/*-
 * Copyright (c) 2003 Dag-Erling Coïdan Smørgrav
 * 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
 *    in this position and unchanged.
 * 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 *
 * $Id$
 */

#include <sys/select.h>
#include <sys/time.h>

#include <err.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static int		it;

#define ITERATIONS 100000

static struct result {
	uint64_t	noclose;
	uint64_t	rndclose;
} results[ITERATIONS];

static inline uint64_t
timeval2usec(struct timeval *tv)
{
	return ((uint64_t)tv->tv_sec * (uint64_t)1000000 +
	    (uint64_t)tv->tv_usec);
}

static inline uint64_t
timeval_diff(struct timeval *a, struct timeval *b)
{
	return ((b->tv_sec - a->tv_sec) * (uint64_t)1000000 +
	    (b->tv_usec - a->tv_usec));
}

static inline uint32_t
lcrng(void)
{
	static uint32_t x = 2003;

	return (x = x * 69069);
}

static void
warmup(const char *fn)
{
	int n;

	if ((it = open(fn, O_RDONLY)) < 0)
		err(1, "%s(): %s", __func__, fn);
	for (n = 0; n < 1000; ++n)
		close(dup(it));
}

static void
fdbench_noclose(void)
{
	struct timeval a, b;
	int n;

	for (n = 0; n < ITERATIONS; ++n) {
		gettimeofday(&a, NULL);
		if (dup(it) < 0)
			break;
		gettimeofday(&b, NULL);
		results[n].noclose = timeval_diff(&a, &b);
	}
	warn("%s(): dup(%d)", __func__, n);
	while (n > it)
		close(n--);
}

static void
fdbench_rndclose(void)
{
	struct timeval a, b;
	int n;

	for (n = 0; n < 10; ++n)
		dup(it);
	for (; n < ITERATIONS; ++n) {
		close((lcrng() % n) + it + 1);
		if (dup(it) < 0)
			break;
		gettimeofday(&a, NULL);
		if (dup(it) < 0)
			break;
		gettimeofday(&b, NULL);
		results[n].rndclose = timeval_diff(&a, &b);
	}
	warn("%s(): dup(%d)", __func__, n);
	while (n > it)
		close(n--);
}

static void
summarize(void)
{
	int n;

	for (n = 10; n < ITERATIONS; ++n) {
		if (results[n].noclose == 0 ||
		    results[n].rndclose == 0)
			break;
		printf("%8d%24ju%24ju\n", n,
		    (uintmax_t)results[n].noclose,
		    (uintmax_t)results[n].rndclose);
	}
}

int
main(void)
{
	warmup("/dev/null");
	fdbench_noclose();
	fdbench_rndclose();
	summarize();
	exit(0);
}