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Reactive Extensions for Java
/*
* 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.flowable;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.exceptions.Exceptions;
import io.reactivex.rxjava3.internal.subscriptions.*;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
public final class FlowableAmb extends Flowable {
final Publisher extends T>[] sources;
final Iterable extends Publisher extends T>> sourcesIterable;
public FlowableAmb(Publisher extends T>[] sources, Iterable extends Publisher extends T>> sourcesIterable) {
this.sources = sources;
this.sourcesIterable = sourcesIterable;
}
@Override
@SuppressWarnings("unchecked")
public void subscribeActual(Subscriber super T> s) {
Publisher extends T>[] sources = this.sources;
int count = 0;
if (sources == null) {
sources = new Publisher[8];
try {
for (Publisher extends T> p : sourcesIterable) {
if (p == null) {
EmptySubscription.error(new NullPointerException("One of the sources is null"), s);
return;
}
if (count == sources.length) {
Publisher extends T>[] b = new Publisher[count + (count >> 2)];
System.arraycopy(sources, 0, b, 0, count);
sources = b;
}
sources[count++] = p;
}
} catch (Throwable e) {
Exceptions.throwIfFatal(e);
EmptySubscription.error(e, s);
return;
}
} else {
count = sources.length;
}
if (count == 0) {
EmptySubscription.complete(s);
return;
} else
if (count == 1) {
sources[0].subscribe(s);
return;
}
AmbCoordinator ac = new AmbCoordinator<>(s, count);
ac.subscribe(sources);
}
static final class AmbCoordinator implements Subscription {
final Subscriber super T> downstream;
final AmbInnerSubscriber[] subscribers;
final AtomicInteger winner = new AtomicInteger();
@SuppressWarnings("unchecked")
AmbCoordinator(Subscriber super T> actual, int count) {
this.downstream = actual;
this.subscribers = new AmbInnerSubscriber[count];
}
public void subscribe(Publisher extends T>[] sources) {
AmbInnerSubscriber[] as = subscribers;
int len = as.length;
for (int i = 0; i < len; i++) {
as[i] = new AmbInnerSubscriber<>(this, i + 1, downstream);
}
winner.lazySet(0); // release the contents of 'as'
downstream.onSubscribe(this);
for (int i = 0; i < len; i++) {
if (winner.get() != 0) {
return;
}
sources[i].subscribe(as[i]);
}
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
int w = winner.get();
if (w > 0) {
subscribers[w - 1].request(n);
} else
if (w == 0) {
for (AmbInnerSubscriber a : subscribers) {
a.request(n);
}
}
}
}
public boolean win(int index) {
int w = winner.get();
if (w == 0) {
if (winner.compareAndSet(0, index)) {
AmbInnerSubscriber[] a = subscribers;
int n = a.length;
for (int i = 0; i < n; i++) {
if (i + 1 != index) {
a[i].cancel();
}
}
return true;
}
}
return false;
}
@Override
public void cancel() {
if (winner.get() != -1) {
winner.lazySet(-1);
for (AmbInnerSubscriber a : subscribers) {
a.cancel();
}
}
}
}
static final class AmbInnerSubscriber extends AtomicReference implements FlowableSubscriber, Subscription {
private static final long serialVersionUID = -1185974347409665484L;
final AmbCoordinator parent;
final int index;
final Subscriber super T> downstream;
boolean won;
final AtomicLong missedRequested = new AtomicLong();
AmbInnerSubscriber(AmbCoordinator parent, int index, Subscriber super T> downstream) {
this.parent = parent;
this.index = index;
this.downstream = downstream;
}
@Override
public void onSubscribe(Subscription s) {
SubscriptionHelper.deferredSetOnce(this, missedRequested, s);
}
@Override
public void request(long n) {
SubscriptionHelper.deferredRequest(this, missedRequested, n);
}
@Override
public void onNext(T t) {
if (won) {
downstream.onNext(t);
} else {
if (parent.win(index)) {
won = true;
downstream.onNext(t);
} else {
get().cancel();
}
}
}
@Override
public void onError(Throwable t) {
if (won) {
downstream.onError(t);
} else {
if (parent.win(index)) {
won = true;
downstream.onError(t);
} else {
get().cancel();
RxJavaPlugins.onError(t);
}
}
}
@Override
public void onComplete() {
if (won) {
downstream.onComplete();
} else {
if (parent.win(index)) {
won = true;
downstream.onComplete();
} else {
get().cancel();
}
}
}
@Override
public void cancel() {
SubscriptionHelper.cancel(this);
}
}
}
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