org.hibernate.engine.internal.StatefulPersistenceContext.java Source code

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008-2011, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.engine.internal;

import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.commons.collections.map.AbstractReferenceMap;
import org.apache.commons.collections.map.ReferenceMap;
import org.jboss.logging.Logger;

import org.hibernate.AssertionFailure;
import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.collection.spi.PersistentCollection;
import org.hibernate.engine.loading.internal.LoadContexts;
import org.hibernate.engine.spi.AssociationKey;
import org.hibernate.engine.spi.BatchFetchQueue;
import org.hibernate.engine.spi.CollectionEntry;
import org.hibernate.engine.spi.CollectionKey;
import org.hibernate.engine.spi.EntityEntry;
import org.hibernate.engine.spi.EntityKey;
import org.hibernate.engine.spi.EntityUniqueKey;
import org.hibernate.engine.spi.PersistenceContext;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.engine.spi.Status;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.LockMode;
import org.hibernate.MappingException;
import org.hibernate.NonUniqueObjectException;
import org.hibernate.PersistentObjectException;
import org.hibernate.TransientObjectException;
import org.hibernate.internal.util.MarkerObject;
import org.hibernate.internal.util.collections.IdentityMap;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.pretty.MessageHelper;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.proxy.LazyInitializer;
import org.hibernate.tuple.ElementWrapper;

import static org.jboss.logging.Logger.Level.WARN;

/**
 * A <tt>PersistenceContext</tt> represents the state of persistent "stuff" which
 * Hibernate is tracking.  This includes persistent entities, collections,
 * as well as proxies generated.
 * </p>
 * There is meant to be a one-to-one correspondence between a SessionImpl and
 * a PersistentContext.  The SessionImpl uses the PersistentContext to track
 * the current state of its context.  Event-listeners then use the
 * PersistentContext to drive their processing.
 *
 * @author Steve Ebersole
 */
public class StatefulPersistenceContext implements PersistenceContext {

    public static final Object NO_ROW = new MarkerObject("NO_ROW");

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class,
            StatefulPersistenceContext.class.getName());
    private static final int INIT_COLL_SIZE = 8;

    private SessionImplementor session;

    // Loaded entity instances, by EntityKey
    private Map entitiesByKey;

    // Loaded entity instances, by EntityUniqueKey
    private Map entitiesByUniqueKey;

    // Identity map of EntityEntry instances, by the entity instance
    private Map entityEntries;

    // Entity proxies, by EntityKey
    private Map proxiesByKey;

    // Snapshots of current database state for entities
    // that have *not* been loaded
    private Map entitySnapshotsByKey;

    // Identity map of array holder ArrayHolder instances, by the array instance
    private Map arrayHolders;

    // Identity map of CollectionEntry instances, by the collection wrapper
    private Map collectionEntries;

    // Collection wrappers, by the CollectionKey
    private Map collectionsByKey; //key=CollectionKey, value=PersistentCollection

    // Set of EntityKeys of deleted objects
    private HashSet nullifiableEntityKeys;

    // properties that we have tried to load, and not found in the database
    private HashSet nullAssociations;

    // A list of collection wrappers that were instantiating during result set
    // processing, that we will need to initialize at the end of the query
    private List nonlazyCollections;

    // A container for collections we load up when the owning entity is not
    // yet loaded ... for now, this is purely transient!
    private Map<CollectionKey, PersistentCollection> unownedCollections;

    // Parent entities cache by their child for cascading
    // May be empty or not contains all relation
    private Map parentsByChild;

    private int cascading = 0;
    private int loadCounter = 0;
    private boolean flushing = false;

    private boolean defaultReadOnly = false;
    private boolean hasNonReadOnlyEntities = false;

    private LoadContexts loadContexts;
    private BatchFetchQueue batchFetchQueue;

    /**
     * Constructs a PersistentContext, bound to the given session.
     *
     * @param session The session "owning" this context.
     */
    public StatefulPersistenceContext(SessionImplementor session) {
        this.session = session;

        entitiesByKey = new HashMap(INIT_COLL_SIZE);
        entitiesByUniqueKey = new HashMap(INIT_COLL_SIZE);
        proxiesByKey = new ReferenceMap(AbstractReferenceMap.HARD, AbstractReferenceMap.WEAK);
        entitySnapshotsByKey = new HashMap(INIT_COLL_SIZE);

        entityEntries = IdentityMap.instantiateSequenced(INIT_COLL_SIZE);
        collectionEntries = IdentityMap.instantiateSequenced(INIT_COLL_SIZE);
        collectionsByKey = new HashMap(INIT_COLL_SIZE);
        arrayHolders = IdentityMap.instantiate(INIT_COLL_SIZE);
        parentsByChild = IdentityMap.instantiateSequenced(INIT_COLL_SIZE);

        nullifiableEntityKeys = new HashSet();

        initTransientState();
    }

    private void initTransientState() {
        nullAssociations = new HashSet(INIT_COLL_SIZE);
        nonlazyCollections = new ArrayList(INIT_COLL_SIZE);
    }

    public boolean isStateless() {
        return false;
    }

    public SessionImplementor getSession() {
        return session;
    }

    public LoadContexts getLoadContexts() {
        if (loadContexts == null) {
            loadContexts = new LoadContexts(this);
        }
        return loadContexts;
    }

    public void addUnownedCollection(CollectionKey key, PersistentCollection collection) {
        if (unownedCollections == null) {
            unownedCollections = new HashMap<CollectionKey, PersistentCollection>(8);
        }
        unownedCollections.put(key, collection);
    }

    public PersistentCollection useUnownedCollection(CollectionKey key) {
        if (unownedCollections == null) {
            return null;
        } else {
            return unownedCollections.remove(key);
        }
    }

    /**
     * Get the <tt>BatchFetchQueue</tt>, instantiating one if
     * necessary.
     */
    public BatchFetchQueue getBatchFetchQueue() {
        if (batchFetchQueue == null) {
            batchFetchQueue = new BatchFetchQueue(this);
        }
        return batchFetchQueue;
    }

    public void clear() {
        for (Object o : proxiesByKey.values()) {
            final LazyInitializer li = ((HibernateProxy) o).getHibernateLazyInitializer();
            li.unsetSession();
        }
        Map.Entry[] collectionEntryArray = IdentityMap.concurrentEntries(collectionEntries);
        for (Map.Entry aCollectionEntryArray : collectionEntryArray) {
            ((PersistentCollection) aCollectionEntryArray.getKey()).unsetSession(getSession());
        }
        arrayHolders.clear();
        entitiesByKey.clear();
        entitiesByUniqueKey.clear();
        entityEntries.clear();
        parentsByChild.clear();
        entitySnapshotsByKey.clear();
        collectionsByKey.clear();
        collectionEntries.clear();
        if (unownedCollections != null) {
            unownedCollections.clear();
        }
        proxiesByKey.clear();
        nullifiableEntityKeys.clear();
        if (batchFetchQueue != null) {
            batchFetchQueue.clear();
        }
        // defaultReadOnly is unaffected by clear()
        hasNonReadOnlyEntities = false;
        if (loadContexts != null) {
            loadContexts.cleanup();
        }
    }

