rt-thread/examples/libc/ex7.c

/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 */
/* ex7
 *
 * Test case that illustrates a timed wait on a condition variable.
 */

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <sys/time.h>
#include <unistd.h>

#define usleep rt_thread_sleep

/* Our event variable using a condition variable contruct. */
typedef struct {
    pthread_mutex_t mutex;
    pthread_cond_t cond;
    int flag;
} event_t;

/* Global event to signal main thread the timeout of the child thread. */
event_t main_event;

static void *test_thread(void *ms_param) {
    int status = 0;
    event_t foo;
    struct timespec time;
    struct timeval now;
    long ms = (long) ms_param;

    /* initialize cond var */
    pthread_cond_init(&foo.cond, NULL);
    pthread_mutex_init(&foo.mutex, NULL);
    foo.flag = 0;

    /* set the time out value */
    printf("waiting %ld ms ...\n", ms);
    gettimeofday(&now, NULL);
    time.tv_sec = now.tv_sec + ms / 1000 + (now.tv_usec + (ms % 1000) * 1000)
            / 1000000;
    time.tv_nsec = ((now.tv_usec + (ms % 1000) * 1000) % 1000000) * 1000;

    /* Just use this to test the time out. The cond var is never signaled. */
    pthread_mutex_lock(&foo.mutex);
    while (foo.flag == 0 && status != ETIMEDOUT) {
        status = pthread_cond_timedwait(&foo.cond, &foo.mutex, &time);
    }
    pthread_mutex_unlock(&foo.mutex);

    /* post the main event */
    pthread_mutex_lock(&main_event.mutex);
    main_event.flag = 1;
    pthread_cond_signal(&main_event.cond);
    pthread_mutex_unlock(&main_event.mutex);

    /* that's it, bye */
    return (void*) status;
}

int libc_ex7(void) {
    unsigned long count;

    setvbuf(stdout, NULL, _IONBF, 0);

    /* initialize main event cond var */
    pthread_cond_init(&main_event.cond, NULL);
    pthread_mutex_init(&main_event.mutex, NULL);
    main_event.flag = 0;

    for (count = 0; count < 20; ++count) {
        pthread_t thread;
        int status;

        /* pass down the milli-second timeout in the void* param */
        status = pthread_create(&thread, NULL, test_thread, (void*) (count
                * 100));
        if (status != 0) {
            printf("status = %d, count = %lu: %s\n", status, count, strerror(
                    errno));
            return 1;
        } else {

            /* wait for the event posted by the child thread */
            pthread_mutex_lock(&main_event.mutex);
            while (main_event.flag == 0) {
                pthread_cond_wait(&main_event.cond, &main_event.mutex);
            }
            main_event.flag = 0;
            pthread_mutex_unlock(&main_event.mutex);

            printf("count = %lu\n", count);
        }

        usleep(10);
    }

    return 0;
}
#include <finsh.h>
FINSH_FUNCTION_EXPORT(libc_ex7, example 7 for libc);