TestLruCache.java

/*
 * Copyright (c) 2002-2009 "Neo Technology,"
 *     Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 * 
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program 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 Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.kernel.impl.cache;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;

import org.junit.Test;
import org.neo4j.kernel.impl.cache.LruCache;

public class TestLruCache
{
    @Test
    public void testCreate()
    {
        try
        {
            new LruCache<Object,Object>( "TestCache", 0, null );
            fail( "Illegal maxSize should throw exception" );
        }
        catch ( IllegalArgumentException e )
        { // good
        }
        LruCache<Object,Object> cache = new LruCache<Object,Object>(
            "TestCache", 70, null );
        try
        {
            cache.put( null, new Object() );
            fail( "Null key should throw exception" );
        }
        catch ( IllegalArgumentException e )
        { // good
        }
        try
        {
            cache.put( new Object(), null );
            fail( "Null element should throw exception" );
        }
        catch ( IllegalArgumentException e )
        { // good
        }
        try
        {
            cache.get( null );
            fail( "Null key should throw exception" );
        }
        catch ( IllegalArgumentException e )
        { // good
        }
        try
        {
            cache.remove( null );
            fail( "Null key should throw exception" );
        }
        catch ( IllegalArgumentException e )
        { // good
        }
        cache.put( new Object(), new Object() );
        cache.clear();
    }

    private static class LruCacheTest<K,E> extends LruCache<K,E>
    {
        private Object cleanedElement = null;

        LruCacheTest( String name, int maxSize )
        {
            super( name, maxSize, null );
        }

        @Override
        public void elementCleaned( E element )
        {
            cleanedElement = element;
        }

        Object getLastCleanedElement()
        {
            return cleanedElement;
        }
    }

    @Test
    public void testSimple()
    {
        LruCacheTest<Object,Object> cache = new LruCacheTest<Object,Object>(
            "TestCache", 3 );
        String s1 = new String( "1" );
        Integer key1 = new Integer( 1 );
        String s2 = new String( "2" );
        Integer key2 = new Integer( 2 );
        String s3 = new String( "3" );
        Integer key3 = new Integer( 3 );
        String s4 = new String( "4" );
        Integer key4 = new Integer( 4 );
        String s5 = new String( "5" );
        Integer key5 = new Integer( 5 );
        cache.put( key1, s1 );
        cache.put( key2, s2 );
        cache.put( key3, s3 );
        cache.get( key2 );
        assertEquals( null, cache.getLastCleanedElement() );
        cache.put( key4, s4 );
        assertEquals( s1, cache.getLastCleanedElement() );
        cache.put( key5, s5 );
        assertEquals( s3, cache.getLastCleanedElement() );
        int size = cache.size();
        assertEquals( 3, size );
        assertEquals( null, cache.get( key1 ) );
        assertEquals( s2, cache.get( key2 ) );
        assertEquals( null, cache.get( key3 ) );
        assertEquals( s4, cache.get( key4 ) );
        assertEquals( s5, cache.get( key5 ) );
        cache.clear();
        assertEquals( 0, cache.size() );
    }

    @Test
    public void testResize()
    {
        LruCacheTest<Object,Object> cache = new LruCacheTest<Object,Object>(
            "TestCache", 3 );
        String s1 = new String( "1" );
        Integer key1 = new Integer( 1 );
        String s2 = new String( "2" );
        Integer key2 = new Integer( 2 );
        String s3 = new String( "3" );
        Integer key3 = new Integer( 3 );
        String s4 = new String( "4" );
        Integer key4 = new Integer( 4 );
        String s5 = new String( "5" );
        Integer key5 = new Integer( 5 );
        cache.put( key1, s1 );
        cache.put( key2, s2 );
        cache.put( key3, s3 );
        cache.get( key2 );
        assertEquals( null, cache.getLastCleanedElement() );
        assertEquals( cache.maxSize(), cache.size() );
        cache.resize( 5 );
        assertEquals( 5, cache.maxSize() );
        assertEquals( 3, cache.size() );
        cache.put( key4, s4 );
        assertEquals( null, cache.getLastCleanedElement() );
        cache.put( key5, s5 );
        assertEquals( null, cache.getLastCleanedElement() );
        assertEquals( cache.maxSize(), cache.size() );
        cache.resize( 4 );
        assertEquals( s1, cache.getLastCleanedElement() );
        assertEquals( cache.maxSize(), cache.size() );
        cache.resize( 3 );
        assertEquals( s3, cache.getLastCleanedElement() );
        assertEquals( 3, cache.maxSize() );
        assertEquals( 3, cache.size() );
    }
}