/*
 * Copyright (c) 2011-2017 Pivotal Software Inc, 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.Objects;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.function.Consumer;

import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;

Drops values if the subscriber doesn't request fast enough.
Type parameters:
  • <T> – the value type
See Also:
/** * Drops values if the subscriber doesn't request fast enough. * * @param <T> the value type * @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a> */
final class FluxOnBackpressureDrop<T> extends InternalFluxOperator<T, T> { static final Consumer<Object> NOOP = t -> { }; final Consumer<? super T> onDrop; FluxOnBackpressureDrop(Flux<? extends T> source) { super(source); this.onDrop = NOOP; } FluxOnBackpressureDrop(Flux<? extends T> source, Consumer<? super T> onDrop) { super(source); this.onDrop = Objects.requireNonNull(onDrop, "onDrop"); } @Override public int getPrefetch() { return Integer.MAX_VALUE; } @Override public CoreSubscriber<? super T> subscribeOrReturn(CoreSubscriber<? super T> actual) { return new DropSubscriber<>(actual, onDrop); } @Override public Object scanUnsafe(Attr key) { if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC; return super.scanUnsafe(key); } static final class DropSubscriber<T> implements InnerOperator<T, T> { final CoreSubscriber<? super T> actual; final Context ctx; final Consumer<? super T> onDrop; Subscription s; volatile long requested; @SuppressWarnings("rawtypes") static final AtomicLongFieldUpdater<DropSubscriber> REQUESTED = AtomicLongFieldUpdater.newUpdater(DropSubscriber.class, "requested"); boolean done; DropSubscriber(CoreSubscriber<? super T> actual, Consumer<? super T> onDrop) { this.actual = actual; this.ctx = actual.currentContext(); this.onDrop = onDrop; } @Override public void request(long n) { if (Operators.validate(n)) { Operators.addCap(REQUESTED, this, n); } } @Override public void cancel() { s.cancel(); } @Override public void onSubscribe(Subscription s) { if (Operators.validate(this.s, s)) { this.s = s; actual.onSubscribe(this); s.request(Long.MAX_VALUE); } } @Override public void onNext(T t) { if (done) { try { onDrop.accept(t); } catch (Throwable e) { Operators.onErrorDropped(e, ctx); } Operators.onDiscard(t, ctx); return; } long r = requested; if (r != 0L) { actual.onNext(t); if(r != Long.MAX_VALUE) { Operators.produced(REQUESTED, this, 1); } } else { try { onDrop.accept(t); } catch (Throwable e) { onError(Operators.onOperatorError(s, e, t, ctx)); } Operators.onDiscard(t, ctx); } } @Override public void onError(Throwable t) { if (done) { Operators.onErrorDropped(t, actual.currentContext()); return; } done = true; actual.onError(t); } @Override public void onComplete() { if (done) { return; } done = true; actual.onComplete(); } @Override public CoreSubscriber<? super T> actual() { return actual; } @Override @Nullable public Object scanUnsafe(Attr key) { if (key == Attr.PARENT) return s; if (key == Attr.REQUESTED_FROM_DOWNSTREAM) return requested; if (key == Attr.TERMINATED) return done; if (key == Attr.PREFETCH) return Integer.MAX_VALUE; if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC; return InnerOperator.super.scanUnsafe(key); } } }