    /**
     * {@inheritDoc}
     */
    public boolean isDefaultReadOnly() {
        return defaultReadOnly;
    }

    /**
     * {@inheritDoc}
     */
    public void setDefaultReadOnly(boolean defaultReadOnly) {
        this.defaultReadOnly = defaultReadOnly;
    }

    public boolean hasNonReadOnlyEntities() {
        return hasNonReadOnlyEntities;
    }

    public void setEntryStatus(EntityEntry entry, Status status) {
        entry.setStatus(status);
        setHasNonReadOnlyEnties(status);
    }

    private void setHasNonReadOnlyEnties(Status status) {
        if (status == Status.DELETED || status == Status.MANAGED || status == Status.SAVING) {
            hasNonReadOnlyEntities = true;
        }
    }

    public void afterTransactionCompletion() {
        cleanUpInsertedKeysAfterTransaction();
        // Downgrade locks
        for (Object o : entityEntries.values()) {
            ((EntityEntry) o).setLockMode(LockMode.NONE);
        }
    }

    /**
     * Get the current state of the entity as known to the underlying
     * database, or null if there is no corresponding row
     */
    public Object[] getDatabaseSnapshot(Serializable id, EntityPersister persister) throws HibernateException {
        final EntityKey key = session.generateEntityKey(id, persister);
        Object cached = entitySnapshotsByKey.get(key);
        if (cached != null) {
            return cached == NO_ROW ? null : (Object[]) cached;
        } else {
            Object[] snapshot = persister.getDatabaseSnapshot(id, session);
            entitySnapshotsByKey.put(key, snapshot == null ? NO_ROW : snapshot);
            return snapshot;
        }
    }

    public Object[] getNaturalIdSnapshot(Serializable id, EntityPersister persister) throws HibernateException {
        if (!persister.hasNaturalIdentifier()) {
            return null;
        }

        // if the natural-id is marked as non-mutable, it is not retrieved during a
        // normal database-snapshot operation...
        int[] props = persister.getNaturalIdentifierProperties();
        boolean[] updateable = persister.getPropertyUpdateability();
        boolean allNatualIdPropsAreUpdateable = true;
        for (int i = 0; i < props.length; i++) {
            if (!updateable[props[i]]) {
                allNatualIdPropsAreUpdateable = false;
                break;
            }
        }

        if (allNatualIdPropsAreUpdateable) {
            // do this when all the properties are updateable since there is
            // a certain likelihood that the information will already be
            // snapshot-cached.
            Object[] entitySnapshot = getDatabaseSnapshot(id, persister);
            if (entitySnapshot == NO_ROW) {
                return null;
            }
            Object[] naturalIdSnapshot = new Object[props.length];
            for (int i = 0; i < props.length; i++) {
                naturalIdSnapshot[i] = entitySnapshot[props[i]];
            }
            return naturalIdSnapshot;
        } else {
            return persister.getNaturalIdentifierSnapshot(id, session);
        }
    }

    /**
     * Retrieve the cached database snapshot for the requested entity key.
     * <p/>
     * This differs from {@link #getDatabaseSnapshot} is two important respects:<ol>
     * <li>no snapshot is obtained from the database if not already cached</li>
     * <li>an entry of {@link #NO_ROW} here is interpretet as an exception</li>
     * </ol>
     * @param key The entity key for which to retrieve the cached snapshot
     * @return The cached snapshot
     * @throws IllegalStateException if the cached snapshot was == {@link #NO_ROW}.
     */
    public Object[] getCachedDatabaseSnapshot(EntityKey key) {
        Object snapshot = entitySnapshotsByKey.get(key);
        if (snapshot == NO_ROW) {
            throw new IllegalStateException("persistence context reported no row snapshot for "
                    + MessageHelper.infoString(key.getEntityName(), key.getIdentifier()));
        }
        return (Object[]) snapshot;
    }

    /*public void removeDatabaseSnapshot(EntityKey key) {
       entitySnapshotsByKey.remove(key);
    }*/

    public void addEntity(EntityKey key, Object entity) {
        entitiesByKey.put(key, entity);
        getBatchFetchQueue().removeBatchLoadableEntityKey(key);
    }

    /**
     * Get the entity instance associated with the given
     * <tt>EntityKey</tt>
     */
    public Object getEntity(EntityKey key) {
        return entitiesByKey.get(key);
    }

    public boolean containsEntity(EntityKey key) {
        return entitiesByKey.containsKey(key);
    }

    /**
     * Remove an entity from the session cache, also clear
     * up other state associated with the entity, all except
     * for the <tt>EntityEntry</tt>
     */
    public Object removeEntity(EntityKey key) {
        Object entity = entitiesByKey.remove(key);
        Iterator iter = entitiesByUniqueKey.values().iterator();
        while (iter.hasNext()) {
            if (iter.next() == entity)
                iter.remove();
        }
        // Clear all parent cache
        parentsByChild.clear();
        entitySnapshotsByKey.remove(key);
        nullifiableEntityKeys.remove(key);
        getBatchFetchQueue().removeBatchLoadableEntityKey(key);
        getBatchFetchQueue().removeSubselect(key);
        return entity;
    }

    /**
     * Get an entity cached by unique key
     */
    public Object getEntity(EntityUniqueKey euk) {
        return entitiesByUniqueKey.get(euk);
    }

    /**
     * Add an entity to the cache by unique key
     */
    public void addEntity(EntityUniqueKey euk, Object entity) {
        entitiesByUniqueKey.put(euk, entity);
    }

    /**
     * Retreive the EntityEntry representation of the given entity.
     *
     * @param entity The entity for which to locate the EntityEntry.
     * @return The EntityEntry for the given entity.
     */
    public EntityEntry getEntry(Object entity) {
        return (EntityEntry) entityEntries.get(entity);
    }

    /**
     * Remove an entity entry from the session cache
     */
    public EntityEntry removeEntry(Object entity) {
        return (EntityEntry) entityEntries.remove(entity);
    }

    /**
     * Is there an EntityEntry for this instance?
     */
    public boolean isEntryFor(Object entity) {
        return entityEntries.containsKey(entity);
    }

