Windows Socket IO模型.doc

Windows Socket I/O模型-重叠I/O模型、完成端口模型 四.重叠I/O模型Winsock2的发布使得Socket I/O有了和文件I/O统一的接口。我们可以通过使用Win32文件操纵函数ReadFile和WriteFile来进行Socket I/O。伴随而来的，用于普通文件I/O的重叠I/O模型和完成端口模型对Socket I/O也适用了。这些模型的优点是可以达到更佳的系统性能，但是实现较为复杂，里面涉及较多的C语言技巧。例如我们在完成端口模型中会经常用到所谓的“尾随数据”。1.用事件通知方式实现的重叠I/O模型#include #include #define PORT 5150#define MSGSIZE 1024#pragma comment(lib, ws2_32.lib)typedef struct WSAOVERLAPPED overlap; WSABUF Buffer; char szMessageMSGSIZE; DWORD NumberOfBytesRecvd; DWORD Flags;PER_IO_OPERATION_DATA, *LPPER_IO_OPERATION_DATA;int g_iTotalConn = 0;SOCKET g_CliSocketArrMAXIMUM_WAIT_OBJECTS;WSAEVENT g_CliEventArrMAXIMUM_WAIT_OBJECTS;LPPER_IO_OPERATION_DATA g_pPerIODataArrMAXIMUM_WAIT_OBJECTS;DWORD WINAPI WorkerThread(LPVOID);void Cleanup(int);int main() WSADATA wsaData; SOCKET sListen, sClient; SOCKADDR_IN local, client; DWORD dwThreadId; int iaddrSize = sizeof(SOCKADDR_IN); / Initialize Windows Socket library WSAStartup(0x0202, &wsaData); / Create listening socket sListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); / Bind local.sin_addr.S_un.S_addr = htonl(INADDR_ANY); local.sin_family = AF_INET; local.sin_port = htons(PORT); bind(sListen, (struct sockaddr *)&local, sizeof(SOCKADDR_IN); / Listen listen(sListen, 3); / Create worker thread CreateThread(NULL, 0, WorkerThread, NULL, 0, &dwThreadId); while (TRUE) / Accept a connection sClient = accept(sListen, (struct sockaddr *)&client, &iaddrSize); printf(Accepted client:%s:%dn, inet_ntoa(client.sin_addr), ntohs(client.sin_port); g_CliSocketArrg_iTotalConn = sClient; / Allocate a PER_IO_OPERATION_DATA structure g_pPerIODataArrg_iTotalConn = (LPPER_IO_OPERATION_DATA)HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(PER_IO_OPERATION_DATA); g_pPerIODataArrg_iTotalConn-Buffer.len = MSGSIZE; g_pPerIODataArrg_iTotalConn-Buffer.buf = g_pPerIODataArrg_iTotalConn-szMessage; g_CliEventArrg_iTotalConn = g_pPerIODataArrg_iTotalConn-overlap.hEvent = WSACreateEvent(); / Launch an asynchronous operation WSARecv( g_CliSocketArrg_iTotalConn, &g_pPerIODataArrg_iTotalConn-Buffer, 1, &g_pPerIODataArrg_iTotalConn-NumberOfBytesRecvd, &g_pPerIODataArrg_iTotalConn-Flags, &g_pPerIODataArrg_iTotalConn-overlap, NULL); g_iTotalConn+; closesocket(sListen); WSACleanup(); return 0;DWORD WINAPI WorkerThread(LPVOID lpParam) int ret, index; DWORD cbTransferred; while (TRUE) ret = WSAWaitForMultipleEvents(g_iTotalConn, g_CliEventArr, FALSE, 1000, FALSE); if (ret = WSA_WAIT_FAILED | ret = WSA_WAIT_TIMEOUT) continue; index = ret - WSA_WAIT_EVENT_0; WSAResetEvent(g_CliEventArrindex); WSAGetOverlappedResult( g_CliSocketArrindex, &g_pPerIODataArrindex-overlap, &cbTransferred, TRUE, &g_pPerIODataArrg_iTotalConn-Flags); if (cbTransferred = 0) / The connection was closed by client Cleanup(index); else / g_pPerIODataArrindex-szMessage contains the received data g_pPerIODataArrindex-szMessagecbTransferred = 0; send(g_CliSocketArrindex, g_pPerIODataArrindex-szMessage, cbTransferred, 0); / Launch another asynchronous operation WSARecv( g_CliSocketArrindex, &g_pPerIODataArrindex-Buffer, 1, &g_pPerIODataArrindex-NumberOfBytesRecvd, &g_pPerIODataArrindex-Flags, &g_pPerIODataArrindex-overlap, NULL); return 0;void Cleanup(int index) closesocket(g_CliSocketArrindex); WSACloseEvent(g_CliEventArrindex); HeapFree(GetProcessHeap(), 0, g_pPerIODataArrindex); if (index overlap.hEvent；使得与该套接字相关联的WSAEVENT对象也被Signaled，所以WSAWaitForMultipleEvents的调用操作成功返回。