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 synchronized Map<String, Object> read() {
        while (!isFinished.get() && queue.isEmpty()) {
            addDocumentToQueue();
        }

        return queue.poll();
    }

    @Override
    public void close() {
        isFinished.set(true);
        queue.clear();
    }

    public void setScrollSize(final int scrollSize) {
        this.scrollSize = scrollSize;

     *
     * @see org.codelibs.fess.crawler.service.UrlQueueService#poll(java.lang.String)
     */
    @Override
    public UrlQueueImpl<Long> poll(final String sessionId) {
        final Queue<UrlQueueImpl<Long>> urlQueueList = dataHelper.getUrlQueueList(sessionId);
        synchronized (urlQueueList) {
            return urlQueueList.poll();
        }
    }

    /*
     * (non-Javadoc)
     *

  @Override
  public @Nullable E poll() {
    final 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());
    assertNull(mmHeap.peekLast());
    assertNull(mmHeap.peek());

    @Override
    public boolean offer(E o) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offer(o);
    }

    @Override
    public @Nullable E poll() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.poll();
    }

    @Override
    public E remove() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove();
    }

    @Override

    return delegate().offer(e, timeout, unit);
  }

  @CanIgnoreReturnValue // TODO(kak): consider removing this
  @Override
  @CheckForNull
  public E poll(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().poll(timeout, unit);
  }

  @Override
  public void put(E e) throws InterruptedException {
    delegate().put(e);
  }

  @Override
  public int remainingCapacity() {

    return delegate().offer(e, timeout, unit);
  }

  @CanIgnoreReturnValue // TODO(kak): consider removing this
  @Override
  @CheckForNull
  public E poll(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().poll(timeout, unit);
  }

  @Override
  public void put(E e) throws InterruptedException {
    delegate().put(e);
  }

  @Override
  public int remainingCapacity() {

    @Override
    public boolean offer(E o) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offer(o);
    }

    @Override
    public @Nullable E poll() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.poll();
    }

    @Override
    public E remove() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove();
    }

    @Override

  }

  @Override
  public E take() throws InterruptedException {
    return delegate().take();
  }

  @Override
  @CheckForNull
  public E poll(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().poll(timeout, unit);
  }

  @Override
  public int drainTo(Collection<? super E> c) {
    return delegate().drainTo(c);
  }

  @Override