posix信号量与互斥锁

Posted 2020-10-13 Malphite

#include <unistd.h>
#include <sys/types.h>
#include <pthread.h>
#include <semaphore.h>

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>

#define ERR_EXIT(m)         do         {                 perror(m);                 exit(EXIT_FAILURE);         } while(0)

#define CONSUMERS_COUNT 1
#define PRODUCERS_COUNT 1
#define BUFFSIZE 10

int g_buffer[BUFFSIZE];

unsigned short in = 0;
unsigned short out = 0;
unsigned short produce_id = 0;
unsigned short consume_id = 0;

sem_t g_sem_full;
sem_t g_sem_empty;
pthread_mutex_t g_mutex;

pthread_t g_thread[CONSUMERS_COUNT+PRODUCERS_COUNT];

void* consume(void *arg)
{
    int num = (int)arg;
    int i;
    while (1)
    {
        printf("%d wait buffer not empty\n", num);
        sem_wait(&g_sem_empty);
        pthread_mutex_lock(&g_mutex);
        //消费产品
        for (i=0; i<BUFFSIZE; i++)
        {
            printf("%02d ", i);
            if (g_buffer[i] == -1)
                printf("%s", "null");
            else
                printf("%d", g_buffer[i]);

            if (i == out)
                printf("\t<--consume");

            printf("\n");
        }

        consume_id = g_buffer[out];
        printf("%d begin consume product %d\n", num, consume_id);
        g_buffer[out] = -1;
        out = (out + 1) % BUFFSIZE;
        printf("%d end consume product %d\n", num, consume_id);

        pthread_mutex_unlock(&g_mutex);
        sem_post(&g_sem_full);

        sleep(1);
    }
    return NULL;
}

void* produce(void *arg)
{
    int num = (int)arg;
    int i;
    while (1)
    {
        printf("%d wait buffer not full\n", num);
        sem_wait(&g_sem_full);
        pthread_mutex_lock(&g_mutex);
        //生产产品的代码
        for (i=0; i<BUFFSIZE; i++)
        {
            printf("%02d ", i);
            if (g_buffer[i] == -1)
                printf("%s", "null");
            else
                printf("%d", g_buffer[i]);

            if (i == in)
                printf("\t<--produce");

            printf("\n");
        }
        
        printf("%d begin produce product %d\n", num, produce_id);
        g_buffer[in] = produce_id;
        in = (in + 1) % BUFFSIZE;
        printf("%d end produce product %d\n", num, produce_id++);
        pthread_mutex_unlock(&g_mutex);
        sem_post(&g_sem_empty);

        sleep(5);
    }
    return NULL;
}

int main(void)
{
    int i;
    for (i=0; i<BUFFSIZE; i++)
        g_buffer[i] = -1;

    sem_init(&g_sem_full, 0, BUFFSIZE);
    sem_init(&g_sem_empty, 0, 0);

    pthread_mutex_init(&g_mutex, NULL);

    for (i=0; i<CONSUMERS_COUNT; i++)
        pthread_create(&g_thread[i], NULL, consume, (void*)i);

    for (i=0; i<PRODUCERS_COUNT; i++)
        pthread_create(&g_thread[CONSUMERS_COUNT+i], NULL, produce, (void*)i);
    
    for (i=0; i<CONSUMERS_COUNT+PRODUCERS_COUNT; i++)
        pthread_join(g_thread[i], NULL);

    sem_destroy(&g_sem_full);
    sem_destroy(&g_sem_empty);
    pthread_mutex_destroy(&g_mutex);

    return 0;
}