我们现在应该做的就是用与调用WSARecv相同的WSAOVERLAPPED结构为参数调用WSAGetOverlappedResult，从而得到本次I/O传送的字节数等相关信息。在取得接收的数据后，把数据原封不动的发送到客户端，然后重新激活一个WSARecv异步操作。2.用完成例程方式实现的重叠I/O模型#include #include #define PORT 5150#define MSGSIZE 1024#pragma comment(lib, ws2_32.lib)typedef struct WSAOVERLAPPED overlap; WSABUF Buffer; char szMessageMSGSIZE; DWORD NumberOfBytesRecvd; DWORD Flags; SOCKET sClient;PER_IO_OPERATION_DATA, *LPPER_IO_OPERATION_DATA;DWORD WINAPI WorkerThread(LPVOID);void CALLBACK CompletionROUTINE(DWORD, DWORD, LPWSAOVERLAPPED, DWORD);SOCKET g_sNewClientConnection;BOOL g_bNewConnectionArrived = FALSE;int main() WSADATA wsaData; SOCKET sListen; SOCKADDR_IN local, client; DWORD dwThreadId; int iaddrSize = sizeof(SOCKADDR_IN); / Initialize Windows Socket library WSAStartup(0x0202, &wsaData); / Create listening socket sListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); / Bind local.sin_addr.S_un.S_addr = htonl(INADDR_ANY); local.sin_family = AF_INET; local.sin_port = htons(PORT); bind(sListen, (struct sockaddr *)&local, sizeof(SOCKADDR_IN); / Listen listen(sListen, 3); / Create worker thread CreateThread(NULL, 0, WorkerThread, NULL, 0, &dwThreadId); while (TRUE) / Accept a connection g_sNewClientConnection = accept(sListen, (struct sockaddr *)&client, &iaddrSize); g_bNewConnectionArrived = TRUE; printf(Accepted client:%s:%dn, inet_ntoa(client.sin_addr), ntohs(client.sin_port); DWORD WINAPI WorkerThread(LPVOID lpParam)LPPER_IO_OPERATION_DATA lpPerIOData = NULL; while (TRUE) if (g_bNewConnectionArrived) / Launch an asynchronous operation for new arrived connection lpPerIOData = (LPPER_IO_OPERATION_DATA)HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(PER_IO_OPERATION_DATA); lpPerIOData-Buffer.len = MSGSIZE; lpPerIOData-Buffer.buf = lpPerIOData-szMessage; lpPerIOData-sClient = g_sNewClientConnection; WSARecv(lpPerIOData-sClient, &lpPerIOData-Buffer, 1, &lpPerIOData-NumberOfBytesRecvd, &lpPerIOData-Flags, &lpPerIOData-overlap, CompletionROUTINE); g_bNewConnectionArrived = FALSE; SleepEx(1000, TRUE); return 0;void CALLBACK CompletionROUTINE(DWORD dwError, DWORD cbTransferred, LPWSAOVERLAPPED lpOverlapped, DWORD dwFlags) LPPER_IO_OPERATION_DATA lpPerIOData = (LPPER_IO_OPERATION_DATA)lpOverlapped; if (dwError != 0 | cbTransferred = 0) / Connection was closed by client closesocket(lpPerIOData-sClient); HeapFree(GetProcessHeap(), 0, lpPerIOData); else lpPerIOData-szMessagecbTransferred = 0; send(lpPerIOData-sClient, lpPerIOData-szMessage, cbTransferred, 0); / Launch another asynchronous operation memset(&lpPerIOData-overlap, 0, sizeof(WSAOVERLAPPED); lpPerIOData-Buffer.len = MSGSIZE; lpPerIOData-Buffer.buf = lpPerIOData-szMessage; WSARecv(lpPerIOData-sClient, &lpPerIOData-Buffer, 1, &lpPerIOData-NumberOfBytesRecvd, &lpPerIOData-Flags, &lpPerIOData-overlap, CompletionROUTINE); 用完成例程来实现重叠I/O比用事件通知简单得多。在这个模型中，主线程只用不停的接受连接即可；辅助线程判断有没有新的客户端连接被建立，如果有，就为那个客户端套接字激活一个异步的WSARecv操作，然后调用SleepEx使线程处于一种可警告的等待状态，以使得I/O完成后CompletionROUTINE可以被内核调用。