/*
* Copyright (C) 2009 eXo Platform SAS.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.exoplatform.services.cache.impl.jboss.lfu;
import org.exoplatform.management.annotations.Managed;
import org.exoplatform.management.annotations.ManagedDescription;
import org.exoplatform.management.annotations.ManagedName;
import org.exoplatform.services.cache.ExoCache;
import org.exoplatform.services.cache.ExoCacheConfig;
import org.exoplatform.services.cache.ExoCacheInitException;
import org.exoplatform.services.cache.impl.jboss.AbstractExoCache;
import org.exoplatform.services.cache.impl.jboss.AbstractExoCacheCreator;
import org.jboss.cache.Cache;
import org.jboss.cache.Fqn;
import org.jboss.cache.eviction.LFUAlgorithmConfig;
import java.io.Serializable;
/**
* The LFU Implementation of an {@link org.exoplatform.services.cache.impl.jboss.ExoCacheCreator}
* Created by The eXo Platform SAS
* Author : eXoPlatform
* exo@exoplatform.com
* 21 juil. 2009
*/
public class LFUExoCacheCreator extends AbstractExoCacheCreator
{
/**
* The expected implementation name
*/
public static final String EXPECTED_IMPL = "LFU";
/**
* The default value for the parameter minNodes
*/
protected int defaultMinNodes;
/**
* {@inheritDoc}
*/
public ExoCache<Serializable, Object> create(ExoCacheConfig config, Cache<Serializable, Object> cache)
throws ExoCacheInitException
{
if (config instanceof LFUExoCacheConfig)
{
final LFUExoCacheConfig lfuConfig = (LFUExoCacheConfig)config;
return create(config, cache, lfuConfig.getMaxNodes(), lfuConfig.getMinNodes(), lfuConfig.getMinTimeToLive());
}
else
{
final long period = config.getLiveTime();
return create(config, cache, config.getMaxSize(), defaultMinNodes, period > 0 ? period * 1000 : 0);
}
}
/**
* Creates a new ExoCache instance with the relevant parameters
*/
private ExoCache<Serializable, Object> create(ExoCacheConfig config, Cache<Serializable, Object> cache,
int maxNodes, int minNodes, long minTimeToLive) throws ExoCacheInitException
{
final LFUAlgorithmConfig lfu = new LFUAlgorithmConfig(maxNodes, minNodes);
lfu.setMinTimeToLive(minTimeToLive);
Fqn<String> rooFqn = addEvictionRegion(config, cache, lfu);
return new LFUExoCache(config, cache, rooFqn, lfu);
}
/**
* {@inheritDoc}
*/
public Class<? extends ExoCacheConfig> getExpectedConfigType()
{
return LFUExoCacheConfig.class;
}
/**
* {@inheritDoc}
*/
public String getExpectedImplementation()
{
return EXPECTED_IMPL;
}
/**
* The LRU implementation of an ExoCache
*/
public static class LFUExoCache extends AbstractExoCache<Serializable, Object>
{
private final LFUAlgorithmConfig lfu;
public LFUExoCache(ExoCacheConfig config, Cache<Serializable, Object> cache, Fqn<String> rooFqn,
LFUAlgorithmConfig lfu)
{
super(config, cache, rooFqn);
this.lfu = lfu;
}
@ManagedName("MinTimeToLive")
@ManagedDescription("the minimum amount of time a node must be allowed to live after being accessed " +
"before it is allowed to be considered for eviction. 0 denotes that this feature is disabled, " +
"which is the default value.")
public long getLiveTime()
{
return lfu.getMinTimeToLive();
}
@ManagedName("MaxNodes")
@ManagedDescription("This is the maximum number of nodes allowed in this region. " +
"0 denotes immediate expiry, -1 denotes no limit.")
public int getMaxSize()
{
return lfu.getMaxNodes();
}
@Managed
@ManagedName("MinNodes")
@ManagedDescription("This is the minimum number of nodes allowed in this region. This value determines " +
"what the eviction queue should prune down to per pass. e.g. If minNodes is 10 and the cache grows " +
"to 100 nodes, the cache is pruned down to the 10 most frequently used nodes when the eviction timer " +
"makes a pass through the eviction algorithm.")
public long getMinNodes()
{
return lfu.getMinNodes();
}
public void setLiveTime(long period)
{
lfu.setMinTimeToLive(period);
}
public void setMaxSize(int max)
{
lfu.setMaxNodes(max);
}
@Managed
public void setMinNodes(int minNodes)
{
lfu.setMinNodes(minNodes);
}
}
}