学步园

pthread_cond_t

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

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

struct msg *head = NULL;
pthread_cond_t has_product = PTHREAD_COND_INITIALIZER;
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

void *producer(void *p)
{
	struct msg *mp;
	for(;;)
	{
		mp = malloc(sizeof(struct msg));
		mp->num = rand() % 2000 + 1;
		printf("Producer  %d\n",mp->num);
		pthread_mutex_lock(&lock);
		mp->next = head;
		head = mp;
		pthread_mutex_unlock(&lock);
		pthread_cond_signal(&has_product);
		sleep(rand() % 5);
	}
	return NULL;
}

void *consumer(void *p)
{
	struct msg *mp;
	for(;;)
	{
		pthread_mutex_lock(&lock);
		while(head == NULL)
			pthread_cond_wait(&has_product,&lock);
		mp = head;
		head = mp->next;
		pthread_mutex_unlock(&lock);
		printf("Consumer %d\n",mp->num);
		free(mp);
		sleep(rand() % 5);
		
	}
	return NULL;
}


int main()
{
	pthread_t pid, cid;
	srand(time(NULL));
	
	pthread_create(&pid,NULL,producer,NULL);
	pthread_create(&cid,NULL,consumer,NULL);
	pthread_join(pid,NULL);
	pthread_join(cid,NULL);
	return 0;
}

pthread_mutex_t

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

#define NLOOP	50
int counter = 0;
pthread_mutex_t counter_mutex = PTHREAD_MUTEX_INITIALIZER;

void* doit(void* p)
{
	int i,val;
	for( i = 0; i < NLOOP; i++)
	{
		pthread_mutex_lock(&counter_mutex);
		counter++;
		printf("%x: %d\n",(unsigned int)pthread_self(),counter);
		pthread_mutex_unlock(&counter_mutex);
		usleep(1);
	}
	return 0;
}

int main()
{
	pthread_t tidA,tidB;
	pthread_create(&tidA,NULL,doit,NULL);
	pthread_create(&tidB,NULL,doit,NULL);
	
	pthread_join(tidA,NULL);
	pthread_join(tidB,NULL);
	
	return 0;
}

sem_t

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

#define NUM	5
int queue[NUM];

sem_t blank_number, product_number;

void *producer(void *p)
{
	int i = 0;
	while(1)
	{
		sem_wait(&blank_number);
		queue[i] = rand() % 1000 + 1;
		sem_post(&product_number);
		printf("product %d\n",queue[i]);
		i = (i + 1) % NUM;
		sleep(rand() % 5);
	}
	return NULL;
}

void *consumer(void *p)
{
	int i = 0;
	while(1)
	{
		sem_wait(&product_number);
		printf("consumer %d\n",queue[i]);
		queue[i] = 0;
		sem_post(&blank_number);
		i = (i+1) % NUM;
		sleep(rand() % 5);
	}
	return NULL;
}


int main()
{
	pthread_t pid,cid;
	srand(time(NULL));
	sem_init(&blank_number,0,NUM);
	sem_init(&product_number,0,0);
	
	pthread_create(&pid, NULL, producer,NULL);
	pthread_create(&cid, NULL, consumer,NULL);
	pthread_join(pid,NULL);
	pthread_join(cid,NULL);
	sem_destroy(&blank_number);
	sem_destroy(&product_number);
	return 0;
}

线程同步