package org.apache.jcs.admin;
/*
* 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.io.ObjectOutputStream;
import java.io.Serializable;
import java.text.DateFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.jcs.engine.behavior.ICacheElement;
import org.apache.jcs.engine.behavior.IElementAttributes;
import org.apache.jcs.engine.control.CompositeCache;
import org.apache.jcs.engine.control.CompositeCacheManager;
import org.apache.jcs.engine.memory.behavior.IMemoryCache;
/**
* A servlet which provides HTTP access to JCS. Allows a summary of regions to be viewed, and
* removeAll to be run on individual regions or all regions. Also provides the ability to remove
* items (any number of key arguments can be provided with action 'remove'). Should be initialized
* with a properties file that provides at least a classpath resource loader.
*/
public class JCSAdminBean
{
/** The logger. */
private static final Log log = LogFactory.getLog( JCSAdminBean.class );
/** The cache maanger. */
private CompositeCacheManager cacheHub = CompositeCacheManager.getInstance();
/**
* Builds up info about each element in a region.
* <p>
* @param cacheName
* @return List of CacheElementInfo objects
* @throws Exception
*/
public LinkedList buildElementInfo( String cacheName )
throws Exception
{
CompositeCache cache = cacheHub.getCache( cacheName );
Object[] keys = cache.getMemoryCache().getKeyArray();
// Attempt to sort keys according to their natural ordering. If that
// fails, get the key array again and continue unsorted.
try
{
Arrays.sort( keys );
}
catch ( Exception e )
{
keys = cache.getMemoryCache().getKeyArray();
}
LinkedList records = new LinkedList();
ICacheElement element;
IElementAttributes attributes;
CacheElementInfo elementInfo;
DateFormat format = DateFormat.getDateTimeInstance( DateFormat.SHORT, DateFormat.SHORT );
long now = System.currentTimeMillis();
for ( int i = 0; i < keys.length; i++ )
{
element = cache.getMemoryCache().getQuiet( (Serializable) keys[i] );
attributes = element.getElementAttributes();
elementInfo = new CacheElementInfo();
elementInfo.key = String.valueOf( keys[i] );
elementInfo.eternal = attributes.getIsEternal();
elementInfo.maxLifeSeconds = attributes.getMaxLifeSeconds();
elementInfo.createTime = format.format( new Date( attributes.getCreateTime() ) );
elementInfo.expiresInSeconds = ( now - attributes.getCreateTime() - ( attributes.getMaxLifeSeconds() * 1000 ) )
/ -1000;
records.add( elementInfo );
}
return records;
}
/**
* Builds up data on every region.
* <p>
* @TODO we need a most light weight method that does not count bytes. The byte counting can
* really swamp a server.
* @return list of CacheRegionInfo objects
* @throws Exception
*/
public LinkedList buildCacheInfo()
throws Exception
{
String[] cacheNames = cacheHub.getCacheNames();
Arrays.sort( cacheNames );
LinkedList cacheInfo = new LinkedList();
CacheRegionInfo regionInfo;
CompositeCache cache;
for ( int i = 0; i < cacheNames.length; i++ )
{
cache = cacheHub.getCache( cacheNames[i] );
regionInfo = new CacheRegionInfo();
regionInfo.cache = cache;
regionInfo.byteCount = getByteCount( cache );
cacheInfo.add( regionInfo );
}
return cacheInfo;
}
/**
* Tries to estimate how much data is in a region. This is expensive. If there are any non
* serializable objects in the region, the count will stop when it encouters the first one.
* <p>
* @param cache
* @return int
* @throws Exception
*/
public int getByteCount( CompositeCache cache )
throws Exception
{
IMemoryCache memCache = cache.getMemoryCache();
Iterator iter = memCache.getIterator();
CountingOnlyOutputStream counter = new CountingOnlyOutputStream();
ObjectOutputStream out = new ObjectOutputStream( counter );
// non serializable objects will cause problems here
// stop at the first non serializable exception.
try
{
while ( iter.hasNext() )
{
ICacheElement ce = (ICacheElement) ( (Map.Entry) iter.next() ).getValue();
out.writeObject( ce.getVal() );
}
}
catch ( Exception e )
{
log.info( "Problem getting byte count. Likley cause is a non serilizable object." + e.getMessage() );
}
// 4 bytes lost for the serialization header
return counter.getCount() - 4;
}
/**
* Clears all regions in the cache.
* <p>
* @throws IOException
*/
public void clearAllRegions()
throws IOException
{
String[] names = cacheHub.getCacheNames();
for ( int i = 0; i < names.length; i++ )
{
cacheHub.getCache( names[i] ).removeAll();
}
}
/**
* Clears a particular cache region.
* <p>
* @param cacheName
* @throws IOException
*/
public void clearRegion( String cacheName )
throws IOException
{
cacheHub.getCache( cacheName ).removeAll();
}
/**
* Removes a particular item from a particular region.
* <p>
* @param cacheName
* @param key
* @throws IOException
*/
public void removeItem( String cacheName, String key )
throws IOException
{
cacheHub.getCache( cacheName ).remove( key );
}
}