基于非阻塞socket的多线程服务器

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大家好，我是涛哥。

没错，今天周三。最近写了一个服务端程序，能与多个客户端进行通信。那么，这个服务端是怎么实现的呢？很简单，它就是很常规的多线程服务器。

涛哥手绘

服务端实现

既然是多线程服务器，那么，这些线程肯定是有明确分工的。主线程来处理网络的连接，而通信线程来处理客户端与服务端的通信。

而且，主线程要负责多个客户端的连接请求，所以不能阻塞主线程哦，因此必须用非阻塞socket. 于是，我写的服务端程序如下：

#include <stdio.h>#include <winsock2.h>   #include <windows.h>#pragma comment(lib, "ws2_32.lib")#define BUF_SIZE  100
sockaddr_in addrClient; // 为了让通信线程获取ip
// 通信线程DWORD  WINAPI  CommThread(LPVOID  lp)  {     SOCKET sClient = (SOCKET)(LPVOID)lp;  
   while(1)   {         char buf[BUF_SIZE] = {0};      int retVal = recv(sClient, buf, BUF_SIZE, 0);     if(SOCKET_ERROR == retVal)        {          int err = WSAGetLastError();       if(WSAEWOULDBLOCK == err) // 暂时没有数据       {         Sleep(100);         continue;       }     }   
    // 输出客户端连接信息    SYSTEMTIME st;    GetLocalTime(&st);    char sDateTime[100] = {0};    sprintf(sDateTime, "%4d-%2d-%2d %2d:%2d:%2d", st.wYear, st.wMonth, st.wDay, st.wHour, st.wMinute, st.wSecond);    printf("%s, The client is [%s:%d]. Msg from client is : %s\n", sDateTime, inet_ntoa(addrClient.sin_addr), addrClient.sin_port, buf);           char msg[BUF_SIZE] = {0};      sprintf(msg, "Message received is : %s", buf);     while(1)    {      retVal = send(sClient, msg, strlen(msg), 0);  // 回显      if(SOCKET_ERROR == retVal)         {           int err = WSAGetLastError();        if(err == WSAEWOULDBLOCK)        {          Sleep(500);          continue;        }      }
      break;    }        }
   closesocket(sClient);   } int main(){    WSADATA wsd;       WSAStartup(MAKEWORD(2, 2), &wsd);       SOCKET sServer = socket(AF_INET, SOCK_STREAM, 0);   
    // 设置套接字为非阻塞模式    int iMode = 1;    ioctlsocket(sServer, FIONBIO, (u_long FAR*) &iMode);
    // 设置服务器套接字地址       SOCKADDR_IN addrServ;       addrServ.sin_family = AF_INET;       addrServ.sin_port = htons(8888);    addrServ.sin_addr.S_un.S_addr = htonl(INADDR_ANY);    
    bind(sServer,(const struct sockaddr*)&addrServ, sizeof(SOCKADDR_IN));   
    listen(sServer, 10);   
    printf("Server start...\n");    int addrClientlen = sizeof(addrClient);       while(1)    {      SOCKET sClient = accept(sServer, (sockaddr FAR*)&addrClient, &addrClientlen);         if(INVALID_SOCKET == sClient)         {           int err = WSAGetLastError();        if(WSAEWOULDBLOCK == err)  // 无法立即完成非阻塞套接字上的操作        {          Sleep(100);          continue;      }    } 
    // 创建通信线程    CreateThread(NULL, NULL, CommThread, (LPVOID)sClient, 0, NULL);   }
    // 释放套接字       closesocket(sServer);       WSACleanup();   
    getchar();    return 0;}

编译并运行程序，开启服务端，等待客户端的连接。

客户端实现

我们可以看到，上述服务端的程序需要有主线程和通信线程，而客户端的程序就相对简单了，主线程本身就是通信线程。程序如下：

#include <winsock2.h>#include <stdio.h>#pragma comment(lib, "ws2_32.lib")
int main(){  WORD wVersionRequested;  WSADATA wsaData;  wVersionRequested = MAKEWORD(2, 2);
  WSAStartup( wVersionRequested, &wsaData );
  SOCKET sockClient = socket(AF_INET, SOCK_STREAM, 0);
  SOCKADDR_IN addrSrv;  addrSrv.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");  addrSrv.sin_family = AF_INET;  addrSrv.sin_port = htons(8888);  connect(sockClient, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));
  send(sockClient, "hello world", strlen("hello world") + 1, 0);  char recvBuf[100] = {0};  recv(sockClient, recvBuf, 100, 0);  printf("%s\n", recvBuf);
  while(1);
  closesocket(sockClient);  WSACleanup();
  return 0;}