    /**
     * Get the collection entry for a persistent collection
     */
    public CollectionEntry getCollectionEntry(PersistentCollection coll) {
        return (CollectionEntry) collectionEntries.get(coll);
    }

    /**
     * Adds an entity to the internal caches.
     */
    public EntityEntry addEntity(final Object entity, final Status status, final Object[] loadedState,
            final EntityKey entityKey, final Object version, final LockMode lockMode,
            final boolean existsInDatabase, final EntityPersister persister, final boolean disableVersionIncrement,
            boolean lazyPropertiesAreUnfetched) {

        addEntity(entityKey, entity);

        return addEntry(entity, status, loadedState, null, entityKey.getIdentifier(), version, lockMode,
                existsInDatabase, persister, disableVersionIncrement, lazyPropertiesAreUnfetched);
    }

    /**
     * Generates an appropriate EntityEntry instance and adds it
     * to the event source's internal caches.
     */
    public EntityEntry addEntry(final Object entity, final Status status, final Object[] loadedState,
            final Object rowId, final Serializable id, final Object version, final LockMode lockMode,
            final boolean existsInDatabase, final EntityPersister persister, final boolean disableVersionIncrement,
            boolean lazyPropertiesAreUnfetched) {

        EntityEntry e = new EntityEntry(status, loadedState, rowId, id, version, lockMode, existsInDatabase,
                persister, persister.getEntityMode(), session.getTenantIdentifier(), disableVersionIncrement,
                lazyPropertiesAreUnfetched);
        entityEntries.put(entity, e);

        setHasNonReadOnlyEnties(status);
        return e;
    }

    public boolean containsCollection(PersistentCollection collection) {
        return collectionEntries.containsKey(collection);
    }

    public boolean containsProxy(Object entity) {
        return proxiesByKey.containsValue(entity);
    }

    /**
     * Takes the given object and, if it represents a proxy, reassociates it with this event source.
     *
     * @param value The possible proxy to be reassociated.
     * @return Whether the passed value represented an actual proxy which got initialized.
     * @throws MappingException
     */
    public boolean reassociateIfUninitializedProxy(Object value) throws MappingException {
        if (value instanceof ElementWrapper) {
            value = ((ElementWrapper) value).getElement();
        }

        if (!Hibernate.isInitialized(value)) {
            HibernateProxy proxy = (HibernateProxy) value;
            LazyInitializer li = proxy.getHibernateLazyInitializer();
            reassociateProxy(li, proxy);
            return true;
        } else {
            return false;
        }
    }

    /**
     * If a deleted entity instance is re-saved, and it has a proxy, we need to
     * reset the identifier of the proxy
     */
    public void reassociateProxy(Object value, Serializable id) throws MappingException {
        if (value instanceof ElementWrapper) {
            value = ((ElementWrapper) value).getElement();
        }

        if (value instanceof HibernateProxy) {
            LOG.debugf("Setting proxy identifier: %s", id);
            HibernateProxy proxy = (HibernateProxy) value;
            LazyInitializer li = proxy.getHibernateLazyInitializer();
            li.setIdentifier(id);
            reassociateProxy(li, proxy);
        }
    }

    /**
     * Associate a proxy that was instantiated by another session with this session
     *
     * @param li The proxy initializer.
     * @param proxy The proxy to reassociate.
     */
    private void reassociateProxy(LazyInitializer li, HibernateProxy proxy) {
        if (li.getSession() != this.getSession()) {
            final EntityPersister persister = session.getFactory().getEntityPersister(li.getEntityName());
            final EntityKey key = session.generateEntityKey(li.getIdentifier(), persister);
            // any earlier proxy takes precedence
            if (!proxiesByKey.containsKey(key)) {
                proxiesByKey.put(key, proxy);
            }
            proxy.getHibernateLazyInitializer().setSession(session);
        }
    }

    /**
     * Get the entity instance underlying the given proxy, throwing
     * an exception if the proxy is uninitialized. If the given object
     * is not a proxy, simply return the argument.
     */
    public Object unproxy(Object maybeProxy) throws HibernateException {
        if (maybeProxy instanceof ElementWrapper) {
            maybeProxy = ((ElementWrapper) maybeProxy).getElement();
        }

        if (maybeProxy instanceof HibernateProxy) {
            HibernateProxy proxy = (HibernateProxy) maybeProxy;
            LazyInitializer li = proxy.getHibernateLazyInitializer();
            if (li.isUninitialized()) {
                throw new PersistentObjectException("object was an uninitialized proxy for " + li.getEntityName());
            }
            return li.getImplementation(); //unwrap the object
        } else {
            return maybeProxy;
        }
    }

    /**
     * Possibly unproxy the given reference and reassociate it with the current session.
     *
     * @param maybeProxy The reference to be unproxied if it currently represents a proxy.
     * @return The unproxied instance.
     * @throws HibernateException
     */
    public Object unproxyAndReassociate(Object maybeProxy) throws HibernateException {
        if (maybeProxy instanceof ElementWrapper) {
            maybeProxy = ((ElementWrapper) maybeProxy).getElement();
        }

        if (maybeProxy instanceof HibernateProxy) {
            HibernateProxy proxy = (HibernateProxy) maybeProxy;
            LazyInitializer li = proxy.getHibernateLazyInitializer();
            reassociateProxy(li, proxy);
            return li.getImplementation(); //initialize + unwrap the object
        } else {
            return maybeProxy;
        }
    }

    /**
     * Attempts to check whether the given key represents an entity already loaded within the
     * current session.
     * @param object The entity reference against which to perform the uniqueness check.
     * @throws HibernateException
     */
    public void checkUniqueness(EntityKey key, Object object) throws HibernateException {
        Object entity = getEntity(key);
        if (entity == object) {
            throw new AssertionFailure("object already associated, but no entry was found");
        }
        if (entity != null) {
            throw new NonUniqueObjectException(key.getIdentifier(), key.getEntityName());
        }
    }

