操作系统实验二，代码二：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <semaphore.h>
#define M 10 /*缓冲数目*/
#define P(x) sem_wait(&x)
#define V(x) sem_post(&x)
int in = 0; /*生产者放置产品的位置*/
int out = 0; /*消费者取产品的位置*/
int buff[M] = {0}; /*缓冲初始化为0， 开始时没有产品*/
sem_t empty_sem; /*同步信号量，当满了时阻止生产者放产品*/
sem_t full_sem; /*同步信号量，当没产品时阻止消费者消费*/
pthread_mutex_t mutex; /*互斥信号量， 一次只有一个线程访问缓冲*/
/*
*output the buffer
*/
void print()
{
int i;
for(i = 0; i < M; i++)
printf("%d ", buff[i]);
printf("\n");
}
/*
*producer
*/
void *producer()
{
for(;;)
{
sleep(1);
P(empty_sem);
pthread_mutex_lock(&mutex);
in = in % M;
printf("(+)produce a product. buffer:");
buff[in] = 1;
print();
++in;
pthread_mutex_unlock(&mutex);
V(full_sem);
}
}
/*
*consumer
*/
void *consumer()
{
for(;;)
{
sleep(2);
P(full_sem);
pthread_mutex_lock(&mutex);
out = out % M;
printf("(-)consume a product. buffer:");
buff[out] = 0;
print();
++out;
pthread_mutex_unlock(&mutex);
V(empty_sem);
}
}
void sem_mutex_init()
{
/*
*semaphore initialize
*/
int init1 = sem_init(&empty_sem, 0, M);
int init2 = sem_init(&full_sem, 0, 0);
if( (init1 != 0) && (init2 != 0))
{
printf("sem init failed \n");
exit(1);
}
/*
*mutex initialize
*/
int init3 = pthread_mutex_init(&mutex, NULL);
if(init3 != 0)
{
printf("mutex init failed \n");
exit(1);
}
}
int main()
{
pthread_t id1;
pthread_t id2;
int i;
int ret;
sem_mutex_init();
/*create the producer thread*/
ret = pthread_create(&id1, NULL, producer, NULL);
if(ret != 0)
{
printf("producer creation failed \n");
exit(1);
}
/*create the consumer thread*/
ret = pthread_create(&id2, NULL, consumer, NULL);
if(ret != 0)
{
printf("consumer creation failed \n");
exit(1);
}
pthread_join(id1,NULL);
pthread_join(id2,NULL);
exit(0);
}