package org.apache.commons.jcs.engine;
   
   import java.io.IOException;
   import java.util.Map;
   import java.util.Set;
   import java.util.concurrent.ConcurrentHashMap;
   import java.util.concurrent.ConcurrentMap;
   import java.util.concurrent.CopyOnWriteArraySet;
   
  /*
   * 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 org.apache.commons.jcs.engine.behavior.ICacheListener;
  import org.apache.commons.jcs.engine.behavior.ICacheObserver;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /**
   * 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 static final Log log = LogFactory.getLog( CacheWatchRepairable.class );
  
      /** the underlying ICacheObserver. */
      private ICacheObserver cacheWatch;
  
      /** Map of cache regions. */
      private final ConcurrentMap<String, Set<ICacheListener<?, ?>>> cacheMap =
          new ConcurrentHashMap<String, Set<ICacheListener<?, ?>>>();
  
      /**
       * Replaces the underlying cache watch service and re-attaches all existing listeners to the new
       * cache watch.
       * <p>
       * @param cacheWatch The new cacheWatch value
       */
      public void setCacheWatch( ICacheObserver cacheWatch )
      {
          this.cacheWatch = cacheWatch;
          for (Map.Entry<String, Set<ICacheListener<?, ?>>> entry : cacheMap.entrySet())
          {
              String cacheName = entry.getKey();
              for (ICacheListener<?, ?> listener : entry.getValue())
              {
                  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
       */
      @Override
      public <K, V> void addCacheListener( String cacheName, ICacheListener<K, V> obj )
          throws IOException
      {
          // Record the added cache listener locally, regardless of whether the
          // remote add-listener operation succeeds or fails.
          Set<ICacheListener<?, ?>> listenerSet = cacheMap.get( cacheName );
          if ( listenerSet == null )
          {
             Set<ICacheListener<?, ?>> newListenerSet = new CopyOnWriteArraySet<ICacheListener<?, ?>>();
             listenerSet = cacheMap.putIfAbsent( cacheName, newListenerSet );
 
             if (listenerSet == null)
             {
                 listenerSet = newListenerSet;
             }
         }
 
         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
      */
     @Override
     public <K, V> void addCacheListener( ICacheListener<K, V> obj )
         throws IOException
     {
         // Record the added cache listener locally, regardless of whether the
         // remote add-listener operation succeeds or fails.
         for (Set<ICacheListener<?, ?>> listenerSet : cacheMap.values())
         {
             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
      */
     @Override
     public <K, V> void removeCacheListener( String cacheName, ICacheListener<K, V> 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.
         Set<ICacheListener<?, ?>> listenerSet = cacheMap.get( cacheName );
         if ( listenerSet != null )
         {
             listenerSet.remove( obj );
         }
         cacheWatch.removeCacheListener( cacheName, obj );
     }
 
     /**
      * @param obj
      * @throws IOException
      */
     @Override
     public <K, V> void removeCacheListener( ICacheListener<K, V> 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.
         for (Set<ICacheListener<?, ?>> listenerSet : cacheMap.values())
         {
             if ( log.isDebugEnabled() )
             {
                 log.debug( "Before removing [" + obj + "] the listenerSet = " + listenerSet );
             }
             listenerSet.remove( obj );
         }
         cacheWatch.removeCacheListener( obj );
     }
 }