}

  // Stable order tests

  // Note: Stable order means that the ordering doesn't change between iterations and versions.
  // Ideally, the ordering in test should never be updated.
  @Test
  public void stableIncidentEdgeOrder_edges_returnsInStableOrder() {
    assume().that(graph.incidentEdgeOrder().type()).isEqualTo(ElementOrder.Type.STABLE);

    populateTShapedGraph();

  }

  // Stable order tests

  // Note: Stable order means that the ordering doesn't change between iterations and versions.
  // Ideally, the ordering in test should never be updated.
  @Test
  public void stableIncidentEdgeOrder_edges_returnsInStableOrder() {
    assume().that(graph.incidentEdgeOrder().type()).isEqualTo(ElementOrder.Type.STABLE);

    populateStarShapedGraph();

    // we really just want to wait for the thread to be in the failure callback so we wait for that
    // explicitly instead.
    failEnter.await();
    assertFalse("State should be updated before calling listeners", manager.isHealthy());
    // now we want to stop the services.
    Thread stoppingThread =
        new Thread() {
          @Override
          public void run() {

  /**
   * Computes the function of current and new value. Subclasses should open-code this update
   * function for most uses, but the virtualized form is needed within retryUpdate.
   *
   * @param currentValue the current value (of either base or a cell)
   * @param newValue the argument from a user update call
   * @return result of the update function
   */
  abstract long fn(long currentValue, long newValue);

  /**

    // let computation complete
    letGetFinishSignal.countDown();
    getFinishedSignal.await();
    checkNothingLogged();

    // asMap view should have been updated
    assertEquals(2, cache.size());
    assertEquals(getKey + suffix, map.get(getKey));
    assertEquals(refreshKey + suffix, map.get(refreshKey));
  }

  private final boolean isDirected;
  private final boolean allowsSelfLoops;
  private final ElementOrder<N> nodeOrder;

  final MapIteratorCache<N, GraphConnections<N, V>> nodeConnections;

  long edgeCount; // must be updated when edges are added or removed

  /** Constructs a graph with the properties specified in {@code builder}. */
  StandardValueGraph(AbstractGraphBuilder<? super N> builder) {
    this(
        builder,

  static final int CONTAINS_VALUE_RETRIES = 3;

  /**
   * Number of cache access operations that can be buffered per segment before the cache's recency
   * ordering information is updated. This is used to avoid lock contention by recording a memento
   * of reads and delaying a lock acquisition until the threshold is crossed or a mutation occurs.
   *
   * <p>This must be a (2^n)-1 as it is used as a mask.

   * This implementation requires O(|N|) time. Classes extending this one may manually keep track of
   * the number of edges as the graph is updated, and override this method for better performance.
   */
  protected long edgeCount() {
    long degreeSum = 0L;
    for (N node : nodes()) {
      degreeSum += degree(node);
    }

    final void addDedupedElement(E e) {
      ensureCapacity(distinct + 1);
      dedupedElements[distinct++] = e;
    }

    /**
     * Adds e to this SetBuilderImpl, returning the updated result. Only use the returned
     * SetBuilderImpl, since we may switch implementations if e.g. hash flooding is detected.
     */
    abstract SetBuilderImpl<E> add(E e);

    }

    @Override
    protected void update(byte b) {
      checkNotDone();
      digest.update(b);
    }

    @Override
    protected void update(byte[] b, int off, int len) {
      checkNotDone();
      digest.update(b, off, len);
    }

    @Override
    protected void update(ByteBuffer bytes) {
      checkNotDone();
      digest.update(bytes);
    }