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* 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.cayenne.cache;
import java.util.List;
import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.di.BeforeScopeEnd;
import org.apache.cayenne.query.QueryMetadata;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class EhCacheQueryCache implements QueryCache {
/**
* Default cache group name.
*/
static final String DEFAULT_CACHE_NAME = "cayenne.default.cachegroup";
private static Log logger = LogFactory.getLog(EhCacheQueryCache.class);
protected CacheManager cacheManager;
public EhCacheQueryCache() {
cacheManager = new CacheManager();
init();
}
public EhCacheQueryCache(String configFile) {
cacheManager = new CacheManager(configFile);
init();
}
public EhCacheQueryCache(CacheManager cacheManager) {
if (cacheManager != null) {
this.cacheManager = cacheManager;
init();
}
else {
throw new CayenneRuntimeException("CacheManager cannot be null.");
}
}
private void init() {
cacheManager.addCacheIfAbsent(DEFAULT_CACHE_NAME);
}
public List get(QueryMetadata metadata) {
String key = metadata.getCacheKey();
if (key == null) {
return null;
}
String cacheName = cacheName(key, metadata.getCacheGroups());
Ehcache cache = cacheManager.getCache(cacheName);
if (cache == null) {
return null;
}
Element result = cache.get(key);
return result != null ? (List) result.getObjectValue() : null;
}
public List get(QueryMetadata metadata, QueryCacheEntryFactory factory) {
String key = metadata.getCacheKey();
if (key == null) {
// TODO: we should really throw here... The method declares that it
// never returns null
return null;
}
String cacheName = cacheName(key, metadata.getCacheGroups());
// create empty cache for cache group here, as we have a factory to
// create an object, and should never ever return null from this
// method.
Ehcache cache = cacheManager.addCacheIfAbsent(cacheName);
Element result = cache.get(key);
if (result != null) {
return (List) result.getObjectValue();
}
// if no result in cache locking the key to write
// and putting it to the cache
cache.acquireWriteLockOnKey(key);
try {
// now that we locked the key, let's reread the cache again, in case
// an object appeared there already
result = cache.get(key);
if (result != null) {
return (List) result.getObjectValue();
}
// if not succeeded in reading again putting
// object to the cache ourselves
Object object = factory.createObject();
if (!(object instanceof List)) {
if (object == null) {
throw new CayenneRuntimeException("Null object created: " + metadata.getCacheKey());
} else {
throw new CayenneRuntimeException("Invalid query result, expected List, got "
+ object.getClass().getName());
}
}
cache.put(new Element(key, object));
return (List) object;
} finally {
cache.releaseWriteLockOnKey(key);
}
}
private String cacheName(String key, String... cacheGroups) {
if (cacheGroups != null && cacheGroups.length > 0) {
if (cacheGroups.length > 1) {
logger.warn("multiple cache groups per key '" + key + "', ignoring all but the first one: "
+ cacheGroups[0]);
}
return cacheGroups[0];
}
return DEFAULT_CACHE_NAME;
}
public void put(QueryMetadata metadata, List results) {
String key = metadata.getCacheKey();
if (key != null) {
String cacheName = cacheName(key, metadata.getCacheGroups());
Ehcache cache = cacheManager.addCacheIfAbsent(cacheName);
cache.put(new Element(key,results));
}
}
public void remove(String key) {
if (key != null) {
for (String cache : cacheManager.getCacheNames()) {
cacheManager.getCache(cache).remove(key);
}
}
}
public void removeGroup(String groupKey) {
Ehcache cache = cacheManager.getEhcache(groupKey);
if(cache != null) {
cache.removeAll();
}
}
public void clear() {
cacheManager.removalAll();
}
public int size() {
int size = 0;
for (String cache : cacheManager.getCacheNames()) {
size += cacheManager.getCache(cache).getSize();
}
return size;
}
/**
* Returns default cache group.
*/
public Ehcache getDefaultCache() {
return cacheManager.getCache(DEFAULT_CACHE_NAME);
}
/**
* Shuts down EhCache CacheManager
*/
@BeforeScopeEnd
public void shutdown() {
cacheManager.shutdown();
}
}