src/java/org/apache/fulcrum/cache/impl/JCSCacheService.java - turbine-fulcrum-cache - Git at Google

 package org.apache.fulcrum.cache.impl;

 /*
  * 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.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;

 import org.apache.avalon.framework.activity.Disposable;
 import org.apache.avalon.framework.activity.Initializable;
 import org.apache.avalon.framework.configuration.Configurable;
 import org.apache.avalon.framework.configuration.Configuration;
 import org.apache.avalon.framework.configuration.ConfigurationException;
 import org.apache.avalon.framework.logger.AbstractLogEnabled;
 import org.apache.avalon.framework.thread.ThreadSafe;
 import org.apache.commons.jcs3.JCS;
 import org.apache.commons.jcs3.access.GroupCacheAccess;
 import org.apache.commons.jcs3.access.exception.CacheException;
 import org.apache.commons.jcs3.engine.ElementAttributes;
 import org.apache.commons.jcs3.engine.control.CompositeCacheManager;
 import org.apache.fulcrum.cache.CachedObject;
 import org.apache.fulcrum.cache.GlobalCacheService;
 import org.apache.fulcrum.cache.ObjectExpiredException;
 import org.apache.fulcrum.cache.RefreshableCachedObject;

 /**
  * Default implementation of JCSCacheService
  *
  * @author <a href="mailto:tv@apache.org">Thomas Vandahl</a>
  * @version $Id$
  */
 public class JCSCacheService extends AbstractLogEnabled implements
         GlobalCacheService, Runnable, Configurable, Disposable, Initializable,
         ThreadSafe
 {
     /**
      * Cache check frequency in Millis (1000 Millis = 1 second). Value must be &gt;
      * 0. Default = 5 seconds
      */
     public static final long DEFAULT_CACHE_CHECK_FREQUENCY = 5000; // 5 seconds

     /**
      * cacheCheckFrequency (default - 5 seconds)
      */
     private long cacheCheckFrequency;

     /**
      * Instance of the JCS cache
      */
     private GroupCacheAccess<String, CachedObject<?>> cacheManager;

     /**
      * JCS region to use
      */
     private String region;

     /**
      * Path name of the JCS configuration file
      */
     private String configFile;

     /**
      * Constant value which provides a group name
      */
     private static String group = "default_group";

     /** thread for refreshing stale items in the cache */
     private Thread refreshing;

     /** flag to stop the housekeeping thread when the component is disposed. */
     private boolean continueThread;

     // ---------------- Avalon Lifecycle Methods ---------------------

     /**
      * @see org.apache.avalon.framework.configuration.Configurable#configure(org.apache.avalon.framework.configuration.Configuration)
      */
     @Override
 	public void configure(Configuration config) throws ConfigurationException
     {
         this.cacheCheckFrequency = config.getChild("cacheCheckFrequency")
                 .getValueAsLong(DEFAULT_CACHE_CHECK_FREQUENCY);
         this.region = config.getChild("region").getValue("fulcrum");
         this.configFile = config.getChild("configurationFile").getValue(
                 "/cache.ccf");
     }

     /**
      * @see org.apache.avalon.framework.activity.Initializable#initialize()
      */
     @Override
 	public void initialize() throws Exception
     {
         JCS.setConfigFilename(this.configFile);
         this.cacheManager = JCS.getGroupCacheInstance(this.region);

         // Start housekeeping thread.
         this.continueThread = true;
         this.refreshing = new Thread(this);

