windows下的IO模型之选择（select）模型

bool UDPNet::SelectSocket()
{
	timeval tv;
	tv.tv_sec =0;
	tv.tv_usec = 100;
	fd_set fdsets;//创建集合
	FD_ZERO(&fdsets); //初始化集合

	FD_SET(m_socklisten,&fdsets);//将socket加入到集合中（此例子是一个socket）,将多个socket加入时，可以用数组加for循环

	select(NULL,&fdsets,NULL,NULL,&tv);//只检查可读性，即fd_set中的fd_read进行操作

	if(!FD_ISSET(m_socklisten,&fdsets))//检查 s是否s e t集合的一名成员；如答案是肯定的是，则返回 T R U E。
	{
		return false;
	}
	return true;
}

#include "stdafx.h"
#include <WinSock2.h>
#include <iostream>
using namespace std;

#include <stdio.h>

#pragma comment(lib,"ws2_32.lib")

#define PORT 8000
#define MSGSIZE 255
#define SRV_IP "127.0.0.1"

int g_nSockConn = 0;//请求连接的数目

//FD_SETSIZE是在winsocket2.h头文件里定义的，这里windows默认最大为64
//在包含winsocket2.h头文件前使用宏定义可以修改这个值


struct ClientInfo
{
    SOCKET sockClient;
    SOCKADDR_IN addrClient;
};

ClientInfo g_Client[FD_SETSIZE];

DWORD WINAPI WorkThread(LPVOID lpParameter);

int _tmain(int argc, _TCHAR* argv[])
{//基本步骤就不解释了，网络编程基础那篇博客里讲的很详细了
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2,2),&wsaData);

    SOCKET sockListen = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);

    SOCKADDR_IN addrSrv;
    addrSrv.sin_addr.S_un.S_addr = inet_addr(SRV_IP);
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(PORT);

    bind(sockListen,(SOCKADDR*)&addrSrv,sizeof(SOCKADDR));

    listen(sockListen,64);

    DWORD dwThreadIDRecv = 0;
    DWORD dwThreadIDWrite = 0;

    HANDLE hand = CreateThread(NULL,0, WorkThread,NULL,0,&dwThreadIDRecv);//用来处理手法消息的进程
    if (hand == NULL)
    {
        cout<<"Create work thread failed\n";
        getchar();
        return -1;
    }

    SOCKET sockClient;
    SOCKADDR_IN addrClient;
    int nLenAddrClient = sizeof(SOCKADDR);//这里用0初试化找了半天才找出错误

    while (true)
    {
        sockClient = accept(sockListen,(SOCKADDR*)&addrClient,&nLenAddrClient);//第三个参数一定要按照addrClient大小初始化
        //输出连接者的地址信息
        //cout<<inet_ntoa(addrClient.sin_addr)<<":"<<ntohs(addrClient.sin_port)<<"has connect !"<<endl;

        if (sockClient != INVALID_SOCKET)
        {
            g_Client[g_nSockConn].addrClient = addrClient;//保存连接端地址信息
            g_Client[g_nSockConn].sockClient = sockClient;//加入连接者队列
            g_nSockConn++;
        }


    }

    closesocket(sockListen);
    WSACleanup();

    return 0;
}

DWORD WINAPI WorkThread(LPVOID lpParameter)
{
    FD_SET fdRead;
    int nRet = 0;//记录发送或者接受的字节数
    TIMEVAL tv;//设置超时等待时间
    tv.tv_sec = 1;
    tv.tv_usec = 0;
    char buf[MSGSIZE] = "";

    while (true)
    {
        FD_ZERO(&fdRead);
        for (int i = 0;i < g_nSockConn;i++)
        {
            FD_SET(g_Client[i].sockClient,&fdRead);
        }

        //只处理read事件，不过后面还是会有读写消息发送的
        nRet = select(0,&fdRead,NULL,NULL,&tv);

        if (nRet == 0)
        {//没有连接或者没有读事件
            continue;
        }

        for (int i = 0;i < g_nSockConn;i++)
        {
            if (FD_ISSET(g_Client[i].sockClient,&fdRead))
            {
                nRet = recv(g_Client[i].sockClient,buf,sizeof(buf),0);

                if (nRet == 0 || (nRet == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET))
                {
                    cout<<"Client "<<inet_ntoa(g_Client[i].addrClient.sin_addr)<<"closed"<<endl;
                    closesocket(g_Client[i].sockClient);

                    if (i < g_nSockConn-1)
                    {
                        //将失效的sockClient剔除，用数组的最后一个补上去
                        g_Client[i--].sockClient = g_Client[--g_nSockConn].sockClient;
                    }
                }
                else
                {
                    cout<<inet_ntoa(g_Client[i].addrClient.sin_addr)<<": "<<endl;
                    cout<<buf<<endl;
                    cout<<"Server:"<<endl;
                    //gets(buf);
                    strcpy(buf,"Hello!");
                    nRet = send(g_Client[i].sockClient,buf,strlen(buf)+1,0);
                }
            }
        }
    }
    return 0;
}