RT-Thread API参考手册  3.1.1
嵌入式实时操作系统
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
*/
/*
* 程序清单:互斥锁例程
*
* 互斥锁是一种保护共享资源的方法。当一个线程拥有互斥锁的时候,
* 可以保护共享资源不被其他线程破坏。线程1对2个number分别进行加1操作
* 线程2也会对2个number分别进行加1操作。使用互斥量保证2个number值保持一致
*/
#include <rtthread.h>
#define THREAD_PRIORITY 8
#define THREAD_TIMESLICE 5
/* 指向互斥量的指针 */
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)
{
/* 线程1获取到互斥量后,先后对number1、number2进行加1操作,然后释放互斥量 */
number1++;
number2++;
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)
{
/* 线程2获取到互斥量后,检查number1、number2的值是否相同,相同则表示mutex起到了锁的作用 */
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;
}
}
/* 互斥量示例的初始化 */
int mutex_sample(void)
{
/* 创建一个动态互斥量 */
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,
&thread1_stack[0],
sizeof(thread1_stack),
THREAD_PRIORITY, THREAD_TIMESLICE);
rt_thread_startup(&thread1);
rt_thread_init(&thread2,
"thread2",
rt_thread_entry2,
&thread2_stack[0],
sizeof(thread2_stack),
THREAD_PRIORITY - 1, THREAD_TIMESLICE);
rt_thread_startup(&thread2);
return 0;
}
/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(mutex_sample, mutex sample);