         // Indicate that this is a system thread. JVM will quit only when
         // there are no more active user threads. Settings threads spawned
         // internally by Turbine as daemons allows commandline applications
         // using Turbine to terminate in an orderly manner.
         this.refreshing.setDaemon(true);
         this.refreshing.setName("JCSCacheService Refreshing");
         this.refreshing.start();

         getLogger().debug("JCSCacheService started.");
     }

     /**
      * @see org.apache.avalon.framework.activity.Disposable#dispose()
      */
     @Override
 	public void dispose()
     {
         this.continueThread = false;
         this.refreshing.interrupt();

         this.cacheManager.dispose();
         this.cacheManager = null;
         CompositeCacheManager.getInstance().shutDown();

         getLogger().debug("JCSCacheService stopped.");
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#getObject(java.lang.String)
      */
     @Override
 	public <T> CachedObject<T> getObject(String id) throws ObjectExpiredException
     {
         @SuppressWarnings("unchecked")
         CachedObject<T> obj = (CachedObject<T>)this.cacheManager.getFromGroup(id, group);

         if (obj == null)
         {
             // Not in the cache.
             throw new ObjectExpiredException();
         }

         if (obj.isStale())
         {
             if (obj instanceof RefreshableCachedObject)
             {
                 RefreshableCachedObject<?> rco = (RefreshableCachedObject<?>) obj;
                 if (rco.isUntouched())
                 {
                     // Do not refresh an object that has exceeded TimeToLive
                     removeObject(id);
                     throw new ObjectExpiredException();
                 }

                 // Refresh Object
                 rco.refresh();
                 if (rco.isStale())
                 {
                     // Object is Expired, remove it from cache.
                     removeObject(id);
                     throw new ObjectExpiredException();
                 }
             }
             else
             {
                 // Expired.
                 removeObject(id);
                 throw new ObjectExpiredException();
             }
         }

         if (obj instanceof RefreshableCachedObject)
         {
             // notify it that it's being accessed.
             RefreshableCachedObject<?> rco = (RefreshableCachedObject<?>) obj;
             rco.touch();
         }

         return obj;
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#addObject(java.lang.String,
      *      org.apache.fulcrum.cache.CachedObject)
      */
     @Override
 	public <T> void addObject(String id, CachedObject<T> o)
     {
         try
         {
             if (!(o.getContents() instanceof Serializable))
             {
                 getLogger()
                         .warn(
                                 "Object with id ["
                                         + id
                                         + "] is not serializable. Expect problems with auxiliary caches.");
             }

             ElementAttributes attrib = (ElementAttributes) this.cacheManager.getDefaultElementAttributes();

             if (o instanceof RefreshableCachedObject)
             {
                 attrib.setIsEternal(true);
             }
             else
             {
                 attrib.setIsEternal(false);
                 // expires in millis, maxlife in seconds
                 double tmp0 = ((double) (o.getExpires() + 500)) / 1000;
                 getLogger().debug( "setting maxlife seconds (minimum 1sec) from expiry + 0.5s: " + (int)tmp0 );
                 attrib.setMaxLife(  (tmp0 > 0 ? (int) Math.floor( tmp0 ) : 1 ) );
             }

             attrib.setLastAccessTimeNow();
             attrib.setCreateTime();

             this.cacheManager.putInGroup(id, group, o, attrib);
         }
         catch (CacheException e)
         {
             getLogger().error("Could not add object " + id + " to cache", e);
         }
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#removeObject(java.lang.String)
      */
     @Override
 	public void removeObject(String id)
     {
         this.cacheManager.removeFromGroup(id, group);
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#getKeys()
      */
     @Override
 	public List<String> getKeys()
     {
         ArrayList<String> keys = new ArrayList<String>();

         keys.addAll(this.cacheManager.getGroupKeys(group));
         return keys;
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#getCachedObjects()
      */
     @Override
 	public List<CachedObject<?>> getCachedObjects()
     {
         ArrayList<CachedObject<?>> values = new ArrayList<CachedObject<?>>();

         for (String key : this.cacheManager.getGroupKeys(group))
         {
             CachedObject<?> o = this.cacheManager.getFromGroup(key, group);
             if (o != null)
             {
                 values.add(o);
             }
         }

         return values;
     }

     /**
      * Circle through the cache and refresh stale objects. Frequency is
      * determined by the cacheCheckFrequency property.
      */
     @Override
 	public void run()
     {
         while (this.continueThread)
         {
             // Sleep for amount of time set in cacheCheckFrequency -
             // default = 5 seconds.
             try
             {
                 Thread.sleep(this.cacheCheckFrequency);
             }
             catch (InterruptedException exc)
             {
                 if (!this.continueThread)
                 {
                     return;
                 }
             }