    /**
     * If the existing proxy is insufficiently "narrow" (derived), instantiate a new proxy
     * and overwrite the registration of the old one. This breaks == and occurs only for
     * "class" proxies rather than "interface" proxies. Also init the proxy to point to
     * the given target implementation if necessary.
     *
     * @param proxy The proxy instance to be narrowed.
     * @param persister The persister for the proxied entity.
     * @param key The internal cache key for the proxied entity.
     * @param object (optional) the actual proxied entity instance.
     * @return An appropriately narrowed instance.
     * @throws HibernateException
     */
    public Object narrowProxy(Object proxy, EntityPersister persister, EntityKey key, Object object)
            throws HibernateException {

        final Class concreteProxyClass = persister.getConcreteProxyClass();
        boolean alreadyNarrow = concreteProxyClass.isAssignableFrom(proxy.getClass());

        if (!alreadyNarrow) {
            if (LOG.isEnabled(WARN)) {
                LOG.narrowingProxy(concreteProxyClass);
            }

            if (object != null) {
                proxiesByKey.remove(key);
                return object; //return the proxied object
            } else {
                proxy = persister.createProxy(key.getIdentifier(), session);
                Object proxyOrig = proxiesByKey.put(key, proxy); //overwrite old proxy
                if (proxyOrig != null) {
                    if (!(proxyOrig instanceof HibernateProxy)) {
                        throw new AssertionFailure(
                                "proxy not of type HibernateProxy; it is " + proxyOrig.getClass());
                    }
                    // set the read-only/modifiable mode in the new proxy to what it was in the original proxy
                    boolean readOnlyOrig = ((HibernateProxy) proxyOrig).getHibernateLazyInitializer().isReadOnly();
                    ((HibernateProxy) proxy).getHibernateLazyInitializer().setReadOnly(readOnlyOrig);
                }
                return proxy;
            }
        } else {

            if (object != null) {
                LazyInitializer li = ((HibernateProxy) proxy).getHibernateLazyInitializer();
                li.setImplementation(object);
            }

            return proxy;

        }

    }

    /**
     * Return the existing proxy associated with the given <tt>EntityKey</tt>, or the
     * third argument (the entity associated with the key) if no proxy exists. Init
     * the proxy to the target implementation, if necessary.
     */
    public Object proxyFor(EntityPersister persister, EntityKey key, Object impl) throws HibernateException {
        if (!persister.hasProxy())
            return impl;
        Object proxy = proxiesByKey.get(key);
        if (proxy != null) {
            return narrowProxy(proxy, persister, key, impl);
        } else {
            return impl;
        }
    }

    /**
     * Return the existing proxy associated with the given <tt>EntityKey</tt>, or the
     * argument (the entity associated with the key) if no proxy exists.
     * (slower than the form above)
     */
    public Object proxyFor(Object impl) throws HibernateException {
        EntityEntry e = getEntry(impl);
        return proxyFor(e.getPersister(), e.getEntityKey(), impl);
    }

    /**
     * Get the entity that owns this persistent collection
     */
    public Object getCollectionOwner(Serializable key, CollectionPersister collectionPersister)
            throws MappingException {
        return getEntity(session.generateEntityKey(key, collectionPersister.getOwnerEntityPersister()));
    }

    /**
     * Get the entity that owned this persistent collection when it was loaded
     *
     * @param collection The persistent collection
     * @return the owner, if its entity ID is available from the collection's loaded key
     * and the owner entity is in the persistence context; otherwise, returns null
     */
    public Object getLoadedCollectionOwnerOrNull(PersistentCollection collection) {
        CollectionEntry ce = getCollectionEntry(collection);
        if (ce.getLoadedPersister() == null) {
            return null; // early exit...
        }
        Object loadedOwner = null;
        // TODO: an alternative is to check if the owner has changed; if it hasn't then
        // return collection.getOwner()
        Serializable entityId = getLoadedCollectionOwnerIdOrNull(ce);
        if (entityId != null) {
            loadedOwner = getCollectionOwner(entityId, ce.getLoadedPersister());
        }
        return loadedOwner;
    }

    /**
     * Get the ID for the entity that owned this persistent collection when it was loaded
     *
     * @param collection The persistent collection
     * @return the owner ID if available from the collection's loaded key; otherwise, returns null
     */
    public Serializable getLoadedCollectionOwnerIdOrNull(PersistentCollection collection) {
        return getLoadedCollectionOwnerIdOrNull(getCollectionEntry(collection));
    }

    /**
     * Get the ID for the entity that owned this persistent collection when it was loaded
     *
     * @param ce The collection entry
     * @return the owner ID if available from the collection's loaded key; otherwise, returns null
     */
    private Serializable getLoadedCollectionOwnerIdOrNull(CollectionEntry ce) {
        if (ce == null || ce.getLoadedKey() == null || ce.getLoadedPersister() == null) {
            return null;
        }
        // TODO: an alternative is to check if the owner has changed; if it hasn't then
        // get the ID from collection.getOwner()
        return ce.getLoadedPersister().getCollectionType().getIdOfOwnerOrNull(ce.getLoadedKey(), session);
    }

    /**
     * add a collection we just loaded up (still needs initializing)
     */
    public void addUninitializedCollection(CollectionPersister persister, PersistentCollection collection,
            Serializable id) {
        CollectionEntry ce = new CollectionEntry(collection, persister, id, flushing);
        addCollection(collection, ce, id);
    }

    /**
     * add a detached uninitialized collection
     */
    public void addUninitializedDetachedCollection(CollectionPersister persister, PersistentCollection collection) {
        CollectionEntry ce = new CollectionEntry(persister, collection.getKey());
        addCollection(collection, ce, collection.getKey());
    }

    /**
     * Add a new collection (ie. a newly created one, just instantiated by the
     * application, with no database state or snapshot)
     * @param collection The collection to be associated with the persistence context
     */
    public void addNewCollection(CollectionPersister persister, PersistentCollection collection)
            throws HibernateException {
        addCollection(collection, persister);
    }

    /**
     * Add an collection to the cache, with a given collection entry.
     *
     * @param coll The collection for which we are adding an entry.
     * @param entry The entry representing the collection.
     * @param key The key of the collection's entry.
     */
    private void addCollection(PersistentCollection coll, CollectionEntry entry, Serializable key) {
        collectionEntries.put(coll, entry);
        CollectionKey collectionKey = new CollectionKey(entry.getLoadedPersister(), key);
        PersistentCollection old = (PersistentCollection) collectionsByKey.put(collectionKey, coll);
        if (old != null) {
            if (old == coll) {
                throw new AssertionFailure("bug adding collection twice");
            }
            // or should it actually throw an exception?
            old.unsetSession(session);
            collectionEntries.remove(old);
            // watch out for a case where old is still referenced
            // somewhere in the object graph! (which is a user error)
        }
    }

    /**
     * Add a collection to the cache, creating a new collection entry for it
     *
     * @param collection The collection for which we are adding an entry.
     * @param persister The collection persister
     */
    private void addCollection(PersistentCollection collection, CollectionPersister persister) {
        CollectionEntry ce = new CollectionEntry(persister, collection);
        collectionEntries.put(collection, ce);
    }

