001package org.cache2k.impl.util;
002
003/*
004 * #%L
005 * cache2k core package
006 * %%
007 * Copyright (C) 2000 - 2015 headissue GmbH, Munich
008 * %%
009 * This program is free software: you can redistribute it and/or modify
010 * it under the terms of the GNU General Public License as
011 * published by the Free Software Foundation, either version 3 of the 
012 * License, or (at your option) any later version.
013 * 
014 * This program is distributed in the hope that it will be useful,
015 * but WITHOUT ANY WARRANTY; without even the implied warranty of
016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
017 * GNU General Public License for more details.
018 * 
019 * You should have received a copy of the GNU General Public 
020 * License along with this program.  If not, see
021 * <http://www.gnu.org/licenses/gpl-3.0.html>.
022 * #L%
023 */
024
025/**
026 * Base class of all classes that contain code constants. For each
027 * cache2k implementation class constants a centralized within an inner class.
028 * The rationale behind this is explained in the following.
029 *
030 * <p/>Wisely chosen constants are sometimes buried within the code.
031 * These are the so called "magic numbers". So lets give them a default
032 * place.
033 *
034 * <p/>There may be a need to change such a "constant". This provides a simple system
035 * wide mechanism to change a parameter, aka "tune" it. So, this can be used for
036 * performance optimizations. It may be also possible to provide a tuning
037 * set that goes tunes towards execution time or towards space efficiency.
038 *
039 * <p/>Testing: Some code has operations that happen very seldom, e.g. for
040 * reorganizing. For testing purposes we can trigger these situations by
041 * de-tuning.
042 *
043 * <p/>If there is a constant need to change a constant, please open a change
044 * request. Either it is better to change the tunable constant to a real parameter
045 * or a assign it to another value which fits the general purpose better.
046 *
047 * @author Jens Wilke; created: 2014-04-27
048 */
049public class TunableConstants implements Cloneable {
050
051  @SuppressWarnings("CloneDoesntDeclareCloneNotSupportedException")
052  @Override
053  public  Object clone() {
054    try {
055      Object o = super.clone();
056      return o;
057    } catch (CloneNotSupportedException e) {
058      throw new UnsupportedOperationException("never happens", e);
059    }
060  }
061
062}