abstract val fileSystemOperations: FileSystemOperations

    private
    var hasCleaned = false

    val logger = Logging.getLogger(CachesCleaner::class.java)

    fun cleanUpCaches() {
        synchronized(this) {
            if (hasCleaned) {
                return
            }
            logger.lifecycle("Cleaning up caches...")
            val homeDir = parameters.homeDir.get()

        } catch (final SQLException e) {
            throw new SQLRuntimeException(e);
        }
    }

    /**
     * 現在のクラスローダに結びつけられている全てのJDBCドライバを登録解除します。
     */
    public static synchronized void deregisterAllDrivers() {
        for (final Enumeration<Driver> e = DriverManager.getDrivers(); e.hasMoreElements();) {
            deregisterDriver(e.nextElement());
        }
    }

  static class Key {
    private final int value;
    private WeakReference<String> toString;

    Key(int value) {
      this.value = value;
    }

    @Override
    public synchronized String toString() {
      String s;
      if (toString != null) {
        s = toString.get();
        if (s != null) {
          return s;
        }
      }
      s = Integer.toString(value);

	// If NoWait is set, Get() will return the last good value,
	// if TTL has expired but 2x TTL has not yet passed,
	// but will fetch a new value in the background.
	NoWait bool
}

// Cache contains a synchronized value that is considered valid
// for a specific amount of time.
// An Update function must be set to provide an updated value when needed.
type Cache[T any] struct {
	// updateFn must return an updated value.

    final TearDownStack result = new TearDownStack();
    tearDownStack.addTearDown(
        new TearDown() {

          @Override
          public void tearDown() throws Exception {
            synchronized (result.lock) {
              assertEquals(
                  "The test should have cleared the stack (say, by virtue of running runTearDown)",
                  0,
                  result.stack.size());

    final TearDownStack result = new TearDownStack();
    tearDownStack.addTearDown(
        new TearDown() {

          @Override
          public void tearDown() throws Exception {
            synchronized (result.lock) {
              assertEquals(
                  "The test should have cleared the stack (say, by virtue of running runTearDown)",
                  0,
                  result.stack.size());

    protected abstract boolean fetchMore () throws CIFSException;


    protected abstract FileEntry[] getResults ();


    /**
     * 
     */
    protected synchronized void doClose () throws CIFSException {
        // otherwise already closed
        if ( !this.closed ) {
            this.closed = true;
            try {
                doCloseInternal();
            }

        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final CrawlerStatsHelper crawlerStatsHelper = ComponentUtil.getCrawlerStatsHelper();
        synchronized (indexUpdateCallback) {
            // required check
            if (!dataMap.containsKey(fessConfig.getIndexFieldUrl()) || dataMap.get(fessConfig.getIndexFieldUrl()) == null) {

                this.uhe = uhe;
            } catch( Exception ex ) {
                this.uhe = new UnknownHostException( ex.getMessage() );
            } finally {
                synchronized( sem ) {
                    sem.count--;
                    sem.notify();
                }
            }
        }
    }

    static NbtAddress lookupServerOrWorkgroup( String name, InetAddress svr )

    }

    @Override
    public void setFile(File file) {
        throw new UnsupportedOperationException("transformed artifact file cannot be set");
    }

    @Override
    public synchronized File getFile() {
        try {
            String state = mayUpdate();
            if (state == null) {
                return null;
            }
            return target.toFile();