Code for Dining Philosopher's Problem

Code for Dining Philosopher's Problem

#include

#include

#include

#define N 5

#define THINKING 0

#define HUNGRY 1

#define EATING 2

#define LEFT (ph_num+4)%N

#define RIGHT (ph_num+1)%N

sem_t mutex;

sem_t S[N];

void * philospher(void *num);

void take_fork(int);

void put_fork(int);

void test(int);

int state[N];

int phil_num[N]={0,1,2,3,4};

int main()

{

    int i;

    pthread_t thread_id[N];

    sem_init(&mutex,0,1);

    for(i=0;i

        sem_init(&S[i],0,0);

    for(i=0;i

    {

        pthread_create(&thread_id[i],NULL,philospher,&phil_num[i]);

        printf("Philosopher %d is thinking\n",i+1);

    }

    for(i=0;i

        pthread_join(thread_id[i],NULL);

}

void *philospher(void *num)

{

    while(1)

    {

        int *i = num;

        sleep(1);

        take_fork(*i);

        sleep(0);

        put_fork(*i);

    }

}

void take_fork(int ph_num)

{

    sem_wait(&mutex);

    state[ph_num] = HUNGRY;

    printf("Philosopher %d is Hungry\n",ph_num+1);

    test(ph_num);

    sem_post(&mutex);

    sem_wait(&S[ph_num]);

    sleep(1);

}

void test(int ph_num)

{

    if (state[ph_num] == HUNGRY && state[LEFT] != EATING && state[RIGHT] != EATING)

    {

        state[ph_num] = EATING;

        sleep(2);

        printf("Philosopher %d takes fork %d and %d\n",ph_num+1,LEFT+1,ph_num+1);

        printf("Philosopher %d is Eating\n",ph_num+1);

        sem_post(&S[ph_num]);

    }

}

void put_fork(int ph_num)

{

    sem_wait(&mutex);

    state[ph_num] = THINKING;

    printf("Philosopher %d putting fork %d and %d down\n",ph_num+1,LEFT+1,ph_num+1);

    printf("Philosopher %d is thinking\n",ph_num+1);

    test(LEFT);

    test(RIGHT);

    sem_post(&mutex);

}

Note: Don’t forgot to link pthread when compiling. It can be done by compiling with -lpthread option. eg: gcc -lpthread philospher.c

OUTPUT

Philosopher 1 is thinking
Philosopher 2 is thinking
Philosopher 3 is thinking
Philosopher 4 is thinking
Philosopher 5 is thinking
Philosopher 1 is Hungry
Philosopher 1 takes fork 5 and 1
Philosopher 1 is Eating
Philosopher 2 is Hungry
Philosopher 3 is Hungry
Philosopher 3 takes fork 2 and 3
Philosopher 3 is Eating
Philosopher 4 is Hungry
Philosopher 5 is Hungry
Philosopher 1 putting fork 5 and 1 down
Philosopher 1 is thinking
Philosopher 5 takes fork 4 and 5
Philosopher 5 is Eating
Philosopher 3 putting fork 2 and 3 down
Philosopher 3 is thinking