哲学家进餐问题的c语言代码

#include 
#include 

#define N 5
#define LEFT (i+N-1)%N
#define RIGHT (i+1)%N
#define THINK_TIME 3
#define EAT_TIME 2

enum { THINKING, HUNGRY, EATING } state[N];

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER, s[N];

void test(int i)
{
    if (state[i] == HUNGRY
     && state[LEFT] != EATING
     && state[RIGHT] != EATING)
    {
        state[i] = EATING;
        pthread_mutex_unlock(&s[i]);
    }
}

void take_forks(int i)
{
    pthread_mutex_lock(&mutex);
    state[i] = HUNGRY;
    test(i);
    pthread_mutex_unlock(&mutex);
    pthread_mutex_lock(&s[i]);
}

void put_forks(int i)
{
    pthread_mutex_lock(&mutex);
    state[i] = THINKING;
    test(LEFT);
    test(RIGHT);
    pthread_mutex_unlock(&mutex);
}

void think(int i)
{
    printf("philosopher %d is thinking...\n", i);
    sleep(THINK_TIME);
}

void eat(int i)
{
    printf("philosopher %d is eating...\n", i);
    sleep(EAT_TIME);
}

void* phi(void* vargp)
{
    int i = *(int*)vargp;
    while (1)
    {
        think(i);
        take_forks(i);
        eat(i);
        put_forks(i);
    }
    return NULL;
}

int main()
{
    int i;
    pthread_t tid[N];
    for (i = 0; i < N; i++)
        pthread_create(&tid[i], NULL, phi, (void*)(&i));
    for (i = 0; i < N; i++)
        pthread_join(tid[i], NULL);
    return 0;
}