package org.apache.commons.jcs.auxiliary.remote;
   
   /*
    * 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.rmi.UnmarshalException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCache;
  import org.apache.commons.jcs.auxiliary.AuxiliaryCacheAttributes;
  import org.apache.commons.jcs.auxiliary.remote.behavior.IRemoteCacheClient;
  import org.apache.commons.jcs.engine.CacheAdaptor;
  import org.apache.commons.jcs.engine.CacheEventQueueFactory;
  import org.apache.commons.jcs.engine.CacheStatus;
  import org.apache.commons.jcs.engine.behavior.ICacheElement;
  import org.apache.commons.jcs.engine.behavior.ICacheEventQueue;
  import org.apache.commons.jcs.engine.behavior.ICacheServiceNonLocal;
  import org.apache.commons.jcs.engine.stats.StatElement;
  import org.apache.commons.jcs.engine.stats.Stats;
  import org.apache.commons.jcs.engine.stats.behavior.IStatElement;
  import org.apache.commons.jcs.engine.stats.behavior.IStats;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /**
   * The RemoteCacheNoWait wraps the RemoteCacheClient. The client holds a handle on the
   * RemoteCacheService.
   * <p>
   * Used to queue up update requests to the underlying cache. These requests will be processed in
   * their order of arrival via the cache event queue processor.
   * <p>
   * Typically errors will be handled down stream. We only need to kill the queue if an error makes it
   * to this level from the queue. That can only happen if the queue is damaged, since the events are
   * Processed asynchronously.
   * <p>
   * There is no reason to create a queue on startup if the remote is not healthy.
   * <p>
   * If the remote cache encounters an error it will zombie--create a balking facade for the service.
   * The Zombie will queue up items until the connection is restored. An alternative way to accomplish
   * the same thing would be to stop, not destroy the queue at this level. That way items would be
   * added to the queue and then when the connection is restored, we could start the worker threads
   * again. This is a better long term solution, but it requires some significant changes to the
   * complicated worker queues.
   */
  public class RemoteCacheNoWait<K, V>
      extends AbstractAuxiliaryCache<K, V>
  {
      /** log instance */
      private static final Log log = LogFactory.getLog( RemoteCacheNoWait.class );
  
      /** The remote cache client */
      private final IRemoteCacheClient<K, V> remoteCacheClient;
  
      /** Event queue for queuing up calls like put and remove. */
      private ICacheEventQueue<K, V> cacheEventQueue;
  
      /** how many times get has been called. */
      private int getCount = 0;
  
      /** how many times getMatching has been called. */
      private int getMatchingCount = 0;
  
      /** how many times getMultiple has been called. */
      private int getMultipleCount = 0;
  
      /** how many times remove has been called. */
      private int removeCount = 0;
  
      /** how many times put has been called. */
      private int putCount = 0;
  
      /**
       * Constructs with the given remote cache, and fires up an event queue for asynchronous
       * processing.
       * <p>
       * @param cache
       */
      public RemoteCacheNoWait( IRemoteCacheClient<K, V> cache )
     {
         remoteCacheClient = cache;
         this.cacheEventQueue = createCacheEventQueue(cache);
 
         if ( remoteCacheClient.getStatus() == CacheStatus.ERROR )
         {
             cacheEventQueue.destroy();
         }
     }
 
     /**
      * Create a cache event queue from the parameters of the remote client
      * @param client the remote client
      */
     private ICacheEventQueue<K, V> createCacheEventQueue( IRemoteCacheClient<K, V> client )
     {
         CacheEventQueueFactory<K, V> factory = new CacheEventQueueFactory<K, V>();
         ICacheEventQueue<K, V> ceq = factory.createCacheEventQueue(
             new CacheAdaptor<K, V>( client ),
             client.getListenerId(),
             client.getCacheName(),
             client.getAuxiliaryCacheAttributes().getEventQueuePoolName(),
             client.getAuxiliaryCacheAttributes().getEventQueueType() );
         return ceq;
     }
 
     /**
      * Adds a put event to the queue.
      * <p>
      * @param element
      * @throws IOException
      */
     @Override
     public void update( ICacheElement<K, V> element )
         throws IOException
     {
         putCount++;
         try
         {
             cacheEventQueue.addPutEvent( element );
         }
         catch ( IOException e )
         {
             log.error( "Problem adding putEvent to queue.", e );
             cacheEventQueue.destroy();
             throw e;
         }
     }
 
