Alternative to gatherFrom: gatherForever about stm-conduit

[qnikst]

Sorry for a late reply. As far as I see this function continues to check for values even the worker has exited. gatherFrom continues to check for values as well, but only while there are no more values in the chan and worker thread is alive.

It seems that such function can exit only with BlockedIndefinitelyOnSTM if there are no more threads that has a access to the chan. It feels pretty unsafe and I think that there should be better API for this case, but I may be wrong here. Can you please share the general structure of the code that uses this function, so we can check if it's the best option for the library in such a case?

[bbarker]

Hi @qnikst ,

I haven't had a chance to process all of what you said just yet (will try to read into this more soon), but I'm using this in a server context; when I used the original gatherFrom, it would exit immediately, perhaps because no TCP accept had been initiated when gatherFrom initially starts.

Here's how I used it, along with some surrounding context and discussion: google/proto-lens#372 (comment)

[qnikst]

Thanks, I'll take a deeper look, but from what I see the problem is that you immediately fork the thread from the worker, and worker exits:

serveTBQ hp port rFun tbq = do
    _ <- async $ withRunInIO $ \run -> TCP.serve hp port $ \(csock, addr) -> do

If you don't use async here then the code will work with gatherFrom.

[bbarker]

@qnikst sorry for taking a while to get back on this. I appreciate the feedback, and yes, that was indeed the issue. Hard to say why I had that async there in the first place, in retrospect.