* A {@link ListenableFuture} whose result can be set by a {@link #set(Object)}, {@link
 * #setException(Throwable)} or {@link #setFuture(ListenableFuture)} call. It can also, like any
 * other {@code Future}, be {@linkplain #cancel cancelled}.
 *
 * <p>{@code SettableFuture} is the recommended {@code ListenableFuture} implementation when your
 * task cannot be implemented with {@link ListeningExecutorService}, the various {@link Futures}

            }

          case CANCELLED:
          case INTERRUPTED:
            throw cancellationExceptionWithCause("Task was cancelled.", exception);

          default:
            throw new IllegalStateException("Error, synchronizer in invalid state: " + state);
        }
      }

      /** Checks if the state is {@link #COMPLETED}, {@link #CANCELLED}, or {@link #INTERRUPTED}. */
      boolean isDone() {

            }

          case CANCELLED:
          case INTERRUPTED:
            throw cancellationExceptionWithCause("Task was cancelled.", exception);

          default:
            throw new IllegalStateException("Error, synchronizer in invalid state: " + state);
        }
      }

      /** Checks if the state is {@link #COMPLETED}, {@link #CANCELLED}, or {@link #INTERRUPTED}. */
      boolean isDone() {

   * input future and that of the future returned by the chain function. That is, if the returned
   * {@code Future} is cancelled, it will attempt to cancel the other two, and if either of the
   * other two is cancelled, the returned {@code Future} will receive a callback in which it will
   * attempt to cancel itself.
   *

      // before the cancelled future completes, it will synchronously complete both the newFuture
      // from the cancelled operation and its own. This can cause one runnable to queue two tasks,
      // breaking the invariant this method relies on to iteratively run the next task after the
      // previous one completes.
      if (get() == RunningState.CANCELLED) {
        delegate = null;
        sequencer = null;

                      "timeout": "0s",
                      "retry_policy": {
                        "retry_on": "connect-failure,refused-stream,unavailable,cancelled,retriable-status-codes",
                        "num_retries": 2,
                        "retry_host_predicate": [
                          {
                            "name": "envoy.retry_host_predicates.previous_hosts"

  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    if (!state.permitsPublicUserToTransitionTo(State.CANCELLED)) {
      return false;
    }

    this.mayInterruptIfRunning = mayInterruptIfRunning;
    state = State.CANCELLED;
    notifyAndClearListeners();

    if (delegate != null) {

   *     cancelled regardless
   * @return {@code false} if the step could not be cancelled, typically because it has already
   *     completed normally; {@code true} otherwise
   */
  @CanIgnoreReturnValue
  public boolean cancel(boolean mayInterruptIfRunning) {
    logger.get().log(FINER, "cancelling {0}", this);
    boolean cancelled = future.cancel(mayInterruptIfRunning);

   * Usually returns {@code null} but, if the given {@code Future} has failed, may <i>optionally</i>
   * return the cause of the failure. "Failure" means specifically "completed with an exception"; it
   * does not include "was cancelled." To be explicit: If this method returns a non-null value,
   * then:
   *
   * <ul>
   *   <li>{@code isDone()} must return {@code true}
   *   <li>{@code isCancelled()} must return {@code false}

import java.util.concurrent.Executor;

/** Measures the size of AbstractFuture implementations. */
public class AbstractFutureFootprintBenchmark {

  enum State {
    NOT_DONE,
    FINISHED,
    CANCELLED,
    FAILED
  }

  @Param State state;
  @Param Impl impl;

  @Param({"0", "1", "5", "10"})
  int numListeners;

  @Param({"0", "1", "5", "10"})
  int numThreads;