class QueueDrainSubscriber extends QueueDrainSubscriberPad4 implements FlowableSubscriber<T>, QueueDrain<U, V> {

    @Override
    public final boolean enter() {
        return wip.getAndIncrement() == 0;
    }

    public  QueueDrainSubscriber(Subscriber<? super V> actual, SimplePlainQueue<U> queue);

}