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Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC
/*
* 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.rxjava3.internal.observers;
import static io.reactivex.rxjava3.internal.util.ExceptionHelper.timeoutMessage;
import java.util.NoSuchElementException;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicReference;
import io.reactivex.rxjava3.annotations.NonNull;
import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
import io.reactivex.rxjava3.internal.util.BlockingHelper;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
/**
* An Observer + Future that expects exactly one upstream value and provides it
* via the (blocking) Future API.
*
* @param the value type
*/
public final class FutureObserver extends CountDownLatch
implements Observer, Future, Disposable {
T value;
Throwable error;
final AtomicReference upstream;
public FutureObserver() {
super(1);
this.upstream = new AtomicReference<>();
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
for (;;) {
Disposable a = upstream.get();
if (a == this || a == DisposableHelper.DISPOSED) {
return false;
}
if (upstream.compareAndSet(a, DisposableHelper.DISPOSED)) {
if (a != null) {
a.dispose();
}
countDown();
return true;
}
}
}
@Override
public boolean isCancelled() {
return DisposableHelper.isDisposed(upstream.get());
}
@Override
public boolean isDone() {
return getCount() == 0;
}
@Override
public T get() throws InterruptedException, ExecutionException {
if (getCount() != 0) {
BlockingHelper.verifyNonBlocking();
await();
}
if (isCancelled()) {
throw new CancellationException();
}
Throwable ex = error;
if (ex != null) {
throw new ExecutionException(ex);
}
return value;
}
@Override
public T get(long timeout, @NonNull TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
if (getCount() != 0) {
BlockingHelper.verifyNonBlocking();
if (!await(timeout, unit)) {
throw new TimeoutException(timeoutMessage(timeout, unit));
}
}
if (isCancelled()) {
throw new CancellationException();
}
Throwable ex = error;
if (ex != null) {
throw new ExecutionException(ex);
}
return value;
}
@Override
public void onSubscribe(Disposable d) {
DisposableHelper.setOnce(this.upstream, d);
}
@Override
public void onNext(T t) {
if (value != null) {
upstream.get().dispose();
onError(new IndexOutOfBoundsException("More than one element received"));
return;
}
value = t;
}
@Override
public void onError(Throwable t) {
if (error == null) {
Disposable a = upstream.get();
if (a != this && a != DisposableHelper.DISPOSED
&& upstream.compareAndSet(a, this)) {
error = t;
countDown();
return;
}
}
RxJavaPlugins.onError(t);
}
@Override
public void onComplete() {
if (value == null) {
onError(new NoSuchElementException("The source is empty"));
return;
}
Disposable a = upstream.get();
if (a == this || a == DisposableHelper.DISPOSED) {
return;
}
if (upstream.compareAndSet(a, this)) {
countDown();
}
}
@Override
public void dispose() {
// ignoring as `this` means a finished Disposable only
}
@Override
public boolean isDisposed() {
return isDone();
}
}
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