4.x: Global instance handling change (and relevant changes to testing) #9193
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,184 @@ | ||
| /* | ||
| * Copyright (c) 2024 Oracle and/or its affiliates. | ||
| * | ||
| * 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 | ||
| * | ||
| * http://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 io.helidon.common.context; | ||
|
|
||
| import java.util.NoSuchElementException; | ||
| import java.util.Objects; | ||
| import java.util.Optional; | ||
| import java.util.concurrent.locks.ReentrantReadWriteLock; | ||
| import java.util.function.Supplier; | ||
|
|
||
| /** | ||
| * A context based "singleton" value holder that provides an indirection mechanism for static values. | ||
| * "Singleton" values are stored and resolved from a context classified with {@value #STATIC_CONTEXT_CLASSIFIER} | ||
| * in the {@link io.helidon.common.context.Contexts#context()} current context}, | ||
| * or the {@link io.helidon.common.context.Contexts#globalContext() global context if none is defined}. | ||
| * | ||
| * @param <T> type of the value stored in context | ||
| */ | ||
| public final class ContextSingleton<T> { | ||
| /** | ||
| * Classifier used to register a context that is to serve as the static context. | ||
| */ | ||
| public static final String STATIC_CONTEXT_CLASSIFIER = "helidon-singleton-context"; | ||
|
There was a problem hiding this comment. ContextSingleton.CLASSIFIERis better than ContextSingleton.STATIC_CONTEXT_CLASSIFIERAt the very least we should not use "static", so either |
||
|
|
||
| private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock(); | ||
| private final ContextSingletonClassifier<T> classifier; | ||
| private final Supplier<T> supplier; | ||
|
|
||
| private ContextSingleton(ContextSingletonClassifier<T> qualifier, Supplier<T> supplier) { | ||
| this.classifier = qualifier; | ||
| this.supplier = supplier; | ||
| } | ||
|
|
||
| /** | ||
| * Create a new context value. | ||
| * | ||
| * @param ownerClass type owning this context singleton | ||
| * @param clazz type of the value | ||
| * @param <T> type of the value | ||
| * @return a new context value with nothing set. | ||
| */ | ||
| public static <T> ContextSingleton<T> create(Class<?> ownerClass, Class<T> clazz) { | ||
| Objects.requireNonNull(ownerClass); | ||
| Objects.requireNonNull(clazz); | ||
|
|
||
| return new ContextSingleton<>(new ContextSingletonClassifier<>(ownerClass, clazz), null); | ||
| } | ||
|
|
||
| /** | ||
| * Create a new context value with a supplier of instances for each context. | ||
| * | ||
| * @param ownerClass type owning this context singleton | ||
| * @param clazz type of the value | ||
| * @param value value supplier | ||
| * @param <T> type of the value | ||
| * @return a new context value | ||
| */ | ||
| public static <T> ContextSingleton<T> create(Class<?> ownerClass, Class<T> clazz, Supplier<T> value) { | ||
| Objects.requireNonNull(ownerClass); | ||
| Objects.requireNonNull(clazz); | ||
| Objects.requireNonNull(value); | ||
|
|
||
| return new ContextSingleton<>(new ContextSingletonClassifier<>(ownerClass, clazz), value); | ||
| } | ||
|
|
||
| /** | ||
| * Set the value in current context. | ||
| * | ||
| * @param value value to use | ||
| */ | ||
| public void set(T value) { | ||
| lock.writeLock().lock(); | ||
| try { | ||
| context().register(classifier, value); | ||
| } finally { | ||
| lock.writeLock().unlock(); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Get the current value in this context, or call the provided supplier to get the value and register | ||
| * it, if not yet registered. | ||
| * | ||
| * @return current value (or the new one obtained from supplier) | ||
| * @throws NoSuchElementException in case there is no value, and no supplier | ||
| * @see #set(Object) | ||
| */ | ||
| public T get() throws NoSuchElementException { | ||
| return get(this.supplier); | ||
| } | ||
|
|
||
| /** | ||
| * Get the current value in this context, or call the provided supplier to get the value and register | ||
| * it, if not yet registered. | ||
| * | ||
| * @param supplier supplier to call if the current value is not present | ||
| * @return current value (or the new one obtained from supplier) | ||
| * @throws NoSuchElementException in case there is no value, and the supplier returned {@code null} | ||
| * @see #set(Object) | ||
| */ | ||
| public T get(Supplier<T> supplier) { | ||
| var current = current(); | ||
| if (current.isPresent()) { | ||
| return current.get(); | ||
| } | ||
| lock.writeLock().lock(); | ||
| try { | ||
| current = current(); | ||
| if (current.isPresent()) { | ||
| return current.get(); | ||
| } | ||
| if (supplier != null) { | ||
| var value = supplier.get(); | ||
| set(value); | ||
| return value; | ||
| } | ||
| throw new NoSuchElementException("There is no value available in the current context, " | ||
| + "and supplier was not provided when creating this instance for: " | ||
| + " " + classifier); | ||
| } finally { | ||
| lock.writeLock().unlock(); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Current value as an {@link java.util.Optional}. | ||
| * | ||
| * @return current value, or empty if not configured | ||
| */ | ||
| public Optional<T> value() { | ||
| return current(); | ||
| } | ||
|
|
||
| /** | ||
| * Whether there is a value in current context. | ||
| * | ||
| * @return {@code true} if there is a value | ||
| */ | ||
| public boolean isPresent() { | ||
| return current().isPresent(); | ||
| } | ||
|
|
||
| private static Context context() { | ||
| Context globalContext = Contexts.globalContext(); | ||
|
|
||
| // this is the context we expect to get (and set global instances) | ||
| return Contexts.context() | ||
| .orElse(globalContext) | ||
| .get(STATIC_CONTEXT_CLASSIFIER, Context.class) | ||
| .orElse(globalContext); | ||
| } | ||
|
|
||
| private Optional<T> current() { | ||
| lock.readLock().lock(); | ||
| try { | ||
| return context().get(classifier, classifier.valueType()); | ||
| } finally { | ||
| lock.readLock().unlock(); | ||
| } | ||
| } | ||
|
|
||
| @SuppressWarnings("rawtypes") | ||
| private record ContextSingletonClassifier<T>(Class<ContextSingleton> contextSingleton, | ||
| Class<?> ownerClass, | ||
| Class<T> valueType) { | ||
| private ContextSingletonClassifier(Class<?> ownerClass, Class<T> valueType) { | ||
| this(ContextSingleton.class, ownerClass, valueType); | ||
| } | ||
| } | ||
| } | ||
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.