Implementing Dining Philosopher problem
Implementing Dining Philosopher problem
Explaination- click
C program for the implementation of Dining Philosopher problem :
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#include<stdio.h>
#include<semaphore.h>
#include<pthread.h>
#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<N;i++)
sem_init(&S[i],0,0);
for(i=0;i<N;i++)
{
pthread_create(&thread_id[i],NULL,philospher,&phil_num[i]);
printf("Philosopher %d is thinking\n",i+1);
}
for(i=0;i<N;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);
}
