cvs commit: jakarta-tomcat-jasper/jasper2/src/share/org/apache/jasper/runtime TagHandlerPool.java

[ki...@apache.org]

kinman      2002/06/07 17:16:45

  Added:       jasper2/src/share/org/apache/jasper/runtime
                        TagHandlerPool.java
  Log:
  - Added a new runtime class.  Patch by Jan Luehe.
  
  Revision  Changes    Path
  1.1                  jakarta-tomcat-jasper/jasper2/src/share/org/apache/jasper/runtime/TagHandlerPool.java
  
  Index: TagHandlerPool.java
  ===================================================================
  /*
   * 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();
  	}
      }
  }
  
  
  
  

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