| /* |
| * Copyright (c) 2003 The Visigoth Software Society. 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 acknowledgement: |
| * "This product includes software developed by the |
| * Visigoth Software Society (http://www.visigoths.org/)." |
| * Alternately, this acknowledgement may appear in the software itself, |
| * if and wherever such third-party acknowledgements normally appear. |
| * |
| * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the |
| * project contributors may be used to endorse or promote products derived |
| * from this software without prior written permission. For written |
| * permission, please contact visigoths@visigoths.org. |
| * |
| * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth" |
| * nor may "FreeMarker" or "Visigoth" appear in their names |
| * without prior written permission of the Visigoth Software Society. |
| * |
| * 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 VISIGOTH SOFTWARE SOCIETY 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. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Visigoth Software Society. For more |
| * information on the Visigoth Software Society, please see |
| * http://www.visigoths.org/ |
| */ |
| |
| package freemarker.cache; |
| |
| import java.lang.ref.Reference; |
| import java.lang.ref.ReferenceQueue; |
| import java.lang.ref.SoftReference; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.util.Map; |
| |
| import freemarker.core._ConcurrentMapFactory; |
| import freemarker.template.utility.UndeclaredThrowableException; |
| |
| /** |
| * Soft cache storage is a cache storage that uses {@link SoftReference} |
| * objects to hold the objects it was passed, therefore allows the garbage |
| * collector to purge the cache when it determines that it wants to free up |
| * memory. |
| * This class is thread-safe to the extent that its underlying map is. The |
| * default implementation uses a concurrent map on Java 5 and above, so it's |
| * thread-safe in that case. |
| * |
| * @see freemarker.template.Configuration#setCacheStorage(CacheStorage) |
| * |
| * @author Attila Szegedi |
| */ |
| public class SoftCacheStorage implements ConcurrentCacheStorage |
| { |
| private static final Method atomicRemove = getAtomicRemoveMethod(); |
| |
| private final ReferenceQueue queue = new ReferenceQueue(); |
| private final Map map; |
| private final boolean concurrent; |
| |
| public SoftCacheStorage() { |
| this(_ConcurrentMapFactory.newMaybeConcurrentHashMap()); |
| } |
| |
| public boolean isConcurrent() { |
| return concurrent; |
| } |
| |
| public SoftCacheStorage(Map backingMap) { |
| map = backingMap; |
| this.concurrent = _ConcurrentMapFactory.isConcurrent(map); |
| } |
| |
| public Object get(Object key) { |
| processQueue(); |
| Reference ref = (Reference)map.get(key); |
| return ref == null ? null : ref.get(); |
| } |
| |
| public void put(Object key, Object value) { |
| processQueue(); |
| map.put(key, new SoftValueReference(key, value, queue)); |
| } |
| |
| public void remove(Object key) { |
| processQueue(); |
| map.remove(key); |
| } |
| |
| public void clear() { |
| map.clear(); |
| processQueue(); |
| } |
| |
| private void processQueue() { |
| for(;;) { |
| SoftValueReference ref = (SoftValueReference)queue.poll(); |
| if(ref == null) { |
| return; |
| } |
| Object key = ref.getKey(); |
| if(concurrent) { |
| try { |
| atomicRemove.invoke(map, new Object[] { key, ref }); |
| } |
| catch(IllegalAccessException e) { |
| throw new UndeclaredThrowableException(e); |
| } |
| catch(InvocationTargetException e) { |
| throw new UndeclaredThrowableException(e); |
| } |
| } |
| else if(map.get(key) == ref) { |
| map.remove(key); |
| } |
| } |
| } |
| |
| private static final class SoftValueReference extends SoftReference { |
| private final Object key; |
| |
| SoftValueReference(Object key, Object value, ReferenceQueue queue) { |
| super(value, queue); |
| this.key = key; |
| } |
| |
| Object getKey() { |
| return key; |
| } |
| } |
| |
| private static Method getAtomicRemoveMethod() { |
| try { |
| return Class.forName("java.util.concurrent.ConcurrentMap").getMethod("remove", new Class[] { Object.class, Object.class }); |
| } |
| catch(ClassNotFoundException e) { |
| return null; |
| } |
| catch(NoSuchMethodException e) { |
| throw new UndeclaredThrowableException(e); |
| } |
| } |
| } |