/**
* 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.
MaybeObserver;
import io.reactivex.annotations.
NonNull;
import io.reactivex.disposables.
Disposable;
import io.reactivex.internal.disposables.
DisposableHelper;
import io.reactivex.internal.util.
EndConsumerHelper;
/**
* An abstract {@link MaybeObserver} that allows asynchronous cancellation by implementing Disposable.
*
* <p>All pre-implemented final methods are thread-safe.
*
* <p>Note that {@link #onSuccess(Object)}, {@link #onError(Throwable)} and {@link #onComplete()} are
* exclusive to each other, unlike a regular {@link io.reactivex.Observer Observer}, and
* {@code onComplete()} is never called after an {@code onSuccess()}.
*
* <p>Like all other consumers, {@code DisposableMaybeObserver} 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 #onSuccess(Object)}, {@link #onError(Throwable)} and
* {@link #onComplete()} are not allowed to throw any unchecked exceptions.
*
* <p>Example<pre><code>
* Disposable d =
* Maybe.just(1).delay(1, TimeUnit.SECONDS)
* .subscribeWith(new DisposableMaybeObserver<Integer>() {
* @Override public void onStart() {
* System.out.println("Start!");
* }
* @Override public void onSuccess(Integer t) {
* System.out.println(t);
* }
* @Override public void onError(Throwable t) {
* t.printStackTrace();
* }
* @Override public void onComplete() {
* System.out.println("Done!");
* }
* });
* // ...
* d.dispose();
* </code></pre>
*
* @param <T> the received value type
*/
public abstract class
DisposableMaybeObserver<T> implements
MaybeObserver<T>,
Disposable {
final
AtomicReference<
Disposable>
upstream = new
AtomicReference<
Disposable>();
@
Override
public final void
onSubscribe(@
NonNull Disposable d) {
if (
EndConsumerHelper.
setOnce(this.
upstream,
d,
getClass())) {
onStart();
}
}
/**
* Called once the single upstream Disposable is set via onSubscribe.
*/
protected void
onStart() {
}
@
Override
public final boolean
isDisposed() {
return
upstream.
get() ==
DisposableHelper.
DISPOSED;
}
@
Override
public final void
dispose() {
DisposableHelper.
dispose(
upstream);
}
}