Bug using Encapsulate with Filtering

Question

Assume I have the following code:

public static IPropagatorBlock<TIn,TOut> CreateSampleBlock<TIn,TOut>(Func<TIn,TOut> transform)
{
    var buffer = new BufferBlock<TOut>();
    var action = new ActionBlock<TIn>( i => buffer.Post(transform(i)));

    action.Completion.ContinueWith(_ => buffer.Complete(), 
        TaskContinuationOptions.OnlyOnRanToCompletion);

    action.Completion.ContinueWith(task => ((IDataflowBlock) buffer).Fault(task.Exception),
        TaskContinuationOptions.OnlyOnFaulted);
            
    return DataflowBlock.Encapsulate(action, buffer);
} 

Then I set up a simple network with filtering between links:

var bb = new BufferBlock<int>();
var mt = CreateSampleBlock<Int32, Int32>(i => i*2);
var a = new ActionBlock<int>(i => Console.WriteLine(i));

bb.LinkTo(mt);
mt.LinkTo(a, i => i < 10);

foreach (var s in Enumerable.Range(1,10))
{
    bb.Post(s);
}

In this scenario an ArgumentException is thrown from within DataflowBlock.FilteredLinkPropagator<T>, obviously because of the following test in the implementation of ITargetBlock<T>.OfferMessage(...):

if (source != this.m_source)
    throw new ArgumentException(Resource.Argument_InvalidSourceForFilteredLink, "source");

m_source holds a reference to the EncapsulatingPropagator<TInput,TOutput>. The ISourceBlock<T> 'source' argument that is passed to the method however references the (encapsulated) BufferBlock<Int32>.

Answer 1

Hi A.Frischke,

Thank you for reporting this issue. This is a bug in Dataflow. It will be fixed in a future release.

Thanks,Cristina

Answer 2

Hi A.Frischke,

The bug was fixed in the latest version of the TPL Dataflow. TPL Dataflow NuGet package version 4.5.9.<o:p></o:p>

Please report any new issues/suggestions for TPL Dataflow; we will be happy to help.

Thanks, Cristina<o:p></o:p>

Answer 3

Hi Cristina,

Great to hear that the issue has been resolved. I will test the new version right away (and keep you posted should I come across any other issues in the library, of course).

Best regards, Andreas