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说明

使用IO完成端口实现简单回显服务器，因为是测试用的，所以代码很粗糙。

• 提醒
  使用的是ReadFile、WriteFile来实现Overlapped IO，正式场合应该用WSARecv、WSASend，原因：来自《Windows网络编程技术》 8.2.5节
  在这里插入图片描述

• 技术点记录下
  io以同步方式立马完成时,系统也会将此通知投递到io完成端口通知列表中，这么做的原因是方便用户编码。
  SetFileCompletionNotificationModes传入FILE_SKIP_COMPLETION_PORT_ON_SUCCESS告诉系统，io以同步方式立马完成时，不要
  将此事件投递到IO完成端口列表中。

  参看《Windows核心编程》第10章 10.5.4
  
  

代码

#include <iostream>
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <WinSock2.h>
#include <set>
#include <memory>
#include <process.h>#pragma comment(lib, "Ws2_32.lib")class MyOverlapped
{
public:MyOverlapped():m_bIsRead(false){memset(&m_Overlapped, 0, sizeof(OVERLAPPED));}OVERLAPPED m_Overlapped;bool m_bIsRead;
};struct ClientSocketItem
{ClientSocketItem(){hSocket = NULL;memset(szRecv, 0, sizeof(szRecv));nRecvSize = 0;bFinished = false;nWriteOffset = 0;readOverlapped.m_bIsRead = true;writeOverlapped.m_bIsRead = false;}SOCKET hSocket;std::string strIp;MyOverlapped readOverlapped;char szRecv[1024];unsigned int nRecvSize;MyOverlapped writeOverlapped;unsigned int nWriteOffset = 0;bool bFinished;
};
std::set<ClientSocketItem*> g_Clients;HANDLE g_hIoCompletionPort = NULL;bool do_read(ClientSocketItem* pClient)
{if (!pClient){return false;}char c = 0; //测试用，每次只读一个字符DWORD dwReadBytes;if (::ReadFile((HANDLE)(pClient->hSocket), &(pClient->szRecv[pClient->nRecvSize]),1, &dwReadBytes, &(pClient->readOverlapped.m_Overlapped))){return true;}DWORD dwError = ::GetLastError();if (ERROR_IO_PENDING == dwError){return true;}std::cerr << "read failed with error " << dwError << std::endl;return false;
}bool do_write(ClientSocketItem* pClient)
{if (!pClient){return false;}//测试用，每次只发送一个字符DWORD dwWriteBytes = 0;if (::WriteFile((HANDLE)(pClient->hSocket), &(pClient->szRecv[pClient->nWriteOffset]),1, &dwWriteBytes, &(pClient->writeOverlapped.m_Overlapped))){return true;}DWORD dwError = ::GetLastError();if (ERROR_IO_PENDING == dwError){return true;}std::cerr << "write failed with error " << dwError << std::endl;return false;
}bool do_accept(SOCKET hListenSocket)
{sockaddr_in mPeerAddr = { 0 };int nAddrLen = sizeof(sockaddr);SOCKET hClientSocket = accept(hListenSocket, (sockaddr*)(&mPeerAddr), &nAddrLen);if (INVALID_SOCKET == hClientSocket){std::cout << "accept failed with error "<< WSAGetLastError() << std::endl;return false;}else{unsigned long nNoBlock = 0;ioctlsocket(hClientSocket, FIONBIO, &nNoBlock);std::string strIpAddr = inet_ntoa(mPeerAddr.sin_addr);std::cout << "accept success, peer ip is " << strIpAddr.c_str() << std::endl;auto pClient = new ClientSocketItem();pClient->hSocket = hClientSocket;pClient->strIp = strIpAddr;g_Clients.insert(pClient);//附加到IO完成端口上if (g_hIoCompletionPort != ::CreateIoCompletionPort(HANDLE(pClient->hSocket),g_hIoCompletionPort, ULONG_PTR(pClient), 0)){std::cerr << "attach socket to io completion port failed with error"<< ::GetLastError() << std::endl;closesocket(hClientSocket);return false;}//触发读取if (!do_read(pClient)){closesocket(pClient->hSocket);g_Clients.erase(pClient);std::cerr << "do_read failed, close client" << std::endl;}return true;}
}//读写线程函数
unsigned __stdcall ReadWriteThreadFun(void* pParam)
