* the cleanup queue and both reference queues.
   */
  // TODO(fry): empirically optimize this
  static final int DRAIN_MAX = 16;

  // Fields

  /**
   * Mask value for indexing into segments. The upper bits of a key's hash code are used to choose
   * the segment.
   */
  final transient int segmentMask;

  /**
   * Shift value for indexing within segments. Helps prevent entries that end up in the same segment

     * #size()} of {@code set} otherwise.
     */
    static int minSize(Set<?> set) {
      return set instanceof SetView ? ((SetView<?>) set).minSize() : set.size();
    }

    /**
     * Returns an upper bound for {@link #size()} based on the sizes of the backing sets.
     *
     * <p>This is more efficient than {@link #size()}, which iterates over the entire {@link
     * SetView}.
     */
    abstract int maxSize();