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/* *******************************************************************
* Copyright (c) 2008 Contributors
* All rights reserved.
* This program and the accompanying materials are made available
* under the terms of the Eclipse Public License v1.0
* which accompanies this distribution and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Andy Clement initial implementation
* ******************************************************************/
package org.aspectj.weaver.bcel;
import org.aspectj.apache.bcel.util.ClassLoaderReference;
import org.aspectj.weaver.WeakClassLoaderReference;
/**
* Wraps a reference to a classloader inside a WeakReference. This should be used where we do not want the existence of a
* classloader reference to prevent garbage collection of that classloader (and possibly an associated weaver instance in the case
* of load time weaving).
*
* In more detail:
* When load time weaving, the class Aj maintains a WeakHashMap from the classloader instance to a weaver instance. The aim is that
* the weaver is around as long as the classloader is and should the classloader be dereferenced then the weaver can also be garbage
* collected. The problem is that if there are many references to the classloader from within the weaver, these are considered hard
* references and cause the classloader to be long lived - even if the user of the classloader has dereferenced it in their code.
* The solution is that the weaver should use instances of WeakClassLoaderReference objects - so that when the users hard reference
* to the classloader goes, nothing in the weaver will cause it to hang around. There is a big assertion here that the
* WeakClassLoaderReference instances will not 'lose' their ClassLoader references until the top level ClassLoader reference is
* null'd. This means there is no need to check for the null case on get() in this WeakReference logic below, because we shouldn't
* be using this weaver if its associated ClassLoader has been collected. See https://bugs.eclipse.org/bugs/show_bug.cgi?id=210470
*
*
* @author Andy Clement
*/
public class BcelWeakClassLoaderReference extends WeakClassLoaderReference implements ClassLoaderReference {
public BcelWeakClassLoaderReference(ClassLoader loader) {
super(loader);
}
public boolean equals(Object obj) {
if (!(obj instanceof BcelWeakClassLoaderReference))
return false;
BcelWeakClassLoaderReference other = (BcelWeakClassLoaderReference) obj;
return (other.hashcode == hashcode);
}
}