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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.observable;
import java.util.Objects;
import java.util.concurrent.atomic.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.*;
import io.reactivex.rxjava3.exceptions.Exceptions;
import io.reactivex.rxjava3.functions.Function;
import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
import io.reactivex.rxjava3.internal.util.AtomicThrowable;
import io.reactivex.rxjava3.operators.SpscLinkedArrayQueue;
/**
* Maps upstream values into SingleSources and merges their signals into one sequence.
* @param the source value type
* @param the result value type
*/
public final class ObservableFlatMapSingle extends AbstractObservableWithUpstream {
final Function> mapper;
final boolean delayErrors;
public ObservableFlatMapSingle(ObservableSource source, Function> mapper,
boolean delayError) {
super(source);
this.mapper = mapper;
this.delayErrors = delayError;
}
@Override
protected void subscribeActual(Observer observer) {
source.subscribe(new FlatMapSingleObserver<>(observer, mapper, delayErrors));
}
static final class FlatMapSingleObserver
extends AtomicInteger
implements Observer, Disposable {
private static final long serialVersionUID = 8600231336733376951L;
final Observer downstream;
final boolean delayErrors;
final CompositeDisposable set;
final AtomicInteger active;
final AtomicThrowable errors;
final Function> mapper;
final AtomicReference> queue;
Disposable upstream;
volatile boolean cancelled;
FlatMapSingleObserver(Observer actual,
Function> mapper, boolean delayErrors) {
this.downstream = actual;
this.mapper = mapper;
this.delayErrors = delayErrors;
this.set = new CompositeDisposable();
this.errors = new AtomicThrowable();
this.active = new AtomicInteger(1);
this.queue = new AtomicReference<>();
}
@Override
public void onSubscribe(Disposable d) {
if (DisposableHelper.validate(this.upstream, d)) {
this.upstream = d;
downstream.onSubscribe(this);
}
}
@Override
public void onNext(T t) {
SingleSource ms;
try {
ms = Objects.requireNonNull(mapper.apply(t), "The mapper returned a null SingleSource");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
upstream.dispose();
onError(ex);
return;
}
active.getAndIncrement();
InnerObserver inner = new InnerObserver();
if (!cancelled && set.add(inner)) {
ms.subscribe(inner);
}
}
@Override
public void onError(Throwable t) {
active.decrementAndGet();
if (errors.tryAddThrowableOrReport(t)) {
if (!delayErrors) {
set.dispose();
}
drain();
}
}
@Override
public void onComplete() {
active.decrementAndGet();
drain();
}
@Override
public void dispose() {
cancelled = true;
upstream.dispose();
set.dispose();
errors.tryTerminateAndReport();
}
@Override
public boolean isDisposed() {
return cancelled;
}
void innerSuccess(InnerObserver inner, R value) {
set.delete(inner);
if (get() == 0 && compareAndSet(0, 1)) {
downstream.onNext(value);
boolean d = active.decrementAndGet() == 0;
SpscLinkedArrayQueue q = queue.get();
if (d && (q == null || q.isEmpty())) {
errors.tryTerminateConsumer(downstream);
return;
}
if (decrementAndGet() == 0) {
return;
}
} else {
SpscLinkedArrayQueue q = getOrCreateQueue();
synchronized (q) {
q.offer(value);
}
active.decrementAndGet();
if (getAndIncrement() != 0) {
return;
}
}
drainLoop();
}
SpscLinkedArrayQueue getOrCreateQueue() {
SpscLinkedArrayQueue current = queue.get();
if (current != null) {
return current;
}
current = new SpscLinkedArrayQueue<>(Observable.bufferSize());
if (queue.compareAndSet(null, current)) {
return current;
}
return queue.get();
}
void innerError(InnerObserver inner, Throwable e) {
set.delete(inner);
if (errors.tryAddThrowableOrReport(e)) {
if (!delayErrors) {
upstream.dispose();
set.dispose();
}
active.decrementAndGet();
drain();
}
}
void drain() {
if (getAndIncrement() == 0) {
drainLoop();
}
}
void clear() {
SpscLinkedArrayQueue q = queue.get();
if (q != null) {
q.clear();
}
}
void drainLoop() {
int missed = 1;
Observer a = downstream;
AtomicInteger n = active;
AtomicReference> qr = queue;
for (;;) {
for (;;) {
if (cancelled) {
clear();
return;
}
if (!delayErrors) {
Throwable ex = errors.get();
if (ex != null) {
clear();
errors.tryTerminateConsumer(a);
return;
}
}
boolean d = n.get() == 0;
SpscLinkedArrayQueue q = qr.get();
R v = q != null ? q.poll() : null;
boolean empty = v == null;
if (d && empty) {
errors.tryTerminateConsumer(downstream);
return;
}
if (empty) {
break;
}
a.onNext(v);
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
final class InnerObserver extends AtomicReference
implements SingleObserver, Disposable {
private static final long serialVersionUID = -502562646270949838L;
@Override
public void onSubscribe(Disposable d) {
DisposableHelper.setOnce(this, d);
}
@Override
public void onSuccess(R value) {
innerSuccess(this, value);
}
@Override
public void onError(Throwable e) {
innerError(this, e);
}
@Override
public boolean isDisposed() {
return DisposableHelper.isDisposed(get());
}
@Override
public void dispose() {
DisposableHelper.dispose(this);
}
}
}
}
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