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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.Objects;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.function.Consumer;
import java.util.function.Function;

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

/**
 * Uses a resource, generated by a supplier for each individual Subscriber,
 * while streaming the values from a
 * Publisher derived from the same resource and makes sure the resource is released
 * if the sequence terminates or the Subscriber cancels.
 * 
 * 
 * Eager resource cleanup happens just before the source termination and exceptions
 * raised by the cleanup Consumer may override the terminal event. Non-eager
 * cleanup will drop any exception.
 *
 * @param  the value type streamed
 * @param  the resource type
 *
 * @see Reactive-Streams-Commons
 */
final class FluxUsing extends Flux implements Fuseable, SourceProducer {

	final Callable resourceSupplier;

	final Function> sourceFactory;

	final Consumer resourceCleanup;

	final boolean eager;

	FluxUsing(Callable resourceSupplier,
			Function> sourceFactory,
			Consumer resourceCleanup,
			boolean eager) {
		this.resourceSupplier =
				Objects.requireNonNull(resourceSupplier, "resourceSupplier");
		this.sourceFactory = Objects.requireNonNull(sourceFactory, "sourceFactory");
		this.resourceCleanup = Objects.requireNonNull(resourceCleanup, "resourceCleanup");
		this.eager = eager;
	}

	@Override
	@SuppressWarnings("unchecked")
	public void subscribe(CoreSubscriber actual) {
		S resource;

		try {
			resource = resourceSupplier.call();
		}
		catch (Throwable e) {
			Operators.error(actual, Operators.onOperatorError(e, actual.currentContext()));
			return;
		}

		Publisher p;

		try {
			p = Objects.requireNonNull(sourceFactory.apply(resource),
					"The sourceFactory returned a null value");
		}
		catch (Throwable e) {
			Throwable _e = Operators.onOperatorError(e, actual.currentContext());
			try {
				resourceCleanup.accept(resource);
			}
			catch (Throwable ex) {
				_e = Exceptions.addSuppressed(ex, _e);
			}

			Operators.error(actual, _e);
			return;
		}

		if (p instanceof Fuseable) {
			from(p).subscribe(new UsingFuseableSubscriber<>(actual,
					resourceCleanup,
					resource,
					eager));
		}
		else if (actual instanceof ConditionalSubscriber) {
			from(p).subscribe(new UsingConditionalSubscriber<>((ConditionalSubscriber) actual,
					resourceCleanup,
					resource,
					eager));
		}
		else {
			from(p).subscribe(new UsingSubscriber<>(actual, resourceCleanup,
					resource, eager));
		}
	}

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

	static final class UsingSubscriber
			implements InnerOperator, QueueSubscription {

		final CoreSubscriber actual;

		final Consumer resourceCleanup;

		final S resource;

		final boolean eager;

		Subscription s;

		volatile int wip;
		@SuppressWarnings("rawtypes")
		static final AtomicIntegerFieldUpdater WIP =
				AtomicIntegerFieldUpdater.newUpdater(UsingSubscriber.class, "wip");

		UsingSubscriber(CoreSubscriber actual,
				Consumer resourceCleanup,
				S resource,
				boolean eager) {
			this.actual = actual;
			this.resourceCleanup = resourceCleanup;
			this.resource = resource;
			this.eager = eager;
		}

		@Override
		@Nullable
		public Object scanUnsafe(Attr key) {
			if (key == Attr.TERMINATED || key == Attr.CANCELLED) return wip == 1;
			if (key == Attr.PARENT) return s;
			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() {
			if (WIP.compareAndSet(this, 0, 1)) {
				s.cancel();

				cleanup();
			}
		}

		void cleanup() {
			try {
				resourceCleanup.accept(resource);
			}
			catch (Throwable e) {
				Operators.onErrorDropped(e, actual.currentContext());
			}
		}

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

				actual.onSubscribe(this);
			}
		}

		@Override
		public void onNext(T t) {
			actual.onNext(t);
		}

		@Override
		public void onError(Throwable t) {
			if (eager && WIP.compareAndSet(this, 0, 1)) {
				try {
					resourceCleanup.accept(resource);
				}
				catch (Throwable e) {
					Throwable _e = Operators.onOperatorError(e, actual.currentContext());
					t = Exceptions.addSuppressed(_e, t);
				}
			}

			actual.onError(t);

			if (!eager && WIP.compareAndSet(this, 0, 1)) {
				cleanup();
			}
		}

		@Override
		public void onComplete() {
			if (eager && WIP.compareAndSet(this, 0, 1)) {
				try {
					resourceCleanup.accept(resource);
				}
				catch (Throwable e) {
					actual.onError(Operators.onOperatorError(e, actual.currentContext()));
					return;
				}
			}

			actual.onComplete();

			if (!eager && WIP.compareAndSet(this, 0, 1)) {
				cleanup();
			}
		}

		@Override
		public int requestFusion(int requestedMode) {
			return NONE; // always reject, upstream turned out to be non-fuseable after all
		}

		@Override
		public void clear() {
			// ignoring fusion methods
		}

		@Override
		public boolean isEmpty() {
			// ignoring fusion methods
			return true;
		}

		@Override
		@Nullable
		public T poll() {
			return null;
		}

		@Override
		public int size() {
			return 0;
		}
	}

	static final class UsingFuseableSubscriber
			implements InnerOperator, QueueSubscription {

		final CoreSubscriber actual;

		final Consumer resourceCleanup;

		final S resource;

		final boolean eager;

		QueueSubscription s;

		volatile int wip;
		@SuppressWarnings("rawtypes")
		static final AtomicIntegerFieldUpdater WIP =
				AtomicIntegerFieldUpdater.newUpdater(UsingFuseableSubscriber.class,
						"wip");

		int mode;

