上一篇文章我详细介绍了如何开发一款高性能的TCP服务器的网络传输层.本章我将谈谈如何开发一个高性能的UDP服务器的网络层.UDP服务器的网络层开发相对与TCP服务器来说要容易和简单的多,UDP服务器的大致流程为创建一个socket然后将其绑定到完成端口上并投递一定数量的recv操作.当有数据到来时从完成队列中取出数据发送到接收队列中即可。
测试结果如下：
WindowsXP Professional，Intel Core Duo E4600 双核2.4G , 2G内存。同时30K个用户和该UDP服务器进行交互其CPU使用率为10%左右，内存占用7M左右。
下面详细介绍该服务器的架构及流程：
下面将主要介绍UdpSer类, 该类主要用来管理UDP服务.其定义如下:
1 class DLLENTRY UdpSer
2 {
3 public:
4 UdpSer();
5 ~UdpSer();
6
7 /**//************************************************************************
8 * Desc : 初始化静态资源，在申请UDP实例对象之前应先调用该函数, 否则程序无法正常运行
9 ************************************************************************/
10 static void InitReource();
11
12 /**//************************************************************************
13 * Desc : 在释放UDP实例以后, 掉用该函数释放相关静态资源
14 ************************************************************************/
15 static void ReleaseReource();
16
17 //用指定本地地址和端口进行初始化
18 BOOL StartServer(const CHAR* szIp = "0.0.0.0", INT nPort = 0);
19
20 //从数据队列的头部获取一个接收数据, pCount不为null时返回队列的长度
21 UDP_RCV_DATA* GetRcvData(DWORD* pCount);
22
23 //向对端发送数据
24 BOOL SendData(const IP_ADDR& PeerAddr, const CHAR* szData, INT nLen);
25
26 /**//****************************************************
27 * Name : CloseServer()
28 * Desc : 关闭服务器
29 ****************************************************/
30 void CloseServer();
31
32 protected:
33 SOCKET m_hSock;
34 vector<UDP_RCV_DATA* > m_RcvDataQue; //接收数据队列
35 CRITICAL_SECTION m_RcvDataLock; //访问m_RcvDataQue的互斥锁
36 long volatile m_bThreadRun; //是否允许后台线程继续运行
37 BOOL m_bSerRun; //服务器是否正在运行
38
39 HANDLE *m_pThreads; //线程数组
40 HANDLE m_hCompletion; //完成端口句柄
41
42 void ReadCompletion(BOOL bSuccess, DWORD dwNumberOfBytesTransfered, LPOVERLAPPED lpOverlapped);
43
44 /**//****************************************************
45 * Name : WorkThread()
46 * Desc : I/O 后台管理线程
47 ****************************************************/
48 static UINT WINAPI WorkThread(LPVOID lpParam);
49 };
1. InitReource() 主要对相关的静态资源进行初始化.其实大致和TcpServer::InitReource()大致相同.在UdpSer实例使用之前必须调用该函数进行静态资源的初始化, 否则服务器无法正常使用.
2.ReleaseReource() 主要对相关静态资源进行释放.只有在应用程序结束时才能调用该函数进行静态资源的释放.
3. StartServer()
该函数的主要功能启动一个UDP服务.其大致流程为先创建服务器UDP socket, 将其绑定到完成端口上然后投递一定数量的recv操作以接收客户端的数据.其实现如下:
1 BOOL UdpSer::StartServer(const CHAR* szIp /**//* = */, INT nPort /**//* = 0 */)
2 {
3 BOOL bRet = TRUE;
4 const int RECV_COUNT = 500;
5 WSABUF RcvBuf = { NULL, 0 };
6 DWORD dwBytes = 0;
7 DWORD dwFlag = 0;
8 INT nAddrLen = sizeof(IP_ADDR);
9 INT iErrCode = 0;
10
11 try
12 {
13 if (m_bSerRun)
14 {
15 THROW_LINE;
16 }
17
18 m_bSerRun = TRUE;
19 m_hSock = WSASocket(AF_INET, SOCK_DGRAM, 0, NULL, 0, WSA_FLAG_OVERLAPPED);
20 if (INVALID_SOCKET == m_hSock)
21 {
22 THROW_LINE;
23 }
24 ULONG ul = 1;
25 ioctlsocket(m_hSock, FIONBIO, &ul);
26
