/**
* 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 java.util.concurrent.atomic.*;
import java.util.concurrent.locks.ReentrantLock;
import io.reactivex.*;
import io.reactivex.disposables.*;
import io.reactivex.functions.Consumer;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.observables.ConnectableObservable;
/**
* Returns an observable sequence that stays connected to the source as long as
* there is at least one subscription to the observable sequence.
*
* @param <T>
* the value type
*/
public final class ObservableRefCount<T> extends AbstractObservableWithUpstream<T, T> {
final ConnectableObservable<? extends T> source;
volatile CompositeDisposable baseDisposable = new CompositeDisposable();
final AtomicInteger subscriptionCount = new AtomicInteger();
/**
* Use this lock for every subscription and disconnect action.
*/
final ReentrantLock lock = new ReentrantLock();
/**
* Constructor.
*
* @param source
* observable to apply ref count to
*/
public ObservableRefCount(ConnectableObservable<T> source) {
super(source);
this.source = source;
}
@Override
public void subscribeActual(final Observer<? super T> subscriber) {
lock.lock();
if (subscriptionCount.incrementAndGet() == 1) {
final AtomicBoolean writeLocked = new AtomicBoolean(true);
try {
// need to use this overload of connect to ensure that
// baseDisposable is set in the case that source is a
// synchronous Observable
source.connect(onSubscribe(subscriber, writeLocked));
} finally {
// need to cover the case where the source is subscribed to
// outside of this class thus preventing the Action1 passed
// to source.connect above being called
if (writeLocked.get()) {
// Action1 passed to source.connect was not called
lock.unlock();
}
}
} else {
try {
// ready to subscribe to source so do it
doSubscribe(subscriber, baseDisposable);
} finally {
// release the read lock
lock.unlock();
}
}
}
private Consumer<Disposable> onSubscribe(final Observer<? super T> observer,
final AtomicBoolean writeLocked) {
return new DisposeConsumer(observer, writeLocked);
}
void doSubscribe(final Observer<? super T> observer, final CompositeDisposable currentBase) {
// handle disposing from the base CompositeDisposable
Disposable d = disconnect(currentBase);
ConnectionObserver s = new ConnectionObserver(observer, currentBase, d);
observer.onSubscribe(s);
source.subscribe(s);
}
private Disposable disconnect(final CompositeDisposable current) {
return Disposables.fromRunnable(new DisposeTask(current));
}
final class ConnectionObserver
extends AtomicReference<Disposable>
implements Observer<T>, Disposable {
private static final long serialVersionUID = 3813126992133394324L;
final Observer<? super T> subscriber;
final CompositeDisposable currentBase;
final Disposable resource;
ConnectionObserver(Observer<? super T> subscriber,
CompositeDisposable currentBase, Disposable resource) {
this.subscriber = subscriber;
this.currentBase = currentBase;
this.resource = resource;
}
@Override
public void onSubscribe(Disposable s) {
DisposableHelper.setOnce(this, s);
}
@Override
public void onError(Throwable e) {
cleanup();
subscriber.onError(e);
}
@Override
public void onNext(T t) {
subscriber.onNext(t);
}
@Override
public void onComplete() {
cleanup();
subscriber.onComplete();
}
@Override
public void dispose() {
DisposableHelper.dispose(this);
resource.dispose();
}
@Override
public boolean isDisposed() {
return DisposableHelper.isDisposed(get());
}
void cleanup() {
// on error or completion we need to dispose the base CompositeDisposable
// and set the subscriptionCount to 0
lock.lock();
try {
if (baseDisposable == currentBase) {
if (source instanceof Disposable) {
((Disposable)source).dispose();
}
baseDisposable.dispose();
baseDisposable = new CompositeDisposable();
subscriptionCount.set(0);
}
} finally {
lock.unlock();
}
}
}
final class DisposeConsumer implements Consumer<Disposable> {
private final Observer<? super T> observer;
private final AtomicBoolean writeLocked;
DisposeConsumer(Observer<? super T> observer, AtomicBoolean writeLocked) {
this.observer = observer;
this.writeLocked = writeLocked;
}
@Override
public void accept(Disposable subscription) {
try {
baseDisposable.add(subscription);
// ready to subscribe to source so do it
doSubscribe(observer, baseDisposable);
} finally {
// release the write lock
lock.unlock();
writeLocked.set(false);
}
}
}
final class DisposeTask implements Runnable {
private final CompositeDisposable current;
DisposeTask(CompositeDisposable current) {
this.current = current;
}
@Override
public void run() {
lock.lock();
try {
if (baseDisposable == current) {
if (subscriptionCount.decrementAndGet() == 0) {
if (source instanceof Disposable) {
((Disposable)source).dispose();
}
baseDisposable.dispose();
// need a new baseDisposable because once
// disposed stays that way
baseDisposable = new CompositeDisposable();
}
}
} finally {
lock.unlock();
}
}
}
}