一个小例子演示下epoll和管道的使用

#include <iostream>
#include <unistd.h>
#include <errno.h>
#include <sys/epoll.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

int main()
{
struct epoll_event ev;                     //事件临时变量
const int MAXEVENTS = 1024;                //最大事件数
struct epoll_event events[MAXEVENTS];      //监听事件数组
int ret,pid;
int pipe_fd[2];
if((ret=pipe(pipe_fd))<0)
{
cout<<"create pipe fail:"<<ret<< ",errno:" << errno <<endl;
return -1;
}
ev.data.fd = pipe_fd[0];        //设置监听文件描述符
ev.events = EPOLLIN|EPOLLET;    //设置要处理的事件类型
int epfd=epoll_create(MAXEVENTS);
ret=epoll_ctl(epfd,EPOLL_CTL_ADD,pipe_fd[0],&ev);
if (ret != 0)
{
cout << "epoll_ctl fail:" << ret << ",errno:" << errno << endl;
close(pipe_fd[0]);
close(pipe_fd[1]);
close(epfd);
return -1;
}
if((pid=fork())>0)
{
int count=epoll_wait(epfd,events,MAXEVENTS,5000);
char r_buf[100];
for(int i=0;i<count;i++)
{
if((events[i].data.fd==pipe_fd[0])&&(events[0].events&EPOLLIN))
{
int r_num=read(pipe_fd[0],r_buf,100);
printf("read num is %d bytes data from the pipe,value is %d \n",r_num,atoi(r_buf));
}
}
close(pipe_fd[1]);
close(pipe_fd[0]);
close(epfd);
cout<<"parent close read fd[0],wirte fd[1] and epfd over"<<endl;

}
else if(pid==0)
{
close(pipe_fd[0]);//read
cout<<"sub close read fd[0] over,sub does't read"<<endl;
char w_buf[100];
strcpy(w_buf,"1234");
if(write(pipe_fd[1],w_buf,5)!=-1)//you can remove this line for learn
printf("sub write over \n");
close(pipe_fd[1]);//write
printf("sub close write fd[1] over \n");

}

return 0;
}