             for (String key : this.cacheManager.getGroupKeys(group))
             {
                 CachedObject<?> o = this.cacheManager.getFromGroup(key, group);
                 if (o == null)
                 {
                     removeObject(key);
                 }
                 else
                 {
                     if (o instanceof RefreshableCachedObject)
                     {
                         RefreshableCachedObject<?> rco = (RefreshableCachedObject<?>) o;
                         if (rco.isUntouched())
                         {
                             this.cacheManager.removeFromGroup(key, group);
                         }
                         else if (rco.isStale())
                         {
                             rco.refresh();
                         }
                     }
                 }
             }
         }
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#getCacheSize()
      */
     @Override
 	public int getCacheSize() throws IOException
     {
         // This is evil!
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         ObjectOutputStream out = new ObjectOutputStream(baos);
         Set<String> keys = this.cacheManager.getGroupKeys(group);

         for (String key : keys)
         {
             out.writeObject(this.cacheManager.getFromGroup(key, group));
         }

         out.flush();

         //
         // Subtract 4 bytes from the length, because the serialization
         // magic number (2 bytes) and version number (2 bytes) are
         // both written to the stream before the object
         //
         int objectsize = baos.toByteArray().length - 4 * keys.size();
         return objectsize;
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#getNumberOfObjects()
      */
     @Override
 	public int getNumberOfObjects()
     {
         int count = 0;

         for (String key : this.cacheManager.getGroupKeys(group))
         {
             if (this.cacheManager.getFromGroup(key, group) != null)
             {
                 count++;
             }
         }

         return count;
     }

     /**
      * @see org.apache.fulcrum.cache.GlobalCacheService#flushCache()
      */
     @Override
 	public void flushCache()
     {
         this.cacheManager.invalidateGroup(group);
     }
 }
	package org.apache.fulcrum.cache.impl;

	/*
	* 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.ByteArrayOutputStream;
	import java.io.IOException;
	import java.io.ObjectOutputStream;
	import java.io.Serializable;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.Set;

	import org.apache.avalon.framework.activity.Disposable;
	import org.apache.avalon.framework.activity.Initializable;
	import org.apache.avalon.framework.configuration.Configurable;
	import org.apache.avalon.framework.configuration.Configuration;
	import org.apache.avalon.framework.configuration.ConfigurationException;
	import org.apache.avalon.framework.logger.AbstractLogEnabled;
	import org.apache.avalon.framework.thread.ThreadSafe;
	import org.apache.commons.jcs3.JCS;
	import org.apache.commons.jcs3.access.GroupCacheAccess;
	import org.apache.commons.jcs3.access.exception.CacheException;
	import org.apache.commons.jcs3.engine.ElementAttributes;
	import org.apache.commons.jcs3.engine.control.CompositeCacheManager;
	import org.apache.fulcrum.cache.CachedObject;
	import org.apache.fulcrum.cache.GlobalCacheService;
	import org.apache.fulcrum.cache.ObjectExpiredException;
	import org.apache.fulcrum.cache.RefreshableCachedObject;

	/**
	* Default implementation of JCSCacheService
	*
	* @author <a href="mailto:tv@apache.org">Thomas Vandahl</a>
	* @version $Id$
	*/
	public class JCSCacheService extends AbstractLogEnabled implements
	GlobalCacheService, Runnable, Configurable, Disposable, Initializable,
	ThreadSafe
	{
	/**
	* Cache check frequency in Millis (1000 Millis = 1 second). Value must be >
	* 0. Default = 5 seconds
	*/
	public static final long DEFAULT_CACHE_CHECK_FREQUENCY = 5000; // 5 seconds

	/**
	* cacheCheckFrequency (default - 5 seconds)
	*/
	private long cacheCheckFrequency;

