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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.jdisc;
import com.yahoo.jdisc.handler.RequestHandler;
import com.yahoo.jdisc.refcount.DebugReferencesByContextMap;
import com.yahoo.jdisc.refcount.DebugReferencesWithStack;
import com.yahoo.jdisc.refcount.DestructableResource;
import com.yahoo.jdisc.service.ClientProvider;
import com.yahoo.jdisc.service.ServerProvider;
import com.yahoo.jdisc.refcount.References;
/**
* This class provides a thread-safe implementation of the {@link SharedResource} interface, and should be used for
* all subclasses of {@link RequestHandler}, {@link ClientProvider} and {@link ServerProvider}. Once the reference count
* of this resource reaches zero, the {@link #destroy()} method is called.
*
* @author Simon Thoresen Hult
*/
public abstract class AbstractResource implements SharedResource {
private static final Debug debug = DEBUG;
private final References references;
protected AbstractResource() {
DestructableResource destructable = new WrappedResource(this);
if (debug == Debug.STACK) {
references = new DebugReferencesWithStack(destructable);
} else {
references = new DebugReferencesByContextMap(destructable, this);
}
}
@Override
public final ResourceReference refer() {
return refer(null);
}
@Override
public final ResourceReference refer(Object context) {
return references.refer(context);
}
@Override
public final void release() {
references.release();
}
/**
* <p>Returns the reference count of this resource. This typically has no value for other than single-threaded unit-
* tests, as it is merely a snapshot of the counter.</p>
*
* @return The current value of the reference counter.
*/
public final int retainCount() {
return references.referenceCount();
}
/**
* <p>This method signals that this AbstractResource can dispose of any internal resources, and commence with shut
* down of any internal threads. This will be called once the reference count of this resource reaches zero.</p>
*/
protected void destroy() { }
/**
* Returns a string describing the current state of references in human-friendly terms. May be used for debugging.
*/
public String currentState() {
return references.currentState();
}
static private class WrappedResource implements DestructableResource {
private final AbstractResource resource;
WrappedResource(AbstractResource resource) { this.resource = resource; }
@Override public void close() { resource.destroy(); }
}
}
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