本文参考于《Windows网络与通信程序设计》
基于WSAEventSelect模型的服务器设计
对于WSAEventSelect模型，一个工作线程最多能够处理64个套接字，故采用线程池来管理大于64个套接字的请求。
//定义套接字结构体
typedef struct _SOCKET_OBJ
{
SOCKET s; //套接字句柄
HANDLE event; //与此套接字相关的事件对象句柄
sockaddr_in addrRemote; //客户端地址信息
_SOCKET_OBJ *pNext; //指向下一个SOCKET_OBJ对象,形成链表
} SOCKET_OBJ, *PSOCKET_OBJ;
//申请一个套接字对象，初始化它的成员
PSOCKET_OBJ GetSocketObj(SOCKET s)
{
PSOCKET_OBJ pSocket = (PSOCKET_OBJ)::GloblAlloc(GPTR, sizeof(SOCKET_OBJ));
if (pSocket != NULL)
{
pSocket->s = s;
pSocket->enent = ::WSACreateEvent();
}
return pSocket;
}
//释放一个套接字对象
void FreeSocketObj(PSOCKET_OBJ pSocket)
{
::CloseHandle(pSocket->event);
if (pSocket->s != INVALID_SOCKET)
{ ::closesocket(pSocket->s); }
::GlobalFree(pSocket);
}
//定义线程结构体
typedef struct _THREAD_OBJ
{
HANDLE enents[WSA_MAXIMUM_WAIT_EVENTS]; //记录当前线程要等待的事件对象句柄
int nSocketCount; //记录当前线程处理的套接字数量<= WSA_MAXIMUM_WAIT_EVENTS
PSOCKET_OBJ pSockHeader; //当前线程处理的套接字对象列表,指向表头
PSOCKET_OBJ pSockTail; //指向表尾
CRITICAL_SECTION cs; //关键代码段变量，为的是同步对本结构对象的访问
_THREAD_OBJ *pNext; //指向下一个THREAD_OBJ对象，为的是连成一个表
}THREAD_OBJ, *PTHREAD_OBJ;
//全局变量
PTHREAD_OBJ g_pThreadList; //指向线程对象列表表头
CRITICAL_SECTION g_cs; //同步对此全局变量的访问
//申请一个线程对象，初始化它的成员，并将它添加到线程对象列表中
PTHREAD_OBJ GetThreadObj()
{
PTHREAD_OBJ pThread = (PTHREAD_OBJ)::GlobalAlloc(GPTR, sizeof(THREAD_OBJ));
if (pThread != NULL)
{
::InitislizeCriticlSection(&pThread->cs);
//创建一个事件对象，用于指示该线程的句柄数组需要重建
pThread->events[0] = ::WSACreateEvent();
//将申请的线程对象添加到列表
::EnterCriticalSection(&g_cs);
pThread->pNext = g_pThreadList;
g_pThreadLsit = pThread;
::LeaveCriticalSection(&g_cs);
}
return pThread;
}
//释放一个线程对象，将它从线程对象列表中移除
void FreeThreadObj(PTHREAD_OBJ pThread)
{
::EnterCriticalSection(&g_cs);
PTHREAD_OBJ p = g_pThreadList;
if (p == pThread ) //是第一个
{ g_pThreadList = p->pNext; }
else
{
while (p != NULL && p->pNext != pThread)
{ p = p->pNext; }
if (p != NULL)
{
p->pNext = pThread->pNext;
}
}
::LeaveCriticalSection(&g_cs);
//释放资源
::CloseHande(pThread->events[0]);
::DeleteCriticalSection(&pThread->cs);
::GlobalFree(pThread);
}
//重写建立线程对象的events数组
void RebulidArray(PTHREAD_OBJ pThread)
{
::EnterCriticalSection(&pThread->cs);
PSOCKET_OBJ pSocket = pThread->pSockHeader;
int n = 1; // 从第一个开始写，第0个用于指示需要重建了
while(pSocket != NULL)
{
pThread->events[n++] = pSocket->event;
pSocket = pSocket->pNext;
}
::LeaveCriticalSection(&pThread->cs);
}
LONG g_nTatolConnections; //总共连接数量
LONG g_nCurrentConnections; //当前连接数量
//向一个线程的套接字列表中插入一个套接字
BOOL InsertSocketObj(PTHREAD_OBJ pThread, PSOCKET_OBJ pSocket)
