private void growIfNeeded() {
    if (size > queue.length) {
      int newCapacity = calculateNewCapacity();
      Object[] newQueue = new Object[newCapacity];
      System.arraycopy(queue, 0, newQueue, 0, queue.length);
      queue = newQueue;
    }
  }

  /** Returns ~2x the old capacity if small; ~1.5x otherwise. */
  private int calculateNewCapacity() {
    int oldCapacity = queue.length;
    int newCapacity =

  private static final int TO_BYTE_ARRAY_DEQUE_SIZE = 20;

  /**
   * Returns a byte array containing the bytes from the buffers already in {@code bufs} (which have
   * a total combined length of {@code totalLen} bytes) followed by all bytes remaining in the given
   * input stream.
   */
  private static byte[] toByteArrayInternal(InputStream in, Queue<byte[]> bufs, int totalLen)
      throws IOException {

  @CanIgnoreReturnValue
  public static Set<Feature<?>> addImpliedFeatures(Set<Feature<?>> features) {
    Queue<Feature<?>> queue = new ArrayDeque<>(features);
    while (!queue.isEmpty()) {
      Feature<?> feature = queue.remove();
      for (Feature<?> implied : feature.getImpliedFeatures()) {
        if (features.add(implied)) {
          queue.add(implied);
        }
      }
    }
    return features;
  }

  /**

     */
    @CheckForNull
    abstract N visitNext(Deque<Iterator<? extends N>> horizon);
  }

  /** Poor man's method reference for {@code Deque::addFirst} and {@code Deque::addLast}. */
  private enum InsertionOrder {
    FRONT {
      @Override
      <T> void insertInto(Deque<T> deque, T value) {
        deque.addFirst(value);
      }
    },
    BACK {
      @Override

      }
    }
  }

  /** Invokes {@code queue.}{@link BlockingQueue#take() take()} uninterruptibly. */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  public static <E> E takeUninterruptibly(BlockingQueue<E> queue) {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          return queue.take();
        } catch (InterruptedException e) {

    private final Queue<T> queue;

    UnIterableQueue(Queue<T> queue) {
      this.queue = queue;
    }

    @Override
    public Iterator<T> iterator() {
      throw new UnsupportedOperationException();
    }

    @Override
    protected Queue<T> delegate() {
      return queue;
    }
  }

  public void testIndexOf_empty() {

                    intervalControlHelper.delayByRules();

                    if (logger.isDebugEnabled()) {
                        logger.debug("Processing documents in IndexUpdater queue.");
                    }

                    updateTime = systemHelper.getCurrentTimeAsLong();

                    List<EsAccessResult> arList = getAccessResultList(cb, cleanupTime);

    private Map<String, Map<String, Map<String, MavenProject>>> allProjects;
    private Path projectLocalRepository;
    // projectId -> Deque<lifecycle>
    private final Map<String, Deque<String>> lifecycles = new ConcurrentHashMap<>();

    @Inject
    ReactorReader(MavenSession session) {
        this.session = session;

        WorkQueue queue = getWorkerExecutor().processIsolation(spec -> {
            spec.getClasspath().from(calculateWorkerClasspath());
            spec.getForkOptions().setMaxHeapSize("1g");
        });
        queue.submit(JApiCmpWorkAction.class, params -> params.getConfiguration().set(calculateWorkerConfiguration(baseline, current)));
    }

   * <p>After execution begins on a thread from the {@code delegate} {@link Executor}, tasks are
   * polled and executed from a task queue until there are no more tasks. The thread will not be
   * released until there are no more tasks to run.
   *
   * <p>If a task is submitted while a thread is executing tasks from the task queue, the thread
   * will not be released until that submitted task is also complete.
   *