服务器分发消息，求服务器压力最小化方案

[qscool1987]

前天开始研究网络编程这块，感觉理解起来还是很容易，这多亏了看过windows核心编程这本书。

不多说了，先上代码：

#include "stdafx.h"   
#include <windows.h>   
#include <process.h>   
#include <iostream>   
#include <string>   
#include <vector>   
using namespace std;  
#pragma comment(lib,"ws2_32.lib")   
  
vector<SOCKET> clientSockets;  
/*recive message thread*/  
DWORD WINAPI ClientThread(LPVOID lp)  
{  
    SOCKET sock = (SOCKET)lp;//----------   
    char szbuff[1024];  
    int ret;  
    while(1)  
    {  
        //perform a blocking recv() call   
        ret = recv(sock,szbuff,1024,0);  
        if(ret == 0)  
            break;  
        else if(ret == SOCKET_ERROR)  
        {  
            cout << "recv() failed " << WSAGetLastError() << endl;  
            break;  
        }  
        szbuff[ret] = '\0';  
        cout << "RECV:" << szbuff <<  " " << ret << "bytes" << endl;  
    }  
    return 0;  
}  
  
/*send message thread*/  
DWORD WINAPI SendThread(LPVOID lp)  
{  
    int ret;  
    string msg;  
    typedef vector<SOCKET>::iterator iter;  
    while(1)  
    {  
        cin >> msg;  
        iter beg = clientSockets.begin();  
        for(;beg != clientSockets.end();beg++)  
        {  
            ret = send(*beg,msg.c_str(),msg.length() + 1,0);  
            if(ret == 0)  
                break;  
            else if(ret == SOCKET_ERROR)  
            {  
                cout << "send failed " << WSAGetLastError() << endl;  
                break;  
            }  
        }  
    }  
    return 0;  
}  
  
int _tmain(int argc, _TCHAR* argv[])  
{  
    //Initialize Winsock   
    WSADATA wsd;  
    if(WSAStartup(MAKEWORD(2,2),&wsd) != 0)  
    {  
        cout << "Failled to load Winsock!" << endl;  
        return 1;  
    }  
    //create our listening socket   
    SOCKET sListen,sClient;  
    sListen = socket(AF_INET,SOCK_STREAM,IPPROTO_IP);  
    if(sListen == SOCKET_ERROR)  
    {  
        cout << "socket() failed " << WSAGetLastError() << endl;  
        return 1;  
    }  
    //Select local interface and bind to it   
    struct sockaddr_in local,client;  
    int iport = 5000;  
    local.sin_addr.s_addr = htonl(INADDR_ANY);  
    local.sin_port = htons(iport);  
    local.sin_family = AF_INET;  
    if(bind(sListen,(SOCKADDR*)&local,sizeof(local)) == SOCKET_ERROR)  
    {  
        cout << "bind() failed " << WSAGetLastError() << endl;  
        return 1;  
    }  
    listen(sListen,8);  
    cout << "server side is in listening status!" << endl;  
    //Waitfor incoming clients,Once one is detected,create thread and pass   
    //the handle off to it   
    int iAddrSize(0);  
    //HANDLE hThread;   
    //DWORD dwThreadId,dwSendThreadId;   
    bool createSendRecvFlag = true;  
    while(1)  
    {  
        iAddrSize = sizeof(client);  
        sClient = accept(sListen,(SOCKADDR*)&client,&iAddrSize);  
        if(sClient == INVALID_SOCKET)  
        {  
            cout << "accept() failed " << WSAGetLastError() << endl;  
            break;  
        }  
        cout << "Accept client:" << inet_ntoa(client.sin_addr) << endl;  
        cout << ntohs(client.sin_port) << endl;  
  
        /*save all the client sockets*/  
        clientSockets.push_back(sClient);  
  
        DWORD dwThreadId,dwSendThreadId;  
        if(createSendRecvFlag)      //create one send thread for all the clients   
        {  
            HANDLE hSendThread = CreateThread(NULL,0,SendThread,  
                (LPVOID)&clientSockets,0,&dwSendThreadId);  
            createSendRecvFlag = false;  
            if(hSendThread == NULL)  
            {  
                cout << "CreateThread() failed " << GetLastError() << endl;  
                break;  
            }  
            CloseHandle(hSendThread);  
        }  
        //create a recive thread for a client   
        HANDLE hThread = CreateThread(NULL,0,ClientThread,  
                (LPVOID)sClient,0,&dwThreadId);  
        if(hThread == NULL)  
        {  
            cout << "CreateThread() failed " << GetLastError() << endl;  
            break;  
        }  
        CloseHandle(hThread);  
    }  
    closesocket(sListen);  
    WSACleanup();  
    return 0;  
}  

这是服务器端代码，这里涉及到两点

1.针对于客服端发来的消息怎么处理

2.如何将消息发送给所有的客服端

我的解决办法是，用一个全局变量vector<SOCKET> clientSockets;保存每一个accept来的客服端socket，给每一个客服端socket创建一个接受消息线程，而只创建一个发送消息线程统一给所有客服端发送消息。

这其实也好理解：其一服务器发送给每个客服端的消息是相同的所以只需要一个线程，遍历每一个客服端socket即可，其二客服端发送给服务器端的消息是不同的，所以采用多线程机制，不过这样也不太好，如果客服端过多，那么服务器要管理的线程就会很多，但是如果只建立一个接受线程又会出现消息阻塞情况，有待深入研究这个问题。