如果辅助线程不调用SleepEx，则内核在完成一次I/O操作后，无法调用完成例程（因为完成例程的运行应该和当初激活WSARecv异步操作的代码在同一个线程之内）。完成例程内的实现代码比较简单，它取出接收到的数据，然后将数据原封不动的发送给客户端，最后重新激活另一个WSARecv异步操作。注意，在这里用到了“尾随数据”。我们在调用WSARecv的时候，参数lpOverlapped实际上指向一个比它大得多的结构PER_IO_OPERATION_DATA，这个结构除了WSAOVERLAPPED以外，还被我们附加了缓冲区的结构信息，另外还包括客户端套接字等重要的信息。这样，在完成例程中通过参数lpOverlapped拿到的不仅仅是WSAOVERLAPPED结构，还有后边尾随的包含客户端套接字和接收数据缓冲区等重要信息。这样的C语言技巧在我后面介绍完成端口的时候还会使用到。五.完成端口模型“完成端口”模型是迄今为止最为复杂的一种I/O模型。然而，假若一个应用程序同时需要管理为数众多的套接字，那么采用这种模型，往往可以达到最佳的系统性能！但不幸的是，该模型只适用于Windows NT和Windows 2000操作系统。因其设计的复杂性，只有在你的应用程序需要同时管理数百乃至上千个套接字的时候，而且希望随着系统内安装的CPU数量的增多，应用程序的性能也可以线性提升，才应考虑采用“完成端口”模型。要记住的一个基本准则是，假如要为Windows NT或Windows 2000开发高性能的服务器应用，同时希望为大量套接字I/O请求提供服务（Web服务器便是这方面的典型例子），那么I/O完成端口模型便是最佳选择！（节选自Windows网络编程第八章）完成端口模型是我最喜爱的一种模型。虽然其实现比较复杂（其实我觉得它的实现比用事件通知实现的重叠I/O简单多了），但其效率是惊人的。我在T公司的时候曾经帮同事写过一个邮件服务器的性能测试程序，用的就是完成端口模型。结果表明，完成端口模型在多连接（成千上万）的情况下，仅仅依靠一两个辅助线程，就可以达到非常高的吞吐量。下面我还是从代码说起：#include #include #define PORT 5150#define MSGSIZE 1024#pragma comment(lib, ws2_32.lib)typedef enum RECV_POSTEDOPERATION_TYPE;typedef struct WSAOVERLAPPED overlap; WSABUF Buffer; char szMessageMSGSIZE; DWORD NumberOfBytesRecvd; DWORD Flags; OPERATION_TYPE OperationType;PER_IO_OPERATION_DATA, *LPPER_IO_OPERATION_DATA;DWORD WINAPI WorkerThread(LPVOID);int main() WSADATA wsaData; SOCKET sListen, sClient; SOCKADDR_IN local, client; DWORD i, dwThreadId; int iaddrSize = sizeof(SOCKADDR_IN); HANDLE CompletionPort = INVALID_HANDLE_VALUE; SYSTEM_INFO systeminfo; LPPER_IO_OPERATION_DATA lpPerIOData = NULL; / Initialize Windows Socket library WSAStartup(0x0202, &wsaData); / Create completion port CompletionPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); / Create worker thread GetSystemInfo(&systeminfo); for (i = 0; i Buffer.len = MSGSIZE; lpPerIOData-Buffer.buf = lpPerIOData-szMessage; lpPerIOData-OperationType = RECV_POSTED; WSARecv(sClient, &lpPerIOData-Buffer, 1, &lpPerIOData-NumberOfBytesRecvd, &lpPerIOData-Flags, &lpPerIOData-overlap, NULL); PostQueuedCompletionStatus(CompletionPort, 0xFFFFFFFF, 0, NULL); CloseHandle(CompletionPort); closesocket(sListen); WSACleanup(); return 0;DWORD WINAPI WorkerThread(LPVOID CompletionPortID) HANDLE CompletionPort=(HANDLE)CompletionPortID; DWORD dwBytesTransferred; SOCKET sClient; LPPER_IO_OPERATION_DATA lpPerIOData = NULL; while (TRUE) GetQueuedCompletionStatus( CompletionPort, &dwBytesTransferred, &sClient, (LPOVERLAPPED *)&lpPerIOData, INFINITE); if (dwBytesTransferred = 0xFFFFFFFF) return 0; if (lpPerIOData-OperationType = RECV_POSTED) if (dwBytesTransferred = 0) / Connection was closed by client closesocket(sClient); HeapFree(GetProcessHeap(), 0, lpPerIOData); else lpPerIOData-szMessagedwBytesTransferred = 0; send(sClient, lpPerIOData-szMessage, dwBytesTransferred, 0); / Launch another asynchronous operation for sClient memset(lpPerIOData, 0, sizeof(PER_IO_OPERATION_DATA); lpPerIOData-Buffer.len = MSGSIZE; lpPerIOData-Buffer.buf = lpPerIOData-szMessage; lpPerIOData-OperationType = RECV_POSTED; WSARecv(sClient, &lpPerIOData-Buffer, 1, &lpPerIOData-NumberOfBytesRecvd, &lpPerIOData-Flags, &lpPerIOData-overlap, NULL); return 0;首先，说说主线程：1.创建完成端口对象2.创建工作者线程（这里工作者线程的数量是按照CPU的个数来决定的，这样可以达到最佳性能）3.创建监听套接字，