	/**
	* Instance of the JCS cache
	*/
	private GroupCacheAccess<String, CachedObject<?>> cacheManager;

	/**
	* JCS region to use
	*/
	private String region;

	/**
	* Path name of the JCS configuration file
	*/
	private String configFile;

	/**
	* Constant value which provides a group name
	*/
	private static String group = "default_group";

	/** thread for refreshing stale items in the cache */
	private Thread refreshing;

	/** flag to stop the housekeeping thread when the component is disposed. */
	private boolean continueThread;

	// ---------------- Avalon Lifecycle Methods ---------------------

	/**
	* @see org.apache.avalon.framework.configuration.Configurable#configure(org.apache.avalon.framework.configuration.Configuration)
	*/
	@Override
	public void configure(Configuration config) throws ConfigurationException
	{
	this.cacheCheckFrequency = config.getChild("cacheCheckFrequency")
	.getValueAsLong(DEFAULT_CACHE_CHECK_FREQUENCY);
	this.region = config.getChild("region").getValue("fulcrum");
	this.configFile = config.getChild("configurationFile").getValue(
	"/cache.ccf");
	}

	/**
	* @see org.apache.avalon.framework.activity.Initializable#initialize()
	*/
	@Override
	public void initialize() throws Exception
	{
	JCS.setConfigFilename(this.configFile);
	this.cacheManager = JCS.getGroupCacheInstance(this.region);

	// Start housekeeping thread.
	this.continueThread = true;
	this.refreshing = new Thread(this);

	// Indicate that this is a system thread. JVM will quit only when
	// there are no more active user threads. Settings threads spawned
	// internally by Turbine as daemons allows commandline applications
	// using Turbine to terminate in an orderly manner.
	this.refreshing.setDaemon(true);
	this.refreshing.setName("JCSCacheService Refreshing");
	this.refreshing.start();

	getLogger().debug("JCSCacheService started.");
	}

	/**
	* @see org.apache.avalon.framework.activity.Disposable#dispose()
	*/
	@Override
	public void dispose()
	{
	this.continueThread = false;
	this.refreshing.interrupt();

	this.cacheManager.dispose();
	this.cacheManager = null;
	CompositeCacheManager.getInstance().shutDown();

	getLogger().debug("JCSCacheService stopped.");
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#getObject(java.lang.String)
	*/
	@Override
	public <T> CachedObject<T> getObject(String id) throws ObjectExpiredException
	{
	@SuppressWarnings("unchecked")
	CachedObject<T> obj = (CachedObject<T>)this.cacheManager.getFromGroup(id, group);

	if (obj == null)
	{
	// Not in the cache.
	throw new ObjectExpiredException();
	}

	if (obj.isStale())
	{
	if (obj instanceof RefreshableCachedObject)
	{
	RefreshableCachedObject<?> rco = (RefreshableCachedObject<?>) obj;
	if (rco.isUntouched())
	{
	// Do not refresh an object that has exceeded TimeToLive
	removeObject(id);
	throw new ObjectExpiredException();
	}

	// Refresh Object
	rco.refresh();
	if (rco.isStale())
	{
	// Object is Expired, remove it from cache.
	removeObject(id);
	throw new ObjectExpiredException();
	}
	}
	else
	{
	// Expired.
	removeObject(id);
	throw new ObjectExpiredException();
	}
	}

	if (obj instanceof RefreshableCachedObject)
	{
	// notify it that it's being accessed.
	RefreshableCachedObject<?> rco = (RefreshableCachedObject<?>) obj;
	rco.touch();
	}

	return obj;
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#addObject(java.lang.String,
	* org.apache.fulcrum.cache.CachedObject)
	*/
	@Override
	public <T> void addObject(String id, CachedObject<T> o)
	{
	try
	{
	if (!(o.getContents() instanceof Serializable))
	{
	getLogger()
	.warn(
	"Object with id ["
	+ id
	+ "] is not serializable. Expect problems with auxiliary caches.");
	}

