/*

  * Copyright 2005-2007 The Kuali Foundation

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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.

  */

 package org.kuali.rice.krad.util.cache;

 import java.util.Properties;

 import org.apache.log4j.Logger;

 import org.apache.ojb.broker.Identity;

 import org.apache.ojb.broker.PersistenceBroker;

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

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

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

 import org.kuali.rice.krad.service.KRADServiceLocatorInternal;

 import com.opensymphony.oscache.base.Cache;

 import com.opensymphony.oscache.base.NeedsRefreshException;

 import com.opensymphony.oscache.general.GeneralCacheAdministrator;

 /*

  * Copyright 2002-2004 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.

  */

 /**

  * ObjectCacheOSCacheImpl

  * 

  * Original source http://db.apache.org/ojb/docu/guides/objectcache.html#oscache

  * 

  * We use the extended caching interface {@link ObjectCacheInternal}to allow usage of this implementation in

  * {@link ObjectCacheTwoLevelImpl}.

  */

 public class ObjectCacheOSCacheImpl implements ObjectCacheInternal {

     private static final Logger LOG = Logger.getLogger(ObjectCacheOSCacheImpl.class);

     private static final int REFRESH_PERIOD = com.opensymphony.oscache.base.CacheEntry.INDEFINITE_EXPIRY;

     // using SpringServiceLocator to get the admin, since there's no obvious way to let Spring inject

     // create/manage the actual cache instance that OJB will use

     private final GeneralCacheAdministrator admin;

     /**

      * Required default constructor.

      */

     public ObjectCacheOSCacheImpl() {

         admin = KRADServiceLocatorInternal.getPersistenceCacheAdministrator();

     }

     /**

      * Required constructor.

      * 

      * @param broker

      * @param prop

      */

     public ObjectCacheOSCacheImpl(PersistenceBroker broker, Properties prop) {

         this();

     }

     /**

      * @see org.apache.ojb.broker.cache.ObjectCache#cache(org.apache.ojb.broker.Identity, java.lang.Object)

      */

     public void cache(Identity oid, Object obj) {

         Cache cache = admin.getCache();

         try {

             /*

              * Actually, OSCache sends notifications (Events) only on flush events. The putInCache method do not flush the cache, so

              * no event is sent. The ObjectCacheOSCacheInternalImpl should force OSCache to flush the entry in order to generate an

              * event. This guarantee that other nodes always in sync with the DB. Alternative a non-indefinite refresh-period could

              * be used in conjunction with optimistic-locking for persistent objects.

              */

             remove(oid);

             admin.putInCache(oid.toString(), obj);

         }

         catch (Exception e) {

             LOG.error("error caching object: " + oid, e);

         }

     }

     /**

      * @see org.apache.ojb.broker.cache.ObjectCacheInternal#doInternalCache(org.apache.ojb.broker.Identity, java.lang.Object, int)

      */

     public void doInternalCache(Identity oid, Object obj, int type) {

         cache(oid, obj);

     }

     /**

      * @see org.apache.ojb.broker.cache.ObjectCacheInternal#cacheIfNew(org.apache.ojb.broker.Identity, java.lang.Object)

      */

     public boolean cacheIfNew(Identity oid, Object obj) {

         boolean result = false;

         Cache cache = admin.getCache();

         try {

             cache.getFromCache(oid.toString());

         }

         catch (NeedsRefreshException e) {

             try {

                 cache.putInCache(oid.toString(), obj);

                 result = true;

             }

             catch (Exception e1) {

                 cache.cancelUpdate(oid.toString());

                 LOG.error("error caching object: " + oid, e);

             }

         }

         return result;

     }

     /**

      * @see org.apache.ojb.broker.cache.ObjectCache#lookup(org.apache.ojb.broker.Identity)

      */

     public Object lookup(Identity oid) {

         Object cachedObject = null;

         Cache cache = admin.getCache();

         try {

             cachedObject = cache.getFromCache(oid.toString(), REFRESH_PERIOD);

         }

         catch (NeedsRefreshException e) {

             cache.cancelUpdate(oid.toString());

         }

         catch (Exception e) {

             cache.cancelUpdate(oid.toString());

             LOG.error("error retrieving object from cache: " + oid, e);

         }

         return cachedObject;

     }

     /**

      * @see org.apache.ojb.broker.cache.ObjectCache#remove(org.apache.ojb.broker.Identity)

      */

     public void remove(Identity oid) {

         try {

             admin.flushEntry(oid.toString());

         }

         catch (Exception e) {

             throw new RuntimeCacheException("error removing object from cache: " + oid, e);

         }

     }

     /**

      * @see org.apache.ojb.broker.cache.ObjectCache#clear()

      */

     public void clear() {

         try {

             admin.flushAll();

         }

         catch (Exception e) {

             throw new RuntimeCacheException("error clearing cache", e);

         }

     }

 }