| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| package freemarker.ext.beans; |
| |
| import java.util.HashSet; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentHashMap; |
| |
| import freemarker.core._DelayedJQuote; |
| import freemarker.core._TemplateModelException; |
| import freemarker.template.TemplateHashModel; |
| import freemarker.template.TemplateModel; |
| import freemarker.template.TemplateModelException; |
| import freemarker.template.utility.ClassUtil; |
| |
| /** |
| * Base class for hash models keyed by Java class names. |
| */ |
| abstract class ClassBasedModelFactory implements TemplateHashModel { |
| private final BeansWrapper wrapper; |
| |
| private final Map<String,TemplateModel> cache = new ConcurrentHashMap<>(); |
| private final Set<String> classIntrospectionsInProgress = new HashSet<>(); |
| |
| protected ClassBasedModelFactory(BeansWrapper wrapper) { |
| this.wrapper = wrapper; |
| } |
| |
| @Override |
| public TemplateModel get(String key) throws TemplateModelException { |
| try { |
| return getInternal(key); |
| } catch (Exception e) { |
| if (e instanceof TemplateModelException) { |
| throw (TemplateModelException) e; |
| } else { |
| throw new _TemplateModelException(e, |
| "Failed to get value for key ", new _DelayedJQuote(key), "; see cause exception."); |
| } |
| } |
| } |
| |
| private TemplateModel getInternal(String key) throws TemplateModelException, ClassNotFoundException { |
| { |
| TemplateModel model = cache.get(key); |
| if (model != null) return model; |
| } |
| |
| final ClassIntrospector classIntrospector; |
| int classIntrospectorClearingCounter; |
| final Object sharedLock = wrapper.getSharedIntrospectionLock(); |
| synchronized (sharedLock) { |
| TemplateModel model = cache.get(key); |
| if (model != null) return model; |
| |
| while (model == null && classIntrospectionsInProgress.contains(key)) { |
| // Another thread is already introspecting this class; |
| // waiting for its result. |
| try { |
| sharedLock.wait(); |
| model = cache.get(key); |
| } catch (InterruptedException e) { |
| throw new RuntimeException("Class inrospection data lookup aborted: " + e); |
| } |
| } |
| if (model != null) return model; |
| |
| // This will be the thread that introspects this class. |
| classIntrospectionsInProgress.add(key); |
| |
| // While the classIntrospector should not be changed from another thread, badly written apps can do that, |
| // and it's cheap to get the classIntrospector from inside the lock here: |
| classIntrospector = wrapper.getClassIntrospector(); |
| classIntrospectorClearingCounter = classIntrospector.getClearingCounter(); |
| } |
| try { |
| final Class<?> clazz = ClassUtil.forName(key); |
| |
| // This is called so that we trigger the |
| // class-reloading detector. If clazz is a reloaded class, |
| // the wrapper will in turn call our clearCache method. |
| // TODO: Why do we check it now and only now? |
| classIntrospector.get(clazz); |
| |
| TemplateModel model = createModel(clazz); |
| // Warning: model will be null if the class is not good for the subclass. |
| // For example, EnumModels#createModel returns null if clazz is not an enum. |
| |
| if (model != null) { |
| synchronized (sharedLock) { |
| // Save it into the cache, but only if nothing relevant has changed while we were outside the lock: |
| if (classIntrospector == wrapper.getClassIntrospector() |
| && classIntrospectorClearingCounter == classIntrospector.getClearingCounter()) { |
| cache.put(key, model); |
| } |
| } |
| } |
| return model; |
| } finally { |
| synchronized (sharedLock) { |
| classIntrospectionsInProgress.remove(key); |
| sharedLock.notifyAll(); |
| } |
| } |
| } |
| |
| void clearCache() { |
| synchronized (wrapper.getSharedIntrospectionLock()) { |
| cache.clear(); |
| } |
| } |
| |
| void removeFromCache(Class<?> clazz) { |
| synchronized (wrapper.getSharedIntrospectionLock()) { |
| cache.remove(clazz.getName()); |
| } |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return false; |
| } |
| |
| protected abstract TemplateModel createModel(Class<?> clazz) throws TemplateModelException; |
| |
| protected BeansWrapper getWrapper() { |
| return wrapper; |
| } |
| |
| } |