hu.akarnokd.rxjava.interop.FlowableV2ToObservableV1 Maven / Gradle / Ivy

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/*
 * Copyright 2016-2018 David Karnok
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package hu.akarnokd.rxjava.interop;

import java.util.concurrent.atomic.*;

/**
 * Convert a V2 Flowable into a V1 Observable, composing backpressure and cancellation.
 *
 * @param  the value type
 */
final class FlowableV2ToObservableV1 implements rx.Observable.OnSubscribe {

    final org.reactivestreams.Publisher source;

    FlowableV2ToObservableV1(org.reactivestreams.Publisher source) {
        this.source = source;
    }

    @Override
    public void call(rx.Subscriber t) {
        SourceSubscriber parent = new SourceSubscriber(t);

        t.add(parent);
        t.setProducer(parent);

        source.subscribe(parent);
    }

    static final class SourceSubscriber
    extends AtomicReference
    implements io.reactivex.FlowableSubscriber, rx.Subscription, rx.Producer {

        private static final long serialVersionUID = -6567012932544037069L;

        final rx.Subscriber actual;

        final AtomicLong requested;

        SourceSubscriber(rx.Subscriber actual) {
            this.actual = actual;
            this.requested = new AtomicLong();
        }

        @Override
        public void request(long n) {
            if (n != 0L) {
                io.reactivex.internal.subscriptions.SubscriptionHelper.deferredRequest(this, requested, n);
            }
        }

        @Override
        public void unsubscribe() {
            io.reactivex.internal.subscriptions.SubscriptionHelper.cancel(this);
        }

        @Override
        public boolean isUnsubscribed() {
            return io.reactivex.internal.subscriptions.SubscriptionHelper.isCancelled(get());
        }

        @Override
        public void onSubscribe(org.reactivestreams.Subscription s) {
            io.reactivex.internal.subscriptions.SubscriptionHelper.deferredSetOnce(this, requested, s);
        }

        @Override
        public void onNext(T t) {
            actual.onNext(t);
        }

        @Override
        public void onError(Throwable t) {
            actual.onError(t);
        }

        @Override
        public void onComplete() {
            actual.onCompleted();
        }
    }
}