posix 信号量---生产者消费者（一）

最新推荐文章于 2024-09-25 15:21:06 发布

jackywgw

最新推荐文章于 2024-09-25 15:21:06 发布

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分类专栏： c++ linux

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本文详细介绍了基于内存的信号量实现的单生产者单消费者机制，包括代码实现、核心概念以及运行流程。

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单生产者单消费者
1.有名信号量的单生产者单消费者

#include "../unipc.h"

#define NBUFF 10
#define SEM_MUTEX "mutex"
#define SEM_NEMPTY "nempty"
#define SEM_NSTORED "nstored"
#define FILE_MODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)
int nitems;

struct {
    int buff[NBUFF];
    sem_t *mutex,*nempty,*nstored;
} shared;

void *produce(void *arg)
{
    int i;
    for(i = 0;i < nitems; i++) {
        sem_wait(shared.nempty);
        sem_wait(shared.mutex);
        shared.buff[i%NBUFF] = i;
        sem_post(shared.mutex);
        sem_post(shared.nstored);
    }
    return NULL;
}

void *consume(void *arg)
{
    int i;
    for(i = 0;i < nitems; i++) {
        sem_wait(shared.nstored);
        sem_wait(shared.mutex);
        if(i != shared.buff[i%NBUFF]) {
            printf("i = %d,buff[%d]=%d\n",i,i,shared.buff[i]);
        }
        sem_post(shared.mutex);
        sem_post(shared.nempty);
    }
    return NULL;
}

int main(int argc ,char *argv[])
{
    pthread_t ptid_produce,ptid_consume;

    if(argc != 2 ) {
        printf("usage produce1 <#items>\n");
        return -1;
    }
    nitems = atoi(argv[1]);
    
    shared.mutex = sem_open(SEM_MUTEX,O_CREAT|O_EXCL,FILE_MODE,1);
    shared.nempty = sem_open(SEM_NEMPTY,O_CREAT|O_EXCL,FILE_MODE,NBUFF);
    shared.nstored = sem_open(SEM_NSTORED,O_CREAT|O_EXCL,FILE_MODE,0);

    pthread_create(&ptid_produce,NULL,produce,NULL);
    pthread_create(&ptid_consume,NULL,consume,NULL);

    pthread_join(ptid_produce,NULL);
    pthread_join(ptid_consume,NULL);

    sem_unlink(SEM_MUTEX);
    sem_unlink(SEM_NEMPTY);
    sem_unlink(SEM_NSTORED);

    return 0;
}

基于内存的信号量的单生产者单消费者

./unipc.h"

#define NBUFF 10
#define FILE_MODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)
int nitems;

struct {
    int buff[NBUFF];
    sem_t mutex,nempty,nstored;
} shared;

void *produce(void *arg)
{
    int i;
    for(i = 0;i < nitems; i++) {
        sem_wait(&shared.nempty);
        sem_wait(&shared.mutex);
        shared.buff[i%NBUFF] = i;
        sem_post(&shared.mutex);
        sem_post(&shared.nstored);
    }
    return NULL;
}

void *consume(void *arg)
{
    int i;
    for(i = 0;i < nitems; i++) {
        sem_wait(&shared.nstored);
        sem_wait(&shared.mutex);
        if(i != shared.buff[i%NBUFF]) {
            printf("i = %d,buff[%d]=%d\n",i,i,shared.buff[i]);
        }
        sem_post(&shared.mutex);
        sem_post(&shared.nempty);
    }
    return NULL;
}

int main(int argc ,char *argv[])
{
    pthread_t ptid_produce,ptid_consume;

    if(argc != 2 ) {
        printf("usage produce1 <#items>\n");
        return -1;
    }
    nitems = atoi(argv[1]);

    sem_init(&shared.mutex,0,1);
    sem_init(&shared.nempty,0,NBUFF);
    sem_init(&shared.nstored,0,0);

    pthread_create(&ptid_produce,NULL,produce,NULL);
    pthread_create(&ptid_consume,NULL,consume,NULL);

    pthread_join(ptid_produce,NULL);
    pthread_join(ptid_consume,NULL);

    sem_destroy(&shared.mutex);
    sem_destroy(&shared.nempty);
    sem_destroy(&shared.nstored);
    return 0;
}