Bug 165188 logging per report
Setting up a dedicated (birt) report server, which serves all our web apps, leads to a logging desaster. Birtegine logs all messages to one file. There's no info which rptdesign caused the logmessage or who (e.g. user) caused the logmessage. Retrieving who/which rpt caused some logmessage is not possible! There are two possible solutions: (a) prefixing each logmessage with a userdefineable message (task.setLogprefix("myprefix")) (b) set an outputstream for each task (task.setLoggingOutputStream(outputstream)) to split the huge logfile to many small pieces.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
*/
	public void cancel( )
	{
		cancelFlag = true;
		executionContext.cancel( );
	}
	public void cancel( Object signal )
	{
		if ( signal == null )
		{
			throw new IllegalArgumentException( "signal can't be null" );
		}
		cancelFlag = true;
		long waitingTime = 0;
		do
		{
			waitingTime += 100;
			try
			{
				Thread.sleep( 100 );
			}
			catch ( Exception ex )
			{
			}
			if ( runningStatus != STATUS_RUNNING )
			{
				return;
			}
		} while ( waitingTime < 5000 );
		return;