复杂一点的生产者消费者-pthread

基础知识思考整理
http://blog.csdn.net/aganlengzi/article/details/51416461

/*
  生产者消费者问题:
  在缓冲区不满时,一个或一组生产者(线程或进程)向缓冲区中插入数据,
  然后由一个或一组消费者(线程或进程)提取这些产品.
  下面是利用pthread实现的线程
  可配置的生产者数目
  可配置的消费者数目
  可配置的缓冲区大小
  可配置的产品数
*/

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define PRODUCER_NUM 3 //生产者数目
#define CONSUMER_NUM 2 //消费者数目
#define ITEM_NUM 5 //最多生产商品数
#define DELAY_TIME 3 //等待时间
#define QUEUE_SIZE (ITEM_NUM + 1) //队列长度

typedef int ElemType;

/* head 指向队头前一个元素 tail 指向队尾元素 empty: head == tail full: (tial + 1)%QUEUE_SIZE == head insert: not full --> elem[++tail] = inserted_num delete: not empty --> delete[++head] */
typedef struct 
{
    ElemType elem[QUEUE_SIZE];
    int head, tail;
}Queue;

Queue the_queue, *p_queue;
pthread_mutex_t queue_lock = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t producer_cond = PTHREAD_COND_INITIALIZER;
pthread_cond_t consumer_cond = PTHREAD_COND_INITIALIZER;

int ERROR_CODE;

/* func : init the queue input : Queue *p_queue output: none */
void init_queue(Queue *p_queue)
{
    memset(p_queue, 0, sizeof(*p_queue));
}

/*
  func  : judge if queue full
  input : Queue* p_queue
  output: 0 not full
          1 is full
 */
int is_queue_full(Queue *p_queue)
{
    if(p_queue->head == (p_queue->tail + 1)% QUEUE_SIZE)
        return 1;
    else
        return 0;
}

/*
  func  : judge if queue empty
  input : Queue* p_queue
  output: 0 not empty
          1 is empty
 */
int is_queue_empty(Queue *p_queue)
{
    if(p_queue->head == p_queue->tail)
        return 1;
    else
        return 0;
}

/*
  func  : get total elem num
  input : Queue* p_queue
  output: num of elem
 */
int get_queue_num(Queue *p_queue)
{
    return (p_queue->tail + QUEUE_SIZE - p_queue->head)%QUEUE_SIZE;
}

/*
  func  : insert an elem into the queue
  input : Queue* p_queue, inserted_elem
  output: 0 and ERROR_CODE=-1: full and wrong
          1: sucess
 */
int insert_queue(Queue *p_queue, ElemType inserted_elem)
{
    if(is_queue_full(p_queue))
    {
        printf("The queue is full\n");
        ERROR_CODE = -1;
        return 0;
    }
    else
    {
        p_queue->tail += 1;
        p_queue->tail %= QUEUE_SIZE;
        p_queue->elem[p_queue->tail] = inserted_elem;
        return 1;
    }
}

/*
  func  : delete an elem from the queue
  input : Queue* p_queue
  output: 0 and ERROR_CODE = -1: empty and wrong  
          other: deleted elem 
 */
int delet_queue(Queue *p_queue)
{
    if(is_queue_empty(p_queue))
    {
        printf("The queue is empty\n");
        ERROR_CODE = -1;
        return 0;
    }
    else
    {
        p_queue->head += 1;
        p_queue->head %= QUEUE_SIZE;
        return p_queue->elem[p_queue->head]; 
    }
}

/*
  func  : get tail of the queue
  input : Queue* p_queue
  output: the tail of the queue
 */
int get_queue_tail(Queue *p_queue)
{
    return p_queue->tail;
}

/*
  func  : get head of the queue
  input : Queue* p_queue
  output: the head of the queue
 */
int get_queue_head(Queue *p_queue)
{
    return p_queue->head;
}

/*
  func  : the consumer thread, detached and is a dead loop
  input : void *para, the index of the all_threads array convenient for locating
  output: void *
 */
void * consumer_thread(void *para)
{
    long thread_no = (long)para;
    while(1)
    {
        pthread_mutex_lock(&queue_lock);
        while(is_queue_empty(p_queue))
        {
            pthread_cond_wait(&consumer_cond, &queue_lock);
        }
        delet_queue(p_queue);
        if(get_queue_num(p_queue) == ITEM_NUM - 1)
        {
            pthread_cond_broadcast(&producer_cond);
        }
        printf("consumer thread[%ld] deletes queue[%d]=%d\n", thread_no, p_queue->head, p_queue->elem[p_queue->head]);
        pthread_mutex_unlock(&queue_lock);
        sleep(rand()%DELAY_TIME + 1);
    }
}


/*
  func  : the producer thread, detached and is a dead loop
  input : void *para, the index of the all_threads array convenient for locating
  output: void *
*/
void * producer_thread(void *para)
{
    long thread_no = (long)para;
    int tmp;
    while(1)
    {
        pthread_mutex_lock(&queue_lock);
        while(is_queue_full(p_queue))
        {
            pthread_cond_wait(&producer_cond, &queue_lock);
        }
        tmp = get_queue_tail(p_queue);
        insert_queue(p_queue, tmp);
        if(get_queue_num(p_queue) == 1)
        {
            pthread_cond_broadcast(&consumer_cond);
        }
        printf("producer thread[%ld] produces queue[%d]=%d\n", thread_no, p_queue->tail, tmp );
        pthread_mutex_unlock(&queue_lock);
        sleep(rand()%DELAY_TIME + 1);
    }
}



int main(int argc, char const *argv[])
{
    // using pointer but not the variable
    p_queue = &the_queue;
    // storing all the ids of the threads
    pthread_t all_threads[CONSUMER_NUM + PRODUCER_NUM];
    // attributes
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
    // tmp index
    int index;

    init_queue(p_queue);

    // creating the consumers
    for (index = 0; index < CONSUMER_NUM; ++index)
    {
        pthread_create(&all_threads[index], &attr, consumer_thread, (void*)index);
    }

    sleep(2);

    // creating the producers
    for (index = 0; index < PRODUCER_NUM; ++index)
    {
        pthread_create(&all_threads[index + CONSUMER_NUM], &attr, producer_thread, (void*)index);
    }

    //destroy the initialized attribute variable
    pthread_attr_destroy(&attr);

    //pthread_exit(NULL);
    while(1);
    return 0;
}

[1] http://www.cnblogs.com/clover-toeic/p/4029269.html