/*******************************************************************************
 * Copyright (c) 1998, 2008 Oracle. 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.security.AccessController;
import java.security.PrivilegedActionException;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.io.*;
import java.lang.reflect.*;

import org.eclipse.persistence.internal.helper.*;
import org.eclipse.persistence.internal.descriptors.*;
import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.expressions.*;
import org.eclipse.persistence.queries.*;
import org.eclipse.persistence.internal.localization.*;
import org.eclipse.persistence.logging.SessionLog;
import org.eclipse.persistence.sessions.SessionProfiler;
import org.eclipse.persistence.sessions.Record;
import org.eclipse.persistence.sessions.factories.ReferenceMode;
import org.eclipse.persistence.internal.security.PrivilegedAccessHelper;
import org.eclipse.persistence.internal.security.PrivilegedGetConstructorFor;
import org.eclipse.persistence.internal.security.PrivilegedInvokeConstructor;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.internal.sessions.UnitOfWorkImpl;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.descriptors.ClassDescriptor;

/**
 * <p><b>Purpose</b>: Maintain identity maps for domain classes mapped with EclipseLink.
 * <p><b>Responsibilities</b>:<ul>
 *    <li> Build new identity maps lazily using info from the descriptor
 *    <li> Insert objects into appropriate identity map
 *    <li> Get object from appropriate identity map using object or primary key with class
 *    <li> Get and Set write lock values for cached objects
 * </ul>
 * @since TOPLink/Java 1.0
 */
public class IdentityMapManager implements Serializable, Cloneable {

    /** A table of identity maps with the key being the domain Class. */
    protected Map<Class, IdentityMap> identityMaps;

    /** A table of identity maps with the key being the query */
    protected Map queryResults;

    /** A reference to the session owning this manager. */
    protected AbstractSession session;

    /** Ensure mutual exclusion depending on the cache isolation.*/
    protected transient ConcurrencyManager cacheMutex;

    /** PERF: Optimize the object retrieval from the identity map. */
    protected IdentityMap lastAccessedIdentityMap = null;

    /** Used to store the write lock manager used for merging. */
    protected transient WriteLockManager writeLockManager;

    /** PERF: Used to avoid readLock and profiler checks to improve performance. */
    protected Boolean isCacheAccessPreCheckRequired;

    public IdentityMapManager(AbstractSession session) {
        this.session = session;
        this.cacheMutex = new ConcurrencyManager();
        // PERF: Avoid query cache for uow as never used.
        if (session.isUnitOfWork()) {
            this.identityMaps = new HashMap();
        } else if (session.isIsolatedClientSession()) {
            this.identityMaps = new HashMap();
            this.queryResults = new HashMap();
        } else {
            this.identityMaps = new ConcurrentHashMap();
            this.queryResults = new ConcurrentHashMap();
        }
    }

    /**
     * Provides access for setting a deferred lock on an object in the IdentityMap.
     */
    public CacheKey acquireDeferredLock(Vector primaryKey, Class domainClass, ClassDescriptor descriptor) {
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = getIdentityMap(descriptor).acquireDeferredLock(primaryKey);
            } finally {
                releaseReadLock();
            }
            getSession().endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = getIdentityMap(descriptor).acquireDeferredLock(primaryKey);
        }

        return cacheKey;
    }

    /**
     * Provides access for setting a concurrency lock on an object in the IdentityMap.
     * called with true from the merge process, if true then the refresh will not refresh the object.
     */
    public CacheKey acquireLock(Vector primaryKey, Class domainClass, boolean forMerge, ClassDescriptor descriptor) {
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = getIdentityMap(descriptor).acquireLock(primaryKey, forMerge);
            } finally {
                releaseReadLock();
            }
            getSession().endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = getIdentityMap(descriptor).acquireLock(primaryKey, forMerge);
        }

        return cacheKey;
    }

    /**
     * Provides access for setting a concurrency lock on an object in the IdentityMap.
     * called with true from the merge process, if true then the refresh will not refresh the object.
     */
    public CacheKey acquireLockNoWait(Vector primaryKey, Class domainClass, boolean forMerge, ClassDescriptor descriptor) {
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = getIdentityMap(descriptor).acquireLockNoWait(primaryKey, forMerge);
            } finally {
                releaseReadLock();
            }
            getSession().endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = getIdentityMap(descriptor).acquireLockNoWait(primaryKey, forMerge);
        }

        return cacheKey;
    }

    /**
     * Provides access for setting a concurrency lock on an object in the IdentityMap.
     * called with true from the merge process, if true then the refresh will not refresh the object.
     */
    public CacheKey acquireLockWithWait(Vector primaryKey, Class domainClass, boolean forMerge, ClassDescriptor descriptor, int wait) {
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = getIdentityMap(descriptor).acquireLockWithWait(primaryKey, forMerge, wait);
            } finally {
                releaseReadLock();
            }
            getSession().endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = getIdentityMap(descriptor).acquireLockWithWait(primaryKey, forMerge, wait);
        }

        return cacheKey;
    }

    /**
     * PERF: Used to micro optimize cache access.
     * Avoid the readLock and profile checks if not required.
     */
    protected boolean isCacheAccessPreCheckRequired() {
        if (this.isCacheAccessPreCheckRequired == null) {
            if ((getSession().getProfiler() != null) || getSession().getDatasourceLogin().shouldSynchronizedReadOnWrite()) {
                this.isCacheAccessPreCheckRequired = Boolean.TRUE;
            } else {
                this.isCacheAccessPreCheckRequired = Boolean.FALSE;
            }
        }
        return this.isCacheAccessPreCheckRequired.booleanValue();
    }

    /**
     * Clear the cache access pre-check flag, used from session when profiler .
     */
    public void clearCacheAccessPreCheck() {
        this.isCacheAccessPreCheckRequired = null;
    }

