linux epoll 简单demo

一个简单的epoll demo ,同时接受多个客户端连接,并把接收到的字符串转化为大写字母返回给客户端

 #include<stdio.h>
 #include<arpa/inet.h>
 #include<sys/epoll.h>
 #include<unistd.h>
 #include<ctype.h>
 #define MAXLEN 1024
 #define SERV_PORT 8000
 #define MAX_OPEN_FD 1024

 int main(int argc,char *argv[])
 {
     int  listenfd,connfd,efd,ret;
     char buf[MAXLEN];
     struct sockaddr_in cliaddr,servaddr;
     socklen_t clilen = sizeof(cliaddr);
     struct epoll_event tep,ep[MAX_OPEN_FD];

     listenfd = socket(AF_INET,SOCK_STREAM,);

     servaddr.sin_family = AF_INET;
     servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
     servaddr.sin_port = htons(SERV_PORT);
     bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
     listen(listenfd,);
     // 创建一个epoll fd
     efd = epoll_create(MAX_OPEN_FD);
     tep.events = EPOLLIN;tep.data.fd = listenfd;
     // 把监听socket 先添加到efd中
     ret = epoll_ctl(efd,EPOLL_CTL_ADD,listenfd,&tep);
     // 循环等待
     for (;;)
     {
         // 返回已就绪的epoll_event,-1表示阻塞,没有就绪的epoll_event,将一直等待
         size_t nready = epoll_wait(efd,ep,MAX_OPEN_FD,-);
         for (int i = ; i < nready; ++i)
         {
             // 如果是新的连接,需要把新的socket添加到efd中
             if (ep[i].data.fd == listenfd )
             {
                 connfd = accept(listenfd,(struct sockaddr*)&cliaddr,&clilen);
                 tep.events = EPOLLIN;
                 tep.data.fd = connfd;
                 ret = epoll_ctl(efd,EPOLL_CTL_ADD,connfd,&tep);
             }
             // 否则,读取数据
             else
             {
                 connfd = ep[i].data.fd;
                 int bytes = read(connfd,buf,MAXLEN);
                 // 客户端关闭连接
                 if (bytes == ){
                     ret =epoll_ctl(efd,EPOLL_CTL_DEL,connfd,NULL);
                     close(connfd);
                     printf("client[%d] closed\n", i);
                 }
                 else
                 {
                     for (int j = ; j < bytes; ++j)
                     {
                         buf[j] = toupper(buf[j]);
                     }
                     // 向客户端发送数据
                     write(connfd,buf,bytes);
                 }
             }
         }
     }
     return ;
 }