001/*
002 * This library is part of OpenCms -
003 * the Open Source Content Management System
004 *
005 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
006 *
007 * This library is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * This library is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * For further information about Alkacon Software GmbH & Co. KG, please see the
018 * company website: http://www.alkacon.com
019 *
020 * For further information about OpenCms, please see the
021 * project website: http://www.opencms.org
022 *
023 * You should have received a copy of the GNU Lesser General Public
024 * License along with this library; if not, write to the Free Software
025 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
026 */
027
028package org.opencms.cache;
029
030/**
031 * Defines the methods which an object being cached by CmsFlexLruCache must implement.<p>
032 *
033 * CmsFlexLruCache is organized as a double linked list, that's why objects implementing this interface
034 * need getters/setter for the next/previous nodes in the list of all cached objects.<p>
035 *
036 * @see CmsLruCache
037 *
038 * @since 6.0.0
039 */
040public interface I_CmsLruCacheObject {
041
042    /**
043     * Set the next object in the double linked list of all cached objects.<p>
044     *
045     * @param theNextObject the next object
046     */
047    void setNextLruObject(I_CmsLruCacheObject theNextObject);
048
049    /**
050     * Returns the next object in the double linked list of all cached objects.<p>
051     *
052     * @return the next object in the double linked list of all cached objects
053     */
054    I_CmsLruCacheObject getNextLruObject();
055
056    /**
057     * Set the previous object in the double linked list of all cached objects.<p>
058     *
059     * @param thePreviousObject the previous object
060     */
061    void setPreviousLruObject(I_CmsLruCacheObject thePreviousObject);
062
063    /**
064     * Returns the previous object in the double linked list of all cached objects.<p>
065     *
066     * @return the previous object in the double linked list of all cached objects
067     */
068    I_CmsLruCacheObject getPreviousLruObject();
069
070    /**
071     * Invoked after an object was added to the cache.<p>
072     */
073    void addToLruCache();
074
075    /**
076     * Invoked after the object was removed to the cache.<p>
077     */
078    void removeFromLruCache();
079
080    /**
081     * Returns the cache costs of this object, as for example it's byte size.<p>
082     *
083     * @return the cache costs of this object
084     */
085    int getLruCacheCosts();
086
087    /**
088     * Returns the Object value.<p>
089     *
090     * @return the Object value
091     */
092    Object getValue();
093}