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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.jdisc;
/**
* <p>Utility class for working with reference-counted {@link SharedResource}s.</p>
*
* <p>Sometimes, you may want a method to return <i>both</i> a resource object <i>and</i>
* a {@link ResourceReference} that refers the resource object (for later release of the resource).
* Java methods cannot return multiple objects, so this class provides Pair-like functionality
* for returning both.</p>
*
* <p>Example usage:</p>
* <pre>
* ReferencedResource<MyResource> getResource() {
* final ResourceReference ref = resource.refer();
* return new ReferencedResource(resource, ref);
* }
*
* void useResource() {
* final ReferencedResource<MyResource> referencedResource = getResource();
* referencedResource.getResource().use();
* referencedResource.getReference().close();
* }
* </pre>
*
* <p>This class implements AutoCloseable, so the latter method may also be written as follows:</p>
* <pre>
* void useResource() {
* for (final ReferencedResource<MyResource> referencedResource = getResource()) {
* referencedResource.getResource().use();
* }
* }
* </pre>
*
* @author bakksjo
*/
public class ReferencedResource<T extends SharedResource> implements AutoCloseable {
private final T resource;
private final ResourceReference reference;
public ReferencedResource(final T resource, final ResourceReference reference) {
this.resource = resource;
this.reference = reference;
}
public T getResource() {
return resource;
}
public ResourceReference getReference() {
return reference;
}
@Override
public void close() {
reference.close();
}
}
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