27 //设置为地址重用，优点在于服务器关闭后可以立即启用
28 int nOpt = 1;
29 setsockopt(m_hSock, SOL_SOCKET, SO_REUSEADDR, (char*)&nOpt, sizeof(nOpt));
30
31 //关闭系统缓存，使用自己的缓存以防止数据的复制操作
32 INT nZero = 0;
33 setsockopt(m_hSock, SOL_SOCKET, SO_SNDBUF, (char*)&nZero, sizeof(nZero));
34 setsockopt(m_hSock, SOL_SOCKET, SO_RCVBUF, (CHAR*)&nZero, sizeof(nZero));
35
36 IP_ADDR addr(szIp, nPort);
37 if (SOCKET_ERROR == bind(m_hSock, (sockaddr*)&addr, sizeof(addr)))
38 {
39 closesocket(m_hSock);
40 THROW_LINE;
41 }
42
43 //将SOCKET绑定到完成端口上
44 CreateIoCompletionPort((HANDLE)m_hSock, m_hCompletion, 0, 0);
45
46 //投递读操作
47 for (int nIndex = 0; nIndex < RECV_COUNT; nIndex++)
48 {
49 UDP_CONTEXT* pRcvContext = new UDP_CONTEXT();
50 if (pRcvContext && pRcvContext->m_pBuf)
51 {
52 dwFlag = 0;
53 dwBytes = 0;
54 nAddrLen = sizeof(IP_ADDR);
55 RcvBuf.buf = pRcvContext->m_pBuf;
56 RcvBuf.len = UDP_CONTEXT::S_PAGE_SIZE;
57
58 pRcvContext->m_hSock = m_hSock;
59 pRcvContext->m_nOperation = OP_READ;
60 iErrCode = WSARecvFrom(pRcvContext->m_hSock, &RcvBuf, 1, &dwBytes, &dwFlag, (sockaddr*)(&pRcvContext->m_RemoteAddr)
61 , &nAddrLen, &(pRcvContext->m_ol), NULL);
62 if (SOCKET_ERROR == iErrCode && ERROR_IO_PENDING != WSAGetLastError())
63 {
64 delete pRcvContext;
65 pRcvContext = NULL;
66 }
67 }
68 else
69 {
70 delete pRcvContext;
71 }
72 }
73 }
74 catch (const long &lErrLine)
75 {
76 bRet = FALSE;
77 _TRACE("Exp : %s -- %ld ", __FILE__, lErrLine);
78 }
79
80 return bRet;
81 }4. GetRcvData(), 从接收队列中取出一个数据包.
1 UDP_RCV_DATA *UdpSer::GetRcvData(DWORD* pCount)
2 {
3 UDP_RCV_DATA* pRcvData = NULL;
4
5 EnterCriticalSection(&m_RcvDataLock);
6 vector<UDP_RCV_DATA* >::iterator iterRcv = m_RcvDataQue.begin();
7 if (iterRcv != m_RcvDataQue.end())
8 {
9 pRcvData = *iterRcv;
10 m_RcvDataQue.erase(iterRcv);
11 }
12
13 if (pCount)
14 {
15 *pCount = (DWORD)(m_RcvDataQue.size());
16 }
17 LeaveCriticalSection(&m_RcvDataLock);
18
19 return pRcvData;
20 }
5. SendData() 发送指定长度的数据包.
1 BOOL UdpSer::SendData(const IP_ADDR& PeerAddr, const CHAR* szData, INT nLen)
2 {
3 BOOL bRet = TRUE;
4 try
5 {
6 if (nLen >= 1500)
7 {
8 THROW_LINE;
9 }
10
11 UDP_CONTEXT* pSendContext = new UDP_CONTEXT();
12 if (pSendContext && pSendContext->m_pBuf)
13 {
14 pSendContext->m_nOperation = OP_WRITE;
15 pSendContext->m_RemoteAddr = PeerAddr;
16
17 memcpy(pSendContext->m_pBuf, szData, nLen);
18
19 WSABUF SendBuf = { NULL, 0 };
20 DWORD dwBytes = 0;
21 SendBuf.buf = pSendContext->m_pBuf;
22 SendBuf.len = nLen;
23
24 INT iErrCode = WSASendTo(m_hSock, &SendBuf, 1, &dwBytes, 0, (sockaddr*)&PeerAddr, sizeof(PeerAddr), &(pSendContext->m_ol), NULL);
25 if (SOCKET_ERROR == iErrCode && ERROR_IO_PENDING != WSAGetLastError())
26 {
27 delete pSendContext;
28 THROW_LINE;
29 }
30 }
31 else
32 {
33 delete pSendContext;
34 THROW_LINE;
35 }
36 }
