WhyCan Forum(哇酷开发者社区)

#include <stdio.h>
#include <pthread.h>
#include <semaphore.h>

pthread_t pt_play;

sem_t sem_cmd_play;
sem_t sem_stopped;

pthread_mutex_t mutex_play;
pthread_cond_t cond_play;
int stop = 0;
int start = 0;

void* thread_play(void* p)
{
	int i = 0;

	while(1)
	{
		pthread_mutex_lock(&mutex_play);
		while (start == 0)
		{
			pthread_cond_wait(&cond_play, &mutex_play);
		}

		for(i=0;i<100;i++)
		{
			if(stop == 1)
				break;

			printf("now play music ... %d\n", i);
			usleep(100*1000);
		}
		start = 0;
		stop = 0;
		printf("play end.\n-----------------\n");
		
		sem_post(&sem_stopped);
		pthread_mutex_unlock(&mutex_play);
	}
}

int main()
{
	char input[16];
	struct timespec tm;

	sem_init(&sem_cmd_play, 0, 0);
	sem_init(&sem_stopped, 0, 0);

	pthread_mutex_init(&mutex_play, NULL);
	pthread_cond_init(&cond_play, NULL);

	pthread_create(&pt_play, NULL, thread_play, NULL);
	
	while(1)
	{
		scanf("%s", input);

		if(strcmp(input, "play") == 0)
		{
			printf("now play:\n");

			pthread_mutex_lock(&mutex_play);
			start = 1;
			pthread_cond_signal(&cond_play);
			pthread_mutex_unlock(&mutex_play);
		}
		else if(strcmp(input, "stop") == 0)
		{
			printf("now stop:\n");
			stop = 1;
		}
		else if(strcmp(input, "replay") == 0)
		{
			printf("now stop:\n");
			stop = 1;

			int wait_count = 0;

			do
			{

				clock_gettime(CLOCK_REALTIME, &tm);
			    tm.tv_nsec += 100000000;

				if(0 == sem_timedwait(&sem_stopped, &tm))
				{
					break;
				}
				printf("\twait %d\n", wait_count);
				wait_count++;
			}
			while(wait_count < 10);

			pthread_mutex_lock(&mutex_play);
			stop = 0;
			start = 1;
			pthread_cond_signal(&cond_play);
			pthread_mutex_unlock(&mutex_play);
		}
	}
}