/*
* 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 org.apache.lenya.cms.metadata;
import org.apache.avalon.framework.component.Component;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.Serviceable;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.excalibur.store.impl.MRUMemoryStore;
import org.apache.lenya.cms.publication.Document;
/**
* Cache for meta data.
*/
public class MetaDataCache implements ThreadSafe, Serviceable, Component {
public static final String ROLE = MetaDataCache.class.getName();
protected static final String STORE_ROLE = MetaDataCache.ROLE + "Store";
private MRUMemoryStore store;
protected ServiceManager manager;
/**
* Get a meta data object from the cache.
* @param document The document.
* @param namespaceUri The namespace URI.
* @return A meta data object.
* @throws MetaDataException if an error occurs.
*/
public synchronized MetaData getMetaData(String cacheKey, MetaData meta, String namespaceUri)
throws MetaDataException {
MRUMemoryStore store = getStore();
String key = getCacheKey(cacheKey, namespaceUri);
MetaData cachedMeta = null;
if (store.containsKey(key)) {
cachedMeta = (MetaData) store.get(key);
if (meta.getLastModified() > cachedMeta.getLastModified()) {
cachedMeta = null;
}
}
if (cachedMeta == null) {
cachedMeta = new CacheableMetaData(meta);
store.hold(key, cachedMeta);
}
return cachedMeta;
}
protected String getCacheKey(String cacheKey, String namespaceUri) {
return cacheKey + ":" + namespaceUri;
}
protected MRUMemoryStore getStore() {
if (this.store == null) {
synchronized (this) {
try {
this.store = (MRUMemoryStore) this.manager.lookup(STORE_ROLE);
} catch (ServiceException e) {
throw new RuntimeException(e);
}
}
}
return this.store;
}
public void service(ServiceManager manager) throws ServiceException {
this.manager = manager;
}
}