    /**
     * add an (initialized) collection that was created by another session and passed
     * into update() (ie. one with a snapshot and existing state on the database)
     */
    public void addInitializedDetachedCollection(CollectionPersister collectionPersister,
            PersistentCollection collection) throws HibernateException {
        if (collection.isUnreferenced()) {
            //treat it just like a new collection
            addCollection(collection, collectionPersister);
        } else {
            CollectionEntry ce = new CollectionEntry(collection, session.getFactory());
            addCollection(collection, ce, collection.getKey());
        }
    }

    /**
     * add a collection we just pulled out of the cache (does not need initializing)
     */
    public CollectionEntry addInitializedCollection(CollectionPersister persister, PersistentCollection collection,
            Serializable id) throws HibernateException {
        CollectionEntry ce = new CollectionEntry(collection, persister, id, flushing);
        ce.postInitialize(collection);
        addCollection(collection, ce, id);
        return ce;
    }

    /**
     * Get the collection instance associated with the <tt>CollectionKey</tt>
     */
    public PersistentCollection getCollection(CollectionKey collectionKey) {
        return (PersistentCollection) collectionsByKey.get(collectionKey);
    }

    /**
     * Register a collection for non-lazy loading at the end of the
     * two-phase load
     */
    public void addNonLazyCollection(PersistentCollection collection) {
        nonlazyCollections.add(collection);
    }

    /**
     * Force initialization of all non-lazy collections encountered during
     * the current two-phase load (actually, this is a no-op, unless this
     * is the "outermost" load)
     */
    public void initializeNonLazyCollections() throws HibernateException {
        if (loadCounter == 0) {
            LOG.debugf("Initializing non-lazy collections");
            //do this work only at the very highest level of the load
            loadCounter++; //don't let this method be called recursively
            try {
                int size;
                while ((size = nonlazyCollections.size()) > 0) {
                    //note that each iteration of the loop may add new elements
                    ((PersistentCollection) nonlazyCollections.remove(size - 1)).forceInitialization();
                }
            } finally {
                loadCounter--;
                clearNullProperties();
            }
        }
    }

    /**
     * Get the <tt>PersistentCollection</tt> object for an array
     */
    public PersistentCollection getCollectionHolder(Object array) {
        return (PersistentCollection) arrayHolders.get(array);
    }

    /**
     * Register a <tt>PersistentCollection</tt> object for an array.
     * Associates a holder with an array - MUST be called after loading
     * array, since the array instance is not created until endLoad().
     */
    public void addCollectionHolder(PersistentCollection holder) {
        //TODO:refactor + make this method private
        arrayHolders.put(holder.getValue(), holder);
    }

    public PersistentCollection removeCollectionHolder(Object array) {
        return (PersistentCollection) arrayHolders.remove(array);
    }

    /**
     * Get the snapshot of the pre-flush collection state
     */
    public Serializable getSnapshot(PersistentCollection coll) {
        return getCollectionEntry(coll).getSnapshot();
    }

    /**
     * Get the collection entry for a collection passed to filter,
     * which might be a collection wrapper, an array, or an unwrapped
     * collection. Return null if there is no entry.
     */
    public CollectionEntry getCollectionEntryOrNull(Object collection) {
        PersistentCollection coll;
        if (collection instanceof PersistentCollection) {
            coll = (PersistentCollection) collection;
            //if (collection==null) throw new TransientObjectException("Collection was not yet persistent");
        } else {
            coll = getCollectionHolder(collection);
            if (coll == null) {
                //it might be an unwrapped collection reference!
                //try to find a wrapper (slowish)
                Iterator wrappers = IdentityMap.keyIterator(collectionEntries);
                while (wrappers.hasNext()) {
                    PersistentCollection pc = (PersistentCollection) wrappers.next();
                    if (pc.isWrapper(collection)) {
                        coll = pc;
                        break;
                    }
                }
            }
        }

        return (coll == null) ? null : getCollectionEntry(coll);
    }

    /**
     * Get an existing proxy by key
     */
    public Object getProxy(EntityKey key) {
        return proxiesByKey.get(key);
    }

    /**
     * Add a proxy to the session cache
     */
    public void addProxy(EntityKey key, Object proxy) {
        proxiesByKey.put(key, proxy);
    }

    /**
     * Remove a proxy from the session cache.
     * <p/>
     * Additionally, ensure that any load optimization references
     * such as batch or subselect loading get cleaned up as well.
     *
     * @param key The key of the entity proxy to be removed
     * @return The proxy reference.
     */
    public Object removeProxy(EntityKey key) {
        if (batchFetchQueue != null) {
            batchFetchQueue.removeBatchLoadableEntityKey(key);
            batchFetchQueue.removeSubselect(key);
        }
        return proxiesByKey.remove(key);
    }

    /**
     * Record the fact that an entity does not exist in the database
     *
     * @param key the primary key of the entity
     */
    /*public void addNonExistantEntityKey(EntityKey key) {
       nonExistantEntityKeys.add(key);
    }*/

    /**
     * Record the fact that an entity does not exist in the database
     *
     * @param key a unique key of the entity
     */
    /*public void addNonExistantEntityUniqueKey(EntityUniqueKey key) {
       nonExistentEntityUniqueKeys.add(key);
    }*/

    /*public void removeNonExist(EntityKey key) {
       nonExistantEntityKeys.remove(key);
    }*/

    /**
     * Retrieve the set of EntityKeys representing nullifiable references
     */
    public HashSet getNullifiableEntityKeys() {
        return nullifiableEntityKeys;
    }

    public Map getEntitiesByKey() {
        return entitiesByKey;
    }

    public Map getProxiesByKey() {
        return proxiesByKey;
    }

    public Map getEntityEntries() {
        return entityEntries;
    }

    public Map getCollectionEntries() {
        return collectionEntries;
    }

    public Map getCollectionsByKey() {
        return collectionsByKey;
    }

    /**
     * Do we already know that the entity does not exist in the
     * database?
     */
    /*public boolean isNonExistant(EntityKey key) {
       return nonExistantEntityKeys.contains(key);
    }*/

    /**
     * Do we already know that the entity does not exist in the
     * database?
     */
    /*public boolean isNonExistant(EntityUniqueKey key) {
       return nonExistentEntityUniqueKeys.contains(key);
    }*/

    public int getCascadeLevel() {
        return cascading;
    }

    public int incrementCascadeLevel() {
        return ++cascading;
    }

    public int decrementCascadeLevel() {
        return --cascading;
    }

    public boolean isFlushing() {
        return flushing;
    }

    public void setFlushing(boolean flushing) {
        this.flushing = flushing;
    }

    /**
     * Call this before begining a two-phase load
     */
    public void beforeLoad() {
        loadCounter++;
    }

