/* threadtest.c
 *              by: john stultz (johnstul@us.ibm.com)
 *              (C) Copyright IBM 2004, 2005, 2006, 2012
 *              Licensed under the GPLv2
 *
 *  To build:
 *      $ gcc threadtest.c -o threadtest -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 <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <pthread.h>
#include "../kselftest.h"

/* serializes shared list access */
pthread_mutex_t list_lock = PTHREAD_MUTEX_INITIALIZER;
/* serializes console output */
pthread_mutex_t print_lock = PTHREAD_MUTEX_INITIALIZER;


#define MAX_THREADS 128
#define LISTSIZE 128

int done = 0;

struct timespec global_list[LISTSIZE];
int listcount = 0;


void checklist(struct timespec *list, int size)
{
        int i, j;
        struct timespec *a, *b;

        /* scan the list */
        for (i = 0; i < size-1; i++) {
                a = &list[i];
                b = &list[i+1];

                /* look for any time inconsistencies */
                if ((b->tv_sec <= a->tv_sec) &&
                        (b->tv_nsec < a->tv_nsec)) {

                        /* flag other threads */
                        done = 1;

                        /*serialize printing to avoid junky output*/
                        pthread_mutex_lock(&print_lock);

                        /* dump the list */
                        printf("\n");
                        for (j = 0; j < size; j++) {
                                if (j == i)
                                        printf("---------------\n");
                                printf("%lu:%lu\n", list[j].tv_sec, list[j].tv_nsec);
                                if (j == i+1)
                                        printf("---------------\n");
                        }
                        printf("[FAILED]\n");

                        pthread_mutex_unlock(&print_lock);
                }
        }
}

/* The shared thread shares a global list
 * that each thread fills while holding the lock.
 * This stresses clock synchronization across cpus.
 */
void *shared_thread(void *arg)
{
        while (!done) {
                /* protect the list */
                pthread_mutex_lock(&list_lock);

                /* see if we're ready to check the list */
                if (listcount >= LISTSIZE) {
                        checklist(global_list, LISTSIZE);
                        listcount = 0;
                }
                clock_gettime(CLOCK_MONOTONIC, &global_list[listcount++]);

                pthread_mutex_unlock(&list_lock);
        }
        return NULL;
}


/* Each independent thread fills in its own
 * list. This stresses clock_gettime() lock contention.
 */
void *independent_thread(void *arg)
{
        struct timespec my_list[LISTSIZE];
        int count;

        while (!done) {
                /* fill the list */
                for (count = 0; count < LISTSIZE; count++)
                        clock_gettime(CLOCK_MONOTONIC, &my_list[count]);
                checklist(my_list, LISTSIZE);
        }
        return NULL;
}

#define DEFAULT_THREAD_COUNT 8
#define DEFAULT_RUNTIME 30

int main(int argc, char **argv)
{
        int thread_count, i;
        time_t start, now, runtime;
        char buf[255];
        pthread_t pth[MAX_THREADS];
        int opt;
        void *tret;
        int ret = 0;
        void *(*thread)(void *) = shared_thread;

        thread_count = DEFAULT_THREAD_COUNT;
        runtime = DEFAULT_RUNTIME;

        /* Process arguments */
        while ((opt = getopt(argc, argv, "t:n:i")) != -1) {
                switch (opt) {
                case 't':
                        runtime = atoi(optarg);
                        break;
                case 'n':
                        thread_count = atoi(optarg);
                        break;
                case 'i':
                        thread = independent_thread;
                        printf("using independent threads\n");
                        break;
                default:
                        printf("Usage: %s [-t <secs>] [-n <numthreads>] [-i]\n", argv[0]);
                        printf("        -t: time to run\n");
                        printf("        -n: number of threads\n");
                        printf("        -i: use independent threads\n");
                        return -1;
                }
        }

        if (thread_count > MAX_THREADS)
                thread_count = MAX_THREADS;


        setbuf(stdout, NULL);

        start = time(0);
        strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&start));
        printf("%s\n", buf);
        printf("Testing consistency with %i threads for %ld seconds: ", thread_count, runtime);
        fflush(stdout);

        /* spawn */
        for (i = 0; i < thread_count; i++)
                pthread_create(&pth[i], 0, thread, 0);

        while (time(&now) < start + runtime) {
                sleep(1);
                if (done) {
                        ret = 1;
                        strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&now));
                        printf("%s\n", buf);
                        goto out;
                }
        }
        printf("[OK]\n");
        done = 1;

out:
        /* wait */
        for (i = 0; i < thread_count; i++)
                pthread_join(pth[i], &tret);

        /* die */
        if (ret)
                ksft_exit_fail();
        return ksft_exit_pass();
}