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/*
* Copyright (c) 2016-2023 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.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Fuseable;
import reactor.core.Scannable;
import reactor.util.annotation.Nullable;
/**
* Exposes the 'rails' as individual GroupedFlux instances, keyed by the rail index (zero based).
*
* Each group can be consumed only once; requests and cancellation compose through. Note
* that cancelling only one rail may result in undefined behavior.
*
* @param the value type
*/
final class ParallelGroup extends Flux> implements
Scannable, Fuseable {
final ParallelFlux extends T> source;
ParallelGroup(ParallelFlux extends T> source) {
this.source = ParallelFlux.from(source);
}
@Override
public void subscribe(CoreSubscriber super GroupedFlux> actual) {
int n = source.parallelism();
@SuppressWarnings("unchecked")
ParallelInnerGroup[] groups = new ParallelInnerGroup[n];
for (int i = 0; i < n; i++) {
groups[i] = new ParallelInnerGroup<>(i);
}
FluxArray.subscribe(actual, groups);
source.subscribe(groups);
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) return source;
if (key == Attr.PREFETCH) return getPrefetch();
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
if (key == InternalProducerAttr.INSTANCE) return true;
return null;
}
static final class ParallelInnerGroup extends GroupedFlux
implements InnerOperator {
final int key;
volatile int once;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater ONCE =
AtomicIntegerFieldUpdater.newUpdater(ParallelInnerGroup.class, "once");
volatile Subscription s;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater S =
AtomicReferenceFieldUpdater.newUpdater(ParallelInnerGroup.class, Subscription.class, "s");
volatile long requested;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(ParallelInnerGroup.class, "requested");
CoreSubscriber super T> actual;
ParallelInnerGroup(int key) {
this.key = key;
}
@Override
public Integer key() {
return key;
}
@Override
public void subscribe(CoreSubscriber super T> actual) {
if (ONCE.compareAndSet(this, 0, 1)) {
this.actual = actual;
actual.onSubscribe(this);
} else {
Operators.error(actual, new IllegalStateException("This ParallelGroup can be subscribed to at most once."));
}
}
@Override
public CoreSubscriber super T> actual() {
return actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) return s;
if (key == Attr.REQUESTED_FROM_DOWNSTREAM) return requested;
if (key == Attr.CANCELLED) return s == Operators.cancelledSubscription();
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.setOnce(S, this, s)) {
long r = REQUESTED.getAndSet(this, 0L);
if (r != 0L) {
s.request(r);
}
}
}
@Override
public void onNext(T t) {
actual.onNext(t);
}
@Override
public void onError(Throwable t) {
actual.onError(t);
}
@Override
public void onComplete() {
actual.onComplete();
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
Subscription a = s;
if (a == null) {
Operators.addCap(REQUESTED, this, n);
a = s;
if (a != null) {
long r = REQUESTED.getAndSet(this, 0L);
if (r != 0L) {
a.request(n);
}
}
} else {
a.request(n);
}
}
}
@Override
public void cancel() {
Operators.terminate(S, this);
}
}
}