#define IPADDRESS   "127.0.0.1"

#define PORT        8787

#define MAXSIZE     1024

#define LISTENQ     5

#define FDSIZE      1000

#define EPOLLEVENTS 100

listenfd = socket_bind(IPADDRESS,PORT);

struct epoll_event events[EPOLLEVENTS];

//创建一个描述符

epollfd = epoll_create(FDSIZE);

//添加监听描述符事件

add_event(epollfd,listenfd,EPOLLIN);

//循环等待

for ( ; ; ){

    //该函数返回已经准备好的描述符事件数目

    ret = epoll_wait(epollfd,events,EPOLLEVENTS,-);

    //处理接收到的连接

    handle_events(epollfd,events,ret,listenfd,buf);

}

//事件处理函数

static void handle_events(int epollfd,struct epoll_event *events,int num,int listenfd,char *buf)

{

     int i;

     int fd;

     //进行遍历;这里只要遍历已经准备好的io事件。num并不是当初epoll_create时的FDSIZE。

     for (i = ;i < num;i++)

     {

         fd = events[i].data.fd;

        //根据描述符的类型和事件类型进行处理

         if ((fd == listenfd) &&(events[i].events & EPOLLIN))

            handle_accpet(epollfd,listenfd);

         else if (events[i].events & EPOLLIN)

            do_read(epollfd,fd,buf);

         else if (events[i].events & EPOLLOUT)

            do_write(epollfd,fd,buf);

     }

}

//添加事件

static void add_event(int epollfd,int fd,int state){

    struct epoll_event ev;

    ev.events = state;

    ev.data.fd = fd;

    epoll_ctl(epollfd,EPOLL_CTL_ADD,fd,&ev);

}

//处理接收到的连接。将文件描述符添加到epoll监控队列

static void handle_accpet(int epollfd,int listenfd){

     int clifd;

     struct sockaddr_in cliaddr;

     socklen_t  cliaddrlen;

     clifd = accept(listenfd,(struct sockaddr*)&cliaddr,&cliaddrlen);

     if (clifd == -)

         perror("accpet error:");

     else {

         printf("accept a new client: %s:%d\n",inet_ntoa(cliaddr.sin_addr),cliaddr.sin_port);  //添加一个客户描述符和事件

         add_event(epollfd,clifd,EPOLLIN);

     }

}

//读处理

static void do_read(int epollfd,int fd,char *buf){

    int nread;

    nread = read(fd,buf,MAXSIZE);

    if (nread == -)     {

        perror("read error:");

        close(fd); //记住close fd

        delete_event(epollfd,fd,EPOLLIN); //删除监听

    }

    else if (nread == )     {

        fprintf(stderr,"client close.\n");

        close(fd); //记住close fd

        delete_event(epollfd,fd,EPOLLIN); //删除监听

    }

    else {

        printf("read message is : %s",buf);

        //修改描述符对应的事件，由读改为写

        modify_event(epollfd,fd,EPOLLOUT);

    }

}

//写处理

static void do_write(int epollfd,int fd,char *buf) {

    int nwrite;

    nwrite = write(fd,buf,strlen(buf));

    if (nwrite == -){

        perror("write error:");

        close(fd);   //记住close fd

        delete_event(epollfd,fd,EPOLLOUT);  //删除监听

    }else{

        modify_event(epollfd,fd,EPOLLIN);

    }

    memset(buf,,MAXSIZE);

}

//删除事件

static void delete_event(int epollfd,int fd,int state) {

    struct epoll_event ev;

    ev.events = state;

    ev.data.fd = fd;

    epoll_ctl(epollfd,EPOLL_CTL_DEL,fd,&ev);

}

//修改事件

static void modify_event(int epollfd,int fd,int state){

    struct epoll_event ev;

    ev.events = state;

    ev.data.fd = fd;

    epoll_ctl(epollfd,EPOLL_CTL_MOD,fd,&ev);

}

//注：另外一端我就省了