RIOT/tests/pthread_condition_variable/main.c

/*
 * Copyright (C) 2014 Hamburg University of Applied Sciences (HAW)
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @ingroup tests
 * @{
 *
 * @file
 * @brief   simple condition variable test application
 *
 * @author  Martin Landsmann <martin.landsmann@haw-hamburg.de>
 *
 * @}
 */

#include <stdio.h>
#include "pthread.h"
#include "thread.h"

static mutex_t mutex = MUTEX_INIT;
static pthread_cond_t cv;
static volatile int is_finished;
static volatile long count;
static volatile long expected_value;
static char stack[THREAD_STACKSIZE_MAIN];

/**
 * @brief   This thread tries to lock the mutex to enter the critical section.
 *          Then it signals one waiting thread to check the condition and it goes to sleep again
 *          If is_finished is set to 1 second_thread ends
 */
static void *second_thread(void *arg)
{
    (void) arg;
    while (1) {
        mutex_lock(&mutex);

        if (is_finished == 1) {
            break;
        }

        pthread_cond_signal(&cv);
        mutex_unlock_and_sleep(&mutex);
    }
    return NULL;
}

int main(void)
{
    count = 0;
    is_finished = 0;
    expected_value = 1000ul * 1000ul;
    pthread_cond_init(&cv, NULL);

    kernel_pid_t pid = thread_create(stack,sizeof(stack), THREAD_PRIORITY_MAIN - 1,
                                     THREAD_CREATE_WOUT_YIELD | THREAD_CREATE_STACKTEST,
                                     second_thread, NULL, "second_thread");

    while (1) {
        mutex_lock(&mutex);
        thread_wakeup(pid);
        count++;

        if ((count % 100000) == 0) {
            printf("Still alive alternated [count: %ldk] times.\n", count / 1000);
        }

        if (count == expected_value) {
            puts("condition fulfilled.");
            is_finished = 1;
            mutex_unlock(&mutex);
            return 0;
        }

        pthread_cond_wait(&cv, &mutex);
        mutex_unlock(&mutex);
    }
}