Linked block doesn't complete

Question

I'm starting with TPL DataFlow. I've the following working code created. the readFilesBlock is a BufferBlock It is filled like this:

public async void ReadItems(ITargetBlock<SourceCodeFile> target)
{
    foreach(var item in Source)
    {
        await target.SendAsync(item); //when To use post instead of sendasync? 
    }
}

target.Complete(); 

Now I cosume the BufferBlock (readFilesBlock) like this

while (await readFilesBlock.OutputAvailableAsync())
    {
        var file = await readFilesBlock.ReceiveAsync();

        ActionBlock<SourceCodeFile> action = new ActionBlock<SourceCodeFile>(item => storeResultsInBag(resultBag, item));
        await action.SendAsync(file);
    }

This Works fine. Now I want to use the link Feature

I tried:

var storeFilesInBagAction = new ActionBlock<SourceCodeFile>(item => storeResultsInBag(resultBag, item));

readFilesBlock.LinkTo(storeFilesInBagAction);

await storeFilesInBagAction.Completion;

But this time i'll never get a completion.

What am I doing wrong?

When I'm not await the storefiles in Bagaction ,not items were returned.

Answer 1

By default, dataflow blocks do not propagate completion. This is by design; dataflows can represent any kind of mesh, including splits, joins, and loops (not just pipelines).

There is a PropagateCompletion option you can set when linking that will propagate completion.

readFilesBlock.LinkTo(storeFilesInBagAction, new DataflowLinkOptions
{
    PropagateCompletion = true,
});