DictionarySectionCachePerThread.java

/**
 * File: $HeadURL: https://hdt-java.googlecode.com/svn/trunk/hdt-java/src/org/rdfhdt/hdt/dictionary/impl/section/DictionarySectionCachePerThread.java $
 * Revision: $Rev: 191 $
 * Last modified: $Date: 2013-03-03 11:41:43 +0000 (dom, 03 mar 2013) $
 * Last modified by: $Author: mario.arias $
 *
 * This library 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 library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Contacting the authors:
 *   Mario Arias:               mario.arias@deri.org
 *   Javier D. Fernandez:       jfergar@infor.uva.es
 *   Miguel A. Martinez-Prieto: migumar2@infor.uva.es
 *   Alejandro Andres:          fuzzy.alej@gmail.com
 */

package org.rdfhdt.hdt.dictionary.impl.section;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

import org.rdfhdt.hdt.dictionary.DictionarySectionPrivate;
import org.rdfhdt.hdt.dictionary.TempDictionarySection;
import org.rdfhdt.hdt.listener.ProgressListener;

/**
 * DictionarySection that caches results returned by a child DictionarySection to increase performance.
 * This one uses one cache per thread, to avoid waits on mutex when having concurrent queries.
 * 
 * @author mario.arias
 *
 */
public class DictionarySectionCachePerThread implements DictionarySectionPrivate {
	
	final int CACHE_ENTRIES = 128;
	private DictionarySectionPrivate child;
	
	private ThreadLocal<Map<CharSequence,Integer>> cacheString =
			new ThreadLocal<Map<CharSequence,Integer>>() {
				@SuppressWarnings("serial")
				@Override
				protected java.util.Map<CharSequence,Integer> initialValue() {
					return new LinkedHashMap<CharSequence,Integer>(CACHE_ENTRIES+1, .75F, true) {
					    // This method is called just after a new entry has been added
						@Override
					    public boolean removeEldestEntry(Map.Entry<CharSequence,Integer> eldest) {
					        return size() > CACHE_ENTRIES;
					    }
					};
				};
	};
	
	private ThreadLocal<Map<Integer,CharSequence>> cacheID =
			new ThreadLocal<Map<Integer,CharSequence>>() {
				@SuppressWarnings("serial")
				@Override
				protected java.util.Map<Integer,CharSequence> initialValue() {
					return new LinkedHashMap<Integer,CharSequence>(CACHE_ENTRIES+1, .75F, true) {
					    // This method is called just after a new entry has been added
						@Override
					    public boolean removeEldestEntry(Map.Entry<Integer,CharSequence> eldest) {
					        return size() > CACHE_ENTRIES;
					    }
					};
				};
	};
	
	public DictionarySectionCachePerThread(DictionarySectionPrivate child) {
		this.child = child;
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#locate(java.lang.CharSequence)
	 */
	@Override
	public int locate(CharSequence s) {
		Map<CharSequence,Integer> map = cacheString.get();
		Integer o = map.get(s);
		if(o==null) {
			o = child.locate(s);
			map.put(s, o);
		}
 		return o;
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#extract(int)
	 */
	@Override
	public CharSequence extract(int pos) {
		Map<Integer,CharSequence> map = cacheID.get();
		CharSequence o = map.get(pos);
		if(o==null) {
			o = child.extract(pos);
			map.put(pos, o);
			//cacheString.put(o, pos);
		}
 		return o;
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#size()
	 */
	@Override
	public long size() {
		return child.size();
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#getNumberOfElements()
	 */
	@Override
	public int getNumberOfElements() {
		return child.getNumberOfElements();
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#getEntries()
	 */
	@Override
	public Iterator<? extends CharSequence> getSortedEntries() {
		return child.getSortedEntries();
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#save(java.io.OutputStream, hdt.listener.ProgressListener)
	 */
	@Override
	public void save(OutputStream output, ProgressListener listener)
			throws IOException {
		child.save(output, listener);
	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#load(java.io.InputStream, hdt.listener.ProgressListener)
	 */
	@Override
	public void load(InputStream input, ProgressListener listener)
			throws IOException {
		child.load(input, listener);

	}

	/* (non-Javadoc)
	 * @see hdt.dictionary.DictionarySection#load(hdt.dictionary.DictionarySection, hdt.listener.ProgressListener)
	 */
	@Override
	public void load(TempDictionarySection other, ProgressListener listener) {
		child.load(other, listener);
	}

	@Override
	public void close() throws IOException {
		cacheString=null;
		cacheID=null;
		child.close();
	}
}