    /**
     * Provides access for setting a concurrency lock on an IdentityMap.
     */
    public void acquireReadLock() {
        getSession().startOperationProfile(SessionProfiler.CACHE);

        if (getSession().getDatasourceLogin().shouldSynchronizedReadOnWrite()) {
            getCacheMutex().acquireReadLock();
        }

        getSession().endOperationProfile(SessionProfiler.CACHE);
    }

    /**
     * INTERNAL:
     * Find the cachekey for the provided primary key and place a readlock on it.
     * This will allow multiple users to read the same object but prevent writes to
     * the object while the read lock is held.
     */
    public CacheKey acquireReadLockOnCacheKey(Vector primaryKey, Class domainClass, ClassDescriptor descriptor) {
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = getIdentityMap(descriptor).acquireReadLockOnCacheKey(primaryKey);
            } finally {
                releaseReadLock();
            }
            getSession().endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = getIdentityMap(descriptor).acquireReadLockOnCacheKey(primaryKey);
        }

        return cacheKey;
    }

    /**
     * INTERNAL:
     * Find the cachekey for the provided primary key and place a readlock on it.
     * This will allow multiple users to read the same object but prevent writes to
     * the object while the read lock is held.
     * If no readlock can be acquired then do not wait but return null.
     */
    public CacheKey acquireReadLockOnCacheKeyNoWait(Vector primaryKey, Class domainClass, ClassDescriptor descriptor) {
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = getIdentityMap(descriptor).acquireReadLockOnCacheKeyNoWait(primaryKey);
            } finally {
                releaseReadLock();
            }
            getSession().endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = getIdentityMap(descriptor).acquireReadLockOnCacheKeyNoWait(primaryKey);
        }

        return cacheKey;
    }

    /**
     * Lock the entire cache if the cache isolation requires.
     * By default concurrent reads and writes are allowed.
     * By write, unit of work merge is meant.
     */
    public boolean acquireWriteLock() {
        if (getSession().getDatasourceLogin().shouldSynchronizedReadOnWrite() || getSession().getDatasourceLogin().shouldSynchronizeWrites()) {
            getCacheMutex().acquire();
            return true;
        }
        return false;
    }

    /**
     * Create the identity map for the unit of work.
     * PERF: UOW uses a special map to avoid locks, always full, and can use special weak refs.
     */
    public IdentityMap buildNewIdentityMapForUnitOfWork(UnitOfWorkImpl unitOfwork, ClassDescriptor descriptor) {
        ReferenceMode mode = unitOfwork.getReferenceMode();
        if (mode == ReferenceMode.FORCE_WEAK) {
            return new WeakUnitOfWorkIdentityMap(32, descriptor);
        } else if ((mode == ReferenceMode.WEAK)
                // Only allow weak if using change tracking.
                && descriptor.getObjectChangePolicy().isAttributeChangeTrackingPolicy()) {
            return new WeakUnitOfWorkIdentityMap(32, descriptor);        
        } else {
            return new UnitOfWorkIdentityMap(32, descriptor);
        }
    }
    
    /**
     * INTERNAL: (Public to allow testing to access)
     * Return a new empty identity map to cache instances of the class.
     */
    public IdentityMap buildNewIdentityMap(ClassDescriptor descriptor) throws ValidationException, DescriptorException {
        if (getSession().isUnitOfWork()) {
            if (((UnitOfWorkImpl)getSession()).getReferenceMode() == ReferenceMode.FORCE_WEAK){
                return new WeakUnitOfWorkIdentityMap(32, descriptor);
            }else if (((UnitOfWorkImpl)getSession()).getReferenceMode() == ReferenceMode.WEAK && descriptor.getObjectChangePolicy().isAttributeChangeTrackingPolicy()){
                return new WeakUnitOfWorkIdentityMap(32, descriptor);        
            }else {
                return new UnitOfWorkIdentityMap(32, descriptor);
            }
        }

        try {
            // Remote session has its own setting.
            if (getSession().isRemoteSession()) {
	        Constructor constructor = null;
	        if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
	            try {
                            constructor = (Constructor)AccessController.doPrivileged(new PrivilegedGetConstructorFor(descriptor.getRemoteIdentityMapClass(), new Class[] { ClassConstants.PINT, ClassDescriptor.class }, false));
                            IdentityMap map = (IdentityMap)AccessController.doPrivileged(new PrivilegedInvokeConstructor(constructor, new Object[] { new Integer(descriptor.getRemoteIdentityMapSize()), descriptor}));
                            if (descriptor.getCacheInterceptorClass() != null){
                                constructor = (Constructor)AccessController.doPrivileged(new PrivilegedGetConstructorFor(descriptor.getCacheInterceptorClass(), new Class[] { IdentityMap.class, AbstractSession.class }, false));
                                Object params[] = new Object[]{map, getSession()};
                                map = (IdentityMap)AccessController.doPrivileged(new PrivilegedInvokeConstructor(constructor, params));
                            }
                            return map;
	            } catch (PrivilegedActionException exception) {
	                throw DescriptorException.invalidIdentityMap(descriptor, exception.getException());
	                }
	        } else {
	            constructor = PrivilegedAccessHelper.getConstructorFor(descriptor.getRemoteIdentityMapClass(), new Class[] { ClassConstants.PINT, ClassDescriptor.class }, false);
	            IdentityMap map = (IdentityMap)PrivilegedAccessHelper.invokeConstructor(constructor, new Object[] { new Integer(descriptor.getRemoteIdentityMapSize()), descriptor});
                    if (descriptor.getCacheInterceptorClass() != null){
                        constructor = PrivilegedAccessHelper.getConstructorFor(descriptor.getCacheInterceptorClass(), new Class[] { IdentityMap.class, AbstractSession.class }, false);
                        Object params[] = new Object[]{map, getSession()};
                        map = (IdentityMap)PrivilegedAccessHelper.invokeConstructor(constructor, params);
                    }
                    return map;
                }
            } else {
                Constructor constructor = null;
                if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
                    try {
                        constructor = (Constructor)AccessController.doPrivileged(new PrivilegedGetConstructorFor(descriptor.getIdentityMapClass(), new Class[] { ClassConstants.PINT, ClassDescriptor.class }, false));
                        IdentityMap map = (IdentityMap)AccessController.doPrivileged(new PrivilegedInvokeConstructor(constructor, new Object[] { new Integer(descriptor.getIdentityMapSize()),descriptor}));
                        if (descriptor.getCacheInterceptorClass() != null){
                            constructor = (Constructor)AccessController.doPrivileged(new PrivilegedGetConstructorFor(descriptor.getCacheInterceptorClass(), new Class[] { IdentityMap.class, AbstractSession.class }, false));
                            Object params[] = new Object[]{map, getSession()};
                            map = (IdentityMap)AccessController.doPrivileged(new PrivilegedInvokeConstructor(constructor, params));
                        }
                        return map;
                    } catch (PrivilegedActionException exception) {
                        throw DescriptorException.invalidIdentityMap(descriptor, exception.getException());
                    }
                } else {
                    constructor = PrivilegedAccessHelper.getConstructorFor(descriptor.getIdentityMapClass(), new Class[] { ClassConstants.PINT, ClassDescriptor.class }, false);
                    IdentityMap map = (IdentityMap)PrivilegedAccessHelper.invokeConstructor(constructor, new Object[] { new Integer(descriptor.getIdentityMapSize()), descriptor});
                    if (descriptor.getCacheInterceptorClass() != null){
                        constructor = PrivilegedAccessHelper.getConstructorFor(descriptor.getCacheInterceptorClass(), new Class[] { IdentityMap.class, AbstractSession.class }, false);
                        Object params[] = new Object[]{map, getSession()};
                        map = (IdentityMap)PrivilegedAccessHelper.invokeConstructor(constructor, params);
                    }
                    return map;
                }
            }
        } catch (Exception exception) {
            throw DescriptorException.invalidIdentityMap(descriptor, exception);
        }
    }

