package org.apache.stratum.jcs.auxiliary.disk.indexed;
/*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Velocity", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.stratum.jcs.auxiliary.disk.indexed.behavior.IIndexedDiskCacheAttributes;
import org.apache.stratum.jcs.engine.behavior.ICache;
import org.apache.stratum.jcs.engine.behavior.ICacheManager;
import java.util.Enumeration;
import java.util.Hashtable;
/**
* Cache manager for IndexedDiskCaches.
*
* @author <a href="mailto:asmuts@yahoo.com">Aaron Smuts</a>
* @author <a href="mailto:james@jamestaylor.org">James Taylor</a>
* @version $Id: IndexedDiskCacheManager.java,v 1.4 2002/03/01 18:31:56 dlr Exp $
*/
public class IndexedDiskCacheManager implements ICacheManager
{
private final static Log log =
LogFactory.getLog( IndexedDiskCacheManager.class );
private static int clients;
private static IndexedDiskCacheManager instance;
private Hashtable caches = new Hashtable();
private IIndexedDiskCacheAttributes defaultCacheAttributes;
/**
* Constructor for the IndexedDiskCacheManager object
*
* @param defaultCacheAttributes Default attributes for caches managed by
* the instance.
*/
private IndexedDiskCacheManager(
IIndexedDiskCacheAttributes defaultCacheAttributes )
{
this.defaultCacheAttributes = defaultCacheAttributes;
}
/**
* Gets the singleton instance of the manager
*
* @param defaultCacheAttributes If the instance has not yet been created,
* it will be initialized with this set of
* default attributes.
* @return The instance value
*/
public static IndexedDiskCacheManager getInstance(
IIndexedDiskCacheAttributes defaultCacheAttributes )
{
if ( instance == null )
{
synchronized ( IndexedDiskCacheManager.class )
{
if ( instance == null )
{
instance =
new IndexedDiskCacheManager( defaultCacheAttributes );
}
}
}
if ( log.isDebugEnabled() )
{
log.debug( "Get instance, manager stats: " + instance.getStats() );
}
clients++;
return instance;
}
/**
* Gets an IndexedDiskCache for the supplied name using the default
* attributes.
*
* @see getCache( IIndexedDiskCacheAttributes }
*
* @param cacheName Name that will be used when creating attributes.
* @return A cache.
*/
public ICache getCache( String cacheName )
{
IIndexedDiskCacheAttributes cacheAttributes =
( IIndexedDiskCacheAttributes ) defaultCacheAttributes.copy();
cacheAttributes.setCacheName( cacheName );
return getCache( cacheAttributes );
}
/**
* Get an IndexedDiskCache for the supplied attributes. Will provide an
* existing cache for the name attribute if one has been created, or will
* create a new cache.
*
* @param cattr Attributes the cache should have.
* @return A cache, either from the existing set or newly created.
*
*/
public ICache getCache( IIndexedDiskCacheAttributes cacheAttributes )
{
ICache cache = null;
String cacheName = cacheAttributes.getCacheName();
log.debug( "Getting cache named: " + cacheName );
synchronized ( caches )
{
// Try to load the cache from the set that have already been
// created. This only looks at the name attribute.
cache = ( ICache ) caches.get( cacheName );
// If it was not found, create a new one using the supplied
// attributes
if ( cache == null )
{
cache = new IndexedDiskCache( cacheAttributes );
caches.put( cacheName, cache );
}
}
if ( log.isDebugEnabled() )
{
log.debug( "After getCache, manager stats: " + instance.getStats() );
}
return cache;
}
/**
* Disposes the cache with the given name, if found in the set of managed
* caches.
*
* @param cacheName Name of cache to dispose.
*/
public void freeCache( String cacheName )
{
ICache cache = ( ICache ) caches.get( cacheName );
if ( cache != null )
{
try
{
cache.dispose();
}
catch ( Exception e )
{
log.error( "Failure disposing cache: " + cacheName, e );
}
}
}
/**
* Returns the stats of all the managed caches.
*
* @return String of stats from each managed cache, seperated by commas.
*/
public String getStats()
{
StringBuffer stats = new StringBuffer();
Enumeration allCaches = caches.elements();
while ( allCaches.hasMoreElements() )
{
ICache raf = ( ICache ) allCaches.nextElement();
if ( raf != null )
{
stats.append( raf.getStats() );
stats.append( ", " );
}
}
return stats.toString();
}
/**
* Gets the cacheType attribute of the DiskCacheManager object
*
* @return The cacheType value
*/
public int getCacheType()
{
return DISK_CACHE;
}
/**
* Releases the cache manager instance. When all clients have released the
* cache manager, all contained caches will be disposed.
*/
public void release()
{
clients--;
if ( --clients != 0 )
{
return;
}
synchronized ( caches )
{
Enumeration allCaches = caches.elements();
while ( allCaches.hasMoreElements() )
{
ICache cache = ( ICache ) allCaches.nextElement();
if ( cache != null )
{
try
{
cache.dispose();
}
catch ( Exception e )
{
log.error( "Failure disposing cache: " +
cache.getCacheName(), e );
}
}
}
}
}
}