网络模型：epoll

#include 
#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 
#include 

#define IPADDRESS "127.0.0.1"
#define PORT      6666
#define MAXSIZE   1024
#define LISTENQ   5
#define FDSIZE    1000
#define EPOLLEVENTS 100

// 创建套接字并进行绑定
int socket_bind(const char * ip, int port);
// IO多路复用epoll
void do_epoll(int listenfd);
// 事件处理函数
void handle_events(int epollfd, struct epoll_event * events, int num, int listenfd, char * buf);
// 处理接收到的连接
void handle_accept(int epollfd, int listenfd);
// 读处理
void do_read(int epollfd, int fd, char * buf);
// 写处理
void do_write(int epollfd, int fd, char * buf);
// 添加事件
void add_event(int epollfd, int fd, int state);
// 修改事件
void modify_event(int epollfd, int fd, int state);
// 删除事件
void delete_event(int epollfd, int fd, int state);

int main(int argc, char * argv[]){
	int listenfd;
	listenfd = socket_bind(IPADDRSS, PORT);
	listen(listenfd, LISTENQ);
	do_epoll(listenfd);
	return 0;
}

int socket_bind(const char * ip, int port){
	int listenfd;
	struct sockaddr_in serveraddr;
	listenfd = socket(AF_INET, SOCK_STREAM, 0);
	if(listenfd == -1){
		perror("socket error:");
		exit(1);
	}
	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	inet_pton(AF_INET, ip, &serveraddr.sin_addr);
	servaddr.sin_port = htons(port);
	if(bind(listenfd, (struct sockaddr*)&serveraddr, sizeof(servaddr)) == -1){
		perror("bind error");
		exit(1);
	}
	return listenfd;
}

void do_epoll(int listenfd){
	int epollfd;
	struct epoll_event events[EPOLLEVENTS];
     int ret;
     char buf[MAXSIZE];
	memset(buf, 0, MAXSIZE);
	// 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);
     while(1){
     	// 获取已经准备好的描述符事件
     	ret = epoll_wait(epollfd, events, EPOLLEVENTS, -1);
     	handle_events(epollfd, events, ret, listenfd, buf);
     }
	close(epollfd);
}

void handle_events(int epollfd, struct epoll_event* events, int num, int listenfd, char *buf){
	int i ;
	int fd;
	// 遍历
	for(i = 0;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_accept(epollfd, listenfd);
		else if(events[i].events & EPOLLIN)
			do_read(epollfd, fd, buf);
		else if(events[i].events & EPOLLIN)
			do_write(epollfd, fd, buf);
	}
}

void handle_accept(int epollfd, int listenfd){
	int clifd;
	struct sockddr_in cliaddr;
	socklen_t cliaddrlen;
	clifd = accept(listenfd, (struct sockaddr*)&cliaddr, &cliaddrlen);
	if(clifd == -1)
		perror("accept error:");
	else{
		printf("...");
		// 添加一个客户描述符和事件
		add_event(epollfd, clifd, EPOLLIN);
	}
}

...
void add_event(int epollfd, int fd, int state){
	sturct epoll_event ev;
	ev.events = state;
	ev.data.fd = fd;
	epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
}