org.eclipse.persistence.internal.identitymaps.NoIdentityMap Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction 346465e
There is a newer version: 5.0.0-B05
/*******************************************************************************
 * Copyright (c) 1998, 2013 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
 ******************************************************************************/  
package org.eclipse.persistence.internal.identitymaps;

import java.util.*;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.indirection.ValueHolderInterface;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.mappings.ForeignReferenceMapping;


/**
 * Purpose: Provide the capability to not cache objects at all.
 * 
Responsibilities:

 *  Do nothing when an object is cached.
 * 
 * @since TOPLink/Java 1.0
 */
public class NoIdentityMap extends AbstractIdentityMap {

    public NoIdentityMap(int size, ClassDescriptor descriptor, AbstractSession session, boolean isolated) {
        super(size, descriptor, session, isolated);
    }
    
    /**
     * NoIdentityMap has no locks.
     */
    @Override
    public void collectLocks(HashMap threadList) {
        return;
    }

    /**
     * Return an empty enumerator.
     */
    @Override
    public Enumeration elements() {
        return new Vector(0).elements();
    }

    /**
     * Return null as no objects are cached.
     */
    @Override
    public Object get(Object primaryKey) {
        return null;
    }

    /**
     * Return null as no objects are cached.
     */
    @Override
    public CacheKey getCacheKey(Object searchKey, boolean forMerge) {
        return null;
    }
    
    /**
     * Return null as no objects are cached.
     */
    @Override
    protected CacheKey putCacheKeyIfAbsent(CacheKey cacheKey) {
        return null;
    }

    /**
     * Return 0 as no objects are cached.
     */
    @Override
    public int getSize() {
        return 0;
    }

    /**
     * Return 0 as no objects are cached.
     */
    @Override
    public int getSize(Class myClass, boolean recurse) {
        return 0;
    }

    /**
     * Return null as no objects are cached.
     */
    @Override
    public Object getWriteLockValue(Object primaryKey) {
        return null;
    }

    /**
     * Return an empty enumerator.
     */
    @Override
    public Enumeration keys() {
        return new Vector(0).elements();
    }

    /**
     * Return an empty enumerator.
     */
    public Enumeration keys(boolean checkReadLocks) {
        return keys();
    }
    
    /**
     * Notify the cache that a lazy relationship has been triggered in the object
     * and the cache may need to be updated
     */
    public void lazyRelationshipLoaded(Object object, ValueHolderInterface valueHolder, ForeignReferenceMapping mapping){
        //NO-OP
    }

    /**
     * Do Nothing.
     */
    @Override
    public CacheKey put(Object primaryKey, Object object, Object writeLockValue, long readTime) {
        return null;
    }

    /**
     * Do Nothing.
     * Return null, since no objects are cached.
     */
    @Override
    public Object remove(Object primaryKey, Object object) {
        return null;
    }

    /**
     * Do Nothing.
     * Return null, since no objects are cached.
     */
    @Override
    public Object remove(CacheKey searchKey) {
        return null;
    }
    
    /**
     * Do Nothing.
     */
    @Override
    public void setWriteLockValue(Object primaryKey, Object writeLockValue) {
        return;
    }
}