* Set runner thread before checking isDone(). If we were to check isDone() first, the task
     * might be cancelled before we set the runner thread. That would make it impossible to
     * interrupt, yet it will still run, since interruptTask will leave the runner value null,
     * allowing the CAS below to succeed.
     */
    Thread currentThread = Thread.currentThread();
    if (!compareAndSet(null, currentThread)) {

   * values are null. This method may update {@code alternatingKeysAndValues} if there are duplicate
   * keys. If so, the return value will indicate how many entries are still valid, and will also
   * include a {@link Builder.DuplicateKey} in case duplicate keys are not allowed now or will not
   * be allowed on a later {@link Builder#buildOrThrow()} call.
   *

  @Override
  public void clear() {
    Arrays.fill(keys, 0, size, null);
    Arrays.fill(values, 0, size, null);
    Arrays.fill(hashTableKToV, ABSENT);
    Arrays.fill(hashTableVToK, ABSENT);
    Arrays.fill(nextInBucketKToV, 0, size, ABSENT);
    Arrays.fill(nextInBucketVToK, 0, size, ABSENT);
    Arrays.fill(prevInInsertionOrder, 0, size, ABSENT);
    Arrays.fill(nextInInsertionOrder, 0, size, ABSENT);
    size = 0;

   *       created by invoking the constructor or static factory method.
   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}:
   *       <ul>
   *         <li>Test will fail if default value for a parameter cannot be determined.

    int mask = tableSize - 1;
    // If duplicates are allowed, this IdentityHashMap will record the final Entry for each
    // duplicated key. We will use this final Entry to overwrite earlier slots in the entries array
    // that have the same key. Then a second pass will remove all but the first of the slots that
    // have this Entry. The value in the map becomes false when this first entry has been copied, so

 * Finally, every possible combination of row and column keys is always considered to have a value
 * associated with it: It is not possible to "remove" a value, only to replace it with {@code null},
 * which will still appear when iterating over the table's contents in a foreach loop or a call to a
 * null-hostile method like {@link ImmutableTable#copyOf}. For alternatives, please see <a

        thumbnailManager.add(generator);

        Map<String, Object> docMap = new HashMap<>();
        docMap.put("_id", "docid1");

        // Fill the queue
        thumbnailManager.offer(docMap);

        // Try to add another - should succeed (warning logged but still returns true)
        Map<String, Object> docMap2 = new HashMap<>();
        docMap2.put("_id", "docid2");

   *     a unique integer (0, 1, etc.) will be supplied as the single parameter. This integer will
   *     be unique to the built instance of the ThreadFactory and will be assigned sequentially. For
   *     example, {@code "rpc-pool-%d"} will generate thread names like {@code "rpc-pool-0"}, {@code
   *     "rpc-pool-1"}, {@code "rpc-pool-2"}, etc.

   *       created by invoking the constructor or static factory method.
   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}:
   *       <ul>
   *         <li>Test will fail if default value for a parameter cannot be determined.

    }

    /**
     * Creates the {@link ListenableFuture} which will return the result of running {@code combiner}
     * when all Futures complete. {@code combiner} will run using {@code executor}.
     *
     * <p>If the combiner throws a {@code CancellationException}, the returned future will be
     * cancelled.
     *
     * <p>Canceling this Future will attempt to cancel all the component futures.
     *
     * @since 23.6