Timeout without using Threads? Iterative deepening of MiniMax-Tree

how can I limit the execution time of my iterate-deepening search without using a thread?

Currently I use this simple implementation, but it is not efficient and sometimes even does not terminate within the given timeframe..

timer.Start();
best = doSearch();
timer.Stop();
dpuble time = timer.Duration;
while (time*1000 < 400)
{
   timer.开发者_JAVA百科Start();
   best = doSearch();
   timer.Stop();
   time += timer.Duration;
}

If you want to avoid threading, you would need to pass a timestamp into your doSearch() method. It could (periodically) check the current time, and if the duration is past some threshold, raise an exception or return the failed case.

How do you want to terminate execution? Do you want to exit the program, or just stop searching? If you're okay with destroying your process, you could do this:

 var timer = new Timer(new TimeSpan(0, 0, 400));
 timer.Elapsed += { throw new Exception("Time's up!"); }
 timer.Start();
 doSearch();
 timer.Stop();

But I think you want something more reasonable. In that case, you probably have to do this within doSearch itself. I assume that the method is iterative or recursive, in which case you can store the start time in an instance variable, then check the elapsed time at a well-known point in the iteration/recursion. For example:

private DateTime _start;
private TimeSpan _maxTime = new TimeSpan(0, 0, 400);

public void TimedSearch()
{
    _start = DateTime.Now;
    DoSearch();
}

public void DoSearch()
{
    while (notFound)
    {
        if (DateTime.Now - _start > _maxTime)
            return;

        // search code
    }
}