/**
     * Careful here: if threads are mutating the atomicLongArray while this method is executing, the
     * final long[] will be a "rolling snapshot" of the state of the bit array. This is usually good
     * enough, but should be kept in mind.
     */
    public static long[] toPlainArray(AtomicLongArray atomicLongArray) {
      long[] array = new long[atomicLongArray.length()];
      for (int i = 0; i < array.length; ++i) {

  // Java 2nd Edition Item 76: Write readObject methods defensively.
  private transient AtomicLongArray longs;

  /**
   * Creates a new {@code AtomicDoubleArray} of the given length, with all elements initially zero.
   *
   * @param length the length of the array
   */
  public AtomicDoubleArray(int length) {
    this.longs = new AtomicLongArray(length);
  }

  /**