/// <summary>Finishes a potentially-limited search. To be called by a <see cref="Search"/> method after
/// <see cref="BeginSearch"/>. This method calls <see cref="Iterate"/> repeatedly until the search completes or the
/// limit expires (if a limit was given), and then returns the result.
/// </summary>
SearchResult FinishLimitedSearch(SearchLimiter limiter, Func<ContextType> contextMaker, out SolutionType solution)
{
TaskCancellationEvent foundEvent = new TaskCancellationEvent();
int parallelism = UseAutomaticParallelism ? GetEffectiveParallelism() : 1;
KeyValuePair<ContextType,SearchResult>[] results = Tasks.Parallelize(task =>
{
ContextType context = contextMaker();
SearchResult result = SearchResult.Pending;
while(result == SearchResult.Pending && !task.WasCanceled && (limiter == null || limiter.LimitReached))
{
result = Iterate(context);
}
if(result == SearchResult.Success) foundEvent.Cancel(); // stop the other threads if we've found a solution
return new KeyValuePair<ContextType,SearchResult>(
context, result == SearchResult.Pending ? SearchResult.LimitReached : result);
}, parallelism, foundEvent);
// find the best result type
SearchResult bestResult = SearchResult.Failed;
foreach(var result in results)
{
if(result.Value != SearchResult.Failed)
{
bestResult = result.Value;
if(bestResult == SearchResult.Success) break;
}
}
// find the best solution among those having the best result type
solution = SelectBestSolution((from r in results where r.Value == bestResult select r.Key).ToArray());
return bestResult;
}
/// <include file="documentation.xml" path="/AI/Search/ISearch/Search_State/*"/>
public override SearchResult Search(StateType initialState, SearchLimiter limiter, out SolutionType solution)
{
return FinishLimitedSearch(limiter, () => BeginSearch(initialState), out solution);
}
/// <include file="documentation.xml" path="/AI/Search/ISearch/Search/*"/>
public override SearchResult Search(SearchLimiter limiter, out SolutionType solution)
{
return FinishLimitedSearch(limiter, () => BeginSearch(), out solution);
}