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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) 2016-2023 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.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.Queue;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Function;
import java.util.function.Supplier;

import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;

import reactor.core.CoreSubscriber;
import reactor.core.Disposable;
import reactor.core.Disposables;
import reactor.core.Exceptions;
import reactor.util.annotation.Nullable;
import reactor.util.concurrent.Queues;

import static reactor.core.Exceptions.wrapSource;

/**
 * Splits the source sequence into potentially overlapping windowEnds controlled by items
 * of a start Publisher and end Publishers derived from the start values.
 *
 * @param  the source value type
 * @param  the window starter value type
 * @param  the window end value type (irrelevant)
 *
 * @see Reactive-Streams-Commons
 */
final class FluxWindowWhen extends InternalFluxOperator> {

	final Publisher start;

	final Function> end;

	final Supplier> processorQueueSupplier;

	FluxWindowWhen(Flux source,
			Publisher start,
			Function> end,
			Supplier> processorQueueSupplier) {
		super(source);
		this.start = Operators.toFluxOrMono(Objects.requireNonNull(start, "start"));
		this.end = Objects.requireNonNull(end, "end");
		this.processorQueueSupplier =
				Objects.requireNonNull(processorQueueSupplier, "processorQueueSupplier");
	}

	@Override
	public int getPrefetch() {
		return Integer.MAX_VALUE;
	}

	@Override
	@Nullable
	public CoreSubscriber subscribeOrReturn(CoreSubscriber> actual) {
		WindowWhenMainSubscriber main = new WindowWhenMainSubscriber<>(actual,
				start, end, processorQueueSupplier);
		actual.onSubscribe(main);

		if (main.cancelled) {
			return null;
		}
		WindowWhenOpenSubscriber os = new WindowWhenOpenSubscriber<>(main);

		if (WindowWhenMainSubscriber.BOUNDARY.compareAndSet(main,null, os)) {
			WindowWhenMainSubscriber.OPEN_WINDOW_COUNT.incrementAndGet(main);
			start.subscribe(os);
			return main;
		}
		else {
			return null;
		}
	}

	@Override
	public Object scanUnsafe(Attr key) {
		if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
		return super.scanUnsafe(key);
	}

	static final class WindowWhenMainSubscriber
			extends QueueDrainSubscriber> {

		final Publisher open;
		final Function> close;
		final Supplier> processorQueueSupplier;
		final Disposable.Composite resources;

		Subscription s;

		volatile Disposable boundary;
		static final AtomicReferenceFieldUpdater BOUNDARY =
				AtomicReferenceFieldUpdater.newUpdater(WindowWhenMainSubscriber.class, Disposable.class, "boundary");

		final List> windows;

		volatile long openWindowCount;
		static final AtomicLongFieldUpdater OPEN_WINDOW_COUNT =
				AtomicLongFieldUpdater.newUpdater(WindowWhenMainSubscriber.class, "openWindowCount");

		WindowWhenMainSubscriber(CoreSubscriber> actual,
				Publisher open, Function> close,
				Supplier> processorQueueSupplier) {
			super(actual, Queues.unboundedMultiproducer().get());
			this.open = open;
			this.close = close;
			this.processorQueueSupplier = processorQueueSupplier;
			this.resources = Disposables.composite();
			this.windows = new ArrayList<>();
			OPEN_WINDOW_COUNT.lazySet(this, 1);
		}

		@Override
		public void onSubscribe(Subscription s) {
			if (Operators.validate(this.s, s)) {
				this.s = s;
				s.request(Long.MAX_VALUE);
			}
		}

		@Override
		public void onNext(T t) {
			if (done) {
				Operators.onNextDropped(t, actual.currentContext());
				return;
			}
			if (fastEnter()) {
				for (Sinks.Many w : windows) {
					w.emitNext(t, Sinks.EmitFailureHandler.FAIL_FAST);
				}
				if (leave(-1) == 0) {
					return;
				}
			} else {
				queue.offer(t);
				if (!enter()) {
					return;
				}
			}
			drainLoop();
		}

		@Override
		public void onError(Throwable t) {
			if (done) {
				Operators.onErrorDropped(t, actual.currentContext());
				return;
			}
			error = t;
			done = true;

			if (enter()) {
				drainLoop();
			}

			if (OPEN_WINDOW_COUNT.decrementAndGet(this) == 0) {
				resources.dispose();
			}
		}

		@Override
		public void onComplete() {
			if (done) {
				return;
			}
			done = true;

			if (enter()) {
				drainLoop();
			}

			if (OPEN_WINDOW_COUNT.decrementAndGet(this) == 0) {
				resources.dispose();
			}
		}

		void error(Throwable t) {
			s.cancel();
			resources.dispose();
			OperatorDisposables.dispose(BOUNDARY, this);

			actual.onError(t);
		}

		@Override
		public void request(long n) {
			requested(n);
		}

		@Override
		public void cancel() {
			cancelled = true;
		}

		void dispose() {
			resources.dispose();
			OperatorDisposables.dispose(BOUNDARY, this);
		}

		void drainLoop() {
			final Queue