Re: wait finishes early?

From:
Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 09 Dec 2009 16:12:46 -0800
Message-ID:
<12XTm.5409$ha3.1951@newsfe19.iad>
Mike Schilling wrote:

This looks to me like the correct logic, encapsulated reasonably well:

public class EventUtils
{
    public static void waitforEvent(
            long maxDelay, Object lock, EventChecker checker)
                throws InterruptedException
    {
        synchronized(lock)
        {
            long start = System.currentTimeMillis();
            long toWait = maxDelay;
            while (true)

// Almost correct, should use:
    while (!checker.isDone())
// because we don't want to wait if the event has already completed.

            {
                lock.wait(toWait);
                if (checker.isDone())
                    break;
                if (maxDelay > 0)
                {
                    long elapsed = System.currentTimeMillis() - start;
                    if (elapsed >= maxDelay)
                        break;
                    toWait = maxDelay - elapsed;
                }
            }
        }
    }

    public interface EventChecker
    {
        boolean isDone();
    }
}


Using Lock and Condition classes may be a better choice for some code bases.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>

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