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最新推荐文章于 2021-10-28 09:45:00 发布

原创最新推荐文章于 2021-10-28 09:45:00 发布 · 192 阅读

CC 4.0 BY-SA版权

本文介绍了一个使用多线程实现的生产者消费者模型示例。该模型利用了pthread库中的互斥锁和条件变量来同步生产者和消费者线程之间的操作。通过一个环形缓冲区作为共享资源，确保数据的正确生产和消费。

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

#define BUFFER_SIZE 16

struct prodcons
{
int buffer[BUFFER_SIZE];
pthread_mutex_t lock;
int readpos,writepos;
pthread_cond_t notempty;
pthread_cond_t notfull;
};

void init(struct prodcons *b)
{
pthread_mutex_init(&b->lock,NULL);
pthread_cond_init(&b->notempty,NULL);
pthread_cond_init(&b->notfull,NULL);
b->readpos = 0;
b->writepos = 0;
}

void put(struct prodcons *b,int data)
{
pthread_mutex_lock(&b->lock);
if((b->writepos + 1) % BUFFER_SIZE == b->readpos)
{
pthread_cond_wait(&b->notfull,&b->lock);
}
b->buffer[b->writepos] = data;
b->writepos++;
if(b->writepos >= BUFFER_SIZE)
{
b->writepos = 0;
}
pthread_cond_signal(&b->notempty);
pthread_mutex_unlock(&b->lock);
}

int get(struct prodcons *b)
{
int data;
pthread_mutex_lock(&b->lock);
if(b->writepos == b->readpos)
{
pthread_cond_wait(&b->notempty,&b->lock);
}

data = b->buffer[b->readpos];
b->readpos++;
if(b->readpos >= BUFFER_SIZE)
{
b->readpos = 0;
}
pthread_cond_signal(&b->notfull);
pthread_mutex_unlock(&b->lock);
return data;
}

#define OVER -1

struct prodcons buffer;

void * producer(void *data)
{
int n;
for(n = 0;n < 20;n++)
{
printf("%d----->\n",n);
put(&buffer,n);
}
put(&buffer,OVER);
return NULL;
}

void * consumer(void *data)
{
int d;
while(1)
{
d = get(&buffer);
if(d == OVER)
break;
printf("----->%d\n",d);
}
return NULL;
}

int main()
{
pthread_t th_a,th_b;
void *retval;

init(&buffer);

pthread_create(&th_a,NULL,producer,0);
pthread_create(&th_b,NULL,consumer,0);

pthread_join(th_a,&retval);
pthread_join(th_b,&retval);

return 0;
}