多路复用io接口-epoll

多路复用io接口-epoll的使用.

服务端使用epoll接口处理多个客户的服务请求.

例:

服务端代码

myepoll.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <sys/time.h>
#include <sys/resource.h>

#define MAXBUF 1024
#define MAXEPOLLSIZE 10000

/*
* setnonblocking - 设置sockfd为非阻塞方式
*/
int setnonblocking(int sockfd)
{
if (fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFD, 0)|O_NONBLOCK) == -1) {
perror("fcntl");
return -1;
}
return 0;
}

/*
* handle_message - 处理每个 socket 上的消息收发
*/
int handle_message(int new_fd)
{
char buf[MAXBUF + 1];
int len;
/* 开始处理每个新连接上的数据收发 */
bzero(buf, MAXBUF + 1);
/* 接收客户端的消息 */
len = recv(new_fd, buf, MAXBUF, 0);
//printf("[%s-%d]*********\n", __func__, __LINE__);
if (len > 0) {
printf ("%d接收消息成功:'%s'，共%d个字节的数据\n", new_fd, buf, len);
} else {
if (len < 0) {
printf("消息接收失败！错误代码是%d，错误信息是'%s'\n", errno, strerror(errno));
}
close(new_fd);
return -1;
}
/* 处理每个新连接上的数据收发结束 */
return len;
}

int main(int argc, char **argv)
{
int listener, new_fd, kdpfd, nfds, n, ret, curfds;
socklen_t len;
struct sockaddr_in my_addr, their_addr;
unsigned int myport, lisnum;
struct epoll_event ev;
struct epoll_event events[MAXEPOLLSIZE];
struct rlimit rt;

//if ((argc >= 2) && isdigit(atoi(argv[1])))
if (argc >= 2) {
myport = atoi(argv[1]);
} else {
myport = 7838;
}
printf("myport = %d\n", myport);

//if ((argc >= 3) && isdigit(atoi(argv[2])))
if (argc >= 3) {
lisnum = atoi(argv[2]);
} else {
lisnum = 2;
}
printf("linum = %d\n", lisnum);

/* 设置每个进程允许打开的最大文件数 */
rt.rlim_max = rt.rlim_cur = MAXEPOLLSIZE;
if (setrlimit(RLIMIT_NOFILE, &rt) == -1) {
perror("setrlimit");
exit(1);
} else {
printf("[line-%d]设置系统资源参数成功！\n", __LINE__);
}

/* 开启 socket 监听 */
if ((listener = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(1);
} else {
printf("[line-%d]socket 创建成功！\n", __LINE__);
}
setnonblocking(listener);

bzero(&my_addr, sizeof(my_addr));
my_addr.sin_family = PF_INET;
my_addr.sin_port = htons(myport);
if(argv[3]) {
my_addr.sin_addr.s_addr = inet_addr(argv[3]);
} else {
my_addr.sin_addr.s_addr = INADDR_ANY;
}
if (bind(listener, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) == -1) {
perror("bind");
exit(1);
} else {
printf("[line-%d]IP 地址和端口绑定成功\n", __LINE__);
}

if (listen(listener, lisnum) == -1) {
perror("listen");
exit(1);
} else {
printf("[line-%d]开启服务成功！\n", __LINE__);
}

/* 创建 epoll 句柄，把监听 socket 加入到 epoll 集合里 */
kdpfd = epoll_create(MAXEPOLLSIZE);
len = sizeof(struct sockaddr_in);
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = listener;
if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, listener, &ev) < 0) {
fprintf(stderr, "epoll set insertion error: fd=%d\n", listener);
return -1;
} else {
printf("[line-%d]监听 socket 加入 epoll 成功！\n", __LINE__);
}
curfds = 1;
while(1) {
/* 等待有事件发生 */
nfds = epoll_wait(kdpfd, events, curfds, -1);
if (nfds == -1) {
perror("epoll_wait");
break;
}
/* 处理所有事件 */
for (n = 0; n < nfds; ++n) {
if (events
.data.fd == listener) {
new_fd = accept(listener, (struct sockaddr *) &their_addr, &len);
if (new_fd < 0) {
perror("accept");
continue;
} else {
printf("有连接来自于： %s:%d， 分配的 socket 为:%d\n",
inet_ntoa(their_addr.sin_addr),
ntohs(their_addr.sin_port), new_fd);
}
setnonblocking(new_fd);
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = new_fd;
if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, new_fd, &ev) < 0) {
fprintf(stderr, "把 socket '%d' 加入 epoll 失败！%s\n", new_fd, strerror(errno));
return -1;
}
curfds++;
} else {
ret = handle_message(events
.data.fd);
if (ret < 1 && errno != 11) {
epoll_ctl(kdpfd, EPOLL_CTL_DEL, events
.data.fd, &ev);
curfds--;
}
}
}
}
close(listener);
return 0;
}

客户端代码:

client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <unistd.h>
/*
send data as "send ipaddr port message"
*/

int    main(int argc, char *argv[])
{
int sock_fd;
struct sockaddr_in client_addr;
struct sockaddr_in server_addr;
char buf[1024];
int    len;
int ret;

if(4 != argc)
{
printf("argc\n");
exit(1);
}

if(-1 == (sock_fd = socket(AF_INET, SOCK_STREAM, 0)))
{
printf("socket\n");
exit(2);
}

server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(atoi(argv[2]));
server_addr.sin_addr.s_addr = inet_addr(argv[1]);

if(-1 == (ret = connect(sock_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)))){
perror("connect");
goto    ERR;
}

strcpy(buf, argv[3]);
len = strlen(argv[3]);
printf("[%s-L%d]\n", __func__, __LINE__);
#if 1
if(-1 == (ret = send(sock_fd, buf, len, 0))){
perror("send: ");
}
#endif
printf("[%s-L%d]\n", __func__, __LINE__);
getchar();
ERR:
close(sock_fd);

}

编译链接, 在两个不同的终端运行,输出如下:

服务端



客户端. 按如下顺序在不同的终端执行, 并输出结果(上图服务端的输出也对应如下客户端执行顺序):