【操作系统原理】【实验4】生产者消费者进程

一、实验目的

通过生产者—消费者例子，熟悉、掌握互斥同步编程。

二、实验内容

模拟实现生产者—消费者例子，当生产者生产了某种产品后，消费者才可以消费该产品，缓冲区里没有个数限制，并且生产者和消费者是两个独立的线程，所以生产者可以一直生产产品，消费者可以消费生产者生产的任意产品。生产者和消费者线程既要同步也需要互斥。

三、实验代码

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

struct msg
{
	int num;
	struct msg * next;
};
struct msg * head;

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

void * consumer(void * pVoid)
{
	struct msg * mp;
	struct msg * mpp;
	while (1)
	{
		pthread_mutex_lock(&mutex);
		if (NULL == head)
			pthread_cond_wait(&cond, &mutex);
		mp = head;
		if (mp -> next)
		{
			while (mp -> next)
			{
				mpp = mp;
				mp = mp -> next;
			}
			printf("Consume %d\n", mp -> num);
			free(mp);
			mpp -> next = mp = NULL;
		} else {
			printf("Consume %d\n", mp -> num);
			free(mp);
			head = mp = NULL;
		}
		pthread_mutex_unlock(&mutex);
		sleep(2);
	}
	return pVoid;
}

void * producer(void * pVoid)
{
	struct msg * mp;
	while (1)
	{
		mp = (struct msg *)malloc(sizeof(struct msg));
		mp -> num = rand()%1000 + 1;
		printf("Produce %d\n", mp -> num);
		pthread_mutex_lock(&mutex);
		mp -> next = head;
		head = mp;
		pthread_mutex_unlock(&mutex);
		pthread_cond_signal(&cond);
		sleep(1);
	}
	return pVoid;
}

int main(void)
{
	pthread_t pid;
	pthread_t cid;
	head = NULL;
	int err;
	err = pthread_create(&pid, NULL, producer, "producer");
	if (0 != err)
	{
		fprintf(stderr, "create thread1 faild:.....!%s\n", strerror(err));
		return -1;
	}
	err = pthread_create(&cid, NULL, consumer, "consumer");
	if (0 != err)
	{
		fprintf(stderr, "creat thread2 failed:......!%s\n", strerror(err));
		return -1;
	}
	pthread_join(pid, NULL);
	pthread_join(cid, NULL);
	return 0;
}