*   It is similar to a Promise in JavaScript.
 *   It allows you to register callbacks that will be executed when the computation is complete,
 *   either successfully (resolve) or with an error (reject).
 * </p>
 *
 * <p>
 *   The Deferred class has a Promise inner class that allows you to register callbacks
 *   to be executed when the computation is complete.

   * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through
   * this method is guaranteed to be called once the computation is complete.
   *

   * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through
   * this method is guaranteed to be called once the computation is complete.
   *

       * to a valid final state ({@link #COMPLETED}, {@link #CANCELLED}, or {@link #INTERRUPTED}).
       *
       * @param v the value to set as the result of the computation.
       * @param t the exception to set as the result of the computation.
       * @param finalState the state to transition to.
       */
      private boolean complete(@Nullable V v, @Nullable Throwable t, int finalState) {

 * asynchronously.
 *
 * <p>To attach to a {@link ListenableFuture} use {@link Futures#addCallback}.
 *
 * @author Anthony Zana
 * @since 10.0
 */
@GwtCompatible
public interface FutureCallback<V extends @Nullable Object> {
  /** Invoked with the result of the {@code Future} computation when it is successful. */
  void onSuccess(@ParametricNullness V result);

   *   <li>To get uninterruptibility and remove checked exceptions, use {@link
   *       Futures#getUnchecked}.
   * </ul>
   *
   * @throws ExecutionException if the computation threw an exception
   * @throws CancellationException if the computation was cancelled
   */
  @CanIgnoreReturnValue
  @ParametricNullness
  public static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)

      }
    }.start();

    getStartedSignal.await();

    // computation is in progress; asMap shouldn't have changed
    assertEquals(1, map.size());
    assertFalse(map.containsKey(getKey));
    assertSame(refreshKey, map.get(refreshKey));

    // let computation complete
    letGetFinishSignal.countDown();
    getFinishedSignal.await();
    checkNothingLogged();

   * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
   * complete} or, if the computation is already complete, immediately.
   *
   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through
   * this method is guaranteed to be called once the computation is complete.
   *

 * asynchronously.
 *
 * <p>To attach to a {@link ListenableFuture} use {@link Futures#addCallback}.
 *
 * @author Anthony Zana
 * @since 10.0
 */
@GwtCompatible
public interface FutureCallback<V extends @Nullable Object> {
  /** Invoked with the result of the {@code Future} computation when it is successful. */
  void onSuccess(@ParametricNullness V result);

    cache.invalidateAll();
    // let the computation proceed
    computingLatch.countDown();
    // don't check cache.size() until we know the get("b") call is complete
    computationComplete.await();

    // At this point, the listener should be holding the seed value (a -> a), and the map should
    // contain the computed value (b -> b), since the clear() happened before the computation
    // completed.