mutex.c

rtlinux3.0 的源代码

#include <rtl.h>
#include <time.h>
#include <pthread.h>

static pthread_t thread;
static pthread_mutex_t mutex /* = PTHREAD_MUTEX_INITIALIZER */;

static void * start_routine(void *arg)
{
	int ret;
	hrtime_t t;
	hrtime_t t2;

	struct sched_param p;
	p . sched_priority = 1;
	pthread_setschedparam (pthread_self(), SCHED_FIFO, &p);

	rtl_printf("RTLinux thread starts on CPU%d\n", rtl_getcpuid());
	ret = pthread_mutex_trylock(&mutex);
	rtl_printf ("RT-thread: pthread_mutex_trylock returned %d\n", ret);

	if (ret != 0) {
		rtl_printf("RT-thread: about to pthread_mutex_lock\n");
		t = gethrtime();
		ret = pthread_mutex_lock (&mutex);
		t2 = gethrtime();
		rtl_printf("RT-thread: pthread_mutex_lock returned %d (%d ns elapsed)\n", ret, (unsigned) (t2 - t));
	}
	ret = pthread_mutex_unlock (&mutex);

	rtl_printf("RT-thread: pthread_mutex_unlock returned %d\n", ret);

	return (void *) 35;
}


int init_module(void)
{
	int ret;
	hrtime_t t;
	int sleep = 500000000;
	pthread_attr_t attr;

	rtl_printf("RTLinux mutex test starts on CPU%d\n", rtl_getcpuid());
	pthread_attr_init (&attr);
	/* try to run the thread on another CPU */
	if (rtl_cpu_exists(!rtl_getcpuid())) {
		pthread_attr_setcpu_np(&attr, !rtl_getcpuid());
	}

	pthread_mutex_init (&mutex, 0);
	ret = pthread_mutex_lock (&mutex);
	rtl_printf("Linux thread: pthread_mutex_lock returned %d\n", ret);

	ret = pthread_create (&thread, &attr, start_routine, 0);
	if (ret) {
		rtl_printf("failed to create a thread\n");
		return ret;
	}


	rtl_printf("Linux thread is about to sleep for %d ns\n", sleep);
	t = gethrtime();
	while (gethrtime() < t + sleep);

	rtl_printf("Linux thread is about to unlock the mutex\n");
	ret = pthread_mutex_unlock (&mutex);
	rtl_printf("Linux thread: pthread_mutex_unlock returned %d\n", ret);

	return 0;
}


void cleanup_module(void)
{
	pthread_delete_np (thread);
	pthread_mutex_destroy (&mutex);
}