org.neo4j.driver.internal.shaded.reactor.core.publisher.FluxSkipLast Maven / Gradle / Ivy
/*
* Copyright (c) 2016-2021 VMware Inc. or its affiliates, All Rights Reserved.
*
* 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
*
* https://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 reactor.core.publisher;
import java.util.ArrayDeque;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.util.annotation.Nullable;
/**
* Skips the last N elements from the source stream.
*
* @param the value type
* @see Reactive-Streams-Commons
*/
final class FluxSkipLast extends InternalFluxOperator {
final int n;
FluxSkipLast(Flux source, int n) {
super(source);
if (n < 0) {
throw new IllegalArgumentException("n >= 0 required but it was " + n);
}
this.n = n;
}
@Override
public CoreSubscriber subscribeOrReturn(CoreSubscriber actual) {
return new SkipLastSubscriber<>(actual, n);
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
//Fixme Does not implement ConditionalSubscriber until the full chain of operators
// supports fully conditional, requesting N onSubscribe cost is offset
static final class SkipLastSubscriber
extends ArrayDeque
implements InnerOperator {
final CoreSubscriber actual;
final int n;
Subscription s;
SkipLastSubscriber(CoreSubscriber actual, int n) {
this.actual = actual;
this.n = n;
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
s.request(n);
}
}
@Override
public void onNext(T t) {
if (size() == n) {
actual.onNext(pollFirst());
}
offerLast(t);
}
@Override
public void onError(Throwable t) {
actual.onError(t);
Operators.onDiscardQueueWithClear(this, actual.currentContext(), null);
}
@Override
public void onComplete() {
actual.onComplete();
Operators.onDiscardQueueWithClear(this, actual.currentContext(), null);
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) return s;
if (key == Attr.PREFETCH) return n;
if (key == Attr.BUFFERED) return size();
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
public void request(long n) {
s.request(n);
}
@Override
public void cancel() {
s.cancel();
Operators.onDiscardQueueWithClear(this, actual.currentContext(), null);
}
}
}