/** * $RCSfile$ * $Revision$ * $Date$ * * Copyright (C) 2004 Jive Software. All rights reserved. * * This software is published under the terms of the GNU Public License (GPL), * a copy of which is included in this distribution. */ package org.jivesoftware.util; import java.util.List; import java.util.Map; /** * Utility class for determining the sizes in bytes of commonly used objects. * Classes implementing the Cacheable interface should use this class to * determine their size. * * @author Matt Tucker */ public class CacheSizes { /** * Returns the size in bytes of a basic Object. This method should only * be used for actual Object objects and not classes that extend Object. * * @return the size of an Object. */ public static int sizeOfObject() { return 4; } /** * Returns the size in bytes of a String. * * @param string the String to determine the size of. * @return the size of a String. */ public static int sizeOfString(String string) { if (string == null) { return 0; } return 4 + string.length() * 2; } /** * Returns the size in bytes of a primitive int. * * @return the size of a primitive int. */ public static int sizeOfInt() { return 4; } /** * Returns the size in bytes of a primitive char. * * @return the size of a primitive char. */ public static int sizeOfChar() { return 2; } /** * Returns the size in bytes of a primitive boolean. * * @return the size of a primitive boolean. */ public static int sizeOfBoolean() { return 1; } /** * Returns the size in bytes of a primitive long. * * @return the size of a primitive long. */ public static int sizeOfLong() { return 8; } /** * Returns the size in bytes of a primitive double. * * @return the size of a primitive double. */ public static int sizeOfDouble() { return 8; } /** * Returns the size in bytes of a Date. * * @return the size of a Date. */ public static int sizeOfDate() { return 12; } /** * Returns the size in bytes of a Map object. All keys and * values <b>must be Strings</b>. * * @param map the Map object to determine the size of. * @return the size of the Map object. */ public static int sizeOfMap(Map map) { if (map == null) { return 0; } // Base map object -- should be something around this size. int size = 36; // Add in size of each value Object[] values = map.values().toArray(); for (int i = 0; i < values.length; i++) { size += sizeOfString((String)values[i]); } Object[] keys = map.keySet().toArray(); // Add in each key for (int i = 0; i < keys.length; i++) { size += sizeOfString((String)keys[i]); } return size; } /** * Returns the size in bytes of a List object. Elements are assumed to be * <tt>String</tt>s, <tt>Long</tt>s or <tt>Cacheable</tt> objects. * * @param list the List object to determine the size of. * @return the size of the List object. */ public static int sizeOfList(List list) { if (list == null) { return 0; } // Base list object (approximate) int size = 36; // Add in size of each value Object[] values = list.toArray(); for (int i = 0; i < values.length; i++) { Object obj = values[i]; if (obj instanceof String) { size += sizeOfString((String)obj); } else if (obj instanceof Long) { size += sizeOfLong() + sizeOfObject(); } else { size += ((Cacheable)obj).getCachedSize(); } } return size; } }