* The specific problem we had was unsafe reads of lastEntryReturnedBySomeIterator. (To fix the
     * problem, we've since marked that field as volatile.)
     *
     * When MapIteratorCache is used from Immutable* classes, the TSAN failure doesn't indicate a
     * real problem: The Entry objects are ImmutableMap entries, whose fields are all final and thus

  private static final class CloseableList extends IdentityHashMap<AutoCloseable, Executor>
      implements Closeable {
    private final DeferredCloser closer = new DeferredCloser(this);
    private volatile boolean closed;
    private volatile @Nullable CountDownLatch whenClosed;

    <V extends @Nullable Object, U extends @Nullable Object>
        ListenableFuture<U> applyClosingFunction(

     */
    protected BlockingQueue<Tuple3<String, String, String>> thumbnailTaskQueue;

    /**
     * Flag indicating whether thumbnail generation is currently in progress.
     */
    protected volatile boolean generating;

    private Thread thumbnailQueueThread;

    /**
     * Size of the thumbnail path cache.
     */
    protected int thumbnailPathCacheSize = 10;

    /**

   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   *
   * <p>For a new instance, where the arrays above have not yet been allocated, the value of {@code

  static final class TimedWaiterThread extends Thread {
    private final AbstractFuture<?> future;
    private final long timeout;
    private final TimeUnit unit;
    private Exception exception;
    private volatile long startTime;
    private long timeSpentBlocked;

    TimedWaiterThread(AbstractFuture<?> future, long timeout, TimeUnit unit) {
      this.future = future;
      this.timeout = timeout;

  private static final class CloseableList extends IdentityHashMap<AutoCloseable, Executor>
      implements Closeable {
    private final DeferredCloser closer = new DeferredCloser(this);
    private volatile boolean closed;
    private volatile @Nullable CountDownLatch whenClosed;

    <V extends @Nullable Object, U extends @Nullable Object>
        ListenableFuture<U> applyClosingFunction(

   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   *
   * <p>For a new instance, where the arrays above have not yet been allocated, the value of {@code

  static final class TimedWaiterThread extends Thread {
    private final AbstractFuture<?> future;
    private final long timeout;
    private final TimeUnit unit;
    private Exception exception;
    private volatile long startTime;
    private long timeSpentBlocked;

    TimedWaiterThread(AbstractFuture<?> future, long timeout, TimeUnit unit) {
      this.future = future;
      this.timeout = timeout;

    /** A thread-local variable to hold the directory context. */
    protected ThreadLocal<DirContextHolder> contextLocal = new ThreadLocal<>();

    /** A flag to indicate if the LDAP connection is bound. */
    protected volatile boolean isBind = false;

    /** The Fess configuration. */
    protected FessConfig fessConfig;

    /**
     * Default constructor.
     */
    public LdapManager() {
        // do nothing
    }