if (crawlingQueue.size() > maxCrawlingQueueSize) {
            crawlingQueue.poll();
        }
        crawlingQueue.add(urlQueue);
        return urlQueue;
    }

    @Override
    public void saveSession(final String sessionId) {
        // TODO use cache
    }

    @Override
    public boolean visited(final EsUrlQueue urlQueue) {
        final String url = urlQueue.getUrl();