使用POSIX线程处理“生产者/消费者”问题
发布时间：2021-11-25 16:00:31 所属栏目：教程 来源：互联网
导读：使用POSIX线程解决生产者/消费者问题： /* * File : pc.cpp * * Title : Demo Producer/Consumer. * * Short : A solution to the producer consumer problem using pthreads. * This is a simple FIFO pipe between two tasks. The primary problem is * en
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使用POSIX线程解决“生产者/消费者”问题： /* * File : pc.cpp * * Title : Demo Producer/Consumer. * * Short : A solution to the producer consumer problem using pthreads. * This is a simple FIFO pipe between two tasks. The primary problem is * ensuring that the producer blocks if the FIFO is full, and the consumer * blocks if it is empty, and avoiding data-races along the way. A secondary * concern is that there is as little interference between the two tasks as * possible. * * Author : Andrae Muys * * Date : 18 September 1997 */ #include <stdlib.h> #include <pthread.h> #include <assert.h> #ifdef _WIN32 # include <windows.h> # define SLEEP(ms) Sleep(ms) #elif defined(LINUX) # include <unistd.h> # define SLEEP(ms) sleep(ms) #endif #define QUEUE_SIZE 10 #define LOOP 20 void* producer (void *args); void* consumer (void *args); typedef struct { int buf[QUEUE_SIZE]; long head, tail; bool full, empty; pthread_mutex_t *mutex; pthread_cond_t *notFull, *notEmpty; } Queue; Queue* queueInit (void); void queueDelete (Queue *q); void queueAdd (Queue *q, int in); void queueDel (Queue *q, int *out); int main(int argc, char* argv[]) { Queue* fifo = queueInit (); assert(fifo != NULL); pthread_t pro, con; pthread_create (&pro, NULL, &producer, fifo); pthread_create (&con, NULL, &consumer, fifo); pthread_join (pro, NULL); pthread_join (con, NULL); queueDelete (fifo); return 0; } void* producer (void *q) { Queue* fifo = (Queue *)q; for (int i = 0; i < LOOP; i++) { // 临界区操作：若队列未满，添加新数据 pthread_mutex_lock (fifo->mutex); while (fifo->full) { printf ("producer: Queue FULL.n"); pthread_cond_wait (fifo->notFull, fifo->mutex); } queueAdd (fifo, i); pthread_mutex_unlock (fifo->mutex); // 数据添加结束，发“队列有数据”信号 pthread_cond_signal (fifo->notEmpty); SLEEP (100); } // 与上面类似 for (int i = 0; i < LOOP; i++) { pthread_mutex_lock (fifo->mutex); while (fifo->full) { printf ("producer: Queue FULL.n"); pthread_cond_wait (fifo->notFull, fifo->mutex); } queueAdd (fifo, i); pthread_mutex_unlock (fifo->mutex); pthread_cond_signal (fifo->notEmpty); SLEEP (200); } return (NULL); } void* consumer (void *q) { int d; Queue *fifo = (Queue *)q; for (int i = 0; i < LOOP; i++) { // 临界区操作：若队列不空，则取出数据 pthread_mutex_lock (fifo->mutex); while (fifo->empty) { printf ("consumer: Queue EMPTY.n"); pthread_cond_wait (fifo->notEmpty, fifo->mutex); } queueDel (fifo, &d); pthread_mutex_unlock (fifo->mutex); // 取完数据，发“队列不满”信号 pthread_cond_signal (fifo->notFull); printf ("consumer: recieved %d.n", d); SLEEP(200); } // 与上面类似 for (int i = 0; i < LOOP; i++) { pthread_mutex_lock (fifo->mutex); while (fifo->empty) { printf ("consumer: Queue EMPTY.n"); pthread_cond_wait (fifo->notEmpty, fifo->mutex); } queueDel (fifo, &d); pthread_mutex_unlock (fifo->mutex); pthread_cond_signal (fifo->notFull); printf ("consumer: recieved %d.n", d); SLEEP (50); } return (NULL); } Queue *queueInit (void) { Queue *q = (Queue *)malloc (sizeof (Queue)); if (q == NULL) return (NULL); q->empty = true; q->full = false; q->head = 0; q->tail = 0; q->mutex = (pthread_mutex_t *) malloc (sizeof (pthread_mutex_t)); pthread_mutex_init (q->mutex, NULL); q->notFull = (pthread_cond_t *) malloc (sizeof (pthread_cond_t)); pthread_cond_init (q->notFull, NULL); q->notEmpty = (pthread_cond_t *) malloc (sizeof (pthread_cond_t)); pthread_cond_init (q->notEmpty, NULL); return (q); } void queueDelete (Queue *q) { pthread_mutex_destroy (q->mutex); free (q->mutex); pthread_cond_destroy (q->notFull); free (q->notFull); pthread_cond_destroy (q->notEmpty); free (q->notEmpty); free (q); } void queueAdd (Queue *q, int in) { q->buf[q->tail] = in; q->tail++; if (q->tail == QUEUE_SIZE) // 循环队列 q->tail = 0; if (q->tail == q->head) // 添加数据时“触顶” q->full = true; q->empty = false; return; } void queueDel (Queue *q, int *out) { *out = q->buf[q->head]; q->head++; if (q->head == QUEUE_SIZE) // 循环队列 q->head = 0; if (q->head == q->tail) // 取出数据时“触底” q->empty = true; q->full = false; return; }  （编辑：大同站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
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