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 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
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 *************************************************************/



package com.sun.star.comp.beans;

//---------------------------------------------------------------------------
/** Helper class to watch calls into AOO with a timeout.
 */
// Do not add the thread instances to a threadgroup. When testing the bean in
// an applet it turned out the ThreadGroup was in an inconsistent state
// after navigating off the site that contains the applet and back to it.
// That was tested with a Sun JRE 1.4.2_06
public class CallWatchThread extends Thread
{
	private static boolean DEBUG = false;

	private Thread aWatchedThread;
	private String aTag;
	private boolean bAlive;
	private long nTimeout;

	public CallWatchThread(long nTimeout)
	{
		this(nTimeout, "");
	}

	public CallWatchThread( long nTimeout, String aTag )
	{
		super(aTag);
		this.aWatchedThread = Thread.currentThread();
		this.nTimeout = nTimeout;

		this.aTag = aTag;
		setDaemon( true );
		dbgPrint( "CallWatchThread(" + this + ").start(" + aTag + ")" );
		start();
	}

	public void cancel()
		throws java.lang.InterruptedException
	{
		dbgPrint( "CallWatchThread(" + this + ".cancel(" + aTag + ")" );
		if ( aWatchedThread != null && aWatchedThread != Thread.currentThread() )
			throw new RuntimeException( "wrong thread" );
		aWatchedThread = null;
		if ( interrupted() )
			throw new InterruptedException();
	}

	public synchronized void restart()
		throws java.lang.InterruptedException
	{
		dbgPrint( "CallWatchThread(" + this + ".restart(" + aTag + ")" );
		if ( aWatchedThread != null && aWatchedThread != Thread.currentThread() )
			throw new RuntimeException( "wrong thread" );
		bAlive = true;
		if ( interrupted() )
			throw new InterruptedException();
		notify();
	}

	public void run()
	{
		dbgPrint( "CallWatchThread(" + this + ".run(" + aTag + ") ***** STARTED *****" );
		long n = 0;
		while ( aWatchedThread != null )
		{
			dbgPrint( "CallWatchThread(" + this + ").run(" + aTag + ") running #" + ++n );
			synchronized(this)
			{
				bAlive = false;
				try
				{
					wait( nTimeout );
				}
				catch ( java.lang.InterruptedException aExc )
				{
					bAlive = false;
				}

				// watched thread seems to be dead (not answering)?
				if ( !bAlive && aWatchedThread != null )
				{
					dbgPrint( "CallWatchThread(" + this + ").run(" + aTag + ") interrupting" );
					aWatchedThread.interrupt();
					aWatchedThread = null;
				}
			}
		}

		dbgPrint( "CallWatchThread(" + this + ").run(" + aTag + ") terminated" );
	}

	private void dbgPrint( String aMessage )
	{
		if (DEBUG)
			System.err.println( "OOoBean: " + aMessage );
	}
}