io.reactivex.rxjava3.internal.subscribers.BasicFuseableConditionalSubscriber 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.subscribers;
import org.reactivestreams.Subscription;
import io.reactivex.rxjava3.exceptions.Exceptions;
import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
import io.reactivex.rxjava3.operators.ConditionalSubscriber;
import io.reactivex.rxjava3.operators.QueueSubscription;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
/**
* Base class for a fuseable intermediate subscriber.
* @param the upstream value type
* @param the downstream value type
*/
public abstract class BasicFuseableConditionalSubscriber implements ConditionalSubscriber, QueueSubscription {
/** The downstream subscriber. */
protected final ConditionalSubscriber super R> downstream;
/** The upstream subscription. */
protected Subscription upstream;
/** The upstream's QueueSubscription if not null. */
protected QueueSubscription qs;
/** Flag indicating no further onXXX event should be accepted. */
protected boolean done;
/** Holds the established fusion mode of the upstream. */
protected int sourceMode;
/**
* Construct a BasicFuseableSubscriber by wrapping the given subscriber.
* @param downstream the subscriber, not null (not verified)
*/
public BasicFuseableConditionalSubscriber(ConditionalSubscriber super R> downstream) {
this.downstream = downstream;
}
// final: fixed protocol steps to support fuseable and non-fuseable upstream
@SuppressWarnings("unchecked")
@Override
public final void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.upstream, s)) {
this.upstream = s;
if (s instanceof QueueSubscription) {
this.qs = (QueueSubscription)s;
}
if (beforeDownstream()) {
downstream.onSubscribe(this);
afterDownstream();
}
}
}
/**
* Override this to perform actions before the call {@code actual.onSubscribe(this)} happens.
* @return true if onSubscribe should continue with the call
*/
protected boolean beforeDownstream() {
return true;
}
/**
* Override this to perform actions after the call to {@code actual.onSubscribe(this)} happened.
*/
protected void afterDownstream() {
// default no-op
}
// -----------------------------------
// Convenience and state-aware methods
// -----------------------------------
@Override
public void onError(Throwable t) {
if (done) {
RxJavaPlugins.onError(t);
return;
}
done = true;
downstream.onError(t);
}
/**
* Rethrows the throwable if it is a fatal exception or calls {@link #onError(Throwable)}.
* @param t the throwable to rethrow or signal to the actual subscriber
*/
protected final void fail(Throwable t) {
Exceptions.throwIfFatal(t);
upstream.cancel();
onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
downstream.onComplete();
}
/**
* Calls the upstream's QueueSubscription.requestFusion with the mode and
* saves the established mode in {@link #sourceMode} if that mode doesn't
* have the {@link QueueSubscription#BOUNDARY} flag set.
*
* If the upstream doesn't support fusion ({@link #qs} is null), the method
* returns {@link QueueSubscription#NONE}.
* @param mode the fusion mode requested
* @return the established fusion mode
*/
protected final int transitiveBoundaryFusion(int mode) {
QueueSubscription qs = this.qs;
if (qs != null) {
if ((mode & BOUNDARY) == 0) {
int m = qs.requestFusion(mode);
if (m != NONE) {
sourceMode = m;
}
return m;
}
}
return NONE;
}
// --------------------------------------------------------------
// Default implementation of the RS and QS protocol (can be overridden)
// --------------------------------------------------------------
@Override
public void request(long n) {
upstream.request(n);
}
@Override
public void cancel() {
upstream.cancel();
}
@Override
public boolean isEmpty() {
return qs.isEmpty();
}
@Override
public void clear() {
qs.clear();
}
// -----------------------------------------------------------
// The rest of the Queue interface methods shouldn't be called
// -----------------------------------------------------------
@Override
public final boolean offer(R e) {
throw new UnsupportedOperationException("Should not be called!");
}
@Override
public final boolean offer(R v1, R v2) {
throw new UnsupportedOperationException("Should not be called!");
}
}