Task Dataflow, can a data block be changed from completion state?

c#, task-parallel-library, tpl-dataflow

Solution

No, you can't “uncomplete” a completed dataflow block. I think what you should do is to add a flag to each message that says whether it's last message in a run. To make it simpler to work with it, you could create set of helper methods like:

public static TransformBlock<Tuple<TInput, bool>, Tuple<TOutput, bool>>
    CreateEnhancedTransformBlock<TInput, TOutput>(Func<TInput, TOutput> transform)
{
    return new TransformBlock<Tuple<TInput, bool>, Tuple<TOutput, bool>>(
        tuple => Tuple.Create(transform(tuple.Item1), tuple.Item2));
}

This way, you enter a `transform` delegate that deals just with `TInput` and `TOuput` and the flag is transfered along with each message.

Problem

I would like to know whether it is possible to change the completion state of data blocks? For example, I marked a `var block = new BufferBlock<int>();` data block complete with `block.Complete()`. The block is linked to other data blocks. I would like to know whether I can make `block` run again by changing its completion state back to its original !complete state. If that is not possible how could I perform multiple runs, including completion, without having to a) de-link all blocks, b) re-instantiate all blocks,and c) re-link all blocks again? Any ideas which may ease the task of running data flow cycles including completing each block down the chain without having to re-create the whole framework? Thanks

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