freeBSD queue.c--定时器

/*- * Copyright (c) 1999 Lu Jiandong [e-mail] * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright *    notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright *    notice, this list of conditions and the following disclaimer in the *    documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. *//* * kqueue 实现的定时器 * kqueue 是FreeBSD操作系统提供的一套高性能，通用的“事件”通知机制。它的最常见应用是网络编程中获取可以读写的socket。 * 它还可以提供定时器，文件操作等通知功能。 */#include <stdio.h>#include <unistd.h>#include <time.h>#include <sys/time.h>#include <sys/types.h>#include <sys/event.h>#include <sys/time.h>

struct kevent
 struct kevent {      uintptr_t ident;       /* 事件 ID */      short     filter;       /* 事件过滤器 */      u_short   flags;        /* 行为标识 */      u_int     fflags;       /* 过滤器标识值 */      intptr_t  data;         /* 过滤器数据 */      void      *udata;       /* 应用透传数据 */  }; 在一个 kqueue 中，{ident, filter} 确定一个唯一的事件。
void test(){int kqueuefd = kqueue();struct kevent ev;

//在给定的描述符上由内核来对这个过滤器进行监控(有好多不同的过滤器)EV_SET(&ev, -1, EVFILT_TIMER, EV_ADD | EV_ENABLE, 0, 40, NULL); //40 millisecondskevent(kqueuefd, &ev, 1, NULL, 0, NULL);struct kevent newev;int count = -1;while(1) {count = kevent(kqueuefd, NULL, 0, &newev, 1, NULL);if (!count){printf("no event\n");continue;}struct timeval tv;gettimeofday(&tv, NULL);printf("time :sec = %u usec = %u\n", tv.tv_sec, tv.tv_usec); usleep(30);}}int main(int argc, char *argv[]){test();return 0;