    /**
     * INTERNAL:
     * Clear the the lastAccessedIdentityMap and the lastAccessedIdentityMapClass
     */
    public void clearLastAccessedIdentityMap() {
        lastAccessedIdentityMap = null;
    }

    /**
     * INTERNAL:
     * Clones itself, used for uow commit and resume on failure.
     */
    public Object clone() {
        IdentityMapManager manager = null;
        try {
            manager = (IdentityMapManager)super.clone();
            manager.setIdentityMaps(new ConcurrentHashMap());
            for (Iterator iterator = this.identityMaps.entrySet().iterator(); iterator.hasNext();) {
                Map.Entry entry = (Map.Entry)iterator.next();
                manager.identityMaps.put((Class)entry.getKey(), (IdentityMap)((IdentityMap)entry.getValue()).clone());
            }
        } catch (CloneNotSupportedException exception) {
            throw new InternalError(exception.toString());
        }
        return manager;
    }

    /**
     * Clear all the query caches.
     */
    public void clearQueryCache() {
        this.queryResults = new ConcurrentHashMap();
    }

    /**
     * Remove the cache key related to a query.
     * Note this method is not synchronized and care should be taken to ensure
     * there are no other threads accessing the cache key.
     * This is used to clean up cached clones of queries.
     */
    public void clearQueryCache(ReadQuery query) {
        if (query != null) {
            queryResults.remove(query);
        }
    }
    
    /**
     * Return true if an CacheKey with the primary key is in the map.
     * User API.
     * @param key is the primary key for the object to search for.
     */
    public boolean containsKey(Vector key, Class theClass, ClassDescriptor descriptor) {
        // Check for null, contains causes null pointer.
        int size = key.size();
        for (int index = 0; index < size; index++) {
            if (key.get(index) == null) {
                return false;
            }
        }
        IdentityMap map = getIdentityMap(descriptor);
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                return map.containsKey(key);
            } finally {
                releaseReadLock();
                getSession().endOperationProfile(SessionProfiler.CACHE);
            }
        } else {
            return map.containsKey(key);
        }
    }

    /**
     * Query the cache in-memory.
     */
    public Vector getAllFromIdentityMap(Expression selectionCriteria, Class theClass, Record translationRow, int valueHolderPolicy, boolean shouldReturnInvalidatedObjects) {
        ClassDescriptor descriptor = getSession().getDescriptor(theClass);
        getSession().startOperationProfile(SessionProfiler.CACHE);
        Vector objects = null;
        try {
            if (selectionCriteria != null) {
                // PERF: Avoid clone of expression.            
                ExpressionBuilder builder = selectionCriteria.getBuilder();
                if (builder.getSession() == null) {
                    builder.setSession(getSession().getRootSession(null));
                    builder.setQueryClass(theClass);
                }
            }
            objects = new Vector();
            IdentityMap map = getIdentityMap(descriptor);

            // cache the current time to avoid calculating it every time through the loop
            long currentTimeInMillis = System.currentTimeMillis();
            for (Enumeration cacheEnum = map.keys(); cacheEnum.hasMoreElements();) {
                CacheKey key = (CacheKey)cacheEnum.nextElement();
                if ((key.getObject() == null) || (!shouldReturnInvalidatedObjects && descriptor.getCacheInvalidationPolicy().isInvalidated(key, currentTimeInMillis))) {
                    continue;
                }
                Object object = key.getObject();

                // Bug # 3216337 - key.getObject() should check for null; object may be GC'd (MWN)
                if (object == null) {
                    continue;
                }

