操作系統實驗——哲學家進餐問題

代碼在gcc上實現

#include <stdio.h>
#include <pthread.h>
#include <errno.h>
#include<unistd.h>
pthread_mutex_t chopstick[6];
void *eat_think(void *arg)
{
	char philosopher = *(char *)arg;
	int left, right; 
	switch (philosopher) {
	case 'A':
		left = 5;
		right = 1;
		break;
	case 'B':
		left = 1;
		right = 2;
		break;
	case 'C':
		left = 2;
		right = 3;
		break;
	case 'D':
		left = 3;
		right = 4;
		break;
	case 'E':
		left = 4;
		right = 5;
		break;
	}
	int i;
	while (1) {
		sleep(2); 
		pthread_mutex_lock(&chopstick[left]); 
		printf("Philosopher %c gets chopstick %d\n", philosopher, left);
		if (pthread_mutex_trylock(&chopstick[right]) == EBUSY) {
			pthread_mutex_unlock(&chopstick[left]);
			continue;
		}
		printf("Philosopher %c gets chopstick %d\n", philosopher, right);
		printf("Philosopher %c is eating.\n", philosopher);
		sleep(2); 
		pthread_mutex_unlock(&chopstick[left]);
		printf("Philosopher %c release chopstick %d\n", philosopher, left);
		pthread_mutex_unlock(&chopstick[right]); 
		printf("Philosopher %c release chopstick %d\n", philosopher, right);

	}
}
int main() {
	pthread_t A, B, C, D, E; 
	int i;
	for (i = 0; i < 5; i++)
		pthread_mutex_init(&chopstick[i], NULL);
	pthread_create(&A, NULL, eat_think, "A");
	pthread_create(&B, NULL, eat_think, "B");
	pthread_create(&C, NULL, eat_think, "C");
	pthread_create(&D, NULL, eat_think, "D");
	pthread_create(&E, NULL, eat_think, "E");
	pthread_join(A, NULL);
	pthread_join(B, NULL);
	pthread_join(C, NULL);
	pthread_join(D, NULL);
	pthread_join(E, NULL);
	return 0;
}