epoll函数分析

来源：互联网发布：巨人网络总部地址编辑：程序博客网时间：2024/06/06 16:25

阻塞IO和进程的多路复用。

相比select的优点：

epoll();
1.高效
2.监控无上限

epoll的使用：
epoll_create/epoll_creatl(创建监听池)
epoll_ctl（添加监听事件）
epoll_wait（等待事件发生）

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <fcntl.h>#include <sys/epoll.h> int main(){      int fd1,fd2;    int efd;    struct epoll_event event;    struct epoll_event *events;    char c;       //创建fifo    mkfifo("/tmp/fifo1",0666);    mkfifo("/tmp/fifo2",0666);       fd1 = open("/tmp/fifo1",O_RDONLY);    fd2 = open("/tmp/fifo2",O_RDONLY);    //创建监听池    efd = epoll_create1(0);    //构造监听事件，加入监听池    event.events = EPOLLIN|EPOLLET;    event.data.fd = fd1;    epoll_ctl(efd,EPOLL_CTL_ADD,fd1,&event);         event.events = EPOLLIN|EPOLLET;    event.data.fd = fd2;    epoll_ctl(efd,EPOLL_CTL_ADD,fd2,&event);         int n = 0;    events = calloc(100,sizeof(event));    n =  epoll_wait(efd,events,100,-1);    int i = 0;    for(i = 0;i<n;i++)    {        if(events[i].events&EPOLLIN)        {            read(events[i].data.fd,&c,1);            printf("file %d can be read\n",events[i].data.fd);        }         if(events[i].events&EPOLLOUT)        {           //处理        }              if(events[i].events&EPOLLERR)        {             //处理        }    }    free(events);    close(fd1);    close(fd2);     }

测试1：ew1.c

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <fcntl.h>#include <sys/epoll.h>int main(){    int fd;    char c='c';    fd = open("/tmp/fifo1",O_WRONLY);    write(fd,&c,1);    close(fd);    return 0;}

测试1：ew2.c

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <fcntl.h>#include <sys/epoll.h>int main(){    int fd;    char c='c';    fd = open("/tmp/fifo2",O_WRONLY);    write(fd,&c,1);    close(fd);    return 0;}

运行epoll 程序进入阻塞状态，然后运行ew1,ew2

打印并退出阻塞。

阅读全文

1 0