io.reactivex.rxjava3.internal.operators.observable.ObservableMergeWithMaybe Maven / Gradle / Ivy
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/*
* 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.concurrent.atomic.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
import io.reactivex.rxjava3.internal.util.AtomicThrowable;
import io.reactivex.rxjava3.operators.SimplePlainQueue;
import io.reactivex.rxjava3.operators.SpscLinkedArrayQueue;
/**
* Merges an Observable and a Maybe by emitting the items of the Observable and the success
* value of the Maybe and waiting until both the Observable and Maybe terminate normally.
* History: 2.1.10 - experimental
* @param the element type of the Observable
* @since 2.2
*/
public final class ObservableMergeWithMaybe extends AbstractObservableWithUpstream {
final MaybeSource other;
public ObservableMergeWithMaybe(Observable source, MaybeSource other) {
super(source);
this.other = other;
}
@Override
protected void subscribeActual(Observer observer) {
MergeWithObserver parent = new MergeWithObserver<>(observer);
observer.onSubscribe(parent);
source.subscribe(parent);
other.subscribe(parent.otherObserver);
}
static final class MergeWithObserver extends AtomicInteger
implements Observer, Disposable {
private static final long serialVersionUID = -4592979584110982903L;
final Observer downstream;
final AtomicReference mainDisposable;
final OtherObserver otherObserver;
final AtomicThrowable errors;
volatile SimplePlainQueue queue;
T singleItem;
volatile boolean disposed;
volatile boolean mainDone;
volatile int otherState;
static final int OTHER_STATE_HAS_VALUE = 1;
static final int OTHER_STATE_CONSUMED_OR_EMPTY = 2;
MergeWithObserver(Observer downstream) {
this.downstream = downstream;
this.mainDisposable = new AtomicReference<>();
this.otherObserver = new OtherObserver<>(this);
this.errors = new AtomicThrowable();
}
@Override
public void onSubscribe(Disposable d) {
DisposableHelper.setOnce(mainDisposable, d);
}
@Override
public void onNext(T t) {
if (compareAndSet(0, 1)) {
downstream.onNext(t);
if (decrementAndGet() == 0) {
return;
}
} else {
SimplePlainQueue q = getOrCreateQueue();
q.offer(t);
if (getAndIncrement() != 0) {
return;
}
}
drainLoop();
}
@Override
public void onError(Throwable ex) {
if (errors.tryAddThrowableOrReport(ex)) {
DisposableHelper.dispose(otherObserver);
drain();
}
}
@Override
public void onComplete() {
mainDone = true;
drain();
}
@Override
public boolean isDisposed() {
return DisposableHelper.isDisposed(mainDisposable.get());
}
@Override
public void dispose() {
disposed = true;
DisposableHelper.dispose(mainDisposable);
DisposableHelper.dispose(otherObserver);
errors.tryTerminateAndReport();
if (getAndIncrement() == 0) {
queue = null;
singleItem = null;
}
}
void otherSuccess(T value) {
if (compareAndSet(0, 1)) {
downstream.onNext(value);
otherState = OTHER_STATE_CONSUMED_OR_EMPTY;
} else {
singleItem = value;
otherState = OTHER_STATE_HAS_VALUE;
if (getAndIncrement() != 0) {
return;
}
}
drainLoop();
}
void otherError(Throwable ex) {
if (errors.tryAddThrowableOrReport(ex)) {
DisposableHelper.dispose(mainDisposable);
drain();
}
}
void otherComplete() {
otherState = OTHER_STATE_CONSUMED_OR_EMPTY;
drain();
}
SimplePlainQueue getOrCreateQueue() {
SimplePlainQueue q = queue;
if (q == null) {
q = new SpscLinkedArrayQueue<>(bufferSize());
queue = q;
}
return q;
}
void drain() {
if (getAndIncrement() == 0) {
drainLoop();
}
}
void drainLoop() {
Observer actual = this.downstream;
int missed = 1;
for (;;) {
for (;;) {
if (disposed) {
singleItem = null;
queue = null;
return;
}
if (errors.get() != null) {
singleItem = null;
queue = null;
errors.tryTerminateConsumer(actual);
return;
}
int os = otherState;
if (os == OTHER_STATE_HAS_VALUE) {
T v = singleItem;
singleItem = null;
otherState = OTHER_STATE_CONSUMED_OR_EMPTY;
os = OTHER_STATE_CONSUMED_OR_EMPTY;
actual.onNext(v);
}
boolean d = mainDone;
SimplePlainQueue q = queue;
T v = q != null ? q.poll() : null;
boolean empty = v == null;
if (d && empty && os == OTHER_STATE_CONSUMED_OR_EMPTY) {
queue = null;
actual.onComplete();
return;
}
if (empty) {
break;
}
actual.onNext(v);
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
static final class OtherObserver extends AtomicReference
implements MaybeObserver {
private static final long serialVersionUID = -2935427570954647017L;
final MergeWithObserver parent;
OtherObserver(MergeWithObserver parent) {
this.parent = parent;
}
@Override
public void onSubscribe(Disposable d) {
DisposableHelper.setOnce(this, d);
}
@Override
public void onSuccess(T t) {
parent.otherSuccess(t);
}
@Override
public void onError(Throwable e) {
parent.otherError(e);
}
@Override
public void onComplete() {
parent.otherComplete();
}
}
}
}