/*
 * Bench program to exercice multi threads using open()/close()/read()/lseek() calls.
 * Usage :
 *    bench [-t XX] [-l len]
 *   XX : number of threads
 *   len : bench time in seconds
 * -s : small fdset : try to use embedded sruct fdtable
 */
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include <signal.h>

static pthread_mutex_t  mut = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

static int sflag; /* small fdset */
static int end_prog;
static unsigned long work_done;
static char onekilo[1024];

static void catch_alarm(int sig)
{
	end_prog = 1;
}

static void *perform_work(void *arg)
{
	int fd, i;
	unsigned long units = 0;
	int fds[64];
	char filename[64];
	char c;
	strcpy(filename, "/tmp/benchXXXXXX");
	fd = mkstemp(filename);
	write(fd, onekilo, sizeof(onekilo));
	close(fd);

	/* force this program to open more than 64 fds */
	if (!sflag)
		for (i = 0 ; i < 64 ; i++)
			fds[i] = open("/dev/null", O_RDONLY);

	while (!end_prog) {
		fd = open(filename, O_RDONLY);
		read(fd, &c, 1);
		lseek(fd, 10, SEEK_SET);
		read(fd, &c, 1);
		lseek(fd, 20, SEEK_SET);
		read(fd, &c, 1);
		lseek(fd, 30, SEEK_SET);
		read(fd, &c, 1);
		lseek(fd, 40, SEEK_SET);
		read(fd, &c, 1);
		close(fd);
		units++;
	}
	unlink(filename);
	if (!sflag)
		for (i = 0 ; i < 64 ; i++)
			close(fds[i]);
	pthread_mutex_lock(&mut);
	work_done += units;
	pthread_mutex_unlock(&mut);
	return 0;
}

static void *idle_thread(void *arg)
{
	pthread_mutex_lock(&mut);
	while (!end_prog) {
		pthread_cond_wait(&cond, &mut);
	}
	pthread_mutex_unlock(&mut);
}

static void usage(int code)
{
	fprintf(stderr, "Usage : bench [-i] [-s] [-a affinity_mask] [-t threads] [-l duration]\n");
	exit(code);
}

int main(int argc, char *argv[])
{
	int i, c;
	int nbthreads = 2;
	int iflag = 0;
	unsigned int length = 10;
	pthread_t *tid;
	struct sigaction sg;
	struct timeval t0, t1;
	long mask = 0;

	while ((c = getopt(argc, argv, "sit:l:a:")) != -1) {
		if (c == 't')
			nbthreads = atoi(optarg);
		else if (c == 'l')
			length = atoi(optarg);
		else if (c == 's')
			sflag = 1;
		else if (c == 'i')
			iflag = 1;
		else if (c == 'a')
			sscanf(optarg, "%li", &mask);
		else usage(1);
	}
	if (mask != 0) {
		int res = sched_setaffinity(0, &mask);
		if (res != 0)
			fprintf(stderr, "sched_affinity(0x%lx)->%d errno=%d\n", mask, res, errno);
	}


	tid = malloc(nbthreads*sizeof(pthread_t));
	gettimeofday(&t0, NULL);
	for (i = 1 ; i < nbthreads; i++)
		pthread_create(tid + i, NULL, perform_work, NULL);
	if (iflag)
		pthread_create(tid, NULL, idle_thread, NULL);
	memset(&sg, 0, sizeof(sg));
	sg.sa_handler = catch_alarm;
	sigaction(SIGALRM, &sg, NULL);
	alarm(length);
	perform_work(NULL);

	if (iflag) {
		pthread_cond_signal(&cond);
		pthread_join(tid[0], NULL);
	}
	for (i = 1 ; i < nbthreads; i++)
		pthread_join(tid[i], NULL); 

	gettimeofday(&t1, NULL);
	t1.tv_sec -= t0.tv_sec;
	t1.tv_usec -= t0.tv_usec;
	if (t1.tv_usec < 0) {
		t1.tv_usec += 1000000;
		t1.tv_sec--;
	}
	pthread_mutex_lock(&mut);
	printf("%d threads, %d.%06d seconds, work_done=%lu\n",
		nbthreads, (int)t1.tv_sec, (int)t1.tv_usec, work_done);
	pthread_mutex_unlock(&mut);
	return 0;
}