     /**
      * Synchronously reads from the remote cache.
      * <p>
      * @param key
      * @return element from the remote cache, or null if not present
      * @throws IOException
      */
     @Override
     public ICacheElement<K, V> get( K key )
         throws IOException
     {
         getCount++;
         try
         {
             return remoteCacheClient.get( key );
         }
         catch ( UnmarshalException ue )
         {
             if ( log.isDebugEnabled() )
             {
                 log.debug( "Retrying the get owing to UnmarshalException." );
             }
 
             try
             {
                 return remoteCacheClient.get( key );
             }
             catch ( IOException ex )
             {
                 if ( log.isInfoEnabled() )
                 {
                     log.info( "Failed in retrying the get for the second time. " + ex.getMessage() );
                 }
             }
         }
         catch ( IOException ex )
         {
             // We don't want to destroy the queue on a get failure.
             // The RemoteCache will Zombie and queue.
             // Since get does not use the queue, I don't want to kill the queue.
             throw ex;
         }
 
         return null;
     }
 
     /**
      * @param pattern
      * @return Map
      * @throws IOException
      *
      */
     @Override
     public Map<K, ICacheElement<K, V>> getMatching( String pattern )
         throws IOException
     {
         getMatchingCount++;
         try
         {
             return remoteCacheClient.getMatching( pattern );
         }
         catch ( UnmarshalException ue )
         {
             if ( log.isDebugEnabled() )
             {
                 log.debug( "Retrying the getMatching owing to UnmarshalException." );
             }
 
             try
             {
                 return remoteCacheClient.getMatching( pattern );
             }
             catch ( IOException ex )
             {
                 if ( log.isInfoEnabled() )
                 {
                     log.info( "Failed in retrying the getMatching for the second time. " + ex.getMessage() );
                 }
             }
         }
         catch ( IOException ex )
         {
             // We don't want to destroy the queue on a get failure.
             // The RemoteCache will Zombie and queue.
             // Since get does not use the queue, I don't want to kill the queue.
             throw ex;
         }
 
         return Collections.emptyMap();
     }
 
     /**
      * Gets multiple items from the cache based on the given set of keys. Sends the getMultiple
      * request on to the server rather than looping through the requested keys.
      * <p>
      * @param keys
      * @return a map of K key to ICacheElement&lt;K, V&gt; element, or an empty map if there is no
      *         data in cache for any of these keys
      * @throws IOException
      */
     @Override
     public Map<K, ICacheElement<K, V>> getMultiple( Set<K> keys )
         throws IOException
     {
         getMultipleCount++;
         try
         {
             return remoteCacheClient.getMultiple( keys );
         }
         catch ( UnmarshalException ue )
         {
             if ( log.isDebugEnabled() )
             {
                 log.debug( "Retrying the getMultiple owing to UnmarshalException..." );
             }
 
             try
             {
                 return remoteCacheClient.getMultiple( keys );
             }
             catch ( IOException ex )
             {
                 if ( log.isInfoEnabled() )
                 {
                     log.info( "Failed in retrying the getMultiple for the second time. " + ex.getMessage() );
                 }
             }
         }
         catch ( IOException ex )
         {
             // We don't want to destroy the queue on a get failure.
             // The RemoteCache will Zombie and queue.
             // Since get does not use the queue, I don't want to kill the queue.
             throw ex;
         }
 
         return new HashMap<K, ICacheElement<K, V>>();
     }
 
     /**
      * Return the keys in this cache.
      * <p>
      * @see org.apache.commons.jcs.auxiliary.AuxiliaryCache#getKeySet()
      */
     @Override
     public Set<K> getKeySet() throws IOException
     {
         return remoteCacheClient.getKeySet();
     }
 
     /**
      * Adds a remove request to the remote cache.
      * <p>
      * @param key
      * @return if this was successful
      * @throws IOException
      */
     @Override
     public boolean remove( K key )
         throws IOException
     {
         removeCount++;
         try
         {
             cacheEventQueue.addRemoveEvent( key );
         }
         catch ( IOException e )
         {
             log.error( "Problem adding RemoveEvent to queue.", e );
             cacheEventQueue.destroy();
             throw e;
         }
         return false;
     }
 
     /**
      * Adds a removeAll request to the remote cache.
      * <p>
      * @throws IOException
      */
     @Override
     public void removeAll()
         throws IOException
     {
         try
         {
             cacheEventQueue.addRemoveAllEvent();
         }
         catch ( IOException e )
         {
             log.error( "Problem adding RemoveAllEvent to queue.", e );
             cacheEventQueue.destroy();
             throw e;
         }
     }
 
     /** Adds a dispose request to the remote cache. */
     @Override
     public void dispose()
     {
         try
         {
             cacheEventQueue.addDisposeEvent();
         }
         catch ( IOException e )
         {
             log.error( "Problem adding DisposeEvent to queue.", e );
             cacheEventQueue.destroy();
         }
     }
 
     /**
      * No remote invocation.
      * <p>
      * @return The size value
      */
     @Override
     public int getSize()
     {
         return remoteCacheClient.getSize();
     }
 
