C/S通信---服务器IO多路复用模型之epoll的使用

服务端代码：

#include<stdio.h>

#include<sys/socket.h>
#include<unistd.h>
#include<sys/types.h>
#include<errno.h>
#include<string.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<sys/epoll.h>    //mac下不支持，可以使用kqueue

int main()
{
int socket_fd,connect_fd;
struct sockaddr_in servaddr, cliaddr;
char buff[3];
struct epoll_event ev;
struct epoll_event events[4096];
int n;
int acceptCount = 0;
socklen_t socklen = sizeof(struct sockaddr_in);
//create socket
if((socket_fd = socket(AF_INET,SOCK_STREAM,0)) == -1)
{
printf("create socket error!\n");
exit(0);
}

//set local address
memset(&servaddr,0,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(8000);

//bind the local addr to socket
if(bind(socket_fd,(struct sockaddr*)&servaddr,sizeof(servaddr)) == -1)
{
printf("bind error %d!\n",errno);
exit(0);
}

//listen client
if(listen(socket_fd,10) == -1)
{
printf("listen error\n");
exit(0);
}
printf("wait for client connection!\n");

/* 创建 epoll 句柄，把监听 socket 加入到 epoll 集合里 */
int kdpfd = epoll_create(4096);
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = listenfd;
if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, socket_fd, &ev) < 0)
{
fprintf(stderr, "epoll set insertion error: fd=%d\n", socket_fd);
return -1;
}
int curfds = 1;

while(1){
/* 等待有事件发生 */
int nfds = epoll_wait(kdpfd, events, curfds, -1);
if (nfds == -1)
{
perror("epoll_wait");
continue;
}
/* 处理所有事件 */
for (n = 0; n < nfds; ++n)
{
if (events[n].data.fd == socket_fd)
{
int connfd = accept(socket_fd, (struct sockaddr *)&cliaddr,&socklen);
if (connfd < 0)
{
perror("accept error");
continue;
}

sprintf(buf, "accept form %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port);
printf("%d:%s", ++acceptCount, buf);

if (curfds >= 4096) {
fprintf(stderr, "too many connection, more than %d\n", 4096);
close(connfd);
continue;
}
if (fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFD, 0)|O_NONBLOCK) == -1)
{
perror("setnonblocking error");
}
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = connfd;
if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, connfd, &ev) < 0)
{
fprintf(stderr, "add socket '%d' to epoll failed: %s\n", connfd, strerror(errno));
return -1;
}
curfds++;
continue;
}
// 处理客户端请求
if (handle(events[n].data.fd) < 0) {
epoll_ctl(kdpfd, EPOLL_CTL_DEL, events[n].data.fd,&ev);
curfds--;


}
}
}
close(socket_fd);
return 0;
}

int handle(int connfd) {
int nread;
char buf[4096];
nread = read(connfd, buf, 4096);//读取客户端socket流
printf("%s\n",buf);

if (nread == 0) {
printf("client close the connection\n");
close(connfd);
return -1;
}
if (nread < 0) {
perror("read error");
close(connfd);
return -1;
}
write(connfd, buf, nread);//响应客户端
return 0;
}