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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * // Copyright (c) 1998, 2007, Oracle. All rights reserved.
 * 
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
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 * 
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 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
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 * elects to include this software in this distribution under the [CDDL or GPL
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package oracle.toplink.essentials.internal.identitymaps;

import java.lang.ref.*;
import java.util.Vector;

/**
 * Purpose: Container class for storing objects in an IdentityMap.
 * The weak cache key uses a weak reference to allow garbage collection of its object.
 * The cache key itself however will remain and thus should cleaned up every no and then.
 * 
Responsibilities:

 *  Hold key and object.
 * 
 Maintain and update the current writeLockValue.
 * 
 * @since TOPLink/Java 1.0
 */
public class WeakCacheKey extends CacheKey {

    /** Reference is maintained weak to allow garbage collection */
    protected WeakReference reference;

    /**
     * Initialize the newly allocated instance of this class.
     * @param primaryKey contains values extracted from the object
     * @param writeLockValue is the write lock value, null if optimistic locking not being used for this object.
     * @param readTime the time TopLInk read the cache key
     */
    public WeakCacheKey(Vector primaryKey, Object object, Object writeLockValue, long readTime) {
        super(primaryKey, object, writeLockValue, readTime);
    }

    public Object getObject() {
        return getReference().get();
    }

    public WeakReference getReference() {
        return reference;
    }

    public void setObject(Object object) {
        setReference(new WeakReference(object));
    }

    protected void setReference(WeakReference reference) {
        this.reference = reference;
    }
}