org.neo4j.driver.internal.shaded.reactor.core.publisher.MonoStreamCollector Maven / Gradle / Ivy
/*
* Copyright (c) 2016-2021 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.Collection;
import java.util.Objects;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.stream.Collector;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Fuseable;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* Collects the values from the source sequence into a {@link java.util.stream.Collector}
* instance.
*
* @param the source value type
* @param an intermediate value type
* @param the output value type
*
* @see Reactive-Streams-Commons
*/
final class MonoStreamCollector extends MonoFromFluxOperator
implements Fuseable {
final Collector collector;
MonoStreamCollector(Flux source,
Collector collector) {
super(source);
this.collector = Objects.requireNonNull(collector, "collector");
}
@Override
public CoreSubscriber subscribeOrReturn(CoreSubscriber actual) {
A container = collector.supplier()
.get();
BiConsumer accumulator = collector.accumulator();
Function finisher = collector.finisher();
return new StreamCollectorSubscriber<>(actual, container, accumulator, finisher);
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
static final class StreamCollectorSubscriber
extends Operators.MonoSubscriber {
final BiConsumer accumulator;
final Function finisher;
A container; //not final to be able to null it out on termination
Subscription s;
boolean done;
StreamCollectorSubscriber(CoreSubscriber actual,
A container,
BiConsumer accumulator,
Function finisher) {
super(actual);
this.container = container;
this.accumulator = accumulator;
this.finisher = finisher;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.TERMINATED) return done;
if (key == Attr.PARENT) return s;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
protected void discardIntermediateContainer(A a) {
Context ctx = actual.currentContext();
if (a instanceof Collection) {
Operators.onDiscardMultiple((Collection) a, ctx);
}
else {
Operators.onDiscard(a, ctx);
}
}
//NB: value and thus discard are not used
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return;
}
try {
accumulator.accept(container, t);
}
catch (Throwable ex) {
Context ctx = actual.currentContext();
Operators.onDiscard(t, ctx);
onError(Operators.onOperatorError(s, ex, t, ctx)); //discards intermediate container
}
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
done = true;
discardIntermediateContainer(container);
container = null;
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
A a = container;
container = null;
R r;
try {
r = finisher.apply(a);
}
catch (Throwable ex) {
discardIntermediateContainer(a);
actual.onError(Operators.onOperatorError(ex, actual.currentContext()));
return;
}
if (r == null) {
actual.onError(Operators.onOperatorError(new NullPointerException("Collector returned null"), actual.currentContext()));
return;
}
complete(r);
}
@Override
public void cancel() {
super.cancel();
s.cancel();
discardIntermediateContainer(container);
container = null;
}
}
}