epool_server_demo.c

void epoll_server()
{
  for(; ;) {
    nfds = epoll_wait(epfd, events, 20/*maxevents*/, 500/*timeout*/);
    for(i = 0; i < nfds; ++i) {
      // 如果是主socket的事件，则表示有新的连接
      if (events[i].data.fd == listenfd) {
	connfd = accept(listenfd,
			(sockaddr *) &clientaddr,
			&clilen);
	// 将新的fd添加到epoll的监听队列中
	ev.data.fd = connfd;
	ev.events = EPOLLIN|EPOLLET;
	epoll_ctl(epfd, EPOLL_CTL_ADD, connfd, &ev);
      } else if (events[i].events & EPOLLIN) { //接收到数据
	if ((sockfd = events[i].data.fd) < 0)
	  continue;
	n = read(sockfd, line, MAXLINE); //< 0 //读
	ev.data.ptr = md;
	// md为自定义类型，添加数据
	ev.events = EPOLLOUT|EPOLLET;
	// 修改标识符，等待下一个循环时发送数据，异步处理的精髓
	epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);
      } else if (events[i].events & EPOLLOUT) {
	// async write?
	struct myepoll_data* md;
	md = (myepoll_data*)events[i].data.ptr;
	sockfd = md->fd;
	send(sockfd, md->ptr, strlen((char*)md->ptr), 0);
	ev.data.fd = sockfd;
	ev.events = EPOLLIN|EPOLLET;
	// 修改标识符，等待下一个循环时接收数据
	epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);
      } else {
	// 其他情况的处理
      }
    }
  }
}