io.reactivex.rxjava3.internal.operators.flowable.FlowableMergeWithMaybe 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.flowable;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
import io.reactivex.rxjava3.internal.util.*;
import io.reactivex.rxjava3.operators.SimplePlainQueue;
import io.reactivex.rxjava3.operators.SpscArrayQueue;
/**
* 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 FlowableMergeWithMaybe extends AbstractFlowableWithUpstream {
final MaybeSource other;
public FlowableMergeWithMaybe(Flowable source, MaybeSource other) {
super(source);
this.other = other;
}
@Override
protected void subscribeActual(Subscriber subscriber) {
MergeWithObserver parent = new MergeWithObserver<>(subscriber);
subscriber.onSubscribe(parent);
source.subscribe(parent);
other.subscribe(parent.otherObserver);
}
static final class MergeWithObserver extends AtomicInteger
implements FlowableSubscriber, Subscription {
private static final long serialVersionUID = -4592979584110982903L;
final Subscriber downstream;
final AtomicReference mainSubscription;
final OtherObserver otherObserver;
final AtomicThrowable errors;
final AtomicLong requested;
final int prefetch;
final int limit;
volatile SimplePlainQueue queue;
T singleItem;
volatile boolean cancelled;
volatile boolean mainDone;
volatile int otherState;
long emitted;
int consumed;
static final int OTHER_STATE_HAS_VALUE = 1;
static final int OTHER_STATE_CONSUMED_OR_EMPTY = 2;
MergeWithObserver(Subscriber downstream) {
this.downstream = downstream;
this.mainSubscription = new AtomicReference<>();
this.otherObserver = new OtherObserver<>(this);
this.errors = new AtomicThrowable();
this.requested = new AtomicLong();
this.prefetch = bufferSize();
this.limit = prefetch - (prefetch >> 2);
}
@Override
public void onSubscribe(Subscription s) {
SubscriptionHelper.setOnce(mainSubscription, s, prefetch);
}
@Override
public void onNext(T t) {
if (compareAndSet(0, 1)) {
long e = emitted;
if (requested.get() != e) {
SimplePlainQueue q = queue;
if (q == null || q.isEmpty()) {
emitted = e + 1;
downstream.onNext(t);
int c = consumed + 1;
if (c == limit) {
consumed = 0;
mainSubscription.get().request(c);
} else {
consumed = c;
}
} else {
q.offer(t);
}
} else {
SimplePlainQueue q = getOrCreateQueue();
q.offer(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 void request(long n) {
BackpressureHelper.add(requested, n);
drain();
}
@Override
public void cancel() {
cancelled = true;
SubscriptionHelper.cancel(mainSubscription);
DisposableHelper.dispose(otherObserver);
errors.tryTerminateAndReport();
if (getAndIncrement() == 0) {
queue = null;
singleItem = null;
}
}
void otherSuccess(T value) {
if (compareAndSet(0, 1)) {
long e = emitted;
if (requested.get() != e) {
emitted = e + 1;
downstream.onNext(value);
otherState = OTHER_STATE_CONSUMED_OR_EMPTY;
} else {
singleItem = value;
otherState = OTHER_STATE_HAS_VALUE;
if (decrementAndGet() == 0) {
return;
}
}
} else {
singleItem = value;
otherState = OTHER_STATE_HAS_VALUE;
if (getAndIncrement() != 0) {
return;
}
}
drainLoop();
}
void otherError(Throwable ex) {
if (errors.tryAddThrowableOrReport(ex)) {
SubscriptionHelper.cancel(mainSubscription);
drain();
}
}
void otherComplete() {
otherState = OTHER_STATE_CONSUMED_OR_EMPTY;
drain();
}
SimplePlainQueue getOrCreateQueue() {
SimplePlainQueue q = queue;
if (q == null) {
q = new SpscArrayQueue<>(bufferSize());
queue = q;
}
return q;
}
void drain() {
if (getAndIncrement() == 0) {
drainLoop();
}
}
void drainLoop() {
Subscriber actual = this.downstream;
int missed = 1;
long e = emitted;
int c = consumed;
int lim = limit;
for (;;) {
long r = requested.get();
while (e != r) {
if (cancelled) {
singleItem = null;
queue = null;
return;
}
if (errors.get() != null) {
singleItem = null;
queue = null;
errors.tryTerminateConsumer(downstream);
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);
e++;
continue;
}
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);
e++;
if (++c == lim) {
c = 0;
mainSubscription.get().request(lim);
}
}
if (e == r) {
if (cancelled) {
singleItem = null;
queue = null;
return;
}
if (errors.get() != null) {
singleItem = null;
queue = null;
errors.tryTerminateConsumer(downstream);
return;
}
boolean d = mainDone;
SimplePlainQueue q = queue;
boolean empty = q == null || q.isEmpty();
if (d && empty && otherState == 2) {
queue = null;
actual.onComplete();
return;
}
}
emitted = e;
consumed = c;
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();
}
}
}
}