Archipelago

/*

 * Copyright 2012 GRNET S.A. 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 GRNET S.A. ``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 GRNET S.A 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.

 *

 * The views and conclusions contained in the software and

 * documentation are those of the authors and should not be

 * interpreted as representing official policies, either expressed

 * or implied, of GRNET S.A.

 */

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/syscall.h>

#include <sys/types.h>

#include <pthread.h>

#include <xseg/xseg.h>

#include <peer.h>

#include <time.h>

#include <sys/util.h>

#include <signal.h>

#include <bench-xseg.h>

#include <limits.h>

#define SEC 1000000000 //1sec = 10^9 nsec

#define SEC2 (uint64_t) SEC*SEC //1sec*1sec = 10^18 nsec^2

void timer_start(struct timer *timer)

{

        //We need a low-latency way to get current time in nanoseconds.

        //Is this way the best way?

        //RAW means that we trust the system's oscilator isn't screwed up

        clock_gettime(CLOCK_MONOTONIC_RAW, &timer->start_time);

}

void timer_stop(struct timer *timer)

{

        struct timespec end_time;

        struct timespec start_time = timer->start_time;

        volatile struct timespec elapsed_time;

        struct timespec2 elapsed_time_sq;

        clock_gettime(CLOCK_MONOTONIC_RAW, &end_time);

        //Get elapsed time by subtracting start time from end time.

        //Subtraction can result to a negative value, so we check for both cases

        if (start_time.tv_nsec > end_time.tv_nsec) {

                elapsed_time.tv_nsec = SEC - start_time.tv_nsec + end_time.tv_nsec;

                elapsed_time.tv_sec = end_time.tv_sec - start_time.tv_sec - 1;

        } else {

                elapsed_time.tv_nsec = end_time.tv_nsec - start_time.tv_nsec;

                elapsed_time.tv_sec = end_time.tv_sec - start_time.tv_sec;

        }

        //Add the elapsed time to the current sum for this timer.

        //For accuracy, nanoseconds' sum has to be always less that 10^9

        if (elapsed_time.tv_nsec + timer->sum.tv_nsec > SEC){

                timer->sum.tv_nsec += elapsed_time.tv_nsec;

                timer->sum.tv_sec += elapsed_time.tv_sec + 1;

        } else {

                timer->sum.tv_nsec += elapsed_time.tv_nsec;

                timer->sum.tv_sec += elapsed_time.tv_sec;

        }

        //Add elapsed_time^2 to the current sum of squares for this timer

        //This is needed to calculate standard deviation.

        //As above, the sum of square of nanoseconds has to be less than 10^18

        elapsed_time_sq.tv_sec2 = elapsed_time.tv_sec*elapsed_time.tv_sec;

        elapsed_time_sq.tv_nsec2 = elapsed_time.tv_nsec*elapsed_time.tv_nsec;

        if (elapsed_time_sq.tv_nsec2 + timer->sum_sq.tv_nsec2 > SEC2) {

                timer->sum_sq.tv_nsec2 =

                        (timer->sum_sq.tv_nsec2 + elapsed_time_sq.tv_nsec2) % SEC2;

                timer->sum_sq.tv_sec2 += elapsed_time_sq.tv_sec2 + 1;

        } else {

                timer->sum_sq.tv_nsec2 += elapsed_time_sq.tv_nsec2;

                timer->sum_sq.tv_sec2 += elapsed_time_sq.tv_sec2;

        }

        //TODO: check if we need to make it volatile

        timer->completed++;

        printf("Start: %lu s %lu ns\n", start_time.tv_sec, start_time.tv_nsec);

        printf("Elpsd: %lu s %lu ns\n", elapsed_time.tv_sec, elapsed_time.tv_nsec);

        printf("End:   %lu s %lu ns\n", end_time.tv_sec, end_time.tv_nsec);

}