package org.apache.ojb.broker.accesslayer;

 /* Copyright 2003-2005 The Apache Software Foundation

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.HashMap;

 import java.util.HashSet;

 import java.util.Iterator;

 import java.util.Map;

 import org.apache.ojb.broker.Identity;

 import org.apache.ojb.broker.PersistenceBroker;

 import org.apache.ojb.broker.cache.ObjectCache;

 import org.apache.ojb.broker.core.PersistenceBrokerImpl;

 import org.apache.ojb.broker.core.proxy.IndirectionHandler;

 import org.apache.ojb.broker.core.proxy.ProxyHelper;

 import org.apache.ojb.broker.query.Query;

 /**

  * Prefetcher for plain list of objects (no relations).

  *

  * @author <a href="mailto:olegnitz@apache.org">Oleg Nitz</a>

  * @version $Id: PlainPrefetcher.java,v 1.1 2007-08-24 22:17:30 ewestfal Exp $

  */

 public class PlainPrefetcher extends BasePrefetcher

 {

     public PlainPrefetcher(PersistenceBrokerImpl aBroker, Class anItemClass)

     {

         super(aBroker, anItemClass);

     }

     public void prepareRelationshipSettings()

     {

         // no op

     }

     public void restoreRelationshipSettings()

     {

         // no op

     }

     protected void associateBatched(Collection proxies, Collection realSubjects)

     {

         PersistenceBroker pb = getBroker();

         IndirectionHandler handler;

         Identity id;

         Object proxy;

         Object realSubject;

         HashMap realSubjectsMap = new HashMap(realSubjects.size());

         for (Iterator it = realSubjects.iterator(); it.hasNext(); )

         {

             realSubject = it.next();

             realSubjectsMap.put(pb.serviceIdentity().buildIdentity(realSubject), realSubject);

         }

         for (Iterator it = proxies.iterator(); it.hasNext(); )

         {

             proxy = it.next();

             handler = ProxyHelper.getIndirectionHandler(proxy);

             if (handler == null)

             {

                 continue;

             }

             id = handler.getIdentity();

             realSubject = realSubjectsMap.get(id);

             if (realSubject != null)

             {

                 handler.setRealSubject(realSubject);

             }

         }

     }

     /**

      * Build the multiple queries for one relationship because of limitation of IN(...)

      * @param proxies Collection containing all proxy objects to load

      * @param realSubjects Collection where real subjects found in the cache should be added.

      */

     protected Query[] buildPrefetchQueries(Collection proxies, Collection realSubjects)

     {

         Collection queries = new ArrayList();

         Collection idsSubset;

         Object proxy;

         IndirectionHandler handler;

         Identity id;

         Class realClass;

         HashMap classToIds = new HashMap();

         Class topLevelClass = getItemClassDescriptor().getClassOfObject();

         PersistenceBroker pb = getBroker();

         ObjectCache cache = pb.serviceObjectCache();

         for (Iterator it = proxies.iterator(); it.hasNext(); )

         {

             proxy = it.next();

             handler = ProxyHelper.getIndirectionHandler(proxy);

             if (handler == null)

             {

                 continue;

             }

             id = handler.getIdentity();

             if (cache.lookup(id) != null)

             {

                 realSubjects.add(pb.getObjectByIdentity(id));

                 continue;

             }

             realClass = id.getObjectsRealClass();

             if (realClass == null)

             {

                 realClass = Object.class; // to remember that the real class is unknown

             }

             idsSubset = (HashSet) classToIds.get(realClass);

             if (idsSubset == null)

             {

                 idsSubset = new HashSet();

                 classToIds.put(realClass, idsSubset);

             }

             idsSubset.add(id);

             if (idsSubset.size() == pkLimit)

             {

                 Query query;

                 if (realClass == Object.class)

                 {

                     query = buildPrefetchQuery(topLevelClass, idsSubset, true);

                 }

                 else

                 {

                     query = buildPrefetchQuery(realClass, idsSubset, false);

                 }

                 queries.add(query);

                 idsSubset.clear();

             }

         }

         for (Iterator it = classToIds.entrySet().iterator(); it.hasNext(); )

         {

             Map.Entry entry = (Map.Entry) it.next();

             realClass = (Class) entry.getKey();

             idsSubset = (HashSet) entry.getValue();

             if (idsSubset.size() > 0)

             {

                 Query query;

                 if (realClass == Object.class)

                 {

                     query = buildPrefetchQuery(topLevelClass, idsSubset, true);

                 }

                 else

                 {

                     query = buildPrefetchQuery(realClass, idsSubset, false);

                 }

                 queries.add(query);

             }

         }

         return (Query[]) queries.toArray(new Query[queries.size()]);

     }

     protected Query buildPrefetchQuery(Class clazz, Collection ids, boolean withExtents)

     {

         Query query = buildPrefetchQuery(clazz, ids,

                 getDescriptorRepository().getDescriptorFor(clazz).getPkFields());

         query.setWithExtents(withExtents);

         return query;

     }

 }