* method is intrinsically racy, it should only be used when it is known that no threads are
   * concurrently updating.
   */
  public void reset() {
    internalReset(0L);
  }

  /**
   * Equivalent in effect to {@link #sum} followed by {@link #reset}. This method may apply for
   * example during quiescent points between multithreaded computations. If there are updates