Linux下实现哲学家就餐问题

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <semaphore.h>
#include <sys/types.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>

#define NUM_THREADS_P 5
#define CHAIR_NUM 4
#define CHOP_NUM  5

int chairflg[CHAIR_NUM][2],dining_num = 0;
sem_t chair,chopstics[CHOP_NUM],mutex,mutex1,print_mutex;
pthread_t threads_p[NUM_THREADS_P];

void *philosopher_thread(void *args);

int main(void)
{
    int i;
    
    sem_init(&chair, 0, CHAIR_NUM);
    for(i=0; i<CHOP_NUM; i++)
    {
        sem_init(&chopstics[i], 0, 1);
    }
    sem_init(&mutex, 0, 1);
    sem_init(&mutex1, 0, 1);
    sem_init(&print_mutex, 0, 1);
    for(i=0; i<CHAIR_NUM; i++)
        chairflg[i][0] = 0;
        
    for(i=0; i<NUM_THREADS_P; i++)
    {
        pthread_create(&threads_p[i], NULL, philosopher_thread, (void *)i);
    }    
    for(i=0; i<NUM_THREADS_P; i++)
    {
        pthread_join(threads_p[i], NULL);
    }
    
    // sem_destroy(&chair);
    // sem_destroy(&chopstics[CHOP_NUM]);
    // sem_destroy(&mutex);
    // sem_destroy(&mutex1);
    // sem_destroy(&print_mutex);
    
    return 0;
}

void *philosopher_thread(void *args)
{
    while(1)
    {
    int i,j;
    i = (int)args;
    printf("philosopher %d is thinking\n",i);
    sleep(rand()%3);
    sem_wait(&chair);
    sem_wait(&mutex);
    
    for(j=0; j<CHAIR_NUM;j++)
    {
        if(chairflg[j][0] == 0)
        {
            chairflg[j][0] = 1;
            chairflg[j][1] = i;
            break;
        }
    }
    dining_num++;
    sem_post(&mutex);
    sem_wait(&chopstics[i]);
    printf("philosopher %d get chopstics %d\n",i,i);
    sem_wait(&chopstics[(i+1)%CHOP_NUM]);
    printf("philosopher %d get chopstics %d\n",i,(i+1)%CHOP_NUM);
    
    sleep(rand()%3);
    sem_wait(&print_mutex);
    printf("philosopher %d is dining,when he is dining,there are %d philosophers at table.\n",i,dining_num);
    
    for(j=0; j<CHAIR_NUM; j++)
    {
        if(chairflg[j][1] == i)
        {
            printf("philosopher %d in chair %d\n",i,j);
        }
    }
    printf("\n\n");
    sem_post(&print_mutex);
    sleep(rand()%3);
    sem_post(&chopstics[i]);
    sem_post(&chopstics[(i+1)%CHOP_NUM]);
    sem_wait(&mutex1);
    
    for(j=0; j<CHAIR_NUM; j++)
    {
        if(chairflg[j][1] == i)
        {
            chairflg[j][0] = 0;
            break;
        }
    }
    dining_num--;
    sem_post(&mutex1);
    sem_post(&chair);
    printf("philosopher %d leaves\n",i);
    
    }
}