    /**
     * Call this after finishing a two-phase load
     */
    public void afterLoad() {
        loadCounter--;
    }

    public boolean isLoadFinished() {
        return loadCounter == 0;
    }

    /**
     * Returns a string representation of the object.
     *
     * @return a string representation of the object.
     */
    @Override
    public String toString() {
        return new StringBuffer().append("PersistenceContext[entityKeys=").append(entitiesByKey.keySet())
                .append(",collectionKeys=").append(collectionsByKey.keySet()).append("]").toString();
    }

    /**
     * Search <tt>this</tt> persistence context for an associated entity instance which is considered the "owner" of
     * the given <tt>childEntity</tt>, and return that owner's id value.  This is performed in the scenario of a
     * uni-directional, non-inverse one-to-many collection (which means that the collection elements do not maintain
     * a direct reference to the owner).
     * <p/>
     * As such, the processing here is basically to loop over every entity currently associated with this persistence
     * context and for those of the correct entity (sub) type to extract its collection role property value and see
     * if the child is contained within that collection.  If so, we have found the owner; if not, we go on.
     * <p/>
     * Also need to account for <tt>mergeMap</tt> which acts as a local copy cache managed for the duration of a merge
     * operation.  It represents a map of the detached entity instances pointing to the corresponding managed instance.
     *
     * @param entityName The entity name for the entity type which would own the child
     * @param propertyName The name of the property on the owning entity type which would name this child association.
     * @param childEntity The child entity instance for which to locate the owner instance id.
     * @param mergeMap A map of non-persistent instances from an on-going merge operation (possibly null).
     *
     * @return The id of the entityName instance which is said to own the child; null if an appropriate owner not
     * located.
     */
    public Serializable getOwnerId(String entityName, String propertyName, Object childEntity, Map mergeMap) {
        final String collectionRole = entityName + '.' + propertyName;
        final EntityPersister persister = session.getFactory().getEntityPersister(entityName);
        final CollectionPersister collectionPersister = session.getFactory().getCollectionPersister(collectionRole);

        // try cache lookup first
        Object parent = parentsByChild.get(childEntity);
        if (parent != null) {
            final EntityEntry entityEntry = (EntityEntry) entityEntries.get(parent);
            //there maybe more than one parent, filter by type
            if (persister.isSubclassEntityName(entityEntry.getEntityName())
                    && isFoundInParent(propertyName, childEntity, persister, collectionPersister, parent)) {
                return getEntry(parent).getId();
            } else {
                parentsByChild.remove(childEntity); // remove wrong entry
            }
        }

        //not found in case, proceed
        // iterate all the entities currently associated with the persistence context.
        Iterator entities = IdentityMap.entries(entityEntries).iterator();
        while (entities.hasNext()) {
            final Map.Entry me = (Map.Entry) entities.next();
            final EntityEntry entityEntry = (EntityEntry) me.getValue();
            // does this entity entry pertain to the entity persister in which we are interested (owner)?
            if (persister.isSubclassEntityName(entityEntry.getEntityName())) {
                final Object entityEntryInstance = me.getKey();

                //check if the managed object is the parent
                boolean found = isFoundInParent(propertyName, childEntity, persister, collectionPersister,
                        entityEntryInstance);

                if (!found && mergeMap != null) {
                    //check if the detached object being merged is the parent
                    Object unmergedInstance = mergeMap.get(entityEntryInstance);
                    Object unmergedChild = mergeMap.get(childEntity);
                    if (unmergedInstance != null && unmergedChild != null) {
                        found = isFoundInParent(propertyName, unmergedChild, persister, collectionPersister,
                                unmergedInstance);
                    }
                }

                if (found) {
                    return entityEntry.getId();
                }

            }
        }

        // if we get here, it is possible that we have a proxy 'in the way' of the merge map resolution...
        //       NOTE: decided to put this here rather than in the above loop as I was nervous about the performance
        //      of the loop-in-loop especially considering this is far more likely the 'edge case'
        if (mergeMap != null) {
            Iterator mergeMapItr = mergeMap.entrySet().iterator();
            while (mergeMapItr.hasNext()) {
                final Map.Entry mergeMapEntry = (Map.Entry) mergeMapItr.next();
                if (mergeMapEntry.getKey() instanceof HibernateProxy) {
                    final HibernateProxy proxy = (HibernateProxy) mergeMapEntry.getKey();
                    if (persister.isSubclassEntityName(proxy.getHibernateLazyInitializer().getEntityName())) {
                        boolean found = isFoundInParent(propertyName, childEntity, persister, collectionPersister,
                                mergeMap.get(proxy));
                        if (!found) {
                            found = isFoundInParent(propertyName, mergeMap.get(childEntity), persister,
                                    collectionPersister, mergeMap.get(proxy));
                        }
                        if (found) {
                            return proxy.getHibernateLazyInitializer().getIdentifier();
                        }
                    }
                }
            }
        }

        return null;
    }

    private boolean isFoundInParent(String property, Object childEntity, EntityPersister persister,
            CollectionPersister collectionPersister, Object potentialParent) {
        Object collection = persister.getPropertyValue(potentialParent, property);
        return collection != null && Hibernate.isInitialized(collection)
                && collectionPersister.getCollectionType().contains(collection, childEntity, session);
    }

    /**
     * Search the persistence context for an index of the child object,
     * given a collection role
     */
    public Object getIndexInOwner(String entity, String property, Object childEntity, Map mergeMap) {

        EntityPersister persister = session.getFactory().getEntityPersister(entity);
        CollectionPersister cp = session.getFactory().getCollectionPersister(entity + '.' + property);

        // try cache lookup first
        Object parent = parentsByChild.get(childEntity);
        if (parent != null) {
            final EntityEntry entityEntry = (EntityEntry) entityEntries.get(parent);
            //there maybe more than one parent, filter by type
            if (persister.isSubclassEntityName(entityEntry.getEntityName())) {
                Object index = getIndexInParent(property, childEntity, persister, cp, parent);

                if (index == null && mergeMap != null) {
                    Object unmergedInstance = mergeMap.get(parent);
                    Object unmergedChild = mergeMap.get(childEntity);
                    if (unmergedInstance != null && unmergedChild != null) {
                        index = getIndexInParent(property, unmergedChild, persister, cp, unmergedInstance);
                    }
                }
                if (index != null) {
                    return index;
                }
            } else {
                parentsByChild.remove(childEntity); // remove wrong entry
            }
        }

        //Not found in cache, proceed
        Iterator entities = IdentityMap.entries(entityEntries).iterator();
        while (entities.hasNext()) {
            Map.Entry me = (Map.Entry) entities.next();
            EntityEntry ee = (EntityEntry) me.getValue();
            if (persister.isSubclassEntityName(ee.getEntityName())) {
                Object instance = me.getKey();

