95 lines
2.6 KiB
C
95 lines
2.6 KiB
C
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/*
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* 程序清单：互斥锁例程
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*
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* 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，
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* 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
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* 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
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*/
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#include <rtthread.h>
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#define THREAD_PRIORITY 8
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#define THREAD_TIMESLICE 5
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/* 指向互斥量的指针 */
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static rt_mutex_t dynamic_mutex = RT_NULL;
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static rt_uint8_t number1, number2 = 0;
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static char thread1_stack[1024];
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static struct rt_thread thread1;
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static void rt_thread_entry1(void *parameter)
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{
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while (1)
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{
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/* 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 */
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rt_mutex_take(dynamic_mutex, RT_WAITING_FOREVER);
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number1++;
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rt_thread_mdelay(10);
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number2++;
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rt_mutex_release(dynamic_mutex);
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}
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}
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static char thread2_stack[1024];
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static struct rt_thread thread2;
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static void rt_thread_entry2(void *parameter)
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{
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while (1)
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{
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/* 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 */
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rt_mutex_take(dynamic_mutex, RT_WAITING_FOREVER);
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if (number1 != number2)
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{
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rt_kprintf("not protect.number1 = %d, mumber2 = %d \n", number1, number2);
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}
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else
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{
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rt_kprintf("mutex protect ,number1 = mumber2 is %d\n", number1);
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}
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number1++;
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number2++;
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rt_mutex_release(dynamic_mutex);
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if (number1 >= 50)
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return;
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}
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}
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/* 互斥量示例的初始化 */
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int mutex_sample(void)
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{
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/* 创建一个动态互斥量 */
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dynamic_mutex = rt_mutex_create("dmutex", RT_IPC_FLAG_PRIO);
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if (dynamic_mutex == RT_NULL)
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{
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rt_kprintf("create dynamic mutex failed.\n");
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return -1;
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}
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rt_thread_init(&thread1,
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"thread1",
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rt_thread_entry1,
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RT_NULL,
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&thread1_stack[0],
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sizeof(thread1_stack),
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THREAD_PRIORITY, THREAD_TIMESLICE);
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rt_thread_startup(&thread1);
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rt_thread_init(&thread2,
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"thread2",
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rt_thread_entry2,
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RT_NULL,
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&thread2_stack[0],
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sizeof(thread2_stack),
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THREAD_PRIORITY - 1, THREAD_TIMESLICE);
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rt_thread_startup(&thread2);
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return 0;
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}
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/* 导出到 msh 命令列表中 */
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MSH_CMD_EXPORT(mutex_sample, mutex sample);
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