     /**
      * No remote invocation.
      * <p>
      * @return The cacheType value
      */
     @Override
     public CacheType getCacheType()
     {
         return CacheType.REMOTE_CACHE;
     }
 
     /**
      * Returns the asyn cache status. An error status indicates either the remote connection is not
      * available, or the asyn queue has been unexpectedly destroyed. No remote invocation.
      * <p>
      * @return The status value
      */
     @Override
     public CacheStatus getStatus()
     {
         return cacheEventQueue.isWorking() ? remoteCacheClient.getStatus() : CacheStatus.ERROR;
     }
 
     /**
      * Gets the cacheName attribute of the RemoteCacheNoWait object
      * <p>
      * @return The cacheName value
      */
     @Override
     public String getCacheName()
     {
         return remoteCacheClient.getCacheName();
     }
 
     /**
      * Replaces the remote cache service handle with the given handle and reset the event queue by
      * starting up a new instance.
      * <p>
      * @param remote
      */
     public void fixCache( ICacheServiceNonLocal<?, ?> remote )
     {
         remoteCacheClient.fixCache( remote );
         resetEventQ();
     }
 
     /**
      * Resets the event q by first destroying the existing one and starting up new one.
      * <p>
      * There may be no good reason to kill the existing queue. We will sometimes need to set a new
      * listener id, so we should create a new queue. We should let the old queue drain. If we were
      * Connected to the failover, it would be best to finish sending items.
      */
     public void resetEventQ()
     {
         ICacheEventQueue<K, V> previousQueue = cacheEventQueue;
 
         this.cacheEventQueue = createCacheEventQueue(this.remoteCacheClient);
 
         if ( previousQueue.isWorking() )
         {
             // we don't expect anything, it would have all gone to the zombie
             if ( log.isInfoEnabled() )
             {
                 log.info( "resetEventQ, previous queue has [" + previousQueue.size() + "] items queued up." );
             }
             previousQueue.destroy();
         }
     }
 
     /**
      * This is temporary. It allows the manager to get the lister.
      * <p>
      * @return the instance of the remote cache client used by this object
      */
     protected IRemoteCacheClient<K, V> getRemoteCache()
     {
         return remoteCacheClient;
     }
 
     /**
      * @return Returns the AuxiliaryCacheAttributes.
      */
     @Override
     public AuxiliaryCacheAttributes getAuxiliaryCacheAttributes()
     {
         return remoteCacheClient.getAuxiliaryCacheAttributes();
     }
 
     /**
      * This is for testing only. It allows you to take a look at the event queue.
      * <p>
      * @return ICacheEventQueue
      */
     protected ICacheEventQueue<K, V> getCacheEventQueue()
     {
         return this.cacheEventQueue;
     }
 
     /**
      * Returns the stats and the cache.toString().
      * <p>
      * @see java.lang.Object#toString()
      */
     @Override
     public String toString()
     {
         return getStats() + "\n" + remoteCacheClient.toString();
     }
 
     /**
      * Returns the statistics in String form.
      * <p>
      * @return String
      */
     @Override
     public String getStats()
     {
         return getStatistics().toString();
     }
 
     /**
      * @return statistics about this communication
      */
     @Override
     public IStats getStatistics()
     {
         IStats stats = new Stats();
         stats.setTypeName( "Remote Cache No Wait" );
 
         ArrayList<IStatElement<?>> elems = new ArrayList<IStatElement<?>>();
 
         elems.add(new StatElement<CacheStatus>( "Status", getStatus() ) );
 
         // get the stats from the cache queue too
         IStats cStats = this.remoteCacheClient.getStatistics();
         if ( cStats != null )
         {
             elems.addAll(cStats.getStatElements());
         }
 
         // get the stats from the event queue too
         IStats eqStats = this.cacheEventQueue.getStatistics();
         elems.addAll(eqStats.getStatElements());
 
         elems.add(new StatElement<Integer>( "Get Count", Integer.valueOf(this.getCount) ) );
         elems.add(new StatElement<Integer>( "GetMatching Count", Integer.valueOf(this.getMatchingCount) ) );
         elems.add(new StatElement<Integer>( "GetMultiple Count", Integer.valueOf(this.getMultipleCount) ) );
         elems.add(new StatElement<Integer>( "Remove Count", Integer.valueOf(this.removeCount) ) );
         elems.add(new StatElement<Integer>( "Put Count", Integer.valueOf(this.putCount) ) );
 
         stats.setStatElements( elems );
 
         return stats;
     }
 
     /**
      * this won't be called since we don't do ICache logging here.
      * <p>
      * @return String
      */
     @Override
     public String getEventLoggingExtraInfo()
     {
         return "Remote Cache No Wait";
     }
 }