reactor.core.scheduler.DelegateServiceScheduler Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of redisson-all Show documentation
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
The newest version!
/*
 * Copyright (c) 2017-2022 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.scheduler;

import java.time.Duration;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Supplier;

import reactor.core.Disposable;
import reactor.core.Exceptions;
import reactor.core.Scannable;
import reactor.core.publisher.Mono;
import reactor.util.annotation.NonNull;
import reactor.util.annotation.Nullable;

/**
 * A simple {@link Scheduler} which uses a backing {@link ExecutorService} to schedule
 * Runnables for async operators. This scheduler is time-capable (can schedule with a
 * delay and/or periodically) if the backing executor is a {@link ScheduledExecutorService}.
 *
 * @author Stephane Maldini
 * @author Simon Baslé
 */
final class DelegateServiceScheduler implements Scheduler, SchedulerState.DisposeAwaiter, Scannable {

	static final ScheduledExecutorService TERMINATED;

	static {
		TERMINATED = Executors.newSingleThreadScheduledExecutor();
		TERMINATED.shutdownNow();
	}

	final String executorName;
	final ScheduledExecutorService original;

	@Nullable
	volatile SchedulerState state;
	@SuppressWarnings("rawtypes")
	static final AtomicReferenceFieldUpdater STATE =
			AtomicReferenceFieldUpdater.newUpdater(DelegateServiceScheduler.class,
					SchedulerState.class, "state");

	DelegateServiceScheduler(String executorName, ExecutorService executorService) {
			this.executorName = executorName;
			this.original = convert(executorService);
	}

	ScheduledExecutorService getOrCreate() {
		SchedulerState s = state;
		if (s == null) {
			init();
			s = state;
			if (s == null) {
				throw new IllegalStateException("executor is null after implicit start()");
			}
		}
		return s.currentResource;
	}

	@Override
	public Worker createWorker() {
		return new ExecutorServiceWorker(getOrCreate());
	}

	@Override
	public Disposable schedule(Runnable task) {
		return Schedulers.directSchedule(getOrCreate(), task, null, 0L, TimeUnit.MILLISECONDS);
	}

	@Override
	public Disposable schedule(Runnable task, long delay, TimeUnit unit) {
		return Schedulers.directSchedule(getOrCreate(), task, null, delay, unit);
	}

	@Override
	public Disposable schedulePeriodically(Runnable task,
			long initialDelay,
			long period,
			TimeUnit unit) {
		return Schedulers.directSchedulePeriodically(getOrCreate(),
				task,
				initialDelay,
				period,
				unit);
	}

	@Override
	public void start() {
		STATE.compareAndSet(this, null,
				SchedulerState.init(Schedulers.decorateExecutorService(this, original)));
	}

	@Override
	public void init() {
		SchedulerState a = this.state;
		if (a != null) {
			if (a.currentResource == TERMINATED) {
				throw new IllegalStateException(
						"Initializing a disposed scheduler is not permitted"
				);
			}
			// return early - scheduler already initialized
			return;
		}

		if (!STATE.compareAndSet(this, null,
				SchedulerState.init(Schedulers.decorateExecutorService(this, original)))) {
			if (isDisposed()) {
				throw new IllegalStateException(
						"Initializing a disposed scheduler is not permitted"
				);
			}
		}
	}

	@Override
	public boolean isDisposed() {
		SchedulerState current = state;
		return current != null && current.currentResource == TERMINATED;
	}

	@Override
	public boolean await(ScheduledExecutorService resource, long timeout, TimeUnit timeUnit)
		throws InterruptedException {
		return resource.awaitTermination(timeout, timeUnit);
	}

	@Override
	public void dispose() {
		SchedulerState previous = state;

		if (previous != null && previous.currentResource == TERMINATED) {
			assert previous.initialResource != null;
			previous.initialResource.shutdownNow();
			return;
		}

		SchedulerState terminated = SchedulerState.transition(
				previous == null ? null : previous.currentResource, TERMINATED, this);

		STATE.compareAndSet(this, previous, terminated);

		// If unsuccessful - either another thread disposed or restarted - no issue,
		// we only care about the one stored in terminated.
		if (terminated.initialResource != null) {
			terminated.initialResource.shutdownNow();
		}
	}

	@Override
	public Mono disposeGracefully() {
		return Mono.defer(() -> {
			SchedulerState previous = state;

			if (previous != null && previous.currentResource == TERMINATED) {
				return previous.onDispose;
			}

