| /* |
| * 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.solr.util.xslt; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| import org.apache.commons.io.IOUtils; |
| |
| import javax.xml.transform.Templates; |
| import javax.xml.transform.Transformer; |
| import javax.xml.transform.TransformerConfigurationException; |
| import javax.xml.transform.TransformerFactory; |
| import javax.xml.transform.stream.StreamSource; |
| |
| import org.apache.lucene.analysis.util.ResourceLoader; |
| import org.apache.solr.util.SystemIdResolver; |
| import org.apache.solr.common.util.XMLErrorLogger; |
| import org.apache.solr.core.SolrConfig; |
| |
| /** Singleton that creates a Transformer for the XSLTServletFilter. |
| * For now, only caches the last created Transformer, but |
| * could evolve to use an LRU cache of Transformers. |
| * |
| * See http://www.javaworld.com/javaworld/jw-05-2003/jw-0502-xsl_p.html for |
| * one possible way of improving caching. |
| */ |
| |
| public class TransformerProvider { |
| private String lastFilename; |
| private Templates lastTemplates = null; |
| private long cacheExpires = 0; |
| |
| private static final Logger log = LoggerFactory.getLogger(TransformerProvider.class.getName()); |
| private static final XMLErrorLogger xmllog = new XMLErrorLogger(log); |
| |
| public static TransformerProvider instance = new TransformerProvider(); |
| |
| /** singleton */ |
| private TransformerProvider() { |
| // tell'em: currently, we only cache the last used XSLT transform, and blindly recompile it |
| // once cacheLifetimeSeconds expires |
| log.warn( |
| "The TransformerProvider's simplistic XSLT caching mechanism is not appropriate " |
| + "for high load scenarios, unless a single XSLT transform is used" |
| + " and xsltCacheLifetimeSeconds is set to a sufficiently high value." |
| ); |
| } |
| |
| /** Return a new Transformer, possibly created from our cached Templates object |
| * @throws IOException If there is a low-level I/O error. |
| */ |
| public synchronized Transformer getTransformer(SolrConfig solrConfig, String filename,int cacheLifetimeSeconds) throws IOException { |
| // For now, the Templates are blindly reloaded once cacheExpires is over. |
| // It'd be better to check the file modification time to reload only if needed. |
| if(lastTemplates!=null && filename.equals(lastFilename) && System.currentTimeMillis() < cacheExpires) { |
| if(log.isDebugEnabled()) { |
| log.debug("Using cached Templates:" + filename); |
| } |
| } else { |
| lastTemplates = getTemplates(solrConfig.getResourceLoader(), filename,cacheLifetimeSeconds); |
| } |
| |
| Transformer result = null; |
| |
| try { |
| result = lastTemplates.newTransformer(); |
| } catch(TransformerConfigurationException tce) { |
| log.error(getClass().getName(), "getTransformer", tce); |
| throw new IOException("newTransformer fails ( " + lastFilename + ")", tce); |
| } |
| |
| return result; |
| } |
| |
| /** Return a Templates object for the given filename */ |
| private Templates getTemplates(ResourceLoader loader, String filename,int cacheLifetimeSeconds) throws IOException { |
| |
| Templates result = null; |
| lastFilename = null; |
| try { |
| if(log.isDebugEnabled()) { |
| log.debug("compiling XSLT templates:" + filename); |
| } |
| final String fn = "xslt/" + filename; |
| final TransformerFactory tFactory = TransformerFactory.newInstance(); |
| tFactory.setURIResolver(new SystemIdResolver(loader).asURIResolver()); |
| tFactory.setErrorListener(xmllog); |
| final StreamSource src = new StreamSource(loader.openResource(fn), |
| SystemIdResolver.createSystemIdFromResourceName(fn)); |
| try { |
| result = tFactory.newTemplates(src); |
| } finally { |
| // some XML parsers are broken and don't close the byte stream (but they should according to spec) |
| IOUtils.closeQuietly(src.getInputStream()); |
| } |
| } catch (Exception e) { |
| log.error(getClass().getName(), "newTemplates", e); |
| throw new IOException("Unable to initialize Templates '" + filename + "'", e); |
| } |
| |
| lastFilename = filename; |
| lastTemplates = result; |
| cacheExpires = System.currentTimeMillis() + (cacheLifetimeSeconds * 1000); |
| |
| return result; |
| } |
| } |