/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.modcluster.demo.servlet;

import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryUsage;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.jboss.logging.Logger;

/**
 * @author Paul Ferraro
 *
 */
public class HeapMemoryLoadServlet extends LoadServlet
{
   /** The serialVersionUID */
   private static final long serialVersionUID = -8183119455180366670L;
   private static Logger log = Logger.getLogger(HeapMemoryLoadServlet.class);

   private static final String RATIO = "ratio";
   private static final String DEFAULT_RATIO = "0.9";
   
   private static final int MB = 1024 * 1024;
   
   /**
    * @{inheritDoc}
    * @see javax.servlet.http.HttpServlet#service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
    */
   @Override
   protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException
   {
      int duration = Integer.parseInt(this.getParameter(request, DURATION, DEFAULT_DURATION)) * 1000;
      float ratio = Float.parseFloat(this.getParameter(request, RATIO, DEFAULT_RATIO));

      System.gc();
      
      MemoryUsage usage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
      
      long max = usage.getMax();
      long total = (max >= 0) ? max : usage.getCommitted();
      long free = total - usage.getUsed();
      
      long reserve = (long) (free * ratio);

      log.info((total / MB) + "MB total memory");
      log.info((free / MB) + "MB free memory");
      log.info("Reserving " + (reserve / MB) + "MB (" + ((int) (ratio * 100)) + "%) of memory");
      
      List<Object> list = new ArrayList<Object>(2);
      
      if (free > Integer.MAX_VALUE)
      {
         list.add(new byte[(int) (reserve / Integer.MAX_VALUE)][Integer.MAX_VALUE]);
      }
      
      list.add(new byte[(int) (reserve % Integer.MAX_VALUE)]);
      
      try
      {
         
         Thread.sleep(duration);
      }
      catch (InterruptedException e)
      {
         Thread.currentThread().interrupt();
      }
      
      log.info("Freeing " + (reserve / MB) + "MB of memory");
      
      list.clear();
      
      System.gc();
      
      this.writeLocalName(request, response);
   }
}
