/**
 * Copyright (C) 2008, 1C
 */
package ru.akimov.gfleak.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
import javax.transaction.UserTransaction;

/**
 * Servlet using a {@link DataSource} resource causes a problem in 
 * J2EETransactionManager it remains in BaseCache as a key even after 
 * the application is undeployed. 
 *
 * @author Akimov
 */
public class LeakServlet
    extends HttpServlet
{
    /* (non-Javadoc)
     * @see javax.servlet.http.HttpServlet#service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void service(HttpServletRequest request,
                           HttpServletResponse response)
        throws ServletException, IOException
    {
        try
        {
            UserTransaction userTransaction = lookupUserTransaction();
            DataSource dataSource = lookupDataSource();
            userTransaction.begin();
            try
            {
                Connection connection = lookupDataSource().getConnection();
                try
                {
                    connection.getMetaData();
                }
                finally
                {
                    connection.close();
                }
                userTransaction.commit();
            }
            catch (SQLException e)
            {
                userTransaction.rollback();
                throw new ServletException(e);
            }
        }
        catch (ServletException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new ServletException(e);
        }
        
        PrintWriter writer = response.getWriter();
        try
        {
            writer.print("Request has been completed. Undeploy application, "
                + "undeploy application and see LeakServlet in the heap dump.");
            writer.flush();
        }
        finally
        {
            writer.close();
        }
    }

    private DataSource lookupDataSource() throws NamingException
    {
        DataSource dataSource = null;
        InitialContext initialContext = new InitialContext();
        try
        {
            dataSource =
                (DataSource)initialContext.lookup("java:comp/env/jdbc/DataSource");
        }
        finally
        {
            initialContext.close();
        }
        return dataSource;
    }

    private UserTransaction lookupUserTransaction() throws NamingException
    {
        UserTransaction userTransaction = null;
        InitialContext initialContext = new InitialContext();
        try
        {
            userTransaction =
                (UserTransaction)initialContext.lookup("java:comp/UserTransaction");
        }
        finally
        {
            initialContext.close();
        }
        return userTransaction;
    }
}