return UNSAFE.compareAndSwapObject(future, WAITERS_OFFSET, expect, update);
    }

    /** Performs a CAS operation on the {@link #listeners} field. */
    @Override
    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
      return UNSAFE.compareAndSwapObject(future, LISTENERS_OFFSET, expect, update);
    }