/**
* (C) Copyright IBM Corp. 2010, 2015
*
* Licensed 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.
*
*/
package com.ibm.bi.dml.runtime.controlprogram.caching;
import java.lang.ref.SoftReference;
import java.util.HashMap;
import java.util.LinkedList;
/**
*
*
*/
public class PageCache
{
private static final int CLEANUP_THRESHOLD = 128;
private static HashMap<Integer, LinkedList<SoftReference<byte[]>>> _pool;
/**
*
*/
public static void init()
{
_pool = new HashMap<Integer, LinkedList<SoftReference<byte[]>>>();
}
/**
*
*/
public static void clear()
{
_pool = null;
}
/**
*
* @param data
*/
public static void putPage( byte[] data )
{
//cleanup if too many different size lists
if( _pool.size()>CLEANUP_THRESHOLD )
_pool.clear();
LinkedList<SoftReference<byte[]>> list = _pool.get( data.length );
if( list==null ){
list = new LinkedList<SoftReference<byte[]>>();
_pool.put(data.length, list);
}
list.addLast(new SoftReference<byte[]>(data));
}
/**
*
* @param size
* @return
*/
public static byte[] getPage( int size )
{
LinkedList<SoftReference<byte[]>> list = _pool.get( size );
if( list!=null ) {
while( !list.isEmpty() ){
SoftReference<byte[]> ref = list.removeFirst();
byte[] tmp = ref.get();
if( tmp!=null )
return tmp;
}
}
return null;
}
}