                // Must check for inheritance.
                if ((object.getClass() == theClass) || (theClass.isInstance(object))) {
                    if (selectionCriteria == null) {
                        objects.add(object);
                        getSession().incrementProfile(SessionProfiler.CacheHits);
                    } else {
                        try {
                            if (selectionCriteria.doesConform(object, getSession(), (AbstractRecord)translationRow, valueHolderPolicy)) {
                                objects.addElement(object);
                                getSession().incrementProfile(SessionProfiler.CacheHits);
                            }
                        } catch (QueryException queryException) {
                            if (queryException.getErrorCode() == QueryException.MUST_INSTANTIATE_VALUEHOLDERS) {
                                if (valueHolderPolicy == InMemoryQueryIndirectionPolicy.SHOULD_IGNORE_EXCEPTION_RETURN_CONFORMED) {
                                    objects.add(object);
                                    getSession().incrementProfile(SessionProfiler.CacheHits);
                                } else if (valueHolderPolicy == InMemoryQueryIndirectionPolicy.SHOULD_THROW_INDIRECTION_EXCEPTION) {
                                    throw queryException;
                                }
                            } else {
                                throw queryException;
                            }
                        }
                    }
                }
            }
        } finally {
            getSession().endOperationProfile(SessionProfiler.CACHE);
        }
        return objects;
    }

    /**
     * Retrieve the cache key for the given identity information.
     */
    public CacheKey getCacheKeyForObjectForLock(Vector primaryKey, Class theClass, ClassDescriptor descriptor) {
        IdentityMap map = getIdentityMap(descriptor);
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = map.getCacheKeyForLock(primaryKey);
            } finally {
                releaseReadLock();
                getSession().endOperationProfile(SessionProfiler.CACHE);
            }
        } else {
            cacheKey = map.getCacheKeyForLock(primaryKey);
        }
        return cacheKey;
    }

    /**
     * Retrieve the cache key for the given identity information.
     */
    public CacheKey getCacheKeyForObject(Vector primaryKey, Class theClass, ClassDescriptor descriptor) {
        IdentityMap map = getIdentityMap(descriptor);
        CacheKey cacheKey = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = map.getCacheKey(primaryKey);
            } finally {
                releaseReadLock();
                getSession().endOperationProfile(SessionProfiler.CACHE);
            }
        } else {
            cacheKey = map.getCacheKey(primaryKey);
        }
        return cacheKey;
    }
    /**
     * Return the cache mutex.
     * This allows for the entire cache to be locked.
     * This is done for transaction isolations on merges, although never locked by default.
     */
    public ConcurrencyManager getCacheMutex() {
        return cacheMutex;
    }

    /**
     * This method is used to get a list of those classes with IdentityMaps in the Session.
     */
    public Vector getClassesRegistered() {
        Iterator classes = getIdentityMaps().keySet().iterator();
        Vector results = new Vector(getIdentityMaps().size());
        while (classes.hasNext()) {
            results.add(((Class)classes.next()).getName());
        }
        return results;
    }

    /**
     * Get the object from the identity map which has the same identity information
     * as the given object.
     */
    public Object getFromIdentityMap(Object object) {
        ClassDescriptor descriptor = getSession().getDescriptor(object);
        Vector primaryKey = descriptor.getObjectBuilder().extractPrimaryKeyFromObject(object, getSession());
        return getFromIdentityMap(primaryKey, object.getClass(), descriptor);
    }

    /**
     * Get the object from the identity map which has the given primary key and class.
     */
    public Object getFromIdentityMap(Vector key, Class theClass, ClassDescriptor descriptor) {
        return getFromIdentityMap(key, theClass, true, descriptor);
    }

    /**
     * Get the object from the identity map which has the given primary key and class.
     * Only return the object if it has not been invalidated.
     */
    public Object getFromIdentityMap(Vector key, Class theClass, boolean shouldReturnInvalidatedObjects, ClassDescriptor descriptor) {
        if (key == null) {
            return null;
        }

        CacheKey cacheKey;
        IdentityMap map = getIdentityMap(descriptor);
        Object domainObject = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = map.getCacheKey(key);
            } finally {
                releaseReadLock();
            }
        } else {
            cacheKey = map.getCacheKey(key);
        }

        if ((cacheKey != null) && (shouldReturnInvalidatedObjects || !descriptor.getCacheInvalidationPolicy().isInvalidated(cacheKey))) {
            // BUG#4772232 - The read-lock must be checked to avoid returning a partial object,
            // PERF: Just check the read-lock to avoid acquire if not locked.
            // This is ok if you get the object first, as the object cannot gc and identity is always maintained.
            domainObject = cacheKey.getObject();
            cacheKey.checkReadLock();
            // Resolve the inheritance issues.
            domainObject = checkForInheritance(domainObject, theClass, descriptor);
        }

        if (isCacheAccessPreCheckRequired()) {
            getSession().endOperationProfile(SessionProfiler.CACHE);
            if (domainObject == null) {
                getSession().incrementProfile(SessionProfiler.CacheMisses);
            } else {
                getSession().incrementProfile(SessionProfiler.CacheHits);
            }
        }

        return domainObject;
    }

    public Object getFromIdentityMap(Expression selectionCriteria, Class theClass, Record translationRow, int valueHolderPolicy, boolean conforming, boolean shouldReturnInvalidatedObjects, ClassDescriptor descriptor) {
        UnitOfWorkImpl unitOfWork = (conforming) ? (UnitOfWorkImpl)getSession() : null;
        getSession().startOperationProfile(SessionProfiler.CACHE);
        try {
            if (selectionCriteria != null) {
                // PERF: Avoid clone of expression.            
                ExpressionBuilder builder = selectionCriteria.getBuilder();
                if (builder.getSession() == null) {
                    builder.setSession(getSession().getRootSession(null));
                    builder.setQueryClass(theClass);
                }
            }
            IdentityMap map = getIdentityMap(descriptor);

            // cache the current time to avoid calculating it every time through the loop
            long currentTimeInMillis = System.currentTimeMillis();
            for (Enumeration cacheEnum = map.keys(); cacheEnum.hasMoreElements();) {
                CacheKey key = (CacheKey)cacheEnum.nextElement();
                if (!shouldReturnInvalidatedObjects && descriptor.getCacheInvalidationPolicy().isInvalidated(key, currentTimeInMillis)) {
                    continue;
                }
                Object object = key.getObject();

                // Bug # 3216337 - key.getObject() should check for null; object may be GC'd (MWN)
                if (object == null) {
                    continue;
                }

