基于重叠IO模型的 回显TCP服务器设计

---------------------1 套接字对象----------------------

为每一个套接字建立一个SOCKET_OBJ对象，记录与之相关的信息。

typedef struct _SOCKET_OBJ{ SOCKET s; int nOutstandingOps;//重叠IO数量
    LPFN_ACCEPTEX lpfnAcceptEx; //扩展AcceptEx指针
}SOCKET_OBJ,*PSOCKET_OBJ;

全部重叠IO提交到特定的套接字上，释放对应套接字对象，必须保证此套接字再没有重叠IO，即nOutstandingOps=0

申请套接字对象，释放套接字对象的函数

 PSOCKET_OBJ GetSocketObj(SOCKET s){ PSOCKET_OBJ pSocket = (PSOCKET_OBJ)::GlobalAlloc(GPTR,sizeof(SOCKET_OBJ)); if(pSocket != NULL) pSocket->s = s; return pSocket; } void FreeSocketObj(PSOCKET_OBJ pSocket){ if(pSocket->s != INVALID_SOCKET) ::closesocket(pSocket->s); ::GlobalFree(pSocket); }

---------------------2 缓冲区对象---------------------

缓冲区对象SOCKET_OBJ，记录重叠IO的全部属性

typedef struct _BUFFER_OBJ{ OVERLAPPED ol;//重叠结构
    char *buff;//使用的缓冲区
    int nLen;//buff长度
    PSOCKET_OBJ pSocket;//次io所属的套接字对象
    int nOperation;//提交的操做类型
#define OP_ACCEPT    1
#define OP_READ        2
#define OP_WRITE    3 SOCKET sAccept;//保存AcceptEx接受客户套接字
    _BUFFER_OBJ *pNext; }BUFFER_OBJ,*PBUFFER_OBJ;

pNext将BUFFER_OBJ对象练成一个链表

事件句柄数组 和 链表地址

HANDLE g_events[WSA_MAXIMUM_WAIT_EVENTS]; int g_nBufferCount;//数量
PBUFFER_OBJ g_pBufferHead,g_pBufferTail;//地址

调用重叠IO函数以前，都要申请BUFFER_OBJ对象，记录信息。IO完成后，再释放BUFFER_OBJ对象

申请BUFFER_OBJ对象 的函数：

PBUFFER_OBJ GetBufferObj(PSOCKET_OBJ pSocket,ULONG nLen){ if(g_nBufferCount > WSA_MAXIMUM_WAIT_EVENTS) return NULL; PBUFFER_OBJ pBuffer = (PBUFFER_OBJ)::GlobalAlloc(GPTR,sizeof(BUFFER_OBJ)); if(pBuffer!=NULL) { pBuffer->buff = (char*)::GlobalAlloc(GPTR,nLen); pBuffer->ol.hEvent = ::WSACreateEvent(); pBuffer->pSocket = pSocket; pBuffer->sAccept = INVALID_SOCKET; //将新的BUFFER_OBJ添加到列表
        if(g_pBufferHead == NULL) { g_pBufferHead = g_pBufferTail = pBuffer; } else { g_pBufferTail->pNext = pBuffer; g_pBufferTail = pBuffer; } g_events[++g_nBufferCount] = pBuffer->ol.hEvent; } return pBuffer; }

释放BUFFER_OBJ对象函数：

void FreeBufferObj(PBUFFER_OBJ pBuffer){ //从列表中移除BUFFER_OBJ对象
    PBUFFER_OBJ pTest = g_pBufferHead; BOOL bFind = FALSE; if(pTest == pBuffer){ g_pBufferHead = g_pBufferTail = NULL; bFind = TRUE; } else{ while(pTest!=NULL && pTest->pNext!=pBuffer) pTest = pTest->pNext; if(pTest!=NULL){ pTest->pNext = pBuffer->pNext; if(pTest->pNext == NULL) g_pBuffer Tail = pTest; bFind = TRUE; } } //释放它占用的空间
    if(bFind) { g_pBufferCount--; ::CloseHandle(pBuffer->ol.hEvent); ::GlobalFree(pBuffer->buff); ::GlobalFree(pBuffer); } }

提交重叠IO，传递参数有重叠结构IO和缓冲区指针buff。在IO完成后，获得的是受信事件对象的句柄。根据这个句柄找到对应的BUFFER_OBJ对象。

查找BUFFER_OBJ对象的代码：

PBUFFER_OBJ FindBufferObj(HANDLE hEvent){ PBUFFER_OBJ pBuffer = g_pBufferHead; while(pBuffer != NULL){ if(pBuffer->ol.hEvent == hEvent) break; pBuffer = pBuffer->pNext; } return pBuffer; }

更新时间句柄数组g_events中的内容：

void RebuildArray(){ PBUFFER_OBJ pBuffer = g_pBufferHead; int i= 1; while(pBuffer != NULL){ g_events[i++] = pBuffer->ol.hEvent; pBuffer = pBuffer->pNext; } }

---------------------3 提交重叠IO---------------------

投递IO以后，线程在重叠IO事件上等待，一旦IO事件对象受信，等待函数就会返回

提交接受链接的BUFFER_OBJ对象代码：

BOOL PostAccept(PBUFFER_OBJ pBuffer){ PSOCKET_OBJ pSocket = pBuffer->pSocket; if(pSocket->lpfnAcceptEx != NULL){ //设置IO类型，增长套接字上的重叠IO计数
        pBuffer->nOperation = OP_ACCEPT; pSocket->nOutstandingOps++; //投递此重叠IO
 DWORD dwBytes; pBuffer->sAccept = ::WSASocket(AF_INET,SOCK_STREAM,0,NULL,0,WSA_FLAG_OVERLAPPED); BOOL b = pSocket->lpfnAcceptEx( pSocket->s, pBuffer->sAccept, pBuffer->buff, BUFFER_SIZE - ((sizeof(sockaddr_in+16))*2), sizeof(sockaddr_in)+16, sizeof(sockaddr_in)+16, &dwBytes, &pBuffer->ol ); if(!b){ if(::WSAGetLastError()!=WSA_IO_PENDING) return FALSE; } return TRUE; } return FALSE; };

接收数据的BUFFER_OBJ对象代码：

BOOL PostRecv(PBUFFER_OBJ pBuffer){ //设置IO类型，增长套接字上的重叠IO计数
    pBuffer->nOperation = OP_ACCEPT; pBuffer->pSocket->nOutstandingOps++; //投递此重叠IO
 DWORD dwBytes; DWORD dwFlags = 0; WSABUF buf; buf.buf = pBuffer->buff; buf.len = pBuffer->nLen; if(::WSARecv(pBuffer->pSocket->s,&buf,1,&dwBytes,&dwFlags,&pBuffer->ol,NULL)!=NO_ERROR){ if(::WSAGetLastError()!= WSA_IO_PENDING) return FALSE; } return TRUE; }

发送数据额BUFFER-obj对象代码：

BOOL PostSend(PBUFFER_OBJ pBuffer){ //设置IO类型，增长套接字上的重叠IO计数
    pBuffer->nOperation = OP_ACCEPT; pBuffer->pSocket->nOutstandingOps++; //投递此重叠IO
 DWORD dwBytes; DWORD dwFlags; WSABUF buf; buf.buf = pBuffer->buff; buf.len = pBuffer->nLen; if(::WSASend(pBuffer->pSocket->s,&buf,1,&dwBytes,&dwFlags,&pBuffer->ol,NULL)!=NO_ERROR){ if(::WSAGetLastError()!=WSA_IO_PENDING) return FALSE; } return TRUE; }

---------------------4 主函数---------------------