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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
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/*
* Copyright (c) 2016-2022 VMware Inc. or its affiliates, All Rights Reserved.
*
* 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
*
* https://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 reactor.core.publisher;
import java.util.Objects;
import java.util.function.BiFunction;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Fuseable;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* Aggregates the source items with an aggregator function and returns the last result.
*
* @param the input and output value type
*
* @see Reactive-Streams-Commons
*/
final class MonoReduce extends MonoFromFluxOperator
implements Fuseable {
final BiFunction aggregator;
MonoReduce(Flux extends T> source, BiFunction aggregator) {
super(source);
this.aggregator = Objects.requireNonNull(aggregator, "aggregator");
}
@Override
public CoreSubscriber super T> subscribeOrReturn(CoreSubscriber super T> actual) {
return new ReduceSubscriber<>(actual, aggregator);
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
static final class ReduceSubscriber implements InnerOperator,
Fuseable,
QueueSubscription {
static final Object CANCELLED = new Object();
final BiFunction aggregator;
final CoreSubscriber super T> actual;
T aggregate;
Subscription s;
boolean done;
ReduceSubscriber(CoreSubscriber super T> actual,
BiFunction aggregator) {
this.actual = actual;
this.aggregator = aggregator;
}
@Override
public CoreSubscriber super T> actual() {
return this.actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.TERMINATED) return done;
if (key == Attr.CANCELLED) return !done && aggregate == CANCELLED;
if (key == Attr.PREFETCH) return 0;
if (key == Attr.PARENT) return s;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return;
}
final T r = this.aggregate;
if (r == CANCELLED) {
Operators.onDiscard(t, actual.currentContext());
return;
}
// initial scenario when aggregate has nothing in it
if (r == null) {
synchronized (this) {
if (this.aggregate == null) {
this.aggregate = t;
return;
}
}
Operators.onDiscard(t, actual.currentContext());
}
else {
try {
synchronized (this) {
if (this.aggregate != CANCELLED) {
this.aggregate = Objects.requireNonNull(aggregator.apply(r, t), "The aggregator returned a null value");
return;
}
}
Operators.onDiscard(t, actual.currentContext());
}
catch (Throwable ex) {
done = true;
Context ctx = actual.currentContext();
synchronized (this) {
this.aggregate = null;
}
Operators.onDiscard(t, ctx);
Operators.onDiscard(r, ctx);
actual.onError(Operators.onOperatorError(s, ex, t,
actual.currentContext()));
}
}
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
done = true;
final T r;
synchronized (this) {
r = this.aggregate;
this.aggregate = null;
}
if (r == CANCELLED) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
if (r != null) {
Operators.onDiscard(r, actual.currentContext());
}
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
final T r;
synchronized (this) {
r = this.aggregate;
this.aggregate = null;
}
if (r == CANCELLED) {
return;
}
if (r == null) {
actual.onComplete();
}
else {
actual.onNext(r);
actual.onComplete();
}
}
@Override
public void cancel() {
s.cancel();
final T r;
synchronized (this) {
r = this.aggregate;
//noinspection unchecked
this.aggregate = (T) CANCELLED;
}
if (r == null || r == CANCELLED) {
return;
}
Operators.onDiscard(r, actual.currentContext());
}
@Override
public void request(long n) {
s.request(Long.MAX_VALUE);
}
@Override
public T poll() {
return null;
}
@Override
public int requestFusion(int requestedMode) {
return Fuseable.NONE;
}
@Override
public int size() {
return 0;
}
@Override
public boolean isEmpty() {
return true;
}
@Override
public void clear() {
}
}
}
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