epoll核反应堆模型

---

/*
*epoll基于非阻塞I/O事件驱动
*/
#include <stdio.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>

#define MAX_EVENTS 1024 //监听上限数
#define BUFLEN 4096
#define SERV_PORT 8080

void recvdata(int fd, int events, void *arg);
void senddata(int fd, int events, void *arg);

/* 描述就绪文件描述符相关信息 */

struct myevent_s {
int fd; //要监听的文件描述符
int events; //对应的监听事件
void *arg; //泛型参数
void (*call_back)(int fd, int events, void *arg); //回调函数
int status; //是否在监听:1->在红黑树上(监听), 0->不在(不监听)
char buf[BUFLEN];
int len;
long last_active; //记录每次加入红黑树 g_efd 的时间值
};

int g_efd; //全局变量, 保存epoll_create返回的文件描述符
struct myevent_s g_events[MAX_EVENTS+1]; //自定义结构体类型数组. +1-->listen fd


/*将结构体 myevent_s 成员变量 初始化*/

void eventset(struct myevent_s *ev, int fd, void (*call_back)(int, int, void *), void *arg)
{
ev->fd = fd;
ev->call_back = call_back;
ev->events = 0;
ev->arg = arg;
ev->status = 0;
//memset(ev->buf, 0, sizeof(ev->buf));
//ev->len = 0;
ev->last_active = time(NULL); //调用eventset函数的时间

return;
}

/* 向 epoll监听的红黑树 添加一个 文件描述符 */

void eventadd(int efd, int events, struct myevent_s *ev)
{
struct epoll_event epv = {0, {0}};
int op;
epv.data.ptr = ev;
epv.events = ev->events = events; //EPOLLIN 或 EPOLLOUT

if (ev->status == 1) { //已经在红黑树 g_efd 里
op = EPOLL_CTL_MOD; //修改其属性
} else { //不在红黑树里
op = EPOLL_CTL_ADD; //将其加入红黑树 g_efd, 并将status置1
ev->status = 1;
}

if (epoll_ctl(efd, op, ev->fd, &epv) < 0) //实际添加/修改
printf("event add failed [fd=%d], events[%d]\n", ev->fd, events);
else
printf("event add OK [fd=%d], op=%d, events[%0X]\n", ev->fd, op, events);

return ;
}

/* 从epoll 监听的 红黑树中删除一个 文件描述符*/

void eventdel(int efd, struct myevent_s *ev)
{
struct epoll_event epv = {0, {0}};

if (ev->status != 1) //不在红黑树上
return ;

epv.data.ptr = ev;
ev->status = 0; //修改状态
epoll_ctl(efd, EPOLL_CTL_DEL, ev->fd, &epv); //从红黑树 efd 上将 ev->fd 摘除

return ;
}

/* 当有文件描述符就绪, epoll返回, 调用该函数 与客户端建立链接 */

void acceptconn(int lfd, int events, void *arg)
{
struct sockaddr_in cin;
socklen_t len = sizeof(cin);
int cfd, i;

if ((cfd = accept(lfd, (struct sockaddr *)&cin, &len)) == -1) {
if (errno != EAGAIN && errno != EINTR) {
/* 暂时不做出错处理 */
}
printf("%s: accept, %s\n", __func__, strerror(errno));
return ;
}

do {
for (i = 0; i < MAX_EVENTS; i++) //从全局数组g_events中找一个空闲元素
if (g_events[i].status == 0) //类似于select中找值为-1的元素
break; //跳出 for

if (i == MAX_EVENTS) {
printf("%s: max connect limit[%d]\n", __func__, MAX_EVENTS);
break; //跳出do while(0) 不执行后续代码
}

int flag = 0;
if ((flag = fcntl(cfd, F_SETFL, O_NONBLOCK)) < 0) { //将cfd也设置为非阻塞
printf("%s: fcntl nonblocking failed, %s\n", __func__, strerror(errno));
break;
}

/* 给cfd设置一个 myevent_s 结构体, 回调函数 设置为 recvdata */

eventset(&g_events[i], cfd, recvdata, &g_events[i]);
eventadd(g_efd, EPOLLIN, &g_events[i]); //将cfd添加到红黑树g_efd中,监听读事件

} while(0);

printf("new connect [%s:%d][time:%ld], pos[%d]\n",
inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), g_events[i].last_active, i);
return ;
}

void recvdata(int fd, int events, void *arg)
{
struct myevent_s *ev = (struct myevent_s *)arg;
int len;

len = recv(fd, ev->buf, sizeof(ev->buf), 0); //读文件描述符, 数据存入myevent_s成员buf中

eventdel(g_efd, ev); //将该节点从红黑树上摘除

if (len > 0) {

ev->len = len;
ev->buf[len] = '\0'; //手动添加字符串结束标记
printf("C[%d]:%s\n", fd, ev->buf);

eventset(ev, fd, senddata, ev); //设置该 fd 对应的回调函数为 senddata
eventadd(g_efd, EPOLLOUT, ev); //将fd加入红黑树g_efd中,监听其写事件

