* 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

        }
        if (init) break;
      } else if (casBase(v = base, fn(v, x))) break; // Fall back on using base
    }
  }

  /** Sets base and all cells to the given value. */
  final void internalReset(long initialValue) {
    Cell[] as = cells;
    base = initialValue;
    if (as != null) {
      int n = as.length;
      for (int i = 0; i < n; ++i) {
        Cell a = as[i];