/*
 * Function to initialize any fields added in PART 3. You SHOULD NOT
 * initialize anything you added in PART 1 or PART 2.
 */
void spool_init_cv1(spool_t* sp) {
    pthread_cond_init(&sp->con_cv, NULL);
    sp->shutdown = 0;
}

/*
 * Function used to notify all threads that a shutdown has occurred. This
 * function will only be called after all produces have finished.
 */
void spool_shutdown_efficient(spool_t* sp) {
    sp->shutdown = 1;
    pthread_cond_broadcast(&sp->con_cv);
}

/*
 * Function used to implement insertion in a thread safe manner. It
 * should use spool_insert_unchecked once it confirms there is room
 * in the spooler. This function should always insert the item.
 */
void spool_insert_cv1(spool_t* sp, char* item) {
    pthread_mutex_lock(&sp->buf_lock);
    while (spool_full(sp)) {
        pthread_cond_wait(&sp->con_cv, &sp->buf_lock);
    }
    spool_insert_unchecked(sp, item);
    pthread_cond_signal(&sp->con_cv);
    pthread_mutex_unlock(&sp->buf_lock);
}

/*
 * Function used to implement removal in a thread safe manner. It
 * should use spool_remove_unchecked once it confirms there is data
 * in the spooler. This function should only return NULL if a shutdown
 * has been issued and otherwise must return an element.
 */
char* spool_remove_cv1(spool_t* sp) {
  pthread_mutex_lock(&sp->buf_lock);
  while (spool_empty(sp) && !sp->shutdown) {
       pthread_cond_wait(&sp->con_cv, &sp->buf_lock);
  }
  if (sp->shutdown) {
    pthread_mutex_unlock(&sp->buf_lock);
    return NULL;
  }
  char* item = spool_remove_unchecked(sp);
  pthread_cond_signal(&sp->con_cv);
  pthread_mutex_unlock(&sp->buf_lock);
  return item;
}