protected MemoryDataHelper dataHelper;

    /*
     * (non-Javadoc)
     *
     * @see
     * org.codelibs.fess.crawler.service.UrlQueueService#updateSessionId(java.lang.String
     * , java.lang.String)
     */
    @Override
    public void updateSessionId(final String oldSessionId, final String newSessionId) {
        // not MT-safe
        final Queue<UrlQueueImpl<Long>> urlQueueList = dataHelper.getUrlQueueList(oldSessionId);

    /**
     * Updates the session ID.
     *
     * @param oldSessionId The old session ID.
     * @param newSessionId The new session ID.
     */
    void updateSessionId(String oldSessionId, String newSessionId);

    /**
     * Adds a URL to the queue.
     *
     * @param sessionId The session ID.
     * @param url The URL.
     */
    void add(String sessionId, String url);