哲学家吃空心粉问题

//      pe.c
//      哲学家吃空心粉的问题
//      Copyright 2011 shiweifu <shiweifu@126.com>
//      

#define _REENTRANT
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

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

#define STR_MAX 256

typedef struct philosophy {
    char name[STR_MAX];
    sem_t *left;
    sem_t *right;
    char is_stop;
} philosophy;

void *thread_function(void *arg);

int main(int argc, char **argv) {    
    
    int i = 0;
    //五只悲剧的筷子
    sem_t sems[5];
    //五个NC哲学家
    philosophy philers[5];
    
    pthread_t threads[5];
    
    int res = 0;
    
    char tmp[255] = {0};
    
    for(; i < 5; i++) {
        philers[i].left = &sems[i];
        philers[i].right = &sems[i];
        
        if (i == 4) {
            philers[i].left = &sems[0];
        }
        philers[i].is_stop = 0;
        sprintf(tmp,"NC %d",i);
        strncpy(philers[i].name,tmp,255);
    }
    

    for(i = 0; i < 5; i++) {
        sem_init(&sems[i], 0, 10);

        res = pthread_create(&threads[i],NULL,thread_function,&philers[i]);
        if (res != 0) {
            perror("创建线程出错啦...");
        }
    }
    
    //给这群吃货吃20秒
    sleep(20);
    
    for(i = 0; i < 5; i++) {
        philers[i].is_stop = 1;
        pthread_join(threads[i],NULL);
        
    }
    for(i = 0; i < 5; i++) {
        sem_destroy(&sems[i]);
    }

    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg) {
    philosophy *p = arg;
    
    while (1) {
        if (sem_trywait(p->left) == 0) {
            if (sem_trywait(p->right) == 0) {
                printf("红烧翅膀真好吃,我是%s\n",p->name);
                sem_post(p->left);
                sem_post(p->right);
                sleep(1);

            } else {
                sem_post(p->left);
            }
        }
        if (p->is_stop == 1) {
            break;
        }
    }
    pthread_exit(NULL);
}