/*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.jasper.runtime;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.Tag;
/**
* Pool of tag handlers that can be reused.
*
* @author Jan Luehe
*/
public class TagHandlerPool {
private static final int MAX_POOL_SIZE = 5;
private Tag[] handlers;
// index of next available tag handler
private int current;
/**
* Constructs a tag handler pool with the default capacity.
*/
public TagHandlerPool() {
this(MAX_POOL_SIZE);
}
/**
* Constructs a tag handler pool with the given capacity.
*
* @param capacity Tag handler pool capacity
*/
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 synchronized Tag get(Class handlerClass) throws JspException {
Tag handler = null;
if (current >= 0) {
handler = handlers[current--];
} else {
try {
return (Tag) handlerClass.newInstance();
} catch (Exception e) {
throw new JspException(e.getMessage(), e);
}
}
return handler;
}
/**
* 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 synchronized void reuse(Tag handler) {
if (current < (handlers.length - 1))
handlers[++current] = handler;
else
handler.release();
}
/**
* 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();
}
}
}