{DWORD dwTransferBytes = 0;ULONG_PTR nCompleteKey = 0;LPOVERLAPPED lpOverlapped = NULL;while (::GetQueuedCompletionStatus(g_hIoCompletionPort, &dwTransferBytes,&nCompleteKey, &lpOverlapped, INFINITE)){if (nCompleteKey == UINT_MAX){std::cout << "user require quit" << std::endl;break;}if (!lpOverlapped){std::cerr << "lpOverlapped is null" << std::endl;break;}ClientSocketItem* pClient = (ClientSocketItem*)nCompleteKey;MyOverlapped* pMyOverlapped = CONTAINING_RECORD(lpOverlapped, MyOverlapped, m_Overlapped);if (!pMyOverlapped || !pClient){std::cerr << "pMyOverlapped or pClient is null" << std::endl;break;}if (pMyOverlapped->m_bIsRead)//read finished notify{char c = pClient->szRecv[pClient->nRecvSize];pClient->nRecvSize += dwTransferBytes;std::cout << "read one char: " << c << std::endl;if (c == '\n'){std::cout << "read finished, start to write" << std::endl;if (!do_write(pClient)){std::cerr << "do_write failed, close socket" << std::endl;closesocket(pClient->hSocket);g_Clients.erase(pClient);}}else{std::cout << "next char read" << std::endl;if (!do_read(pClient)){std::cerr << "do_read failed, close socket" << std::endl;closesocket(pClient->hSocket);g_Clients.erase(pClient);}}}else //write finished notify{char c = pClient->szRecv[pClient->nWriteOffset];std::cout << "send one char: " << c << std::endl;pClient->nWriteOffset += dwTransferBytes;if (pClient->nWriteOffset == pClient->nRecvSize){std::cout << "send finished, close client(" << pClient->strIp.c_str()<< ")" << std::endl;closesocket(pClient->hSocket);g_Clients.erase(pClient);}else{std::cout << "next send" << std::endl;if (!do_write(pClient)){std::cerr << "do_write failed, close socket" << std::endl;closesocket(pClient->hSocket);g_Clients.erase(pClient);}}}}std::cout << "thread quit" << std::endl;return 0;
}int main(int argc, char* argv)
{WORD wVersionRequested = MAKEWORD(2, 2);WSADATA wsaData = { 0 };int err = WSAStartup(wVersionRequested, &wsaData);if (err != 0){return -1;}if (LOBYTE(wsaData.wVersion) != 2 ||HIBYTE(wsaData.wVersion) != 2){WSACleanup();return -1;}SOCKET hListenSocket = socket(AF_INET, SOCK_STREAM, 0);if (INVALID_SOCKET == hListenSocket){std::cerr << "create socket failed with error " << WSAGetLastError()<< std::endl;return -1;}sockaddr_in mSockAddrIn = { 0 };mSockAddrIn.sin_family = AF_INET;mSockAddrIn.sin_port = htons((u_short)8878);mSockAddrIn.sin_addr.S_un.S_addr = inet_addr("0.0.0.0");if (SOCKET_ERROR == bind(hListenSocket, (sockaddr*)(&mSockAddrIn),sizeof(sockaddr))){std::cerr << "bind failed with error " << WSAGetLastError() << std::endl;return -1;}if (SOCKET_ERROR == listen(hListenSocket, SOMAXCONN)){std::cerr << "listen failed with error " << WSAGetLastError() << std::endl;return -1;}//创建完成端口g_hIoCompletionPort = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);if (NULL == g_hIoCompletionPort){std::cerr << "create io completion port failed with error " << ::GetLastError() << std::endl;return -1;}//创建一堆服务线程for (int i = 0; i < 4; ++i){_beginthreadex(0, 0, ReadWriteThreadFun, 0, 0, nullptr);}while (true){if (!do_accept(hListenSocket)){break;}}::PostQueuedCompletionStatus(g_hIoCompletionPort, 0, UINT_MAX, nullptr);Sleep(2000); return 0;
}