kernel-sample/en/mutex_sample.c

/*
 * Copyright (c) 2006-2018, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2018-08-24     yangjie      the first version
 * 2020-10-17     Meco Man     translate to English comment
 */

/*
 * Demo: mutex(es)
 *
 * This demo demonstrates how the mutex manage the shared resource.
 *
 * read more:
 *    https://www.rt-thread.io/document/site/thread-sync/thread-sync/#mutex
 */
 
#include <rtthread.h>

#define THREAD_PRIORITY         8
#define THREAD_TIMESLICE        5

/* mutex handler */
static rt_mutex_t dynamic_mutex = RT_NULL;
static rt_uint8_t number1, number2 = 0;

ALIGN(RT_ALIGN_SIZE)
static char thread1_stack[1024];
static struct rt_thread thread1;
static void rt_thread_entry1(void *parameter)
{
    while (1)
    {
        /* pending the mutex */
        rt_mutex_take(dynamic_mutex, RT_WAITING_FOREVER);
        
        /* protect and deal with public variables */
        number1++;
        rt_thread_mdelay(10);
        number2++;
        
        /* release the mutex */
        rt_mutex_release(dynamic_mutex);
    }
}

ALIGN(RT_ALIGN_SIZE)
static char thread2_stack[1024];
static struct rt_thread thread2;
static void rt_thread_entry2(void *parameter)
{
    while (1)
    {
        rt_mutex_take(dynamic_mutex, RT_WAITING_FOREVER);
        if (number1 != number2)
        {
            rt_kprintf("not protect.number1 = %d, mumber2 = %d \n", number1, number2);
        }
        else
        {
            rt_kprintf("mutex protect ,number1 = mumber2 is %d\n", number1);
        }

        number1++;
        number2++;
        rt_mutex_release(dynamic_mutex);

        if (number1 >= 50)
            return;
    }
}

int mutex_sample(void)
{
    /* create mutex */
    dynamic_mutex = rt_mutex_create("dmutex", RT_IPC_FLAG_FIFO);
    if (dynamic_mutex == RT_NULL)
    {
        rt_kprintf("create dynamic mutex failed.\n");
        return -1;
    }

    rt_thread_init(&thread1,
                   "thread1",
                   rt_thread_entry1,
                   RT_NULL,
                   &thread1_stack[0],
                   sizeof(thread1_stack),
                   THREAD_PRIORITY, THREAD_TIMESLICE);
    rt_thread_startup(&thread1);

    rt_thread_init(&thread2,
                   "thread2",
                   rt_thread_entry2,
                   RT_NULL,
                   &thread2_stack[0],
                   sizeof(thread2_stack),
                   THREAD_PRIORITY - 1, THREAD_TIMESLICE);
    rt_thread_startup(&thread2);
    return 0;
}

/* export the msh command */
MSH_CMD_EXPORT(mutex_sample, mutex sample);