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.observers;
import java.util.concurrent.atomic.AtomicReference;
import io.reactivex.Observer;
import io.reactivex.annotations.NonNull;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.*;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.util.EndConsumerHelper;
An abstract Observer that allows asynchronous cancellation of its subscription and associated resources. All pre-implemented final methods are thread-safe.
To release the associated resources, one has to call dispose() in onError() and onComplete() explicitly.
Use add(Disposable) to associate resources (as Disposables) with this ResourceObserver that will be cleaned up when dispose() is called. Removing previously associated resources is not possible but one can create a CompositeDisposable, associate it with this ResourceObserver and then add/remove resources to/from the CompositeDisposable freely.
Use the dispose() to dispose the sequence from within an onNext implementation.
Like all other consumers, ResourceObserver can be subscribed only once. Any subsequent attempt to subscribe it to a new source will yield an IllegalStateException with message "It is not allowed to subscribe with a(n) <class name> multiple times.".
Implementation of onStart(), Observer.onNext(Object), Observer.onError(Throwable) and Observer.onComplete() are not allowed to throw any unchecked exceptions. If for some reason this can't be avoided, use Observable.safeSubscribe(Observer) instead of the standard subscribe() method.
Example
Disposable d =
Observable.range(1, 5)
.subscribeWith(new ResourceObserver<Integer>() {
@Override public void onStart() {
add(Schedulers.single()
.scheduleDirect(() -> System.out.println("Time!"),
2, TimeUnit.SECONDS));
request(1);
}
@Override public void onNext(Integer t) {
if (t == 3) {
dispose();
}
System.out.println(t);
}
@Override public void onError(Throwable t) {
t.printStackTrace();
dispose();
}
@Override public void onComplete() {
System.out.println("Done!");
dispose();
}
});
// ...
d.dispose();
Type parameters: - <T> – the value type
/**
* An abstract {@link Observer} that allows asynchronous cancellation of its subscription and associated resources.
*
* <p>All pre-implemented final methods are thread-safe.
*
* <p>To release the associated resources, one has to call {@link #dispose()}
* in {@code onError()} and {@code onComplete()} explicitly.
*
* <p>Use {@link #add(Disposable)} to associate resources (as {@link io.reactivex.disposables.Disposable Disposable}s)
* with this {@code ResourceObserver} that will be cleaned up when {@link #dispose()} is called.
* Removing previously associated resources is not possible but one can create a
* {@link io.reactivex.disposables.CompositeDisposable CompositeDisposable}, associate it with this
* {@code ResourceObserver} and then add/remove resources to/from the {@code CompositeDisposable}
* freely.
*
* <p>Use the {@link #dispose()} to dispose the sequence from within an
* {@code onNext} implementation.
*
* <p>Like all other consumers, {@code ResourceObserver} can be subscribed only once.
* Any subsequent attempt to subscribe it to a new source will yield an
* {@link IllegalStateException} with message {@code "It is not allowed to subscribe with a(n) <class name> multiple times."}.
*
* <p>Implementation of {@link #onStart()}, {@link #onNext(Object)}, {@link #onError(Throwable)}
* and {@link #onComplete()} are not allowed to throw any unchecked exceptions.
* If for some reason this can't be avoided, use {@link io.reactivex.Observable#safeSubscribe(io.reactivex.Observer)}
* instead of the standard {@code subscribe()} method.
*
* <p>Example<pre><code>
* Disposable d =
* Observable.range(1, 5)
* .subscribeWith(new ResourceObserver<Integer>() {
* @Override public void onStart() {
* add(Schedulers.single()
* .scheduleDirect(() -> System.out.println("Time!"),
* 2, TimeUnit.SECONDS));
* request(1);
* }
* @Override public void onNext(Integer t) {
* if (t == 3) {
* dispose();
* }
* System.out.println(t);
* }
* @Override public void onError(Throwable t) {
* t.printStackTrace();
* dispose();
* }
* @Override public void onComplete() {
* System.out.println("Done!");
* dispose();
* }
* });
* // ...
* d.dispose();
* </code></pre>
*
* @param <T> the value type
*/
public abstract class ResourceObserver<T> implements Observer<T>, Disposable {
The active subscription. /** The active subscription. */
private final AtomicReference<Disposable> upstream = new AtomicReference<Disposable>();
The resource composite, can never be null. /** The resource composite, can never be null. */
private final ListCompositeDisposable resources = new ListCompositeDisposable();
Adds a resource to this ResourceObserver.
Params: - resource – the resource to add
Throws: - NullPointerException – if resource is null
/**
* Adds a resource to this ResourceObserver.
*
* @param resource the resource to add
*
* @throws NullPointerException if resource is null
*/
public final void add(@NonNull Disposable resource) {
ObjectHelper.requireNonNull(resource, "resource is null");
resources.add(resource);
}
@Override
public final void onSubscribe(Disposable d) {
if (EndConsumerHelper.setOnce(this.upstream, d, getClass())) {
onStart();
}
}
Called once the upstream sets a Subscription on this ResourceObserver.
You can perform initialization at this moment. The default
implementation does nothing.
/**
* Called once the upstream sets a Subscription on this ResourceObserver.
*
* <p>You can perform initialization at this moment. The default
* implementation does nothing.
*/
protected void onStart() {
}
Cancels the main disposable (if any) and disposes the resources associated with
this ResourceObserver (if any).
This method can be called before the upstream calls onSubscribe at which
case the main Disposable will be immediately disposed.
/**
* Cancels the main disposable (if any) and disposes the resources associated with
* this ResourceObserver (if any).
*
* <p>This method can be called before the upstream calls onSubscribe at which
* case the main Disposable will be immediately disposed.
*/
@Override
public final void dispose() {
if (DisposableHelper.dispose(upstream)) {
resources.dispose();
}
}
Returns true if this ResourceObserver has been disposed/cancelled.
Returns: true if this ResourceObserver has been disposed/cancelled
/**
* Returns true if this ResourceObserver has been disposed/cancelled.
* @return true if this ResourceObserver has been disposed/cancelled
*/
@Override
public final boolean isDisposed() {
return DisposableHelper.isDisposed(upstream.get());
}
}