return urlQueueList.poll();
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.codelibs.fess.crawler.service.UrlQueueService#saveSession(java.lang.String)
     */
    @Override
    public void saveSession(final String sessionId) {
        // NOP
    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.service.UrlQueueService#visited(UrlQueue)

    void insert(QUEUE urlQueue);

    void delete(String sessionId);

    void deleteAll();

    void offerAll(String sessionId, List<QUEUE> newUrlQueueList);

    QUEUE poll(String sessionId);

    void saveSession(String sessionId);

    boolean visited(QUEUE urlQueue);

    void generateUrlQueues(String previousSessionId, String sessionId);

                logger.warn("Interrupted job at {}", threads[i].getName());
            }
        }
        crawlerContext.setStatus(CrawlerStatus.DONE);

        urlQueueService.saveSession(crawlerContext.sessionId);
    }

    public CrawlerContext getCrawlerContext() {
        return crawlerContext;
    }

    public void setNumOfThread(final int numOfThread) {

                SortBuilders.fieldSort(OpenSearchUrlQueue.WEIGHT).order(SortOrder.DESC),
                SortBuilders.fieldSort(CREATE_TIME).order(SortOrder.ASC));
    }

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

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