* eliminating explicit signaling, this class can guarantee that only one thread is awakened when a
 * condition becomes true (no "signaling storms" due to use of {@link
 * java.util.concurrent.locks.Condition#signalAll Condition.signalAll}) and that no signals are lost
 * (no "hangs" due to incorrect use of {@link java.util.concurrent.locks.Condition#signal
 * Condition.signal}).
 *

      lock.lock();
      try {
        condition.signal();
      } finally {
        lock.unlock();
      }
    }

    @Override
    public void signalAll() {
      lock.lock();
      try {
        condition.signalAll();
      } finally {
        lock.unlock();
      }
    }
  }