                // Must check for inheritance.
                if ((object.getClass() == theClass) || (theClass.isInstance(object))) {
                    if (selectionCriteria == null) {
                        // bug 2782991: if first found was deleted nothing returned. 
                        if (!(conforming && unitOfWork.isObjectDeleted(object))) {
                            getSession().incrementProfile(SessionProfiler.CacheHits);
                            return object;
                        }
                    }

                    //CR 3677 integration of a ValueHolderPolicy
                    try {
                        if (selectionCriteria.doesConform(object, getSession(), (AbstractRecord)translationRow, valueHolderPolicy)) {
                            // bug 2782991: if first found was deleted nothing returned. 
                            if (!(conforming && unitOfWork.isObjectDeleted(object))) {
                                getSession().incrementProfile(SessionProfiler.CacheHits);
                                return object;
                            }
                        }
                    } catch (QueryException queryException) {
                        if (queryException.getErrorCode() == QueryException.MUST_INSTANTIATE_VALUEHOLDERS) {
                            if (valueHolderPolicy == InMemoryQueryIndirectionPolicy.SHOULD_IGNORE_EXCEPTION_RETURN_CONFORMED) {
                                // bug 2782991: if first found was deleted nothing returned. 
                                if (!(conforming && unitOfWork.isObjectDeleted(object))) {
                                    getSession().incrementProfile(SessionProfiler.CacheHits);
                                    return object;
                                }
                            } else if (valueHolderPolicy == InMemoryQueryIndirectionPolicy.SHOULD_IGNORE_EXCEPTION_RETURN_NOT_CONFORMED) {
                                // For bug 2667870 just skip this item, but do not abort.
                            } else {
                                throw queryException;
                            }
                        } else {
                            throw queryException;
                        }
                    }
                }
            }
        } finally {
            getSession().endOperationProfile(SessionProfiler.CACHE);
        }
        return null;
    }

    /**
     * Get the object from the cache with the given primary key and class.
     * Do not return the object if it was invalidated.
     */
    public Object getFromIdentityMapWithDeferredLock(Vector key, Class theClass, boolean shouldReturnInvalidatedObjects, ClassDescriptor descriptor) {
        if (key == null) {
            getSession().incrementProfile(SessionProfiler.CacheMisses);
            return null;
        }

        IdentityMap map = getIdentityMap(descriptor);
        CacheKey cacheKey;
        Object domainObject = null;
        if (isCacheAccessPreCheckRequired()) {
            getSession().startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                cacheKey = map.getCacheKey(key);
            } finally {
                releaseReadLock();
            }
        } else {
            cacheKey = map.getCacheKey(key);
        }

        if ((cacheKey != null) && (shouldReturnInvalidatedObjects || !descriptor.getCacheInvalidationPolicy().isInvalidated(cacheKey))) {
            // PERF: Just check the read-lock to avoid acquire if not locked.
            // This is ok if you get the object first, as the object cannot gc and identity is always maintained.
            domainObject = cacheKey.getObject();
            cacheKey.checkDeferredLock();
            // Reslove inheritance issues.
            domainObject = checkForInheritance(domainObject, theClass, descriptor);
        }


        if (isCacheAccessPreCheckRequired()) {
            getSession().endOperationProfile(SessionProfiler.CACHE);
            if (domainObject == null) {
                getSession().incrementProfile(SessionProfiler.CacheMisses);
            } else {
                getSession().incrementProfile(SessionProfiler.CacheHits);
            }
        }

        return domainObject;
    }

    /**
     * INTERNAL: (public to allow test cases to check)
     * Return the identity map for the class, if missing create a new one.
     */
    public IdentityMap getIdentityMap(ClassDescriptor descriptor) {
        // Ensure that an im is only used for the root descriptor for inheritance.
        // This is required to obtain proper cache hits.
        if (descriptor.hasInheritance()) {
            descriptor = descriptor.getInheritancePolicy().getRootParentDescriptor();
        }
        Class descriptorClass = descriptor.getJavaClass();

        // PERF: First check if same as lastAccessedIdentityMap to avoid lookup.
        IdentityMap tempMap = this.lastAccessedIdentityMap;
        if ((tempMap != null) && (tempMap.getDescriptorClass() == descriptorClass)) {
            return tempMap;
        }

        // PERF: Avoid synchronization through get and putIfAbsent double-check.
        IdentityMap identityMap = this.identityMaps.get(descriptorClass);
        if (identityMap == null) {
            IdentityMap newIdentityMap = null;
            if (this.session.isUnitOfWork()) {
                newIdentityMap = buildNewIdentityMapForUnitOfWork((UnitOfWorkImpl)this.session, descriptor);
                identityMap = this.identityMaps.put(descriptorClass, newIdentityMap);
            } else if (this.session.isIsolatedClientSession()) {
                newIdentityMap = buildNewIdentityMap(descriptor);
                identityMap = this.identityMaps.put(descriptorClass, newIdentityMap);
            } else {
                newIdentityMap = buildNewIdentityMap(descriptor);
                identityMap = (IdentityMap)((ConcurrentMap)this.identityMaps).putIfAbsent(descriptorClass, newIdentityMap);
            }
            if (identityMap == null) {
                identityMap = newIdentityMap;
            }
        }
        this.lastAccessedIdentityMap = identityMap;
            
        return identityMap;
    }

    protected Map<Class, IdentityMap> getIdentityMaps() {
        return identityMaps;
    }
    
    /**
     * Return an iterator of the classes in the identity map. 
     */
    public Iterator getIdentityMapClasses() {
        return getIdentityMaps().keySet().iterator();
    }

    /**
     * Get the cached results associated with a query.  Results are cached by the
     * values of the parameters to the query so different parameters will have
     * different cached results.
     */
    public Object getQueryResult(ReadQuery query, Vector parameters, boolean shouldCheckExpiry) {
        if (query.getQueryResultsCachePolicy() == null) {
            return null;
        }
        IdentityMap map = (IdentityMap)queryResults.get(query);
        if (map == null) {
            return null;
        }

