/*
 * Código incompleto
 */ 
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <unistd.h> 

pthread_mutex_t lock;
pthread_barrier_t barrier;

/* Thread que segura o lock tem a menor prioridade */

void* f_thread0(void *v) {
  int i;

  pthread_barrier_wait(&barrier);

  pthread_mutex_lock(&lock);
  sleep(10);
  for (i = 0; i < 1000; i++)
    int k = i*i*i;
  pthread_mutex_unlock(&lock);

  return NULL;
}

/* Thread de maior prioridade aguarda o lock */
void* f_thread1(void *v) {

  pthread_barrier_wait(&barrier);

  pthread_mutex_lock(&lock);
  printf("Thread 1.\n");
  pthread_mutex_lock(&lock);

  return NULL;
}

/* Outra thread com prioridade alta quer o processador só para ela. */
                      
void* f_thread2(void *v) {

  pthread_barrier_wait(&barrier);
  while(1);
  return NULL;
}

int main() {
  pthread_t thr0, thr1, thr2;

  pthread_barrier_init(&barrier, NULL, 3);

  pthread_mutexattr_t attr;
  pthread_mutexattr_init(&attr);
  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_PRIO_INHERIT_NP);

  pthread_mutex_init(&lock, NULL);

  pthread_create(&thr0, NULL, f_thread0, NULL);
  pthread_create(&thr1, NULL, f_thread1, NULL);
  pthread_create(&thr2, NULL, f_thread2, NULL);

  pthread_join(thr0, NULL);
  pthread_join(thr1, NULL);
  pthread_join(thr2, NULL);

  return 0;
}