/**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code
   * Callable}.
   *
   * @param callable the callable task
   * @since 10.0
   */
  public static <V extends @Nullable Object> ListenableFutureTask<V> create(Callable<V> callable) {
    return new ListenableFutureTask<>(callable);
  }

  /**

@ElementTypesAreNonnullByDefault
public abstract class AbstractListeningExecutorService extends AbstractExecutorService
    implements ListeningExecutorService {

  /**
   * @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0)
   */
  @CanIgnoreReturnValue // TODO(kak): consider removing this
  @Override
  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(

  protected final CountDownLatch listenerLatch = new CountDownLatch(1);

  protected volatile boolean throwException = false;

  protected final ListenableFutureTask<Integer> task =
      ListenableFutureTask.create(
          new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
              runLatch.countDown();
              taskLatch.await();

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link RunnableFuture} that also implements the {@link ListenableFuture} interface.
 *
 * <p>This should be used in preference to {@link ListenableFutureTask} when possible for
 * performance reasons.
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
class TrustedListenableFutureTask<V extends @Nullable Object> extends FluentFuture.TrustedFuture<V>

  protected final CountDownLatch listenerLatch = new CountDownLatch(1);

  protected volatile boolean throwException = false;

  protected final ListenableFutureTask<Integer> task =
      ListenableFutureTask.create(
          new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
              runLatch.countDown();
              taskLatch.await();

   *
   * <p>Prefer to create {@code ListenableFuture} instances with {@link SettableFuture}, {@link
   * MoreExecutors#listeningDecorator( java.util.concurrent.ExecutorService)}, {@link
   * ListenableFutureTask}, {@link AbstractFuture}, and other utilities over creating plain {@code
   * Future} instances to be upgraded to {@code ListenableFuture} after the fact.
   */

      public V load(K key) throws Exception {
        return loader.load(key);
      }

      @Override
      public ListenableFuture<V> reload(final K key, final V oldValue) {
        ListenableFutureTask<V> task =
            ListenableFutureTask.create(() -> loader.reload(key, oldValue).get());
        executor.execute(task);
        return task;
      }

      @Override

      public V load(K key) throws Exception {
        return loader.load(key);
      }

      @Override
      public ListenableFuture<V> reload(final K key, final V oldValue) {
        ListenableFutureTask<V> task =
            ListenableFutureTask.create(() -> loader.reload(key, oldValue).get());
        executor.execute(task);
        return task;
      }

      @Override

 *
 * <p>{@code SettableFuture} is the recommended {@code ListenableFuture} implementation when your
 * task cannot be implemented with {@link ListeningExecutorService}, the various {@link Futures}
 * utility methods, or {@link ListenableFutureTask}. Those APIs have less opportunity for developer
 * error. If your needs are more complex than {@code SettableFuture} supports, use {@link
 * AbstractFuture}, which offers an extensible version of the API.
 *

    return new SequentialExecutor(delegate);
  }

  /**
   * Creates an {@link ExecutorService} whose {@code submit} and {@code invokeAll} methods submit
   * {@link ListenableFutureTask} instances to the given delegate executor. Those methods, as well
   * as {@code execute} and {@code invokeAny}, are implemented in terms of calls to {@code