Mercurial > hg > blitz_condensed
diff 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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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/com/go/trove/util/WrappedCache.java Sat Mar 21 11:00:06 2009 +0000 @@ -0,0 +1,176 @@ +/* ==================================================================== + * 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(); + } +}