Copyright (c) 2016-present, RxJava Contributors.
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.
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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 io.reactivex.internal.operators.observable;

import io.reactivex.*;
import io.reactivex.annotations.Nullable;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Action;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.fuseable.*;
import io.reactivex.internal.observers.BasicIntQueueDisposable;
import io.reactivex.plugins.RxJavaPlugins;

Execute an action after an onError, onComplete or a dispose event.
History: 2.0.1 - experimental
Type parameters:
<T> – the value type
Since:
2.1/**
 * Execute an action after an onError, onComplete or a dispose event.
 * <p>History: 2.0.1 - experimental
 * @param <T> the value type
 * @since 2.1
 */
public final class ObservableDoFinally<T> extends AbstractObservableWithUpstream<T, T> {

    final Action onFinally;

    public ObservableDoFinally(ObservableSource<T> source, Action onFinally) {
        super(source);
        this.onFinally = onFinally;
    }

    @Override
    protected void subscribeActual(Observer<? super T> observer) {
        source.subscribe(new DoFinallyObserver<T>(observer, onFinally));
    }

    static final class DoFinallyObserver<T> extends BasicIntQueueDisposable<T> implements Observer<T> {

        private static final long serialVersionUID = 4109457741734051389L;

        final Observer<? super T> downstream;

        final Action onFinally;

        Disposable upstream;

        QueueDisposable<T> qd;

        boolean syncFused;

        DoFinallyObserver(Observer<? super T> actual, Action onFinally) {
            this.downstream = actual;
            this.onFinally = onFinally;
        }

        @SuppressWarnings("unchecked")
        @Override
        public void onSubscribe(Disposable d) {
            if (DisposableHelper.validate(this.upstream, d)) {
                this.upstream = d;
                if (d instanceof QueueDisposable) {
                    this.qd = (QueueDisposable<T>)d;
                }

                downstream.onSubscribe(this);
            }
        }

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

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

        @Override
        public void onComplete() {
            downstream.onComplete();
            runFinally();
        }

        @Override
        public void dispose() {
            upstream.dispose();
            runFinally();
        }

        @Override
        public boolean isDisposed() {
            return upstream.isDisposed();
        }

        @Override
        public int requestFusion(int mode) {
            QueueDisposable<T> qd = this.qd;
            if (qd != null && (mode & BOUNDARY) == 0) {
                int m = qd.requestFusion(mode);
                if (m != NONE) {
                    syncFused = m == SYNC;
                }
                return m;
            }
            return NONE;
        }

        @Override
        public void clear() {
            qd.clear();
        }

        @Override
        public boolean isEmpty() {
            return qd.isEmpty();
        }

        @Nullable
        @Override
        public T poll() throws Exception {
            T v = qd.poll();
            if (v == null && syncFused) {
                runFinally();
            }
            return v;
        }

        void runFinally() {
            if (compareAndSet(0, 1)) {
                try {
                    onFinally.run();
                } catch (Throwable ex) {
                    Exceptions.throwIfFatal(ex);
                    RxJavaPlugins.onError(ex);
                }
            }
        }
    }
}