urlQueueService.insert(urlQueue);

        // Poll should return the item
        final OpenSearchUrlQueue polled = urlQueueService.poll(sessionId);
        assertNotNull(polled);
        assertEquals("http://www.example.com/page1", polled.getUrl());
        assertEquals(sessionId, polled.getSessionId());

        // Second poll should return null (queue is empty)

   * like [poll]. It is only usable within task faker tasks.
   */
  private inner class TaskFakerBlockingQueue<T>(
    val delegate: BlockingQueue<T>,
  ) : AbstractQueue<T>(),
    BlockingQueue<T> {
    override val size: Int = delegate.size

    private var editCount = 0

    override fun poll(): T = delegate.poll()

    override fun poll(
      timeout: Long,

     */
    @Override
    public OpenSearchUrlQueue poll(final String sessionId) {
        final QueueHolder queueHolder = getQueueHolder(sessionId);
        final Queue<OpenSearchUrlQueue> waitingQueue = queueHolder.waitingQueue;
        final Queue<OpenSearchUrlQueue> crawlingQueue = queueHolder.crawlingQueue;

        OpenSearchUrlQueue urlQueue = waitingQueue.poll();
        if (urlQueue == null) {

    while (added < numElements) {
      // we could rely solely on #poll, but #drainTo might be more efficient when there are multiple
      // elements already available (e.g. LinkedBlockingQueue#drainTo locks only once)
      added += q.drainTo(buffer, numElements - added);
      if (added < numElements) { // not enough elements immediately available; will have to poll
        E e = q.poll(deadline - System.nanoTime(), NANOSECONDS);
        if (e == null) {

  @Override
  public @Nullable E poll() {
    Monitor monitor = this.monitor;
    monitor.enter();
    try {
      return q.poll();
    } finally {
      monitor.leave();
    }
  }

  @CanIgnoreReturnValue // pushed down from class to method
  @Override
  public @Nullable E poll(long timeout, TimeUnit unit) throws InterruptedException {

    assertEquals(1, (int) mmHeap.peek());
    assertEquals(1, (int) mmHeap.poll());
    assertEquals(3, (int) mmHeap.peekLast());
    assertEquals(2, (int) mmHeap.peek());
    assertEquals(2, (int) mmHeap.poll());
    assertEquals(3, (int) mmHeap.peekLast());
    assertEquals(3, (int) mmHeap.peek());
    assertEquals(3, (int) mmHeap.poll());
    assertThat(mmHeap.peekLast()).isNull();
    assertThat(mmHeap.peek()).isNull();

    while (added < numElements) {
      // we could rely solely on #poll, but #drainTo might be more efficient when there are multiple
      // elements already available (e.g. LinkedBlockingQueue#drainTo locks only once)
      added += q.drainTo(buffer, numElements - added);
      if (added < numElements) { // not enough elements immediately available; will have to poll
        E e = q.poll(deadline - System.nanoTime(), NANOSECONDS);
        if (e == null) {

    sendRequest(methodName, arguments);
    Thread.sleep(DUE_DILIGENCE_MILLIS);
    assertEquals(true, invokeMethod("hasQueuedThread", this));
    assertThat(responseQueue.poll()).isNull();
  }

  /**
   * Causes this thread to call the named method, and asserts that this thread thereby waits on the
   * given condition-like object. The lock-like object must have a method equivalent to {@link

     *
     * @return an encryption cipher
     */
    protected Cipher pollEncryptoCipher() {
        Cipher cipher = encryptoQueue.poll();
        if (cipher == null) {
            try {
                final SecretKeySpec sksSpec = new SecretKeySpec(key.getBytes(charsetName), algorithm);
                cipher = Cipher.getInstance(algorithm);

    assertEquals(1, (int) mmHeap.peek());
    assertEquals(1, (int) mmHeap.poll());
    assertEquals(3, (int) mmHeap.peekLast());
    assertEquals(2, (int) mmHeap.peek());
    assertEquals(2, (int) mmHeap.poll());
    assertEquals(3, (int) mmHeap.peekLast());
    assertEquals(3, (int) mmHeap.peek());
    assertEquals(3, (int) mmHeap.poll());
    assertThat(mmHeap.peekLast()).isNull();
    assertThat(mmHeap.peek()).isNull();