生产者---消费者模型之信号量

信号量：

（1）定义信号量：

sem_t semaphore; //定义一个名为semaphore的信号量；

（2）初始化信号量 

int sem_init(sem_t *sem, int pshared, unsigned int value); 

参数：

sem_t*  sem：要初始化的信号量；

int pshared:pshared = 0;

usigned int value：该信号信号量的初值；

返回值：

a.返回0，表示初始化成功；

b.返回-1，表示操作失败；

（3）P操作

int sem_wait(sem_t* sem);        //对于信号量sem进行P操作；int sem_trywait(sem_t* sem);

（4）V操作

int sem_post(sem_t* sem);        //对于信号量sem进行V操作

生产者-消费者模型：

交易场所：环形队列；

注：使用信号量进行互斥和同步；

单进程单生产者--单消费者代码实现：

producter_consumer.c

#include<stdio.h>#include<pthread.h>#include<semaphore.h>sem_t blank_count;sem_t data_count;int cycle_queue[20];void* producter_running(void* arg){    int step = 0;    while(1)    {        sem_wait(&blank_count);   //P        int data = rand()%1000;        cycle_queue[step] = data;        step++;        step %= 20;        printf("the producter is %d\n",data);        sem_post(&data_count); //V    }}void* consumer_running(void* arg){    int step =0;    while(1)    {        sleep(1);        sem_wait(&data_count);        int data = cycle_queue[step];        step++;        step %= 20;        printf("the consumer is %d\n",data);        sem_post(&blank_count);    }}//producter_consumer based on single threadint main(){    pthread_t producter1;    pthread_t consumer1;    sem_init(&blank_count,0,20);    sem_init(&data_count,0,0);       pthread_create(&producter1,NULL,producter_running,NULL);    pthread_create(&consumer1,NULL,consumer_running,NULL);    pthread_join(producter1,NULL);    pthread_join(consumer1,NULL);    return 0;}

Makefile：

producter_consumer:producter_consumer.c    gcc -o $@ $^ -lpthread.PHONY:cleanclean:    rm -f producter_consumer

运行结果： 

单进程多生产者多消费者的生产者消费者模型：

producter_consumer.c

#include<stdio.h>#include<pthread.h>#include<semaphore.h>sem_t blank_count;sem_t data_count;int cycle_queue[20];pthread_mutex_t pro = PTHREAD_MUTEX_INITIALIZER;pthread_mutex_t con = PTHREAD_MUTEX_INITIALIZER;void* producter_running(void* arg){    static int step = 0;    while(1)    {        pthread_mutex_lock(&pro);        sem_wait(&blank_count);   //P        int data = rand()%1000;        cycle_queue[step] = data;        step++;        step %= 20;        printf("producter:pthread_id:%u--->data:%d\n",pthread_self(),data);        sem_post(&data_count); //V        pthread_mutex_unlock(&pro);    }    return NULL;}void* consumer_running(void* arg){    static    int step =0;    while(1)    {        pthread_mutex_lock(&con);        sem_wait(&data_count);        int data = cycle_queue[step];        step++;        step %= 20;        printf("consumeer；pthread_id:%u--->data:%d\n",pthread_self(),data);        sem_post(&blank_count);        pthread_mutex_unlock(&con);        sleep(1);    }}//producter_consumer based on single threadint main(){    pthread_t producter1;    pthread_t producter2;    pthread_t consumer1;    pthread_t consumer2;    sem_init(&blank_count,0,20);    sem_init(&data_count,0,0);       pthread_create(&producter1,NULL,producter_running,NULL);    pthread_create(&producter2,NULL,producter_running,NULL);    pthread_create(&consumer1,NULL,consumer_running,NULL);    pthread_create(&consumer2,NULL,consumer_running,NULL);    pthread_join(producter1,NULL);    pthread_join(producter2,NULL);    pthread_join(consumer1,NULL);    pthread_join(consumer2,NULL);    sem_destroy(&blank_count);    sem_destroy(&data_count);    pthread_mutex_destroy(&pro);    pthread_mutex_destroy(&con);    return 0;}

运行结果：

作者水平有限，若有问题，请留言，谢谢!!!