*/
  static final int DRAIN_THRESHOLD = 0x3F;

  /**
   * Maximum number of entries to be drained in a single cleanup run. This applies independently to
   * the cleanup queue and both reference queues.
   */
  // TODO(fry): empirically optimize this
  static final int DRAIN_MAX = 16;

  // Fields

  static final Logger logger = Logger.getLogger(LocalCache.class.getName());

  /**

/**
 * Static utility methods pertaining to {@link Map} instances (including instances of {@link
 * SortedMap}, {@link BiMap}, etc.). Also see this class's counterparts {@link Lists}, {@link Sets}
 * and {@link Queues}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#maps">{@code Maps}</a>.
 *
 * @author Kevin Bourrillion
 * @author Mike Bostock

<a href="#Length_and_capacity"><code>cap</code></a> and
<a href="#Length_and_capacity"><code>len</code></a>
by any number of goroutines without further synchronization.
Channels act as first-in-first-out queues.
For example, if one goroutine sends values on a channel
and a second goroutine receives them, the values are
received in the order sent.
</p>