循环队列 - 生产者与消费者模型

循环队列可以实现一个生产者与一个消费者模型， 不使用锁。

 

循环队列：容量大小为10

生产者线程：把从0递增的整数依次push到队列，队列满了就等1s(尾部不存储，也就是最大存9个数)。

消费者线程：每3s从队列pop一个元素。

[xiongli@localhost data_struct]$ ./a.out            
push 0 at data[0]
push 1 at data[1]
push 2 at data[2]
push 3 at data[3]
push 4 at data[4]
push 5 at data[5]
push 6 at data[6]
push 7 at data[7]
push 8 at data[8]
the queue is full!
the queue is full!
the queue is full!
                pop 0 at data[0]
push 9 at data[9]
the queue is full!
the queue is full!
the queue is full!
                pop 1 at data[1]
push 10 at data[0]
the queue is full!
the queue is full!
the queue is full!
                pull 2 at data[2]
push 11 at data[1]
the queue is full!
the queue is full!
the queue is full!
                pop 3 at data[3]
push 12 at data[2]
the queue is full!
the queue is full!
the queue is full!
                pop 4 at data[4]
push 13 at data[3]
the queue is full!
the queue is full!
the queue is full!

 

 

#include <stdio.h>
#include <pthread.h>
#define QUEUE_SIZE 10

struct EnQueue {
        unsigned int nHead;
        unsigned int nTail;
        int data[QUEUE_SIZE];
} Queue;

int isFull()
{
        if((Queue.nTail+1) % QUEUE_SIZE == Queue.nHead)
                return 1;
        else
                return 0;
}

void* push()
{
        int i=0;
        while(1)
        {
                if(isFull())
                {
                        printf("the queue is full!\n");
                        sleep(1);
                        continue;
                }

                Queue.data[Queue.nTail] = i++;
                printf("push %d at data[%d]\n",Queue.data[Queue.nTail],Queue.nTail);

                Queue.nTail = (Queue.nTail+1) % QUEUE_SIZE;     //设置尾部
        }
        return NULL;
}

void* pop()
{
        int n;
        while(1)
        {
                sleep(3);
                if(Queue.nHead != Queue.nTail)
                {
                        n = Queue.data[Queue.nHead];
                        printf("\t\tpull %d at data[%d]\n",n,Queue.nHead);
                        Queue.nHead = (Queue.nHead+1) % QUEUE_SIZE;     //设置头部
                }
        }
        printf("pull exit\n");
        return NULL;
}

int main()
{
        pthread_t tid1,tid2;
        pthread_create(&tid1,NULL,push,NULL);
        pthread_create(&tid2,NULL,pop,NULL);

        pthread_join(tid1,NULL);
        pthread_join(tid2,NULL);
}