                Object index = getIndexInParent(property, childEntity, persister, cp, instance);

                if (index == null && mergeMap != null) {
                    Object unmergedInstance = mergeMap.get(instance);
                    Object unmergedChild = mergeMap.get(childEntity);
                    if (unmergedInstance != null && unmergedChild != null) {
                        index = getIndexInParent(property, unmergedChild, persister, cp, unmergedInstance);
                    }
                }

                if (index != null)
                    return index;
            }
        }
        return null;
    }

    private Object getIndexInParent(String property, Object childEntity, EntityPersister persister,
            CollectionPersister collectionPersister, Object potentialParent) {
        Object collection = persister.getPropertyValue(potentialParent, property);
        if (collection != null && Hibernate.isInitialized(collection)) {
            return collectionPersister.getCollectionType().indexOf(collection, childEntity);
        } else {
            return null;
        }
    }

    /**
     * Record the fact that the association belonging to the keyed
     * entity is null.
     */
    public void addNullProperty(EntityKey ownerKey, String propertyName) {
        nullAssociations.add(new AssociationKey(ownerKey, propertyName));
    }

    /**
     * Is the association property belonging to the keyed entity null?
     */
    public boolean isPropertyNull(EntityKey ownerKey, String propertyName) {
        return nullAssociations.contains(new AssociationKey(ownerKey, propertyName));
    }

    private void clearNullProperties() {
        nullAssociations.clear();
    }

    public boolean isReadOnly(Object entityOrProxy) {
        if (entityOrProxy == null) {
            throw new AssertionFailure("object must be non-null.");
        }
        boolean isReadOnly;
        if (entityOrProxy instanceof HibernateProxy) {
            isReadOnly = ((HibernateProxy) entityOrProxy).getHibernateLazyInitializer().isReadOnly();
        } else {
            EntityEntry ee = getEntry(entityOrProxy);
            if (ee == null) {
                throw new TransientObjectException("Instance was not associated with this persistence context");
            }
            isReadOnly = ee.isReadOnly();
        }
        return isReadOnly;
    }

    public void setReadOnly(Object object, boolean readOnly) {
        if (object == null) {
            throw new AssertionFailure("object must be non-null.");
        }
        if (isReadOnly(object) == readOnly) {
            return;
        }
        if (object instanceof HibernateProxy) {
            HibernateProxy proxy = (HibernateProxy) object;
            setProxyReadOnly(proxy, readOnly);
            if (Hibernate.isInitialized(proxy)) {
                setEntityReadOnly(proxy.getHibernateLazyInitializer().getImplementation(), readOnly);
            }
        } else {
            setEntityReadOnly(object, readOnly);
            // PersistenceContext.proxyFor( entity ) returns entity if there is no proxy for that entity
            // so need to check the return value to be sure it is really a proxy
            Object maybeProxy = getSession().getPersistenceContext().proxyFor(object);
            if (maybeProxy instanceof HibernateProxy) {
                setProxyReadOnly((HibernateProxy) maybeProxy, readOnly);
            }
        }
    }

    private void setProxyReadOnly(HibernateProxy proxy, boolean readOnly) {
        if (proxy.getHibernateLazyInitializer().getSession() != getSession()) {
            throw new AssertionFailure(
                    "Attempt to set a proxy to read-only that is associated with a different session");
        }
        proxy.getHibernateLazyInitializer().setReadOnly(readOnly);
    }

    private void setEntityReadOnly(Object entity, boolean readOnly) {
        EntityEntry entry = getEntry(entity);
        if (entry == null) {
            throw new TransientObjectException("Instance was not associated with this persistence context");
        }
        entry.setReadOnly(readOnly, entity);
        hasNonReadOnlyEntities = hasNonReadOnlyEntities || !readOnly;
    }

    public void replaceDelayedEntityIdentityInsertKeys(EntityKey oldKey, Serializable generatedId) {
        Object entity = entitiesByKey.remove(oldKey);
        EntityEntry oldEntry = (EntityEntry) entityEntries.remove(entity);
        parentsByChild.clear();

        final EntityKey newKey = session.generateEntityKey(generatedId, oldEntry.getPersister());
        addEntity(newKey, entity);
        addEntry(entity, oldEntry.getStatus(), oldEntry.getLoadedState(), oldEntry.getRowId(), generatedId,
                oldEntry.getVersion(), oldEntry.getLockMode(), oldEntry.isExistsInDatabase(),
                oldEntry.getPersister(), oldEntry.isBeingReplicated(),
                oldEntry.isLoadedWithLazyPropertiesUnfetched());
    }

    /**
     * Used by the owning session to explicitly control serialization of the
     * persistence context.
     *
     * @param oos The stream to which the persistence context should get written
     * @throws IOException serialization errors.
     */
    public void serialize(ObjectOutputStream oos) throws IOException {
        LOG.trace("Serializing persistent-context");

        oos.writeBoolean(defaultReadOnly);
        oos.writeBoolean(hasNonReadOnlyEntities);

        oos.writeInt(entitiesByKey.size());
        LOG.trace("Starting serialization of [" + entitiesByKey.size() + "] entitiesByKey entries");
        Iterator itr = entitiesByKey.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            ((EntityKey) entry.getKey()).serialize(oos);
            oos.writeObject(entry.getValue());
        }

        oos.writeInt(entitiesByUniqueKey.size());
        LOG.trace("Starting serialization of [" + entitiesByUniqueKey.size() + "] entitiesByUniqueKey entries");
        itr = entitiesByUniqueKey.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            ((EntityUniqueKey) entry.getKey()).serialize(oos);
            oos.writeObject(entry.getValue());
        }

        oos.writeInt(proxiesByKey.size());
        LOG.trace("Starting serialization of [" + proxiesByKey.size() + "] proxiesByKey entries");
        itr = proxiesByKey.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            ((EntityKey) entry.getKey()).serialize(oos);
            oos.writeObject(entry.getValue());
        }

        oos.writeInt(entitySnapshotsByKey.size());
        LOG.trace("Starting serialization of [" + entitySnapshotsByKey.size() + "] entitySnapshotsByKey entries");
        itr = entitySnapshotsByKey.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            ((EntityKey) entry.getKey()).serialize(oos);
            oos.writeObject(entry.getValue());
        }

        oos.writeInt(entityEntries.size());
        LOG.trace("Starting serialization of [" + entityEntries.size() + "] entityEntries entries");
        itr = entityEntries.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            oos.writeObject(entry.getKey());
            ((EntityEntry) entry.getValue()).serialize(oos);
        }