} else if (len == 0) {
close(ev->fd);
/* ev-g_events 地址相减得到偏移元素位置 */
printf("[fd=%d] pos[%ld], closed\n", fd, ev-g_events);
} else {
close(ev->fd);
printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
}

return;
}

void senddata(int fd, int events, void *arg)
{
struct myevent_s *ev = (struct myevent_s *)arg;
int len;

len = send(fd, ev->buf, ev->len, 0); //直接将数据 回写给客户端。未作处理
/*
printf("fd=%d\tev->buf=%s\ttev->len=%d\n", fd, ev->buf, ev->len);
printf("send len = %d\n", len);
*/

if (len > 0) {

printf("send[fd=%d], [%d]%s\n", fd, len, ev->buf);
eventdel(g_efd, ev); //从红黑树g_efd中移除
eventset(ev, fd, recvdata, ev); //将该fd的 回调函数改为 recvdata
eventadd(g_efd, EPOLLIN, ev); //从新添加到红黑树上， 设为监听读事件

} else {
close(ev->fd); //关闭链接
eventdel(g_efd, ev); //从红黑树g_efd中移除
printf("send[fd=%d] error %s\n", fd, strerror(errno));
}

return ;
}

/*创建 socket, 初始化lfd */

void initlistensocket(int efd, short port)
{
int lfd = socket(AF_INET, SOCK_STREAM, 0);
fcntl(lfd, F_SETFL, O_NONBLOCK); //将socket设为非阻塞

/* void eventset(struct myevent_s *ev, int fd, void (*call_back)(int, int, void *), void *arg); */
eventset(&g_events[MAX_EVENTS], lfd, acceptconn, &g_events[MAX_EVENTS]);

/* void eventadd(int efd, int events, struct myevent_s *ev) */
eventadd(efd, EPOLLIN, &g_events[MAX_EVENTS]);

struct sockaddr_in sin;
memset(&sin, 0, sizeof(sin)); //bzero(&sin, sizeof(sin))
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons(port);

bind(lfd, (struct sockaddr *)&sin, sizeof(sin));

listen(lfd, 20);

return ;
}

int main(int argc, char *argv[])
{
unsigned short port = SERV_PORT;

if (argc == 2)
port = atoi(argv[1]); //使用用户指定端口.如未指定,用默认端口

g_efd = epoll_create(MAX_EVENTS+1); //创建红黑树,返回给全局 g_efd
if (g_efd <= 0)
printf("create efd in %s err %s\n", __func__, strerror(errno));

initlistensocket(g_efd, port); //初始化监听socket

struct epoll_event events[MAX_EVENTS+1]; //保存已经满足就绪事件的文件描述符数组
printf("server running:port[%d]\n", port);

int checkpos = 0, i;
while (1) {
/* 超时验证，每次测试100个链接，不测试listenfd 当客户端60秒内没有和服务器通信，则关闭此客户端链接 */

long now = time(NULL); //当前时间
for (i = 0; i < 100; i++, checkpos++) { //一次循环检测100个。 使用checkpos控制检测对象
if (checkpos == MAX_EVENTS)
checkpos = 0;
if (g_events[checkpos].status != 1) //不在红黑树 g_efd 上
continue;

long duration = now - g_events[checkpos].last_active; //客户端不活跃的世间

if (duration >= 60) {
close(g_events[checkpos].fd); //关闭与该客户端链接
printf("[fd=%d] timeout\n", g_events[checkpos].fd);
eventdel(g_efd, &g_events[checkpos]); //将该客户端 从红黑树 g_efd移除
}
}

/*监听红黑树g_efd, 将满足的事件的文件描述符加至events数组中, 1秒没有事件满足, 返回 0*/
int nfd = epoll_wait(g_efd, events, MAX_EVENTS+1, 1000);
if (nfd < 0) {
printf("epoll_wait error, exit\n");
break;
}

for (i = 0; i < nfd; i++) {
/*使用自定义结构体myevent_s类型指针, 接收 联合体data的void *ptr成员*/
struct myevent_s *ev = (struct myevent_s *)events[i].data.ptr;

if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN)) { //读就绪事件
ev->call_back(ev->fd, events[i].events, ev->arg);
}
if ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT)) { //写就绪事件
ev->call_back(ev->fd, events[i].events, ev->arg);
}
}
}

/* 退出前释放所有资源 */
return 0;
}