/*
 * $Id$
 *
 * Copyright (C) 2003-2015 JNode.org
 *
 * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
package org.jnode.fs.ext2.cache;

import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.Map;

import org.apache.log4j.Logger;

/**
 * @author Andras Nagy
 */
public final class BlockCache extends LinkedHashMap<Object, Block> {
    private static final long serialVersionUID = 1L;

    // at most MAX_SIZE blocks fit in the cache
    static final int MAX_SIZE = 10;

    private static final Logger log = Logger.getLogger(BlockCache.class);

    private ArrayList<CacheListener> cacheListeners;

    public BlockCache(int initialCapacity, float loadFactor) {
        super(Math.min(MAX_SIZE, initialCapacity), loadFactor, true);
        cacheListeners = new ArrayList<CacheListener>();
    }

    public void addCacheListener(CacheListener listener) {
        cacheListeners.add(listener);
    }

    protected synchronized boolean removeEldestEntry(Map.Entry<Object, Block> eldest) {
        log.debug("BlockCache size: " + size());
        if (size() > MAX_SIZE) {
            try {
                eldest.getValue().flush();
                // notify the listeners
                final CacheEvent event = new CacheEvent(eldest.getValue(), CacheEvent.REMOVED);
                for (CacheListener l : cacheListeners) {
                    l.elementRemoved(event);
                }
            } catch (IOException e) {
                log.error("Exception when flushing a block from the cache", e);
            }
            return true;
        } else {
            return false;
        }
    }
}