Dutor

#include <iostream>
#include <pthread.h>
#include <semaphore.h>
 
using namespace std;
 
const int N = 5;
sem_t empty; //~ 剩余空位数
sem_t full; //~ item数
pthread_mutex_t lock; //~ 互斥锁
typedef int item; //~ 产品类型
item buffer[N]; //~ 产品缓冲区
item new_item(); //~ 制造产品
void use_item(item&); //~ 使用产品
void * producer(void*); //~ 生产者进程
void *consumer(void*); //~ 消费者进程
 
int 
main()
{
	//~ 初始化各信号量、互斥锁
	sem_init(&empty, 0, N); 
	sem_init(&full, 0, 0);
	pthread_mutex_init(&lock, NULL);
	//~ 消费者、生产者进程id
	pthread_t consumer_id;
	pthread_t producer_id;
	//~ 创建消费者、生产者进程
	pthread_create(&consumer_id, NULL, consumer, NULL);
	pthread_create(&producer_id, NULL, producer, NULL);
	//~ join
	pthread_join(consumer_id, NULL);
	pthread_join(producer_id, NULL);
	//~ 销毁各信号量、互斥锁
	sem_destroy(&empty);
	sem_destroy(&full);
	pthread_mutex_destroy(&lock);
	return 0;
}
 
item new_item()
{
	return item();
}
 
void use_item(item&)
{
}
 
void * producer(void*)
{
	while(true)
	{
		usleep(500000); //~ 延时0.5s
		item tmp = new_item();
		int pos;
		sem_wait(&empty); //~ 等待空位
		pthread_mutex_lock(&lock); //~ 获得互斥锁
		sem_getvalue(&full, &pos);
		//~ 输出当前产品数
		cout<<"item produced..."<<pos+1<<" in buffer..."<<endl;
		buffer[pos] = tmp;
		pthread_mutex_unlock(&lock); //~ 释放互斥锁
		sem_post(&full); //~ 增加full
	}
	return NULL;
}
 
void *consumer(void*)
{
	while(true)
	{
		sleep(1); //~ 延时1s
		item tmp;
		int pos;
		sem_wait(&full); //~ 没有产品则等待
		pthread_mutex_lock(&lock); //~ 获得互斥锁
		sem_getvalue(&full, &pos);
		cout<<"item consumed..."<<pos<<" in buffer..."<<endl;
		tmp = buffer[pos-1];
		pthread_mutex_unlock(&lock); //~ 释放互斥锁
		sem_post(&empty); //~ 增加空位数
		use_item(tmp);
	}
	return NULL;
}