{
BOOL bRet = FALSE;
::EnterCriticalSection(&pThread->cs);
if (pThread->nSocketCount < WSA_MAXIMUM_WAIT_EVENTS -1)
{
if (pThread->pSocketHeader == NULL)
{ pThread->pSocketHeader = pThead->pSocketTail = pSocket;}
else
{
pThread->pSockTail->pNext = pSocket;
pThread->pSockTail = pSocket;
}
pThead->nSocketCount++;
bRet = TRUE;
}
::LeaveCriticalSection(&pThread->cs);
//插入成功，说明成功处理了客户的连接请求
if (bRet)
{
::InterlockedIncrement(&g_nTatolConnections);
::InterlockedIncrement(&g_nCurrentConnections);
}
return bRet;
}
//将一个套接字对象安排给空闲的线程处理
void AssignToFreeThread(PSOCKET_OBJ pSocket)
{
pSocket->pNext = NULL;
::EnterCriticalSection(&g_cs);
PTHREAD_OBJ pThread = g_pThreadList;
while (pThread != NULL)
{
if (InsertSocketObj(pThread,pSocket)) break;
pThread = pThread->pNext;
}
//没有空闲的线程，为这个套接字创建新的线程
if (pThread == NULL)
{
pThread = GetThreadObj();
InsertSocketObj(pThread,pSocket);
::CreateThread(NULL, 0 , ServerThread, pThread, 0 , NULL);
}
::LeaveCriticalSection(&g_cs);
//指示线程重建句柄数组
::WSASetEvent(pThread->events[0]);
}
//从给定线程的套接字对象列表中移除一个套接字对象
void RemoveSocketObj(PTHREAD_OBJ pThread, PSOCKET_OBJ pSocket)
{
::EnterCriticakSection(&pThread->cs);
//在套接字对象列表中查找指定的套接字对象，找到之后将之移除
PSOCKET_OBJ pTest = pThread->pSockHeader;
if (pTest == pSocket)
{
if (pThread->pSockHeader == pThread->pSockTail)
pThread->pSockTail = pThread->pSockHeader = pTest->pNext;
else
pThread->pSockHeader = pTest->pNext;
}
else
{
while (pTest != NULL && pTest->pNext != pSocket)
pTest = pTest->pNext;
if (pTest != NULL)
{
if (pThread->pSockTail == pSocket) pThread->pSockTail = pTest;
pTest->pNext = pSocket->pNext;
}
}
pThread->nSocketCount--;
::LeaveCriticalSection(&pThread->cs);
::WSASetEvent(pThread->event[0]); //指示线程重建句柄数组
::InterlockedDecrement(&g_nCurrentConnections); //说明一个连接中断
}
//处理I/O的线程
DWORD WINAPI ServerThread(LPVOID lpParam)
{
//取得本线程对象的指针
PTHREAD_OBJ pThread = (PTHREAD_OBJ)lpParam;
while(TRUE)
{
//等待网络事件
int nIndex = ::WSAWaitForMultipleEvents(
pThread->nSocketCount + 1, pThread->events,FALSE,WSA_INFINITE,FALSE);
nIndex = nIndex - WSA_WAIT_EVENT_0;
//查看受信的事件对象
for (int i = nIndex; i < pThread->nSocketCount + 1; i++)
{
nIndex = ::WSAWaitForMultipleEvents(1, &pThread->events[i], TRUE,1000,FALSE);
if (nIndex == WSA_WAIT_FAILED || nIndex == WSA_WAIT_TIMEOUT)
continue;
else
{
if (i == 0) //enents[0]受信，重建数组
{
RebuildArray(pThread);
//如果没有客户I/O处理了，则本线程退出
if (pThread->nSocketCount == 0)
{
FreeThreadObj(pThread);
return 0;
}
::WSAResetEvent(pThread->events[0]);
