* a regular priority queue, the methods {@link #peekLast}, {@link #pollLast} and {@link
 * #removeLast} are also provided, to act on the <i>greatest</i> element in the queue instead.
 *
 * <p>A min-max priority queue can be configured with a maximum size. If so, each time the size of
 * the queue exceeds that value, the queue automatically removes its greatest element according to

 * a regular priority queue, the methods {@link #peekLast}, {@link #pollLast} and {@link
 * #removeLast} are also provided, to act on the <i>greatest</i> element in the queue instead.
 *
 * <p>A min-max priority queue can be configured with a maximum size. If so, each time the size of
 * the queue exceeds that value, the queue automatically removes its greatest element according to

     * fraction of read operations.
     */
    final AtomicInteger readCount = new AtomicInteger();

    /**
     * A queue of elements currently in the map, ordered by write time. Elements are added to the
     * tail of the queue on write.
     */
    @GuardedBy("this")
    final Queue<ReferenceEntry<K, V>> writeQueue;

    /**

    WeakValueReferenceImpl(ReferenceQueue<V> queue, V referent, E entry) {
      super(referent, queue);
      this.entry = entry;
    }

    @Override
    public E getEntry() {
      return entry;
    }

    @Override
    public WeakValueReference<K, V, E> copyFor(ReferenceQueue<V> queue, E entry) {
      return new WeakValueReferenceImpl<>(queue, get(), entry);
    }
  }

  /**

     * fraction of read operations.
     */
    final AtomicInteger readCount = new AtomicInteger();

    /**
     * A queue of elements currently in the map, ordered by write time. Elements are added to the
     * tail of the queue on write.
     */
    @GuardedBy("this")
    final Queue<ReferenceEntry<K, V>> writeQueue;

    /**

    WeakValueReferenceImpl(ReferenceQueue<V> queue, V referent, E entry) {
      super(referent, queue);
      this.entry = entry;
    }

    @Override
    public E getEntry() {
      return entry;
    }

    @Override
    public WeakValueReference<K, V, E> copyFor(ReferenceQueue<V> queue, E entry) {
      return new WeakValueReferenceImpl<>(queue, get(), entry);
    }
  }

  /**

/**
 * A bounded {@linkplain BlockingQueue blocking queue} backed by an array. This queue orders
 * elements FIFO (first-in-first-out). The head of the queue is that element that has been
 * on the queue the longest time. The tail of the queue is that element that has been on
 * the queue the shortest time. New elements are inserted at the tail of the queue, and the queue
 * retrieval operations obtain elements at the head of the queue.

/**
 * A bounded {@linkplain BlockingQueue blocking queue} backed by an array. This queue orders
 * elements FIFO (first-in-first-out). The head of the queue is that element that has been
 * on the queue the longest time. The tail of the queue is that element that has been on
 * the queue the shortest time. New elements are inserted at the tail of the queue, and the queue
 * retrieval operations obtain elements at the head of the queue.

    assertFalse(segment.clearValueForTesting(key, hash, valueRef));
    segment.setWeakValueReferenceForTesting(entry, valueRef);
    assertTrue(segment.clearValueForTesting(key, hash, valueRef));
  }

  // reference queues

  public void testDrainKeyReferenceQueueOnWrite() {
    for (MapMaker maker : allWeakKeyStrengthMakers()) {
      MapMakerInternalMap<Object, Object, ?, ?> map = makeMap(maker.concurrencyLevel(1));

    assertFalse(segment.clearValueForTesting(key, hash, valueRef));
    segment.setWeakValueReferenceForTesting(entry, valueRef);
    assertTrue(segment.clearValueForTesting(key, hash, valueRef));
  }

  // reference queues

  public void testDrainKeyReferenceQueueOnWrite() {
    for (MapMaker maker : allWeakKeyStrengthMakers()) {
      MapMakerInternalMap<Object, Object, ?, ?> map = makeMap(maker.concurrencyLevel(1));