task2

#include <sys/time.h>
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>

#define NUMP 5

pthread_mutex_t fork_mutex[NUMP];
pthread_mutex_t phils_eating_lock;
pthread_cond_t phils_eating_less_than_five;
unsigned phils_eating;

void increment(){
  pthread_mutex_lock(&phils_eating_lock);
  while (phils_eating == 4)
    pthread_cond_wait(&phils_eating_less_than_five, &phils_eating_lock);
  phils_eating++;
  pthread_mutex_unlock(&phils_eating_lock);
}

void decrement(){
  pthread_mutex_lock(&phils_eating_lock);
  phils_eating--;
  if (phils_eating < 4)
    pthread_cond_signal(&phils_eating_less_than_five);
  pthread_mutex_unlock(&phils_eating_lock);
}

int main(){
  int i;
  pthread_t diner_thread[NUMP];
  int dn[NUMP];
  void *diner();
  for (i=0;i<NUMP;i++)
    pthread_mutex_init(&fork_mutex[i], NULL);
  pthread_cond_init(&phils_eating_less_than_five, NULL);

  for (i=0;i<NUMP;i++){
    dn[i] = i;
    pthread_create(&diner_thread[i],NULL,diner,&dn[i]);
  }
  for (i=0;i<NUMP;i++)
    pthread_join(diner_thread[i],NULL);

  for (i=0;i<NUMP;i++)
    pthread_mutex_destroy(&fork_mutex[i]);

  pthread_exit(0);

}

void *diner(int *i){
  int v;
  int eating = 0;
  printf("I'm diner %d\n",*i);
  v = *i;
  while (eating < 5) {
    printf("%d is thinking\n", v);
    sleep( v/2);
    printf("%d is hungry\n", v);
    increment();
    pthread_mutex_lock(&fork_mutex[v]);
    pthread_mutex_lock(&fork_mutex[(v+1)%NUMP]);
    decrement();
    printf("%d is eating\n", v);
    eating++;
    sleep(1);
    printf("%d is done eating\n", v);
    pthread_mutex_unlock(&fork_mutex[v]);
    pthread_mutex_unlock(&fork_mutex[(v+1)%NUMP]);

  }
  pthread_exit(NULL);
}