package org.apache.jcs.engine;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.io.IOException;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.jcs.engine.behavior.ICacheListener;
  import org.apache.jcs.engine.behavior.ICacheObserver;
  
  /***
   * Intercepts the requests to the underlying ICacheObserver object so that the listeners can be
   * recorded locally for remote connection recovery purposes. (Durable subscription like those in JMS
   * is not implemented at this stage for it can be too expensive.)
   */
  public class CacheWatchRepairable
      implements ICacheObserver
  {
      /*** The logger */
      private final static Log log = LogFactory.getLog( CacheWatchRepairable.class );
  
      /*** the underlying ICacheObserver. */
      private ICacheObserver cacheWatch;
  
      /*** Map of cache regions. */
      private Map cacheMap = new HashMap();
  
      /***
       * Replaces the underlying cache watch service and reattached all existing listeners to the new
       * cache watch.
       * <p>
       * @param cacheWatch The new cacheWatch value
       */
      public void setCacheWatch( ICacheObserver cacheWatch )
      {
          this.cacheWatch = cacheWatch;
          synchronized ( cacheMap )
          {
              for ( Iterator itr = cacheMap.entrySet().iterator(); itr.hasNext(); )
              {
                  Map.Entry entry = (Map.Entry) itr.next();
                  String cacheName = (String) entry.getKey();
                  Set listenerSet = (Set) entry.getValue();
                  for ( Iterator itr2 = listenerSet.iterator(); itr2.hasNext(); )
                  {
                      ICacheListener listener = (ICacheListener) itr2.next();
                      try
                      {
                          if ( log.isInfoEnabled() )
                          {
                              log.info( "Adding listener to cache watch. ICacheListener = " + listener
                                  + " | ICacheObserver = " + cacheWatch );
                          }
                          cacheWatch.addCacheListener( cacheName, listener );
                      }
                      catch ( IOException ex )
                      {
                          log.error( "Problem adding listener. ICacheListener = " + listener + " | ICacheObserver = "
                              + cacheWatch, ex );
                      }
                  }
              }
          }
      }
  
      /***
       * Adds a feature to the CacheListener attribute of the CacheWatchRepairable object
       * <p>
       * @param cacheName The feature to be added to the CacheListener attribute
       * @param obj The feature to be added to the CacheListener attribute
       * @throws IOException
       */
      public void addCacheListener( String cacheName, ICacheListener obj )
          throws IOException
      {
          // Record the added cache listener locally, regardless of whether the
         // remote add-listener operation succeeds or fails.
         synchronized ( cacheMap )
         {
             Set listenerSet = (Set) cacheMap.get( cacheName );
             if ( listenerSet == null )
             {
                 listenerSet = new HashSet();
                 
                 cacheMap.put( cacheName, listenerSet );
             }
             listenerSet.add( obj );
         }
         if ( log.isInfoEnabled() )
         {
             log.info( "Adding listener to cache watch. ICacheListener = " + obj
                 + " | ICacheObserver = " + cacheWatch + " | cacheName = " + cacheName );
         }
         cacheWatch.addCacheListener( cacheName, obj );
     }
 
     /***
      * Adds a feature to the CacheListener attribute of the CacheWatchRepairable object
      * <p>
      * @param obj The feature to be added to the CacheListener attribute
      * @throws IOException
      */
     public void addCacheListener( ICacheListener obj )
         throws IOException
     {
         // Record the added cache listener locally, regardless of whether the
         // remote add-listener operation succeeds or fails.
         synchronized ( cacheMap )
         {
             for ( Iterator itr = cacheMap.values().iterator(); itr.hasNext(); )
             {
                 Set listenerSet = (Set) itr.next();
                 listenerSet.add( obj );
             }
         }
         if ( log.isInfoEnabled() )
         {
             log.info( "Adding listener to cache watch. ICacheListener = " + obj
                 + " | ICacheObserver = " + cacheWatch );
         }        
         cacheWatch.addCacheListener( obj );
     }
 
     /***
      * Tell the server to release us.
      * <p>
      * @param cacheName
      * @param obj
      * @throws IOException
      */
     public void removeCacheListener( String cacheName, ICacheListener obj )
         throws IOException
     {
         if ( log.isInfoEnabled() )
         {
             log.info( "removeCacheListener, cacheName [" + cacheName + "]" );
         }
         // Record the removal locally, regardless of whether the remote
         // remove-listener operation succeeds or fails.
         synchronized ( cacheMap )
         {
             Set listenerSet = (Set) cacheMap.get( cacheName );
             if ( listenerSet != null )
             {
                 listenerSet.remove( obj );
             }
         }
         cacheWatch.removeCacheListener( cacheName, obj );
     }
 
     /***
      * @param obj
      * @throws IOException
      */
     public void removeCacheListener( ICacheListener obj )
         throws IOException
     {
         if ( log.isInfoEnabled() )
         {
             log.info( "removeCacheListener, ICacheListener [" + obj + "]" );
         }
 
         // Record the removal locally, regardless of whether the remote
         // remove-listener operation succeeds or fails.
         synchronized ( cacheMap )
         {
             for ( Iterator itr = cacheMap.values().iterator(); itr.hasNext(); )
             {
                 Set listenerSet = (Set) itr.next();
                 if ( log.isDebugEnabled() )
                 {
                     log.debug( "Before removing [" + obj + "] the listenerSet = " + listenerSet );
                 }
                 listenerSet.remove( obj );
             }
         }
         cacheWatch.removeCacheListener( obj );
     }
 }