}
else
{
PSOCKET_OBJ pSocket = (PSOCKET_OBJ)FindSocketObj(pThread, i);
if (pSocket != NULL)
{
if (!HandleIO(pThread, pSocket))
RebuildArray(pThread);
}
else
printf("Unable to find socket object \n");
}
}
}
}
return 0;
}
//根据事件对象在events数组中的索引查找相应的套接字对象
PSOCKET_OBJ FindSocketObj(PTHREAD_OBJ pThread, int nIndex) //nIndex从1开始
{
//在套接字列表中查询
PSOCKET_OBJ pSocket = pThread->pSockHeader;
while (--nIndex)
{
if (pSocket == NULL)
return NULL;
pSocket = pSocket->pNext;
}
return pSocket;
}
//具体发生的网络事件
BOOL HandleIO(PTHREAD_OBJ pThread, PSOCKET_OBJ pSocket)
{
//获取具体发生的网络事件
WSANETWORKEVENTS event;
::WSAEnumNetworkEvents(pSocket->s, pSocket->event,&event);
do
{
if (event.lNetworkEvents & FD_READ) //套接字可读
{
if (event.iErrorCode[FD_READ_BIT] == 0)
{
char szText[256];
int nRecv = ::recv(pSocket->s,szText,strlen(szText),0);
if (nRecv > 0)
{
szText[nRecv] = '\0';
printf("接收到数据: %s \n",szText);
}
}
else
break;
}
else if (event.lNetworkEvents & FD_CLOSE) //套接字关闭
break;
else if (event.lNetworkEvents & FD_WRITE) //套接字可写
{
if (event.iErrorCode[FD_WRITE_BIT] == 0)
{ }
else
break;
return TRUE;
}
}while(FALSE);
RemoveSocketObj(pThread,pSocket);
FreeSocketObj(pSocket);
return FALSE;
}
//主线程
int main()
{
USHORT nPort = 4567; //此服务器监听端口
SOCKET sListen = ::socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
sockaddr_in sin;
sin.sin_family = AF_INET;
sin.sin_port = htons(nPort);
sin.sin_addr.S_un.S_addr = INADDR_ANY;
if (::bind(sListen, (sockaddr*)&sin, sizeof(sin)) == SOCKET_ERROR)
{
printf("Failed bind() \n");
return -1;
}
::listen(sListen,200);
//创建事件对象，并关联到监听的套接字
WSAEVENT event = ::WSACreateEvent();
::WSAEventSelect(sListen, event, FD_ACCEPT|FD_CLOSE);
::InitializeCriticalSection(&g_cs);
//处理客户连接请求，打印状态信息
while(TRUE)
{
int nRet = ::WaitForSingleObject(event, 5*1000);
if (nRet == WAIT_FAILED)
{
printf("Failed WaitForSingleObject() \n");
break;
}
else if (nRet == WSA_WAIT_TIMEOUT)
{
printf("\n");
printf(" TatolConnections:%d\n",g_nTatolConnections);
printf("CurrentConnections:%d\n",g_nCurrentConnections);
continue;
}
else //有新的连接
{
::ResetEvent(event);
//循环处理所有的未决的连接请求
while(TRUE)
{
sockaddr_in si;
int nLen = sizeof(si);
SOCKET sNew = ::accept(sListen, (sockaddr*)&si, &nLen);
if (sNew == SOCKET_ERROR)
break;
PSOCKET_OBJ pSocket = GetSocketObj(sNew);
pSocket->addrRemote = si;
::WSAEventSelect(pSocket->s, pSocket->evnet, FD_READ|FD_CLOSE|FD_WRITE);
AssignToFreeThread(pSocket);
}
}
}
::DeleteCriticalSection(&g_cs);
return 0;
}