        Vector lookupParameters = parameters;
        if (lookupParameters == null) {
            lookupParameters = new Vector();
        }

        CacheKey key = map.getCacheKey(lookupParameters);
        if ((key == null) || (shouldCheckExpiry && query.getQueryResultsCachePolicy().getCacheInvalidationPolicy().isInvalidated(key))) {
            return null;
        }
        return key.getObject();
    }

    protected AbstractSession getSession() {
        return session;
    }

    /**
     * Get the wrapper object from the cache key associated with the given primary key,
     * this is used for EJB.
     */
    public Object getWrapper(Vector primaryKey, Class theClass) {
        ClassDescriptor descriptor = this.session.getDescriptor(theClass);
        IdentityMap map = getIdentityMap(descriptor);
        Object wrapper;
        if (isCacheAccessPreCheckRequired()) {
            this.session.startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                wrapper = map.getWrapper(primaryKey);
            } finally {
                releaseReadLock();
            }
            this.session.endOperationProfile(SessionProfiler.CACHE);
        } else {
            wrapper = map.getWrapper(primaryKey);
        }
        return wrapper;
    }

    /**
     * Returns the single write Lock manager for this session
     */
    public WriteLockManager getWriteLockManager() {
        // With Isolated Sessions not all Identity maps need a WriteLockManager so
        //lazy initialize
        synchronized (this) {
            if (this.writeLockManager == null) {
                this.writeLockManager = new WriteLockManager();
            }
        }
        return this.writeLockManager;
    }

    /**
     * Retrieve the write lock value of the cache key associated with the given primary key,
     */
    public Object getWriteLockValue(Vector primaryKey, Class domainClass, ClassDescriptor descriptor) {
        IdentityMap map = getIdentityMap(descriptor);
        Object value;
        if (isCacheAccessPreCheckRequired()) {
            this.session.startOperationProfile(SessionProfiler.CACHE);
            acquireReadLock();
            try {
                value = map.getWriteLockValue(primaryKey);
            } finally {
                releaseReadLock();
            }
            this.session.endOperationProfile(SessionProfiler.CACHE);
        } else {
            value = map.getWriteLockValue(primaryKey);
        }
        return value;
    }

    /**
     * Reset the identity map for only the instances of the class.
     * For inheritance the user must make sure that they only use the root class.
     */
    public void initializeIdentityMap(Class theClass) throws EclipseLinkException {
        ClassDescriptor descriptor = this.session.getDescriptor(theClass);

        if (descriptor == null) {
            throw ValidationException.missingDescriptor(String.valueOf(theClass));
        }
        if (descriptor.isChildDescriptor()) {
            throw ValidationException.childDescriptorsDoNotHaveIdentityMap();
        }
        // Bug 3736313 - look up identity map by descriptor's java class
        Class javaClass = descriptor.getJavaClass();
        IdentityMap identityMap = buildNewIdentityMap(descriptor);
        getIdentityMaps().put(javaClass, identityMap);
        clearLastAccessedIdentityMap();
    }

    public void initializeIdentityMaps() {
        clearLastAccessedIdentityMap();
        setIdentityMaps(new ConcurrentHashMap());
        clearQueryCache();
    }

    /**
     * Used to print all the objects in the identity map of the passed in class.
     * The output of this method will be logged to this session's SessionLog at SEVERE level.
     */
    public void printIdentityMap(Class businessClass) {
        String cr = Helper.cr();
        ClassDescriptor descriptor = this.session.getDescriptor(businessClass);
        int cacheCounter = 0;
        StringWriter writer = new StringWriter();
        if (descriptor.isAggregateDescriptor()) {
            return;//do nothing if descriptor is aggregate
        }

        IdentityMap map = getIdentityMap(descriptor);
        writer.write(LoggingLocalization.buildMessage("identitymap_for", new Object[] { cr, Helper.getShortClassName(map.getClass()), Helper.getShortClassName(businessClass) }));
        if (descriptor.hasInheritance()) {
            if (descriptor.getInheritancePolicy().isRootParentDescriptor()) {
                writer.write(LoggingLocalization.buildMessage("includes"));
                Vector childDescriptors;
                childDescriptors = descriptor.getInheritancePolicy().getChildDescriptors();
                if ((childDescriptors != null) && (childDescriptors.size() != 0)) {//Bug#2675242
                    Enumeration enum2 = childDescriptors.elements();
                    writer.write(Helper.getShortClassName(((ClassDescriptor)enum2.nextElement()).getJavaClass()));
                    while (enum2.hasMoreElements()) {
                        writer.write(", " + Helper.getShortClassName(((ClassDescriptor)enum2.nextElement()).getJavaClass()));
                    }
                }
                writer.write(")");
            }
        }

        for (Enumeration enumtr = map.keys(); enumtr.hasMoreElements();) {
            org.eclipse.persistence.internal.identitymaps.CacheKey cacheKey = (org.eclipse.persistence.internal.identitymaps.CacheKey)enumtr.nextElement();
            Object object = cacheKey.getObject();
            if (businessClass.isInstance(object)) {
                cacheCounter++;
                if (object == null) {
                    writer.write(LoggingLocalization.buildMessage("key_object_null", new Object[] { cr, cacheKey.getKey(), "\t" }));
                } else {
                    writer.write(LoggingLocalization.buildMessage("key_identity_hash_code_object", new Object[] { cr, cacheKey.getKey(), "\t", String.valueOf(System.identityHashCode(object)), object }));
                }
            }
        }
        writer.write(LoggingLocalization.buildMessage("elements", new Object[] { cr, String.valueOf(cacheCounter) }));
        this.session.log(SessionLog.SEVERE, SessionLog.CACHE, writer.toString(), null, null, false);
    }