37 catch (const long &lErrLine)
38 {
39 bRet = FALSE;
40 _TRACE("Exp : %s -- %ld ", __FILE__, lErrLine);
41 }
42
43 return bRet;
44 }
6. CloseServer() 关闭服务
1 void UdpSer::CloseServer()
2 {
3 m_bSerRun = FALSE;
4 closesocket(m_hSock);
5 }
7. WorkThread() 在完成端口上工作的后台线程
1 UINT WINAPI UdpSer::WorkThread(LPVOID lpParam)
2 {
3 UdpSer *pThis = (UdpSer *)lpParam;
4 DWORD dwTrans = 0, dwKey = 0;
5 LPOVERLAPPED pOl = NULL;
6 UDP_CONTEXT *pContext = NULL;
7
8 while (TRUE)
9 {
10 BOOL bOk = GetQueuedCompletionStatus(pThis->m_hCompletion, &dwTrans, &dwKey, (LPOVERLAPPED *)&pOl, WSA_INFINITE);
11
12 pContext = CONTAINING_RECORD(pOl, UDP_CONTEXT, m_ol);
13 if (pContext)
14 {
15 switch (pContext->m_nOperation)
16 {
17 case OP_READ:
18 pThis->ReadCompletion(bOk, dwTrans, pOl);
19 break;
20 case OP_WRITE:
21 delete pContext;
22 pContext = NULL;
23 break;
24 }
25 }
26
27 if (FALSE == InterlockedExchangeAdd(&(pThis->m_bThreadRun), 0))
28 {
29 break;
30 }
31 }
32
33 return 0;
34 }
8.ReadCompletion(), 接收操作完成后的回调函数
1 void UdpSer::ReadCompletion(BOOL bSuccess, DWORD dwNumberOfBytesTransfered, LPOVERLAPPED lpOverlapped)
2 {
3 UDP_CONTEXT* pRcvContext = CONTAINING_RECORD(lpOverlapped, UDP_CONTEXT, m_ol);
4 WSABUF RcvBuf = { NULL, 0 };
5 DWORD dwBytes = 0;
6 DWORD dwFlag = 0;
7 INT nAddrLen = sizeof(IP_ADDR);
8 INT iErrCode = 0;
9
10 if (TRUE == bSuccess && dwNumberOfBytesTransfered <= UDP_CONTEXT::S_PAGE_SIZE)
11 {
12#ifdef _XML_NET_
13 EnterCriticalSection(&m_RcvDataLock);
14
15 UDP_RCV_DATA* pRcvData = new UDP_RCV_DATA(pRcvContext->m_pBuf, dwNumberOfBytesTransfered, pRcvContext->m_RemoteAddr);
16 if (pRcvData && pRcvData->m_pData)
17 {
18 m_RcvDataQue.push_back(pRcvData);
19 }
20 else
21 {
22 delete pRcvData;
23 }
24
25 LeaveCriticalSection(&m_RcvDataLock);
26#else
27 if (dwNumberOfBytesTransfered >= sizeof(PACKET_HEAD))
28 {
29 EnterCriticalSection(&m_RcvDataLock);
30
31 UDP_RCV_DATA* pRcvData = new UDP_RCV_DATA(pRcvContext->m_pBuf, dwNumberOfBytesTransfered, pRcvContext->m_RemoteAddr);
32 if (pRcvData && pRcvData->m_pData)
33 {
34 m_RcvDataQue.push_back(pRcvData);
35 }
36 else
37 {
38 delete pRcvData;
39 }
40
41 LeaveCriticalSection(&m_RcvDataLock);
42 }
43#endif
44
45 //投递下一个接收操作
46 RcvBuf.buf = pRcvContext->m_pBuf;
47 RcvBuf.len = UDP_CONTEXT::S_PAGE_SIZE;
48
49 iErrCode = WSARecvFrom(pRcvContext->m_hSock, &RcvBuf, 1, &dwBytes, &dwFlag, (sockaddr*)(&pRcvContext->m_RemoteAddr)
50 , &nAddrLen, &(pRcvContext->m_ol), NULL);
51 if (SOCKET_ERROR == iErrCode && ERROR_IO_PENDING != WSAGetLastError())
52 {
53 ATLTRACE("/r/n%s -- %ld dwNumberOfBytesTransfered = %ld, LAST_ERR = %ld"
54 , __FILE__, __LINE__, dwNumberOfBytesTransfered, WSAGetLastError());
55 delete pRcvContext;
56 pRcvContext = NULL;
57 }
58 }
59 else
60 {
61 delete pRcvContext;
62 }
63 }