        oos.writeInt(collectionsByKey.size());
        LOG.trace("Starting serialization of [" + collectionsByKey.size() + "] collectionsByKey entries");
        itr = collectionsByKey.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            ((CollectionKey) entry.getKey()).serialize(oos);
            oos.writeObject(entry.getValue());
        }

        oos.writeInt(collectionEntries.size());
        LOG.trace("Starting serialization of [" + collectionEntries.size() + "] collectionEntries entries");
        itr = collectionEntries.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            oos.writeObject(entry.getKey());
            ((CollectionEntry) entry.getValue()).serialize(oos);
        }

        oos.writeInt(arrayHolders.size());
        LOG.trace("Starting serialization of [" + arrayHolders.size() + "] arrayHolders entries");
        itr = arrayHolders.entrySet().iterator();
        while (itr.hasNext()) {
            Map.Entry entry = (Map.Entry) itr.next();
            oos.writeObject(entry.getKey());
            oos.writeObject(entry.getValue());
        }

        oos.writeInt(nullifiableEntityKeys.size());
        LOG.trace("Starting serialization of [" + nullifiableEntityKeys.size() + "] nullifiableEntityKey entries");
        itr = nullifiableEntityKeys.iterator();
        while (itr.hasNext()) {
            EntityKey entry = (EntityKey) itr.next();
            entry.serialize(oos);
        }
    }

    public static StatefulPersistenceContext deserialize(ObjectInputStream ois, SessionImplementor session)
            throws IOException, ClassNotFoundException {
        LOG.trace("Serializing persistent-context");
        StatefulPersistenceContext rtn = new StatefulPersistenceContext(session);

        // during deserialization, we need to reconnect all proxies and
        // collections to this session, as well as the EntityEntry and
        // CollectionEntry instances; these associations are transient
        // because serialization is used for different things.

        try {
            rtn.defaultReadOnly = ois.readBoolean();
            // todo : we can actually just determine this from the incoming EntityEntry-s
            rtn.hasNonReadOnlyEntities = ois.readBoolean();

            int count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] entitiesByKey entries");
            rtn.entitiesByKey = new HashMap(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                rtn.entitiesByKey.put(EntityKey.deserialize(ois, session), ois.readObject());
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] entitiesByUniqueKey entries");
            rtn.entitiesByUniqueKey = new HashMap(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                rtn.entitiesByUniqueKey.put(EntityUniqueKey.deserialize(ois, session), ois.readObject());
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] proxiesByKey entries");
            rtn.proxiesByKey = new ReferenceMap(AbstractReferenceMap.HARD, AbstractReferenceMap.WEAK,
                    count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count, .75f);
            for (int i = 0; i < count; i++) {
                EntityKey ek = EntityKey.deserialize(ois, session);
                Object proxy = ois.readObject();
                if (proxy instanceof HibernateProxy) {
                    ((HibernateProxy) proxy).getHibernateLazyInitializer().setSession(session);
                    rtn.proxiesByKey.put(ek, proxy);
                } else
                    LOG.trace("Encountered prunded proxy");
                // otherwise, the proxy was pruned during the serialization process
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] entitySnapshotsByKey entries");
            rtn.entitySnapshotsByKey = new HashMap(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                rtn.entitySnapshotsByKey.put(EntityKey.deserialize(ois, session), ois.readObject());
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] entityEntries entries");
            rtn.entityEntries = IdentityMap.instantiateSequenced(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                Object entity = ois.readObject();
                EntityEntry entry = EntityEntry.deserialize(ois, session);
                rtn.entityEntries.put(entity, entry);
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] collectionsByKey entries");
            rtn.collectionsByKey = new HashMap(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                rtn.collectionsByKey.put(CollectionKey.deserialize(ois, session), ois.readObject());
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] collectionEntries entries");
            rtn.collectionEntries = IdentityMap
                    .instantiateSequenced(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                final PersistentCollection pc = (PersistentCollection) ois.readObject();
                final CollectionEntry ce = CollectionEntry.deserialize(ois, session);
                pc.setCurrentSession(session);
                rtn.collectionEntries.put(pc, ce);
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] arrayHolders entries");
            rtn.arrayHolders = IdentityMap.instantiate(count < INIT_COLL_SIZE ? INIT_COLL_SIZE : count);
            for (int i = 0; i < count; i++) {
                rtn.arrayHolders.put(ois.readObject(), ois.readObject());
            }

            count = ois.readInt();
            LOG.trace("Starting deserialization of [" + count + "] nullifiableEntityKey entries");
            rtn.nullifiableEntityKeys = new HashSet();
            for (int i = 0; i < count; i++) {
                rtn.nullifiableEntityKeys.add(EntityKey.deserialize(ois, session));
            }

        } catch (HibernateException he) {
            throw new InvalidObjectException(he.getMessage());
        }

        return rtn;
    }

    /**
     * @see org.hibernate.engine.spi.PersistenceContext#addChildParent(java.lang.Object, java.lang.Object)
     */
    public void addChildParent(Object child, Object parent) {
        parentsByChild.put(child, parent);
    }

    /**
     * @see org.hibernate.engine.spi.PersistenceContext#removeChildParent(java.lang.Object)
     */
    public void removeChildParent(Object child) {
        parentsByChild.remove(child);
    }

    private HashMap<String, List<Serializable>> insertedKeysMap;

    /**
     * {@inheritDoc}
     */
    public void registerInsertedKey(EntityPersister persister, Serializable id) {
        // we only are about regsitering these if the persister defines caching
        if (persister.hasCache()) {
            if (insertedKeysMap == null) {
                insertedKeysMap = new HashMap<String, List<Serializable>>();
            }
            final String rootEntityName = persister.getRootEntityName();
            List<Serializable> insertedEntityIds = insertedKeysMap.get(rootEntityName);
            if (insertedEntityIds == null) {
                insertedEntityIds = new ArrayList<Serializable>();
                insertedKeysMap.put(rootEntityName, insertedEntityIds);
            }
            insertedEntityIds.add(id);
        }
    }

    /**
     * {@inheritDoc}
     */
    public boolean wasInsertedDuringTransaction(EntityPersister persister, Serializable id) {
        // again, we only really care if the entity is cached
        if (persister.hasCache()) {
            if (insertedKeysMap != null) {
                List<Serializable> insertedEntityIds = insertedKeysMap.get(persister.getRootEntityName());
                if (insertedEntityIds != null) {
                    return insertedEntityIds.contains(id);
                }
            }
        }
        return false;
    }

    private void cleanUpInsertedKeysAfterTransaction() {
        if (insertedKeysMap != null) {
            insertedKeysMap.clear();
        }
    }
}