/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. 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. For additional information regarding
* copyright in this work, please see the NOTICE file in the top level
* directory of this distribution.
*/
package org.apache.roller.ui.rendering.util.cache;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.roller.config.RollerConfig;
import org.apache.roller.ui.rendering.util.WeblogFeedRequest;
import org.apache.roller.util.Utilities;
import org.apache.roller.util.cache.Cache;
import org.apache.roller.util.cache.CacheManager;
import org.apache.roller.util.cache.LazyExpiringCacheEntry;
/**
* Cache for weblog feed content.
*/
public class WeblogFeedCache {
private static Log log = LogFactory.getLog(WeblogFeedCache.class);
// a unique identifier for this cache, this is used as the prefix for
// roller config properties that apply to this cache
public static final String CACHE_ID = "cache.weblogfeed";
// keep cached content
private boolean cacheEnabled = true;
private Cache contentCache = null;
// reference to our singleton instance
private static WeblogFeedCache singletonInstance = new WeblogFeedCache();
private WeblogFeedCache() {
cacheEnabled = RollerConfig.getBooleanProperty(CACHE_ID+".enabled");
Map cacheProps = new HashMap();
cacheProps.put("id", CACHE_ID);
Enumeration allProps = RollerConfig.keys();
String prop = null;
while(allProps.hasMoreElements()) {
prop = (String) allProps.nextElement();
// we are only interested in props for this cache
if(prop.startsWith(CACHE_ID+".")) {
cacheProps.put(prop.substring(CACHE_ID.length()+1),
RollerConfig.getProperty(prop));
}
}
log.info(cacheProps);
if(cacheEnabled) {
contentCache = CacheManager.constructCache(null, cacheProps);
} else {
log.warn("Caching has been DISABLED");
}
}
public static WeblogFeedCache getInstance() {
return singletonInstance;
}
public Object get(String key, long lastModified) {
if(!cacheEnabled)
return null;
Object entry = null;
LazyExpiringCacheEntry lazyEntry =
(LazyExpiringCacheEntry) this.contentCache.get(key);
if(lazyEntry != null) {
entry = lazyEntry.getValue(lastModified);
if(entry != null) {
log.debug("HIT "+key);
} else {
log.debug("HIT-EXPIRED "+key);
}
} else {
log.debug("MISS "+key);
}
return entry;
}
public void put(String key, Object value) {
if(!cacheEnabled)
return;
contentCache.put(key, new LazyExpiringCacheEntry(value));
log.debug("PUT "+key);
}
public void remove(String key) {
if(!cacheEnabled)
return;
contentCache.remove(key);
log.debug("REMOVE "+key);
}
public void clear() {
if(!cacheEnabled)
return;
contentCache.clear();
log.debug("CLEAR");
}
/**
* Generate a cache key from a parsed weblog feed request.
* This generates a key of the form ...
*
* <handle>/<type>/<format>/[/category][/language][/excerpts]
*
* examples ...
*
* foo/entries/rss/en
* foo/comments/rss/MyCategory/en
* foo/entries/atom/en/excerpts
*
*/
public String generateKey(WeblogFeedRequest feedRequest) {
StringBuffer key = new StringBuffer();
key.append(this.CACHE_ID).append(":");
key.append(feedRequest.getWeblogHandle());
key.append("/").append(feedRequest.getType());
key.append("/").append(feedRequest.getFormat());
if(feedRequest.getWeblogCategoryName() != null) {
String cat = feedRequest.getWeblogCategoryName();
try {
cat = URLEncoder.encode(cat, "UTF-8");
} catch (UnsupportedEncodingException ex) {
// should never happen, utf-8 is always supported
}
key.append("/").append(cat);
}
if(feedRequest.getTags() != null && feedRequest.getTags().size() > 0) {
Set ordered = new TreeSet(feedRequest.getTags());
String[] tags = (String[]) ordered.toArray(new String[ordered.size()]);
key.append("/tags/").append(Utilities.stringArrayToString(tags,"+"));
}
if(feedRequest.getLocale() != null) {
key.append("/").append(feedRequest.getLocale());
}
if(feedRequest.isExcerpts()) {
key.append("/excerpts");
}
return key.toString();
}
}