    /**
     * Used to print all the objects in every identity map in this session.
     * The output of this method will be logged to this session's SessionLog at SEVERE level.
     */
    public void printIdentityMaps() {
        for (Iterator iterator = this.session.getDescriptors().keySet().iterator();
                 iterator.hasNext();) {
            Class businessClass = (Class)iterator.next();
            ClassDescriptor descriptor = this.session.getDescriptor(businessClass);
            if (descriptor.hasInheritance()) {
                if (descriptor.getInheritancePolicy().isRootParentDescriptor()) {
                    printIdentityMap(businessClass);
                }
            } else {
                printIdentityMap(businessClass);
            }
        }
    }

    /**
     * Used to print all the Locks in every identity map in this session.
     * The output of this method will be logged to this session's SessionLog at FINEST level.
     */
    public void printLocks() {
        StringWriter writer = new StringWriter();
        HashMap threadCollection = new HashMap();
        writer.write(TraceLocalization.buildMessage("lock_writer_header", (Object[])null) + Helper.cr());
        Iterator idenityMapsIterator = this.session.getIdentityMapAccessorInstance().getIdentityMapManager().getIdentityMaps().values().iterator();
        while (idenityMapsIterator.hasNext()) {
            IdentityMap idenityMap = (IdentityMap)idenityMapsIterator.next();
            idenityMap.collectLocks(threadCollection);
        }
        Object[] parameters = new Object[1];
        for (Iterator threads = threadCollection.keySet().iterator(); threads.hasNext();) {
            Thread activeThread = (Thread)threads.next();
            parameters[0] = activeThread.getName();
            writer.write(TraceLocalization.buildMessage("active_thread", parameters) + Helper.cr());
            for (Iterator cacheKeys = ((HashSet)threadCollection.get(activeThread)).iterator();
                     cacheKeys.hasNext();) {
                CacheKey cacheKey = (CacheKey)cacheKeys.next();
                parameters[0] = cacheKey.getObject();
                writer.write(TraceLocalization.buildMessage("locked_object", parameters) + Helper.cr());
                parameters[0] = new Integer(cacheKey.getMutex().getDepth());
                writer.write(TraceLocalization.buildMessage("depth", parameters) + Helper.cr());
            }
            DeferredLockManager deferredLockManager = ConcurrencyManager.getDeferredLockManager(activeThread);
            if (deferredLockManager != null) {
                for (Iterator deferredLocks = deferredLockManager.getDeferredLocks().iterator();
                         deferredLocks.hasNext();) {
                    ConcurrencyManager lock = (ConcurrencyManager)deferredLocks.next();
                    parameters[0] = lock.getOwnerCacheKey().getObject();
                    writer.write(TraceLocalization.buildMessage("deferred_locks", parameters) + Helper.cr());
                }
            }
        }
        writer.write(Helper.cr() + TraceLocalization.buildMessage("lock_writer_footer", (Object[])null) + Helper.cr());
        this.session.log(SessionLog.FINEST, SessionLog.CACHE, writer.toString(), null, null, false);
    }

    /**
     * Used to print all the Locks in the specified identity map in this session.
     * The output of this method will be logged to this session's SessionLog at FINEST level.
     */
    public void printLocks(Class theClass) {
        ClassDescriptor descriptor = this.session.getDescriptor(theClass);
        StringWriter writer = new StringWriter();
        HashMap threadCollection = new HashMap();
        writer.write(TraceLocalization.buildMessage("lock_writer_header", (Object[])null) + Helper.cr());
        IdentityMap identityMap = getIdentityMap(descriptor);
        identityMap.collectLocks(threadCollection);

        Object[] parameters = new Object[1];
        for (Iterator threads = threadCollection.keySet().iterator(); threads.hasNext();) {
            Thread activeThread = (Thread)threads.next();
            parameters[0] = activeThread.getName();
            writer.write(TraceLocalization.buildMessage("active_thread", parameters) + Helper.cr());
            for (Iterator cacheKeys = ((HashSet)threadCollection.get(activeThread)).iterator();
                     cacheKeys.hasNext();) {
                CacheKey cacheKey = (CacheKey)cacheKeys.next();
                parameters[0] = cacheKey.getObject();
                writer.write(TraceLocalization.buildMessage("locked_object", parameters) + Helper.cr());
                parameters[0] = new Integer(cacheKey.getMutex().getDepth());
                writer.write(TraceLocalization.buildMessage("depth", parameters) + Helper.cr());
            }
            DeferredLockManager deferredLockManager = ConcurrencyManager.getDeferredLockManager(activeThread);
            if (deferredLockManager != null) {
                for (Iterator deferredLocks = deferredLockManager.getDeferredLocks().iterator();
                         deferredLocks.hasNext();) {
                    ConcurrencyManager lock = (ConcurrencyManager)deferredLocks.next();
                    parameters[0] = lock.getOwnerCacheKey().getObject();
                    writer.write(TraceLocalization.buildMessage("deferred_locks", parameters) + Helper.cr());
                }
            }
        }
        writer.write(Helper.cr() + TraceLocalization.buildMessage("lock_writer_footer", (Object[])null) + Helper.cr());
        this.session.log(SessionLog.FINEST, SessionLog.CACHE, writer.toString(), null, null, false);
    }

    /**
     * Register the object with the identity map.
     * The object must always be registered with its version number if optimistic locking is used.
     * The readTime may also be included in the cache key as it is constructed
     */
    public CacheKey putInIdentityMap(Object domainObject, Vector keys, Object writeLockValue, long readTime, ClassDescriptor descriptor) {
        ObjectBuilder builder = descriptor.getObjectBuilder();
        Object implementation = builder.unwrapObject(domainObject, this.session);

        IdentityMap map = getIdentityMap(descriptor);
        CacheKey cacheKey;

        if (isCacheAccessPreCheckRequired()) {
            this.session.startOperationProfile(SessionProfiler.CACHE);
            // This is atomic so considered a read lock.
            acquireReadLock();
            try {
                cacheKey = map.put(keys, implementation, writeLockValue, readTime);
            } finally {
                releaseReadLock();
            }
            this.session.endOperationProfile(SessionProfiler.CACHE);
        } else {
            cacheKey = map.put(keys, implementation, writeLockValue, readTime);
        }
        return cacheKey;
    }

