org.xwiki.cache.util.AbstractCache Maven / Gradle / Ivy

Go to download
/*
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This 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 software 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 software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.xwiki.cache.util;

import javax.swing.event.EventListenerList;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xwiki.cache.Cache;
import org.xwiki.cache.DisposableCacheValue;
import org.xwiki.cache.config.CacheConfiguration;
import org.xwiki.cache.event.CacheEntryEvent;
import org.xwiki.cache.event.CacheEntryListener;

/**
 * Base class for {@link Cache} implementations. It provides events {@link DisposableCacheValue} management.
 * 
 * @param  the class of the data stored in the cache.
 * @version $Id: 0215579da91f5c992e51213a0604d939f3483c40 $
 */
public abstract class AbstractCache implements Cache
{
    /**
     * The logger to use to log.
     */
    private static final Logger LOGGER = LoggerFactory.getLogger(AbstractCache.class);

    /**
     * The configuration used to create the cache.
     */
    protected final CacheConfiguration configuration;

    /**
     * The list of listener to called when events appends on a cache entry.
     */
    protected final EventListenerList cacheEntryListeners = new EventListenerList();

    /**
     * @deprecated since 8.3RC1, use {@link #AbstractCache(CacheConfiguration)} instead
     */
    @Deprecated
    public AbstractCache()
    {
        this(null);
    }

    /**
     * @param configuration the configuration of the cache
     */
    public AbstractCache(CacheConfiguration configuration)
    {
        this.configuration = configuration;
    }

    @Override
    public void dispose()
    {
        for (CacheEntryListener listener : this.cacheEntryListeners.getListeners(CacheEntryListener.class)) {
            this.cacheEntryListeners.remove(CacheEntryListener.class, listener);
        }
    }

    @Override
    public void addCacheEntryListener(CacheEntryListener listener)
    {
        this.cacheEntryListeners.add(CacheEntryListener.class, listener);
    }

    @Override
    public void removeCacheEntryListener(CacheEntryListener listener)
    {
        cacheEntryListeners.remove(CacheEntryListener.class, listener);
    }

    /**
     * Helper method to send event when a new cache entry is inserted.
     * 
     * @param event the event to send.
     */
    protected void sendEntryAddedEvent(CacheEntryEvent event)
    {
        for (org.xwiki.cache.event.CacheEntryListener listener : this.cacheEntryListeners
            .getListeners(org.xwiki.cache.event.CacheEntryListener.class)) {
            listener.cacheEntryAdded(event);
        }
    }

    /**
     * Helper method to send event when an existing cache entry is removed.
     * 
     * @param event the event to send.
     */
    protected void sendEntryRemovedEvent(CacheEntryEvent event)
    {
        for (org.xwiki.cache.event.CacheEntryListener listener : this.cacheEntryListeners
            .getListeners(org.xwiki.cache.event.CacheEntryListener.class)) {
            listener.cacheEntryRemoved(event);
        }

        disposeCacheValue(event.getEntry().getValue());
    }

    /**
     * Helper method to send event when a cache entry is modified.
     * 
     * @param event the event to send.
     */
    protected void sendEntryModifiedEvent(CacheEntryEvent event)
    {
        for (org.xwiki.cache.event.CacheEntryListener listener : this.cacheEntryListeners
            .getListeners(org.xwiki.cache.event.CacheEntryListener.class)) {
            listener.cacheEntryModified(event);
        }
    }

    /**
     * Dispose the value being removed from the cache.
     * 
     * @param value the value to dispose
     */
    protected void disposeCacheValue(T value)
    {
        if (value instanceof DisposableCacheValue) {
            try {
                ((DisposableCacheValue) value).dispose();
            } catch (Throwable e) {
                // We catch Throwable because this method is usually automatically called by an event send by the cache
                // implementation and there is no reason to crash the whole cache because of some badly implemented
                // dispose() we don't control.
                LOGGER.warn("Error when trying to dispose a cache object of cache [{}]",
                    this.configuration != null ? this.configuration.getConfigurationId() : null, e);
            }
        }
    }
}