epoll的简单用法示例（程序还有bug，但只是为了示例epoll的用法就不改了）

//epoll用法示例//创建PIPENUM个pipe和子进程，子进程负责写，父进程负责读#include <stdio.h>#include <stdlib.h>#include <sys/epoll.h>#include <sys/time.h>#include <sys/types.h>#include <unistd.h>#include <string.h>#define PIPENUM 4int fdPipe[PIPENUM][2];int createPipe(void){int i, ret;for (i = 0; i < PIPENUM; i++) {ret = pipe(fdPipe[i]);if (ret == -1)return -1;}return 0;}int childWork(int index){int i;for (i = 0; i < PIPENUM; i++) {if (i != index) {close(fdPipe[i][0]);close(fdPipe[i][1]);} else {close(fdPipe[i][0]);}}srand(getpid());int sleepers = 3 + rand() % 8;sleep(sleepers);char buf[256];sprintf(buf, "hello, this is process %d.", getpid());int ret = write(fdPipe[index][1], buf, strlen(buf)+1);if (ret == -1)return ret;return 0;}int fatherWork(void){int i;for (i = 0; i < PIPENUM; i++) {close(fdPipe[i][1]);}int ret = fatherActualWork();if (ret == -1) {printf("pollo fail/n");return -1;}return 0;}int fatherActualWork(void){int i;int ret;char buf[256];int epfd=epoll_create(PIPENUM);if( -1==epfd ){perror("epoll_create");return -1;}struct epoll_event epe[PIPENUM], rev;for( i=0 ; i<PIPENUM ; i++ ){epe[i].events=EPOLLIN;epe[i].data.fd=fdPipe[i][0];ret=epoll_ctl(epfd, EPOLL_CTL_ADD, fdPipe[i][0], &epe[i]);if( -1==ret ){perror("epoll_ctl");return -1;}}while( 1 ){ret=epoll_wait(epfd, &rev, 1, -1);if( ret==-1 ){perror("epoll_wait");return -1;}if( rev.events&EPOLLIN==EPOLLIN ){memset(buf, 0, 256);read(rev.data.fd, buf, 256);printf("%s/n", buf);}}}int main(void){int ret = createPipe();if (ret == -1) exit(1);int i;pid_t pid;for (i = 0; i < PIPENUM; i++) {pid = fork();if (pid < 0) {perror("fork");exit(1);} else if (pid == 0) {ret = childWork(i);if (ret == -1) {printf("write fail/n");sleep(100);exit(1);}exit(0);} }ret = fatherWork();if (ret == -1) {printf("read fail/n");exit(1);}exit(0);}