		UsingFuseableSubscriber(CoreSubscriber actual,
				Consumer resourceCleanup,
				S resource,
				boolean eager) {
			this.actual = actual;
			this.resourceCleanup = resourceCleanup;
			this.resource = resource;
			this.eager = eager;
		}

		@Override
		@Nullable
		public Object scanUnsafe(Attr key) {
			if (key == Attr.TERMINATED || key == Attr.CANCELLED)
				return wip == 1;
			if (key == Attr.PARENT) return s;
			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() {
			if (WIP.compareAndSet(this, 0, 1)) {
				s.cancel();

				cleanup();
			}
		}

		void cleanup() {
			try {
				resourceCleanup.accept(resource);
			}
			catch (Throwable e) {
				Operators.onErrorDropped(e, actual.currentContext());
			}
		}

		@SuppressWarnings("unchecked")
		@Override
		public void onSubscribe(Subscription s) {
			if (Operators.validate(this.s, s)) {
				this.s = (QueueSubscription) s;

				actual.onSubscribe(this);
			}
		}

		@Override
		public void onNext(T t) {
			actual.onNext(t);
		}

		@Override
		public void onError(Throwable t) {
			if (eager && WIP.compareAndSet(this, 0, 1)) {
				try {
					resourceCleanup.accept(resource);
				}
				catch (Throwable e) {
					Throwable _e = Operators.onOperatorError(e, actual.currentContext());
					t = Exceptions.addSuppressed(_e, t);
				}
			}

			actual.onError(t);

			if (!eager && WIP.compareAndSet(this, 0, 1)) {
				cleanup();
			}
		}

		@Override
		public void onComplete() {
			if (eager && WIP.compareAndSet(this, 0, 1)) {
				try {
					resourceCleanup.accept(resource);
				}
				catch (Throwable e) {
					actual.onError(Operators.onOperatorError(e, actual.currentContext()));
					return;
				}
			}

			actual.onComplete();

			if (!eager && WIP.compareAndSet(this, 0, 1)) {
				cleanup();
			}
		}

		@Override
		public void clear() {
			s.clear();
		}

		@Override
		public boolean isEmpty() {
			return s.isEmpty();
		}

		@Override
		@Nullable
		public T poll() {
			T v = s.poll();

			if (v == null && mode == SYNC) {
				if (WIP.compareAndSet(this, 0, 1)) {
					resourceCleanup.accept(resource);
				}
			}
			return v;
		}

		@Override
		public int requestFusion(int requestedMode) {
			int m = s.requestFusion(requestedMode);
			mode = m;
			return m;
		}

		@Override
		public int size() {
			return s.size();
		}
	}

	static final class UsingConditionalSubscriber
			implements ConditionalSubscriber, InnerOperator,
			           QueueSubscription {

		final ConditionalSubscriber actual;

		final Consumer resourceCleanup;

		final S resource;

		final boolean eager;

		Subscription s;

		volatile int wip;
		@SuppressWarnings("rawtypes")
		static final AtomicIntegerFieldUpdater WIP =
				AtomicIntegerFieldUpdater.newUpdater(UsingConditionalSubscriber.class,
						"wip");

		UsingConditionalSubscriber(ConditionalSubscriber actual,
				Consumer resourceCleanup,
				S resource,
				boolean eager) {
			this.actual = actual;
			this.resourceCleanup = resourceCleanup;
			this.resource = resource;
			this.eager = eager;
		}

		@Override
		@Nullable
		public Object scanUnsafe(Attr key) {
			if (key == Attr.TERMINATED || key == Attr.CANCELLED)
				return wip == 1;
			if (key == Attr.PARENT) return s;
			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() {
			if (WIP.compareAndSet(this, 0, 1)) {
				s.cancel();

				cleanup();
			}
		}

		void cleanup() {
			try {
				resourceCleanup.accept(resource);
			}
			catch (Throwable e) {
				Operators.onErrorDropped(e, actual.currentContext());
			}
		}

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

				actual.onSubscribe(this);
			}
		}

		@Override
		public void onNext(T t) {
			actual.onNext(t);
		}

		@Override
		public boolean tryOnNext(T t) {
			return actual.tryOnNext(t);
		}

		@Override
		public void onError(Throwable t) {
			if (eager && WIP.compareAndSet(this, 0, 1)) {
				try {
					resourceCleanup.accept(resource);
				}
				catch (Throwable e) {
					Throwable _e = Operators.onOperatorError(e, actual.currentContext());
					t = Exceptions.addSuppressed(_e, t);
				}
			}

			actual.onError(t);

			if (!eager && WIP.compareAndSet(this, 0, 1)) {
				cleanup();
			}
		}

		@Override
		public void onComplete() {
			if (eager && WIP.compareAndSet(this, 0, 1)) {
				try {
					resourceCleanup.accept(resource);
				}
				catch (Throwable e) {
					actual.onError(Operators.onOperatorError(e, actual.currentContext()));
					return;
				}
			}

			actual.onComplete();

			if (!eager && WIP.compareAndSet(this, 0, 1)) {
				cleanup();
			}
		}

		@Override
		public int requestFusion(int requestedMode) {
			return NONE; // always reject, upstream turned out to be non-fuseable after all
		}

		@Override
		public void clear() {
			// ignoring fusion methods
		}

		@Override
		public boolean isEmpty() {
			// ignoring fusion methods
			return true;
		}

		@Override
		@Nullable
		public T poll() {
			return null;
		}

		@Override
		public int size() {
			return 0;
		}
	}
}