/*

  * 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.kns.util.cache;

 import java.util.HashSet;

 import java.util.Set;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import com.opensymphony.oscache.base.events.CacheEntryEvent;

 import com.opensymphony.oscache.base.events.CacheEntryEventListener;

 import com.opensymphony.oscache.base.events.CacheGroupEvent;

 import com.opensymphony.oscache.base.events.CachePatternEvent;

 import com.opensymphony.oscache.base.events.CachewideEvent;

 /**

  * Monitor entry-related events for a cache.

  */

 @SuppressWarnings("unchecked")

 abstract public class OSCacheMonitor implements CacheEntryEventListener {

     private static final Log LOG = LogFactory.getLog(OSCacheMonitor.class);

     private final String purpose;

     private final Set entries;

     /**

      * Constructs a OSCacheMonitor with the given purpose

      * 

      * @param purpose

      */

         public OSCacheMonitor(String purpose) {

         this.purpose = purpose;

         entries = new HashSet();

         if ( LOG.isInfoEnabled() ) {

                 LOG.info("created " + purpose + " CacheMonitor ");

         }

     }

     public void cacheEntryAdded(CacheEntryEvent event) {

         entries.add(event.getKey());

         if ( LOG.isDebugEnabled() ) {

                 logEntryEvent("added", event);

         }

     }

     public void cacheEntryUpdated(CacheEntryEvent event) {

             if ( LOG.isDebugEnabled() ) {

                     logEntryEvent("updated", event);

             }

     }

     public void cacheEntryFlushed(CacheEntryEvent event) {

         entries.remove(event.getKey());

         if ( LOG.isDebugEnabled() ) {

                 logEntryEvent("flushed", event);

         }

     }

     public void cacheEntryRemoved(CacheEntryEvent event) {

         entries.remove(event.getKey());

         if ( LOG.isDebugEnabled() ) {

                 logEntryEvent("removed", event);

         }

     }

     public void cacheFlushed(CachewideEvent event) {

         entries.clear();

         if ( LOG.isDebugEnabled() ) {

                 LOG.debug(purpose + " flushed cache (" + entries.size() + " entries)");

         }

     }

     public void cacheGroupFlushed(CacheGroupEvent event) {

         // if I read the code correctly, each entry gets its own cacheEntryFlused event

             if ( LOG.isInfoEnabled() ) {

                     LOG.info(purpose + " flushed cache group '" + event.getGroup() + "'");

             }

     }

     public void cachePatternFlushed(CachePatternEvent event) {

         // if I read the code correctly, each entry gets its own cacheEntryFlused event

             if ( LOG.isInfoEnabled() ) {

                     LOG.info(purpose + " flushed cache pattern '" + event.getPattern() + "'");

             }

     }

     private void logEntryEvent(String verb, CacheEntryEvent event) {

         LOG.debug(purpose + " " + verb + " entry '" + event.getKey() + "' (" + entries.size() + " entries)");

     }

 }