的性能不能随着系统CPU数量的增长而线程增长，不过在我看来已经很强了，呵呵～！ 

说白了，这些连接都是由系统来帮你管理的。你只需做的一件事就是：开启一个线程来accept进来的连接，剩下的工作交由系统来处理。而你，则需要提供给系统一个回调函数，发生新的网络事件的时候系统将执行这个函数： 

procedure WorkerRoutine( const dwError, cbTransferred : DWORD; const lpOverlapped : LPWSAOVERLAPPED; const dwFlags : DWORD ); stdcall; 

然后告诉系统用WorkerRoutine函数处理接收到的数据： 

WSARecv( m_socket, @FBuf, 1, dwTemp, dwFlag, @m_overlap, WorkerRoutine ); 

然后......没有什么然后了，系统什么都给你做了！ 

1. #pragma comment(lib,"ws2_32.lib") 
2. #include <winsock2.h> 
3. #include <stdio.h> 
4. #define DATA_BUFSIZE 1024        // 接收缓冲区大小 
5. #define MAXSESSION 10000        // 最大连接数 
6. typedef struct _SOCKET_INFORMATION { 
7.    OVERLAPPED Overlapped; 
8.    SOCKET Socket; 
9.    WSABUF DataBuf; 
10.    DWORD BytesSEND; 
11.    DWORD BytesRECV; 
12. } SOCKET_INFORMATION, * LPSOCKET_INFORMATION; 
14. SOCKET        ListenSocket = INVALID_SOCKET; 
15. DWORD   Flags = 0;                                                                // WSARecv的参数 
16. void CALLBACK WorkerRoutine(DWORD Error, DWORD BytesTransferred,LPWSAOVERLAPPED Overlapped, DWORD InFlags); 
17. DWORD WINAPI AcceptThread(LPVOID lpParameter) 
18. { 
19.         WSADATA wsaData; 
20.         WSAStartup(MAKEWORD(2,2),&wsaData); 
21.         ListenSocket = WSASocket(AF_INET,SOCK_STREAM,IPPROTO_TCP,NULL,NULL,WSA_FLAG_OVERLAPPED); 
22.         SOCKADDR_IN ServerAddr; 
23.         ServerAddr.sin_family = AF_INET; 
24.         ServerAddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY); 
25.         ServerAddr.sin_port = htons(1234); 
26.         bind(ListenSocket,(LPSOCKADDR)&ServerAddr,sizeof(ServerAddr)); 
27.         listen(ListenSocket,100); 
28.         printf("listenning.../n"); 
29.         SOCKADDR_IN ClientAddr; 
30.         int addr_length=sizeof(ClientAddr); 
31.         while (TRUE) 
32.         { 
33.                 LPSOCKET_INFORMATION  SI = new SOCKET_INFORMATION; 
34.                 if ((SI->Socket = accept(ListenSocket,(SOCKADDR*)&ClientAddr, &addr_length)) != INVALID_SOCKET) 
35.                 { 
36.                         printf("accept ip:%s port:%d/n",inet_ntoa(ClientAddr.sin_addr),ClientAddr.sin_port); 
37.                         memset(&SI->Overlapped,0,sizeof(WSAOVERLAPPED)); 
38.                         SI->DataBuf.buf = new char[DATA_BUFSIZE]; 
39.                         SI->DataBuf.len = DATA_BUFSIZE; 
40.                         memset(SI->DataBuf.buf,0,DATA_BUFSIZE); 
41.                         if(WSARecv(SI->Socket, &SI->DataBuf, 1, &SI->BytesRECV, &Flags, &SI->Overlapped, WorkerRoutine) == SOCKET_ERROR) 
42.                         { 
43.                                 int err = WSAGetLastError(); 
44.                                 if(WSAGetLastError() != WSA_IO_PENDING) 
45.                                 { 
46.                                         printf("disconnect/n"); 
47.                                         closesocket(SI->Socket); 
48.                                         delete [] SI->DataBuf.buf; 
49.                                         delete SI; 
50.                                         continue; 
51.                                 } 
52.                         } 
53.                 } 
54.                  
55.         } 
56. return FALSE; 
57. } 
58. void CALLBACK WorkerRoutine(DWORD Error, DWORD BytesTransferred, LPWSAOVERLAPPED Overlapped, DWORD InFlags) 
59. { 
60.         LPSOCKET_INFORMATION SI = (LPSOCKET_INFORMATION)Overlapped; 
61.         if (Error != 0 || BytesTransferred == 0) 
62.         { 
63.                 printf("disconnect/n"); 
64.                 closesocket(SI->Socket); 
65.                 delete [] SI->DataBuf.buf; 
66.                 delete SI; 
67.                 return; 
68.         } 
69.         //使用数据 
70.         printf("call back:%s/n",SI->DataBuf.buf); 
71.         memset(SI->DataBuf.buf,0,DATA_BUFSIZE); 
72.          
73.         if(WSARecv(SI->Socket, &SI->DataBuf, 1, &SI->BytesRECV, &Flags, &SI->Overlapped, WorkerRoutine) == SOCKET_ERROR) 
74.         { 
75.                 int err = WSAGetLastError(); 
76.                 if(WSAGetLastError() != WSA_IO_PENDING) 
77.                 { 
78.                         printf("disconnect/n"); 
79.                         closesocket(SI->Socket); 
80.                         delete [] SI->DataBuf.buf; 
81.                         delete SI; 
82.                         return; 
83.                 } 
84.         } 
85. } 
86. void main()   
87. { 
88.         HANDLE hThreads = CreateThread(NULL, 0, AcceptThread, NULL, NULL, NULL); 
89.            
90.         WaitForSingleObject(hThreads,INFINITE); 
91.         printf("exit/n"); 
92.         CloseHandle(hThreads); 
93. }