/* Measure mqueue timeout latency
 *              by: john stultz (john.stultz@linaro.org)
 *              (C) Copyright Linaro 2013
 *
 *              Inspired with permission from example test by:
 *                      Romain Francoise <romain@orebokech.com>
 *              Licensed under the GPLv2
 *
 *  To build:
 *      $ gcc mqueue-lat.c -o mqueue-lat -lrt
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <mqueue.h>
#include <include/vdso/time64.h>
#include "kselftest.h"


#define TARGET_TIMEOUT          100000000       /* 100ms in nanoseconds */
#define UNRESONABLE_LATENCY     40000000        /* 40ms in nanosecs */


long long timespec_sub(struct timespec a, struct timespec b)
{
        long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;

        ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
        return ret;
}

struct timespec timespec_add(struct timespec ts, unsigned long long ns)
{
        ts.tv_nsec += ns;
        while (ts.tv_nsec >= NSEC_PER_SEC) {
                ts.tv_nsec -= NSEC_PER_SEC;
                ts.tv_sec++;
        }
        return ts;
}

int mqueue_lat_test(void)
{

        mqd_t q;
        struct mq_attr attr;
        struct timespec start, end, now, target;
        int i, count, ret;

        q = mq_open("/foo", O_CREAT | O_RDONLY, 0666, NULL);
        if (q < 0) {
                perror("mq_open");
                return -1;
        }
        mq_getattr(q, &attr);


        count = 100;
        clock_gettime(CLOCK_MONOTONIC, &start);

        for (i = 0; i < count; i++) {
                char buf[attr.mq_msgsize];

                clock_gettime(CLOCK_REALTIME, &now);
                target = now;
                target = timespec_add(now, TARGET_TIMEOUT); /* 100ms */

                ret = mq_timedreceive(q, buf, sizeof(buf), NULL, &target);
                if (ret < 0 && errno != ETIMEDOUT) {
                        perror("mq_timedreceive");
                        return -1;
                }
        }
        clock_gettime(CLOCK_MONOTONIC, &end);

        mq_close(q);

        if ((timespec_sub(start, end)/count) > TARGET_TIMEOUT + UNRESONABLE_LATENCY)
                return -1;

        return 0;
}

int main(int argc, char **argv)
{
        int ret;

        printf("Mqueue latency :                          ");
        fflush(stdout);

        ret = mqueue_lat_test();
        if (ret < 0) {
                printf("[FAILED]\n");
                ksft_exit_fail();
        }
        printf("[OK]\n");
        ksft_exit_pass();
}