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/*
 * Copyright (c) 2001-2002, Marco Hunsicker. All rights reserved.
 *
 * This software is distributable under the BSD license. See the terms of the
 * BSD license in the documentation provided with this software.
 */
package de.hunsicker.util.concurrent;

/**
 * TimedCallable runs a Callable function for a given length of time. The function is run
 * in its own thread. If the function completes in time, its result is returned;
 * otherwise the thread is interrupted and an InterruptedException is thrown.
 * 
 * 
 * Note: TimedCallable will always return within the given time limit (modulo timer
 * inaccuracies), but whether or not the worker thread stops in a timely fashion depends
 * on the interrupt handling in the Callable function's implementation.
 * 
 * 
 * 
 * This class was taken from the util.concurrent package written by Doug Lea. See http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html
 * for an introduction to this package.
 * 
 *
 * @author Joseph Bowbeer
 * @author Doug Lea
 * @version 1.0
 */
public class TimedCallable
    extends ThreadFactoryUser
    implements Callable
{
    //~ Instance variables ---------------------------------------------------------------

    private final Callable _function;
    private final long _millis;

    //~ Constructors ---------------------------------------------------------------------

    /**
     * Creates a new TimedCallable object.
     *
     * @param function DOCUMENT ME!
     * @param millis DOCUMENT ME!
     */
    public TimedCallable(
        Callable function,
        long     millis)
    {
        _function = function;
        _millis = millis;
    }

    //~ Methods --------------------------------------------------------------------------

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     *
     * @throws Exception DOCUMENT ME!
     */
    public Object call()
      throws Exception
    {
        FutureResult result = new FutureResult();
        Thread thread = getThreadFactory().newThread(result.setter(_function));
        thread.start();

        try
        {
            return result.timedGet(_millis);
        }
        catch (InterruptedException ex)
        {
            /* Stop thread if we were interrupted or timed-out
               while waiting for the result. */
            thread.interrupt();
            throw ex;
        }
    }
}