Prioritization missing

[tobbee]

I started looking into how the stream prioritization values for different streams are propagated and found out that they are not used at all.

The underlying quic-go library does not have a way to use them in its scheduling either, but just uses round-robin
scheduling among the streams in a QUIC session.
Seems to be an old outstanding issue: quic-go/quic-go#437

I think that it is quite important that there is a working priorities when switching tracks or mixing SUBSCRIBE with JOINING_FETCH. Furthermore, according to the spec the control messages should have the highest priority.

As far as I can tell, this needs to be fixed in quic-go first. I tried to open for a contribution in quic-go/quic-go#3470 which was tagged "Help wanted", but it was turned down. May pursue that anyway, if I get the time.

[mengelbart]

As you said, this depends on quic-go implementing priorities. I'll add the won't fix label for now to indicate that we don't work on this until quic-go has an API at which time it should hopefully be easy to implement.