private long expiry = 30 * 24 * 60 * 60 * 1000L;

    public String execute() {
        try {
            final long count = ComponentUtil.getThumbnailManager().purge(getExpiry());
            return "Deleted " + count + " thumbnail files.";
        } catch (final Exception e) {
            logger.error("Failed to purge thumbnails.", e);
            return e.getMessage();

        int count = 1;
        final ExecutorService executorService = Executors.newFixedThreadPool(options.numOfThreads);
        try {
            while (count != 0) {
                count = ComponentUtil.getThumbnailManager().generate(executorService, options.cleanup);
                totalCount += count;
            }
            executorService.shutdown();
            executorService.awaitTermination(60, TimeUnit.SECONDS);

    protected String name;

    protected int maxRedirectCount = 10;

    protected Boolean available = null;

    public void register() {
        ComponentUtil.getThumbnailManager().add(this);
    }

    public void addCondition(final String key, final String regex) {
        final String value = conditionMap.get(key);
        if (StringUtil.isBlank(value)) {

        }
        try {
            if (fessConfig.isThumbnailCrawlerEnabled()) {
                final ThumbnailManager thumbnailManager = ComponentUtil.getThumbnailManager();
                final String thumbnailField = fessConfig.getIndexFieldThumbnail();
                docList.stream().forEach(doc -> {
                    if (!thumbnailManager.offer(doc)) {

                cmdList.add("-Dpdfbox.fontcache=" + ownTmpDir.getAbsolutePath());
            } else {
                ownTmpDir = null;
            }
        }

        cmdList.add(ComponentUtil.getThumbnailManager().getThumbnailPathOption());

        if (!jvmOptions.isEmpty()) {
            jvmOptions.stream().filter(StringUtil::isNotBlank).forEach(cmdList::add);
        }

        return getComponent(PERMISSION_HELPER);
    }

    public static SsoManager getSsoManager() {
        return getComponent(SSO_MANAGER);
    }

    public static ThumbnailManager getThumbnailManager() {
        return getComponent(THUMBNAIL_MANAGER);
    }

    public static AuthenticationManager getAuthenticationManager() {
        return getComponent(AUTHENTICATION_MANAGER);
    }