    /**
     * Set the results for a query.
     * Query results are cached based on the parameter values provided to the query
     * different parameter values access different caches.
     */
    public void putQueryResult(ReadQuery query, Vector parameters, Object results) {
        IdentityMap map = (IdentityMap)queryResults.get(query);
        if (map == null) {
            synchronized (queryResults) {
                map = (IdentityMap)queryResults.get(query);
                if (map == null) {
                    map = new CacheIdentityMap(query.getQueryResultsCachePolicy().getMaximumCachedResults());
                    queryResults.put(query, map);
                }
            }
        }
        Vector lookupParameters = parameters;
        if (lookupParameters == null) {
            lookupParameters = new Vector();
        }
        long queryTime = 0;
        if (query.isObjectLevelReadQuery()) {
            queryTime = ((ObjectLevelReadQuery)query).getExecutionTime();
        }
        if (queryTime == 0) {
            queryTime = System.currentTimeMillis();
        }
        // Bug 6138532 - store InvalidObject for "no results", do not store null
        if (results == null) {
            results = InvalidObject.instance();
        }
        map.put(lookupParameters, results, null, queryTime);
    }

    /**
     * Read-release the local-map and the entire cache.
     */
    protected void releaseReadLock() {
        if (this.session.getDatasourceLogin().shouldSynchronizedReadOnWrite()) {
            getCacheMutex().releaseReadLock();
        }
    }

    /**
     * Lock the entire cache if the cache isolation requires.
     * By default concurrent reads and writes are allowed.
     * By write, unit of work merge is meant.
     */
    public void releaseWriteLock() {
       if (this.session.getDatasourceLogin().shouldSynchronizedReadOnWrite() || this.session.getDatasourceLogin().shouldSynchronizeWrites()) {
             getCacheMutex().release();
        }
    }

    /**
     * Remove the object from the object cache.
     */
    public Object removeFromIdentityMap(Vector key, Class domainClass, ClassDescriptor descriptor, Object objectToRemove) {
        IdentityMap map = getIdentityMap(descriptor);
        Object value;

        if (isCacheAccessPreCheckRequired()) {
            this.session.startOperationProfile(SessionProfiler.CACHE);
            // This is atomic so considered a read lock.
            acquireReadLock();
            try {
                value = map.remove(key, objectToRemove);
            } finally {
                releaseReadLock();
            }
            this.session.endOperationProfile(SessionProfiler.CACHE);
        } else {
            value = map.remove(key, objectToRemove);
        }
        return value;
    }

    /**
     * Set the cache mutex.
     * This allows for the entire cache to be locked.
     * This is done for transaction isolations on merges, although never locked by default.
     */
    protected void setCacheMutex(ConcurrencyManager cacheMutex) {
        this.cacheMutex = cacheMutex;
    }

    public void setIdentityMaps(ConcurrentMap identityMaps) {
        clearLastAccessedIdentityMap();
        this.identityMaps = identityMaps;
    }

    protected void setSession(AbstractSession session) {
        this.session = session;
    }

    /**
     * Update the wrapper object the cache key associated with the given primary key,
     * this is used for EJB.
     */
    public void setWrapper(Vector primaryKey, Class theClass, Object wrapper) {
        ClassDescriptor descriptor = this.session.getDescriptor(theClass);
        IdentityMap map = getIdentityMap(descriptor);

        if (isCacheAccessPreCheckRequired()) {
            this.session.startOperationProfile(SessionProfiler.CACHE);
            // This is atomic so considered a read lock.
            acquireReadLock();
            try {
                map.setWrapper(primaryKey, wrapper);
            } finally {
                releaseReadLock();
            }
            this.session.endOperationProfile(SessionProfiler.CACHE);
        } else {
            map.setWrapper(primaryKey, wrapper);
        }
    }

    /**
     * Update the write lock value of the cache key associated with the given primary key,
     */
    public void setWriteLockValue(Vector primaryKey, Class theClass, Object writeLockValue) {
        ClassDescriptor descriptor = this.session.getDescriptor(theClass);
        IdentityMap map = getIdentityMap(descriptor);

        if (isCacheAccessPreCheckRequired()) {
            this.session.startOperationProfile(SessionProfiler.CACHE);
            // This is atomic so considered a read lock.
            acquireReadLock();
            try {
                map.setWriteLockValue(primaryKey, writeLockValue);
            } finally {
                releaseReadLock();
            }
            this.session.endOperationProfile(SessionProfiler.CACHE);
        } else {
            map.setWriteLockValue(primaryKey, writeLockValue);
        }
    }

    /**
     * This method is used to resolve the inheritance issues arisen when conforming from the identity map
     * 1. Avoid reading the unintended subclass during in-memory query(e.g. when querying on large project, do not want
     *    to check small project,  both are inherited from the project, and stored in the same identity map).
     * 2. EJB container-generated classes broke the inheritance hierarchy. Need to use associated descriptor to track
     *    the relationship. CR4005-2612426, King-Sept-18-2002
     */
    protected Object checkForInheritance(Object domainObject, Class superClass, ClassDescriptor descriptor) {
        if ((domainObject != null) && ((domainObject.getClass() != superClass) && (!superClass.isInstance(domainObject)))) {
            // Before returning null, check if we are using EJB inheritance.
            if (descriptor.hasInheritance() && descriptor.getInheritancePolicy().getUseDescriptorsToValidateInheritedObjects()) {
                // EJB inheritance on the descriptors, not the container-generated classes/objects. We need to check the
                // identity map for the bean instance through the descriptor.
                if (descriptor.getInheritancePolicy().getSubclassDescriptor(domainObject.getClass()) == null) {
                    return null;
                }
                return domainObject;
            }
            return null;
        }
        return domainObject;
    }
}
