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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.operators.single;
import java.util.concurrent.atomic.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.Disposable;
public final class SingleCache extends Single implements SingleObserver {
@SuppressWarnings("rawtypes")
static final CacheDisposable[] EMPTY = new CacheDisposable[0];
@SuppressWarnings("rawtypes")
static final CacheDisposable[] TERMINATED = new CacheDisposable[0];
final SingleSource extends T> source;
final AtomicInteger wip;
final AtomicReference[]> observers;
T value;
Throwable error;
@SuppressWarnings("unchecked")
public SingleCache(SingleSource extends T> source) {
this.source = source;
this.wip = new AtomicInteger();
this.observers = new AtomicReference<>(EMPTY);
}
@Override
protected void subscribeActual(final SingleObserver super T> observer) {
CacheDisposable d = new CacheDisposable<>(observer, this);
observer.onSubscribe(d);
if (add(d)) {
if (d.isDisposed()) {
remove(d);
}
} else {
Throwable ex = error;
if (ex != null) {
observer.onError(ex);
} else {
observer.onSuccess(value);
}
return;
}
if (wip.getAndIncrement() == 0) {
source.subscribe(this);
}
}
boolean add(CacheDisposable observer) {
for (;;) {
CacheDisposable[] a = observers.get();
if (a == TERMINATED) {
return false;
}
int n = a.length;
@SuppressWarnings("unchecked")
CacheDisposable[] b = new CacheDisposable[n + 1];
System.arraycopy(a, 0, b, 0, n);
b[n] = observer;
if (observers.compareAndSet(a, b)) {
return true;
}
}
}
@SuppressWarnings("unchecked")
void remove(CacheDisposable observer) {
for (;;) {
CacheDisposable[] a = observers.get();
int n = a.length;
if (n == 0) {
return;
}
int j = -1;
for (int i = 0; i < n; i++) {
if (a[i] == observer) {
j = i;
break;
}
}
if (j < 0) {
return;
}
CacheDisposable[] b;
if (n == 1) {
b = EMPTY;
} else {
b = new CacheDisposable[n - 1];
System.arraycopy(a, 0, b, 0, j);
System.arraycopy(a, j + 1, b, j, n - j - 1);
}
if (observers.compareAndSet(a, b)) {
return;
}
}
}
@Override
public void onSubscribe(Disposable d) {
// not supported by this operator
}
@SuppressWarnings("unchecked")
@Override
public void onSuccess(T value) {
this.value = value;
for (CacheDisposable d : observers.getAndSet(TERMINATED)) {
if (!d.isDisposed()) {
d.downstream.onSuccess(value);
}
}
}
@SuppressWarnings("unchecked")
@Override
public void onError(Throwable e) {
this.error = e;
for (CacheDisposable d : observers.getAndSet(TERMINATED)) {
if (!d.isDisposed()) {
d.downstream.onError(e);
}
}
}
static final class CacheDisposable
extends AtomicBoolean
implements Disposable {
private static final long serialVersionUID = 7514387411091976596L;
final SingleObserver super T> downstream;
final SingleCache parent;
CacheDisposable(SingleObserver super T> actual, SingleCache parent) {
this.downstream = actual;
this.parent = parent;
}
@Override
public boolean isDisposed() {
return get();
}
@Override
public void dispose() {
if (compareAndSet(false, true)) {
parent.remove(this);
}
}
}
}
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