ParallelFor: TestBreak()

fwilleke80

Hello,

I'm successfully using the Parallel stuff from the API.

What I didn't understand yet is how to check for a user break within a ParallelFor worker lambda. I'm thinking the BreakContext has something to do with it, but I couldn't figure out yet how to do it.

With the old C4DThreads, we could simply do it like this:

// Check for user break every 64 iterations
if (thread && !(x & 63))
{
	if (thread->TestBreak())
		break;
}

How does this work with the new Parallel functions?

Cheers,
Frank

m_magalhaes

hi,
sorry for the late reply.

you have to use the BreakContext in the template of the parrallelFor.

And pass your thread to the lamba function as a reference. In the lambda function you call the Break function if needed.

there are other context you can use

        maxon::Result<void> errReturn;
	auto worker = [&escThread]
	(maxon::Int32 y , maxon::ParallelFor::BreakContext& context) -> maxon::Result < void >
	{
		
		for (maxon::Int32 loop = 0; loop < 10000; loop++)
		{
			if (MAXON_UNLIKELY(escThread->TestBreak()))
				context.Break(maxon::UnexpectedError(MAXON_SOURCE_LOCATION));
			continue;
		}
		return maxon::OK;
	};

	errReturn = maxon::ParallelFor::Dynamic<maxon::ParallelFor::BreakContext>(0, 100000, worker, numThreads, maxon::PARALLELFOR_DEFAULTGRANULARITY );
	
	if (errReturn == maxon::OK)
		ApplicationOutput("we didn't got stoped");
	else if (errReturn == maxon::FAILED)
		ApplicationOutput("we've been stopped @", errReturn.GetError());

Sorry i cant really provide a fully working example but that's the way to do it :)

Cheers,
Manuel

fwilleke80

Super cool, thank you for the example code!

Greetings,
Frank

fwilleke80

Oh wait, what's escThread in your example code? Where did that come from?

PluginStudent

I would guess that's the thread returned by GeGetEscTestThread(). See Thread Utility Manual.

Or it is just the thread that provides the context for your call.

fwilleke80

That makes sense. Thanks again!

Cheers,
Frank

m_magalhaes

hi,

as @PluginStudent said i was using GeGetEscTestThread and by the way, it's not really working =)

But that's the same question with your code.
You test the thread that have been provided to you or your own thread. For that you pass that thread as a reference to the lambda function.

Cheers,
Manuel