feat(cca): cubic

[FrankSpitulski]

mostly copied from quiche, modified to fit here

still working out the best way to get a ref to the current RTT inside the CCA

Relates to #693

[Ralith]

Thanks for taking a swing at this! I think it'd be fine to pass the current RTT to be made an argument to whatever congestion::Controller methods need it. The current interface for Controller isn't expected to be comprehensive, just a starting point to grow as needed.

e: Then that argument would be populated with self.path.rtt.get() from callsites inside Connection.

[FrankSpitulski]

@Ralith thanks for the suggestion, I've pushed that impl up.

[Matthias247]

Some more discussions around Cubic and QUIC (also around min_rtt):

NTAP/rfc8312bis#45

quicwg/base-drafts#4833

[Ralith]

The RFC8312bis draft seems to be continuing to diverge from what we have here, but it's a moving target, so unless you're feeling super motivated to track it closely then I think we can call the underlying math here good.

[Ralith]

Thanks!

[djc]

Sorry, must have lost track of this one!