/*
* 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.sling.scripting.jsp.jasper.runtime;
import javax.servlet.ServletConfig;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.Tag;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.sling.scripting.jsp.jasper.Constants;
/**
* Pool of tag handlers that can be reused.
*
* @author Jan Luehe
*/
public class TagHandlerPool {
private Tag[] handlers;
public static String OPTION_TAGPOOL="tagpoolClassName";
public static String OPTION_MAXSIZE="tagpoolMaxSize";
private Log log = LogFactory.getLog(TagHandlerPool.class);
// index of next available tag handler
private int current;
protected AnnotationProcessor annotationProcessor = null;
public static TagHandlerPool getTagHandlerPool( ServletConfig config) {
final TagHandlerPool result = new TagHandlerPool();
result.init(config);
return result;
}
protected void init( ServletConfig config ) {
int maxSize=-1;
String maxSizeS=getOption(config, OPTION_MAXSIZE, null);
if( maxSizeS != null ) {
try {
maxSize=Integer.parseInt(maxSizeS);
} catch( Exception ex) {
maxSize=-1;
}
}
if( maxSize <0 ) {
maxSize=Constants.MAX_POOL_SIZE;
}
this.handlers = new Tag[maxSize];
this.current = -1;
this.annotationProcessor =
(AnnotationProcessor) config.getServletContext().getAttribute(AnnotationProcessor.class.getName());
}
/**
* Constructs a tag handler pool with the default capacity.
*/
public TagHandlerPool() {
// Nothing - jasper generated servlets call the other constructor,
// this should be used in future + init .
}
/**
* Constructs a tag handler pool with the given capacity.
*
* @param capacity Tag handler pool capacity
* @deprecated Use static getTagHandlerPool
*/
@Deprecated
public TagHandlerPool(int capacity) {
this.handlers = new Tag[capacity];
this.current = -1;
}
/**
* Gets the next available tag handler from this tag handler pool,
* instantiating one if this tag handler pool is empty.
*
* @param handlerClass Tag handler class
*
* @return Reused or newly instantiated tag handler
*
* @throws JspException if a tag handler cannot be instantiated
*/
public Tag get(Class handlerClass) throws JspException {
Tag handler = null;
synchronized( this ) {
if (current >= 0) {
handler = handlers[current--];
return handler;
}
}
// Out of sync block - there is no need for other threads to
// wait for us to construct a tag for this thread.
try {
Tag instance = (Tag) handlerClass.newInstance();
AnnotationHelper.postConstruct(annotationProcessor, instance);
return instance;
} catch (Exception e) {
throw new JspException(e.getMessage(), e);
}
}
/**
* Adds the given tag handler to this tag handler pool, unless this tag
* handler pool has already reached its capacity, in which case the tag
* handler's release() method is called.
*
* @param handler Tag handler to add to this tag handler pool
*/
public void reuse(Tag handler) {
synchronized( this ) {
if (current < (handlers.length - 1)) {
handlers[++current] = handler;
return;
}
}
// There is no need for other threads to wait for us to release
handler.release();
if (annotationProcessor != null) {
try {
AnnotationHelper.preDestroy(annotationProcessor, handler);
} catch (Exception e) {
log.warn("Error processing preDestroy on tag instance of "
+ handler.getClass().getName(), e);
}
}
}
/**
* Calls the release() method of all available tag handlers in this tag
* handler pool.
*/
public synchronized void release() {
for (int i = current; i >= 0; i--) {
handlers[i].release();
if (annotationProcessor != null) {
try {
AnnotationHelper.preDestroy(annotationProcessor, handlers[i]);
} catch (Exception e) {
log.warn("Error processing preDestroy on tag instance of "
+ handlers[i].getClass().getName(), e);
}
}
}
}
protected static String getOption( ServletConfig config, String name, String defaultV) {
if( config == null ) return defaultV;
String value=config.getInitParameter(name);
if( value != null ) return value;
if( config.getServletContext() ==null )
return defaultV;
value=config.getServletContext().getInitParameter(name);
if( value!=null ) return value;
return defaultV;
}
}