// override .get() (since it is final) and therefore this is equivalent to calling .get()
      // and unpacking the exceptions like we do below (just much faster because it is a single
      // field read instead of a read, several branches and possibly creating exceptions).
      Object v = ((AbstractFuture<?>) future).value;
      if (v instanceof Cancellation) {

    }

    void execute() {
      try {
        executor.execute(command);
      } catch (RuntimeException e) {
        log.log(
            Level.SEVERE,
            "RuntimeException while executing runnable " + command + " with executor " + executor,
            e);
      }
    }
  }

  private final class SetFuture implements Runnable {
    final ListenableFuture<? extends V> delegate;