123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869 |
- /* *******************************************************************
- * 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;
-
- import java.lang.ref.WeakReference;
-
- /**
- * 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).
- * <p>
- * In more detail:<br>
- * 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, Abraham Nevado
- */
- public class WeakClassLoaderReference{
-
- protected final int hashcode;
-
- private final WeakReference loaderRef;
-
- public WeakClassLoaderReference(ClassLoader loader) {
- loaderRef = new WeakReference(loader);
- if(loader == null){
- // Bug: 363962
- // Check that ClassLoader is not null, for instance when loaded from BootStrapClassLoader
- hashcode = System.identityHashCode(this);
- }else{
- hashcode = loader.hashCode() * 37;
- }
- }
-
- public ClassLoader getClassLoader() {
- ClassLoader instance = (ClassLoader) loaderRef.get();
- // Assert instance!=null
- return instance;
- }
-
- public boolean equals(Object obj) {
- if (!(obj instanceof WeakClassLoaderReference))
- return false;
- WeakClassLoaderReference other = (WeakClassLoaderReference) obj;
- return (other.hashcode == hashcode);
- }
-
- public int hashCode() {
- return hashcode;
- }
-
- }
|