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Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC

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/*
 * 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.Objects;
import java.util.function.BiFunction;

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

/**
 * Accumulates the source values with an accumulator function and
 * returns the intermediate results of this function.
 * 

* Unlike {@link FluxScan}, this operator doesn't take an initial value * but treats the first source value as initial value. *
* The accumulation works as follows: *


 * result[0] = accumulator(source[0], source[1])
 * result[1] = accumulator(result[0], source[2])
 * result[2] = accumulator(result[1], source[3])
 * ...
 * 
* * @param the input and accumulated value type * @see Reactive-Streams-Commons */ final class FluxScan extends InternalFluxOperator { final BiFunction accumulator; FluxScan(Flux source, BiFunction accumulator) { super(source); this.accumulator = Objects.requireNonNull(accumulator, "accumulator"); } @Override public CoreSubscriber subscribeOrReturn(CoreSubscriber actual) { return new ScanSubscriber<>(actual, accumulator); } @Override public Object scanUnsafe(Attr key) { if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC; return super.scanUnsafe(key); } static final class ScanSubscriber implements InnerOperator { final CoreSubscriber actual; final BiFunction accumulator; Subscription s; T value; boolean done; ScanSubscriber(CoreSubscriber actual, BiFunction accumulator) { this.actual = actual; this.accumulator = accumulator; } @Override public void onSubscribe(Subscription s) { if (Operators.validate(this.s, s)) { this.s = s; actual.onSubscribe(this); } } @Override public void onNext(T t) { if (done) { Operators.onNextDropped(t, actual.currentContext()); return; } T v = value; if (v != null) { try { t = Objects.requireNonNull(accumulator.apply(v, t), "The accumulator returned a null value"); } catch (Throwable e) { onError(Operators.onOperatorError(s, e, t, actual.currentContext())); return; } } value = t; actual.onNext(t); } @Override public void onError(Throwable t) { if (done) { Operators.onErrorDropped(t, actual.currentContext()); return; } done = true; value = null; actual.onError(t); } @Override public void onComplete() { if (done) { return; } done = true; value = null; actual.onComplete(); } @Override @Nullable public Object scanUnsafe(Attr key) { if (key == Attr.PARENT) return s; if (key == Attr.TERMINATED) return done; if (key == Attr.BUFFERED) return value != null ? 1 : 0; 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(); //unless we want to pay a volatile, cancel() nulling out might race with onNext //and result in re-setting value, retaining it. So we don't null out, nor discard. } } }




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