Mercurial > hg > blitz_condensed
view src/com/go/trove/util/WrappedCache.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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/* ==================================================================== * Trove - Copyright (c) 1997-2001 Walt Disney Internet Group * ==================================================================== * The Tea Software License, Version 1.1 * * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, * if any, must include the following acknowledgment: * "This product includes software developed by the * Walt Disney Internet Group (http://opensource.go.com/)." * Alternately, this acknowledgment may appear in the software itself, * if and wherever such third-party acknowledgments normally appear. * * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must * not be used to endorse or promote products derived from this * software without prior written permission. For written * permission, please contact opensource@dig.com. * * 5. Products derived from this software may not be called "Tea", * "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet", * "Kettle", "Trove" or "BeanDoc" appear in their name, without prior * written permission of the Walt Disney Internet Group. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ==================================================================== * * For more information about Tea, please see http://opensource.go.com/. */ package com.go.trove.util; import java.util.*; /****************************************************************************** * A Map that implements a write-through cache to another map. Two maps are * supplied: one for caching and one for main storage. WrappedCache is not * thread-safe and must be wrapped with Collections.synchronizedMap to be made * thread-safe. * * @author Brian S O'Neill * @version * <!--$$Revision:--> 2 <!-- $-->, <!--$$JustDate:--> 01/07/31 <!-- $--> */ public class WrappedCache extends AbstractMap implements Map { private final Map mCacheMap; private final Map mBackingMap; /** * @param cacheMap the cache map should offer fast access, but it should * automatically limit its maximum size * @param backingMap the backingMap will be read from only if the requested * entry isn't in the cache */ public WrappedCache(Map cacheMap, Map backingMap) { mCacheMap = cacheMap; mBackingMap = backingMap; } /** * Returns the size of the backing map. */ public int size() { return mBackingMap.size(); } /** * Returns the empty status of the backing map. */ public boolean isEmpty() { return mBackingMap.isEmpty(); } /** * Returns true if the cache contains the key or else if the backing map * contains the key. */ public boolean containsKey(Object key) { return mCacheMap.containsKey(key) || mBackingMap.containsKey(key); } /** * Returns true if the cache contains the value or else if the backing map * contains the value. */ public boolean containsValue(Object value) { return mCacheMap.containsValue(value) || mBackingMap.containsValue(value); } /** * Returns the value from the cache, or if not found, the backing map. * If the backing map is accessed, the value is saved in the cache for * future gets. */ public Object get(Object key) { Object value = mCacheMap.get(key); if (value != null || mCacheMap.containsKey(key)) { return value; } value = mBackingMap.get(key); if (value != null || mBackingMap.containsKey(key)) { mCacheMap.put(key, value); } return value; } /** * Puts the entry into both the cache and backing map. The old value in * the backing map is returned. */ public Object put(Object key, Object value) { mCacheMap.put(key, value); return mBackingMap.put(key, value); } /** * Removes the key from both the cache and backing map. The old value in * the backing map is returned. */ public Object remove(Object key) { mCacheMap.remove(key); return mBackingMap.remove(key); } /** * Clears both the cache and backing map. */ public void clear() { mCacheMap.clear(); mBackingMap.clear(); } /** * Returns the key set of the backing map. */ public Set keySet() { return mBackingMap.keySet(); } /** * Returns the values of the backing map. */ public Collection values() { return mBackingMap.values(); } /** * Returns the entry set of the backing map. */ public Set entrySet() { return mBackingMap.entrySet(); } }