下面是客服端代码：

#include "stdafx.h"   
#include <windows.h>   
#include <process.h>   
#include <iostream>   
#include <string>   
using namespace std;  
#pragma comment(lib,"ws2_32.lib")   
  
/*recive message thread*/  
DWORD WINAPI ClientThread(LPVOID lp)  
{  
    SOCKET sock = (SOCKET)lp;  
    char szbuff[1024];  
    int ret;  
    while(1)  
    {  
        ret = recv(sock,szbuff,1024,0);  
        if(ret == 0)  
            break;  
        else if(ret == SOCKET_ERROR)  
        {  
            cout << "recv() failed " << WSAGetLastError() << endl;  
            break;  
        }  
        szbuff[ret] = '\0';  
        cout << "recv " << szbuff << " " << ret << "bytes" << endl;  
    }  
    return 0;  
}  
/*send message thread*/  
DWORD WINAPI SendThread(LPVOID lp)  
{  
    SOCKET sock = (SOCKET)lp;  
    string msg;  
    int ret;  
    while(1)  
    {  
        cin >> msg;  
        ret = send(sock,msg.c_str(),msg.length() + 1,0);  
        if(ret == 0)  
            break;  
        else if(ret == SOCKET_ERROR)  
        {  
            cout << "send failed " << WSAGetLastError() << endl;  
            break;  
        }  
    }  
    return 0;  
}  
  
int _tmain(int argc, _TCHAR* argv[])  
{  
    WSADATA wsd;  
    SOCKET  sClient;  
    struct sockaddr_in server;  
    struct hostent *host = NULL;  
    //load Winsock   
    if(WSAStartup(MAKEWORD(2,2),&wsd) != 0)  
    {  
        cout << "Failled to load Winsock!" << endl;  
        return 1;  
    }  
    //create socket and attempt to connect to the server   
    sClient = socket(AF_INET,SOCK_STREAM,IPPROTO_IP);  
    if(sClient == INVALID_SOCKET)  
    {  
        cout << "socket failed " << WSAGetLastError() << endl;  
        return 1;  
    }  
    string szServer;  
    u_short iport;  
    cout << "please input IP address: " << endl;  
    cin >> szServer;  
    cout << "please input port number: " << endl;  
    cin >> iport;  
    server.sin_addr.s_addr = inet_addr(INADDR_ANY);  
    server.sin_family = AF_INET;  
    server.sin_port = htons(iport);  
    //if the supplied server address isn't in the form   
    //"aaa.bbb.ccc.ddd" it's a host name,so try to resolve it   
    if(server.sin_addr.s_addr == INADDR_NONE)  
    {  
        host = gethostbyname(szServer.c_str());  
        if(host == NULL)  
        {  
            cout << "unable to resolve server: " << szServer << endl;  
            return 1;  
        }  
        CopyMemory(&server.sin_addr,host->h_addr_list[0],host->h_length);  
    }  
      
    if(connect(sClient,(SOCKADDR*)&server,sizeof(server))==SOCKET_ERROR)  
    {  
        cout << "connect failed " << WSAGetLastError() << endl;  
        return 1;  
    }  
    cout << "connect succeed!" << endl;  
    DWORD dwThreadId,dwSendThreadId;  
    HANDLE hThread = CreateThread(NULL,0,ClientThread,  
            (LPVOID)sClient,0,&dwThreadId);  
    HANDLE hSendThread = CreateThread(NULL,0,SendThread,  
            (LPVOID)sClient,0,&dwSendThreadId);  
    if(hThread == NULL)  
    {  
        cout << "CreateThread() failed " << GetLastError() << endl;  
    }  
    if(hSendThread == NULL)  
    {  
        cout << "CreateThread() failed " << GetLastError() << endl;  
    }  
    CloseHandle(hThread);  
    CloseHandle(hSendThread);  
  
    //prevent main thread exit;   
    while(1)  
    {  
  
    }  
    closesocket(sClient);  
    WSACleanup();  
    return 0;  
}  

客服端就简单多了，就是一个收线程，一个发线程，不过这种问题只适合CS架构。至于服务器转发P2P架构就需要服务器帮助解析客服端地址了，这个想来应该不难，稍后再做研究吧

总体来说，网络编程还是要比较深厚的编程基础的，至少对于多线程要有很好的理解，难度到不大，主要就是理解一些库函数，所以更重要的问题就是设计问题，如何让服务器端的压力最小化，最优化，这点需要长期思考。
如果谁有更好的解决方案请留个言，谢谢了！

[qscool1987]

运行客服端输入 192.168.0.2，端口输入 5000
不过这是在我的机子上可以连上，如果要拿去试先用下面这段代码看看电脑的IP地址

if(gethostname (Name, sizeof(Name)) == 0)
    { 
         //如果成功地将本地主机名存放入由name参数指定的缓冲区中 
        if((hostinfo = gethostbyname(Name)) != NULL) 
        { 
            //这是获取主机名，如果获得主机名成功的话，将返回一个指针，指向hostinfo，hostinfo 
            //为PHOSTENT型的变量，下面即将用到这个结构体 
            strIP = inet_ntoa (*(struct in_addr *)*hostinfo->h_addr_list);
        }
    }

[dickbarry]

你可以看一下IOCP相关的知识，一定会有所裨益