/*

 * Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies). 

 * All rights reserved.

 * This component and the accompanying materials are made available

 * under the terms of the License "Eclipse Public License v1.0"

 * which accompanies this distribution, and is available

 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

 *

 * Initial Contributors:

 * Nokia Corporation - initial contribution.

 *

 * Contributors:

 *

 * Description: 

 *

 */

package com.nokia.carbide.cpp.internal.pi.manager;

import java.util.Hashtable;

import java.util.Vector;

/**

 * A utility for predictively resolving classes

 * This can be used to help offset one of the biggest detractors from

 * the Java language:  Class loading delays.

 *

 **/

{

	/**

	 * Thread used to load classes in the background

	 **/

	private static Thread controlThread;

	/**

	 * Storage for the class names still to be resolved

	 **/

	private static Vector queue;

	static

	{

		try

		{

			// This is an IBM-specific code that prevents a nasty error in the IBM resource lookup code -JDM

			java.text.DateFormat.getDateInstance();

		}

		catch (Exception e)

		{

		}

		queue = new Vector();

	}

    /**

     * Private constructor, to enforce singleton status

     * Creation date: (12/20/99 3:10:32 PM)

     **/

    private BackgroundLoader()

    {

    }

    /**

     * Enqueue a class for background loading

     * Creation date: (12/20/99 3:23:28 PM)

     * @param className java.lang.String

     **/

    public static void enqueueClass(String className)

    {

    	synchronized(queue)

    	{

    		queue.addElement(className);

    		if (controlThread == null)

    			start();

    		else

    			queue.notify();

    	}

    }

    /**

     * Start loading

     * Creation date: (12/20/99 3:15:29 PM)

     **/

    public void run()

    {

    	if (Thread.currentThread() != controlThread)

    		return;

    	Hashtable done = new Hashtable();

    	while (controlThread.isAlive())

    	{

    		String className;

    		synchronized(queue)

    		{

    			if (queue.isEmpty())

    			{

    				try

    				{

    					queue.wait();

    				}

    				catch (InterruptedException ie)

    				{

    				}

    			}

    			if (!queue.isEmpty())

    			{

    				className = (String) queue.elementAt(0);

    				queue.removeElementAt(0);

    			}

    			else

    				continue;

    		}

    		if (!done.containsKey(className))

    		{

    			try

    			{

    				Class resolved = Class.forName(className);

    				done.put(resolved.getName(), resolved);

    			}

    			catch (Exception e)

    			{

    				e.printStackTrace();

    			}

    		}

    		className = null;

    	}

    	controlThread = null;

    }

    /**

     * Insert the method's description here.

     * Creation date: (4/5/00 3:24:04 PM)

     */

    private static void start()

    {

    	controlThread = new Thread(new BackgroundLoader());

    	try

    	{

    		controlThread.setName(Messages.getString("BackgroundLoader.backgroundLoader")); //$NON-NLS-1$

    		controlThread.setPriority((Thread.MIN_PRIORITY + Thread.NORM_PRIORITY) / 2);

    	}

    	catch (Exception e)

    	{

    	}

    	controlThread.start();

    }

}