			SchedulerState terminated = SchedulerState.transition(
					previous == null ? null : previous.currentResource, TERMINATED, this);

			STATE.compareAndSet(this, previous, terminated);

			// If unsuccessful - either another thread disposed or restarted - no issue,
			// we only care about the one stored in terminated.
			if (terminated.initialResource != null) {
				terminated.initialResource.shutdown();
			}
			return terminated.onDispose;
		});
	}

	@SuppressWarnings("unchecked")
	static ScheduledExecutorService convert(ExecutorService executor) {
		if (executor instanceof ScheduledExecutorService) {
			return (ScheduledExecutorService) executor;
		}
		return new UnsupportedScheduledExecutorService(executor);
	}

	@Override
	public Object scanUnsafe(Attr key) {
		if (key == Attr.TERMINATED || key == Attr.CANCELLED) return isDisposed();
		if (key == Attr.NAME) return toString();

		SchedulerState s = state;
		if (s != null) {
			return Schedulers.scanExecutor(s.currentResource, key);
		}
		return null;
	}

	@Override
	public String toString() {
		return Schedulers.FROM_EXECUTOR_SERVICE + '(' + executorName + ')';
	}

	static final class UnsupportedScheduledExecutorService
			implements ScheduledExecutorService, Supplier {

		final ExecutorService exec;

		UnsupportedScheduledExecutorService(ExecutorService exec) {
			this.exec = exec;
		}

		@Override
		public ExecutorService get() {
			return exec;
		}

		@Override
		public void shutdown() {
			exec.shutdown();
		}

		@NonNull
		@Override
		public List shutdownNow() {
			return exec.shutdownNow();
		}

		@Override
		public boolean isShutdown() {
			return exec.isShutdown();
		}

		@Override
		public boolean isTerminated() {
			return exec.isTerminated();
		}

		@Override
		public boolean awaitTermination(long timeout, @NonNull TimeUnit unit)
				throws InterruptedException {
			return exec.awaitTermination(timeout, unit);
		}

		@NonNull
		@Override
		public  Future submit(@NonNull Callable task) {
			return exec.submit(task);
		}

		@NonNull
		@Override
		public  Future submit(@NonNull Runnable task, T result) {
			return exec.submit(task, result);
		}

		@NonNull
		@Override
		public Future submit(@NonNull Runnable task) {
			return exec.submit(task);
		}

		@NonNull
		@Override
		public  List> invokeAll(@NonNull Collection> tasks)
				throws InterruptedException {
			return exec.invokeAll(tasks);
		}

		@NonNull
		@Override
		public  List> invokeAll(@NonNull Collection> tasks,
				long timeout,
				@NonNull TimeUnit unit) throws InterruptedException {
			return exec.invokeAll(tasks, timeout, unit);
		}

		@NonNull
		@Override
		public  T invokeAny(@NonNull Collection> tasks)
				throws InterruptedException, ExecutionException {
			return exec.invokeAny(tasks);
		}

		@Override
		public  T invokeAny(@NonNull Collection> tasks,
				long timeout,
				@NonNull TimeUnit unit)
				throws InterruptedException, ExecutionException, TimeoutException {
			return exec.invokeAny(tasks, timeout, unit);
		}

		@Override
		public void execute(@NonNull Runnable command) {
			exec.execute(command);
		}

		@NonNull
		@Override
		public ScheduledFuture schedule(@NonNull Runnable command,
				long delay,
				@NonNull TimeUnit unit) {
			throw Exceptions.failWithRejectedNotTimeCapable();
		}

		@NonNull
		@Override
		public  ScheduledFuture schedule(@NonNull Callable callable,
				long delay,
				@NonNull TimeUnit unit) {
			throw Exceptions.failWithRejectedNotTimeCapable();
		}

		@NonNull
		@Override
		public ScheduledFuture scheduleAtFixedRate(@NonNull Runnable command,
				long initialDelay,
				long period,
				@NonNull TimeUnit unit) {
			throw Exceptions.failWithRejectedNotTimeCapable();
		}

		@NonNull
		@Override
		public ScheduledFuture scheduleWithFixedDelay(@NonNull Runnable command,
				long initialDelay,
				long delay,
				@NonNull TimeUnit unit) {
			throw Exceptions.failWithRejectedNotTimeCapable();
		}

		@Override
		public String toString() {
			return exec.toString();
		}
	}

}