	ElementAttributes attrib = (ElementAttributes) this.cacheManager.getDefaultElementAttributes();

	if (o instanceof RefreshableCachedObject)
	{
	attrib.setIsEternal(true);
	}
	else
	{
	attrib.setIsEternal(false);
	// expires in millis, maxlife in seconds
	double tmp0 = ((double) (o.getExpires() + 500)) / 1000;
	getLogger().debug( "setting maxlife seconds (minimum 1sec) from expiry + 0.5s: " + (int)tmp0 );
	attrib.setMaxLife( (tmp0 > 0 ? (int) Math.floor( tmp0 ) : 1 ) );
	}

	attrib.setLastAccessTimeNow();
	attrib.setCreateTime();

	this.cacheManager.putInGroup(id, group, o, attrib);
	}
	catch (CacheException e)
	{
	getLogger().error("Could not add object " + id + " to cache", e);
	}
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#removeObject(java.lang.String)
	*/
	@Override
	public void removeObject(String id)
	{
	this.cacheManager.removeFromGroup(id, group);
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#getKeys()
	*/
	@Override
	public List<String> getKeys()
	{
	ArrayList<String> keys = new ArrayList<String>();

	keys.addAll(this.cacheManager.getGroupKeys(group));
	return keys;
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#getCachedObjects()
	*/
	@Override
	public List<CachedObject<?>> getCachedObjects()
	{
	ArrayList<CachedObject<?>> values = new ArrayList<CachedObject<?>>();

	for (String key : this.cacheManager.getGroupKeys(group))
	{
	CachedObject<?> o = this.cacheManager.getFromGroup(key, group);
	if (o != null)
	{
	values.add(o);
	}
	}

	return values;
	}

	/**
	* Circle through the cache and refresh stale objects. Frequency is
	* determined by the cacheCheckFrequency property.
	*/
	@Override
	public void run()
	{
	while (this.continueThread)
	{
	// Sleep for amount of time set in cacheCheckFrequency -
	// default = 5 seconds.
	try
	{
	Thread.sleep(this.cacheCheckFrequency);
	}
	catch (InterruptedException exc)
	{
	if (!this.continueThread)
	{
	return;
	}
	}

	for (String key : this.cacheManager.getGroupKeys(group))
	{
	CachedObject<?> o = this.cacheManager.getFromGroup(key, group);
	if (o == null)
	{
	removeObject(key);
	}
	else
	{
	if (o instanceof RefreshableCachedObject)
	{
	RefreshableCachedObject<?> rco = (RefreshableCachedObject<?>) o;
	if (rco.isUntouched())
	{
	this.cacheManager.removeFromGroup(key, group);
	}
	else if (rco.isStale())
	{
	rco.refresh();
	}
	}
	}
	}
	}
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#getCacheSize()
	*/
	@Override
	public int getCacheSize() throws IOException
	{
	// This is evil!
	ByteArrayOutputStream baos = new ByteArrayOutputStream();
	ObjectOutputStream out = new ObjectOutputStream(baos);
	Set<String> keys = this.cacheManager.getGroupKeys(group);

	for (String key : keys)
	{
	out.writeObject(this.cacheManager.getFromGroup(key, group));
	}

	out.flush();

	//
	// Subtract 4 bytes from the length, because the serialization
	// magic number (2 bytes) and version number (2 bytes) are
	// both written to the stream before the object
	//
	int objectsize = baos.toByteArray().length - 4 * keys.size();
	return objectsize;
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#getNumberOfObjects()
	*/
	@Override
	public int getNumberOfObjects()
	{
	int count = 0;

	for (String key : this.cacheManager.getGroupKeys(group))
	{
	if (this.cacheManager.getFromGroup(key, group) != null)
	{
	count++;
	}
	}

	return count;
	}

	/**
	* @see org.apache.fulcrum.cache.GlobalCacheService#flushCache()
	*/
	@Override
	public void flushCache()
	{
	this.cacheManager.invalidateGroup(group);
	}
	}