/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2009, 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.web.tomcat.service.session;

import java.io.IOException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.valves.ValveBase;
import org.jboss.servlet.http.HttpEvent;

/**
 * Generic valve that applies a given lock to a request.
 * 
 * @author Paul Ferraro
 */
public class LockingValve extends ValveBase
{
   private final Lock lock;
   
   public LockingValve(Lock lock)
   {
      this.lock = lock;
   }
   
   /**
    * {@inheritDoc}
    */
   @Override
   public void invoke(Request request, Response response) throws IOException, ServletException
   {
      try
      {
         if (this.lock.tryLock(0, TimeUnit.SECONDS))
         {
            try
            {
               this.next.invoke(request, response);
            }
            finally
            {
               this.lock.unlock();
            }
         }
         else
         {
            response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
         }
      }
      catch (InterruptedException e)
      {
         Thread.currentThread().interrupt();
      }
   }

   /**
    * {@inheritDoc}
    */
   @Override
   public void event(Request request, Response response, HttpEvent event) throws IOException, ServletException
   {
      try
      {
         if (this.lock.tryLock(0, TimeUnit.SECONDS))
         {
            try
            {
               this.next.event(request, response, event);
            }
            finally
            {
               this.lock.unlock();
            }
         }
         else
         {
            response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
         }
      }
      catch (InterruptedException e)
      {
         Thread.currentThread().interrupt();
      }
   }
}