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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 OOo with a timeout.
 */
//Do not add the thread instances to a threadgroup. When testing the bean in
//an applet it turned out the 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 );
	}
}