/*	$OpenBSD: kqueue-timer.c,v 1.1 2015/12/05 10:51:49 blambert Exp $	*/
/*
 * Copyright (c) 2015 Bret Stephen Lambert <blambert@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <sys/types.h>
#include <sys/time.h>
#include <sys/event.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>

int do_timer(void);

int
do_timer(void)
{
	int kq, n;
	struct kevent ev;
	struct timespec ts;

	if ((kq = kqueue()) == -1)
		return (1);

	memset(&ev, 0, sizeof(ev));
	ev.filter = EVFILT_TIMER;
	ev.flags = EV_ADD | EV_ENABLE | EV_ONESHOT;
	ev.data = 500;			/* 1/2 second in ms */

	if (kevent(kq, &ev, 1, NULL, 0, NULL) == -1)
		return (1);

	ts.tv_sec = 2;			/* wait 2s for kqueue timeout */
	ts.tv_nsec = 0;

	if ((n = kevent(kq, NULL, 0, &ev, 1, &ts)) != 1)
		return (1);

	/* Now retry w/o EV_ONESHOT, as EV_CLEAR is implicit */

	memset(&ev, 0, sizeof(ev));
	ev.filter = EVFILT_TIMER;
	ev.flags = EV_ADD | EV_ENABLE;
	ev.data = 500;			/* 1/2 second in ms */

	if (kevent(kq, &ev, 1, NULL, 0, NULL) == -1)
		return (1);

	ts.tv_sec = 2;			/* wait 2s for kqueue timeout */
	ts.tv_nsec = 0;

	if ((n = kevent(kq, NULL, 0, &ev, 1, &ts)) != 1)
		return (1);

	return (0);
}