@Nullable Listener gasListeners(AbstractFutureState<?> future, Listener update) {
      return (Listener) listenersUpdater.getAndSet(future, update);
    }

    @Override
    @Nullable Waiter gasWaiters(AbstractFutureState<?> future, Waiter update) {
      return (Waiter) waitersUpdater.getAndSet(future, update);
    }

    @Override

    @Override
    @Nullable Listener gasListeners(AbstractFutureState<?> future, Listener update) {
      return listenersUpdater.getAndSet(future, update);
    }

    @Override
    @Nullable Waiter gasWaiters(AbstractFutureState<?> future, Waiter update) {
      return waitersUpdater.getAndSet(future, update);
    }

    @Override
    boolean casValue(AbstractFutureState<?> future, @Nullable Object expect, Object update) {

        // not all.  See the test cases for examples on how this can happen.
        try {
          ((Thread) currentRunner).interrupt();
        } finally {
          Runnable prev = getAndSet(DONE);
          if (prev == PARKED) {
            LockSupport.unpark((Thread) currentRunner);
          }
        }
      }
    }
  }

  /**

     * It's called both during normal shutdown and in error conditions.
     */
    private static void destroyContainer() {
        if (running.getAndSet(false)) {
            TimeoutManager.getInstance().stop();
            if (logger.isDebugEnabled()) {
                logger.debug("Destroying LaContainer...");
            }

     * cancelled before the callable started execution.
     */
    SettableFuture<@Nullable Void> newFuture = SettableFuture.create();

    ListenableFuture<@Nullable Void> oldFuture = ref.getAndSet(newFuture);

    // Invoke our task once the previous future completes.
    TrustedListenableFutureTask<T> taskFuture = TrustedListenableFutureTask.create(task);
    oldFuture.addListener(taskFuture, taskExecutor);

     * @param status The current cluster status.
     * @return true if the state has changed, false otherwise.
     */
    public boolean isChangedClusterState(final int status) {
        return previousClusterState.getAndSet(status) != status;
    }

    /**
     * Creates a new action validator.
     *
     * @param requestManager  The request manager.
     * @param messagesCreator The messages creator.