Make private traits in public api, sealed and public

[programatik29]

Resolves #2051, resolves #3097

• Moved, sealed, renamed ConnStreamExec to Http2ConnExec and made it public.
• Changed pub(super) restriction of HttpService to pub.

[seanmonstar]

Thanks so much! I do think this is the direction that solves all the problems listed in #3097.

What do others think? @sfackler, @LucioFranco

[programatik29]

I think documentation can be better. Where do you think it should be @seanmonstar ?

Some ideas:

• serve_connection method.
• hyper::server::conn::http2 module.
• Executor trait.
• hyper::rt module.
• hyper::rt::bounds module.
• Http2ConnExec trait.

[programatik29]

In my opinion, there should be a documentation of how should an executor be in Executor trait and link to that trait in related places. Also explain in Http2ConnExec docs that it can be used with any executor implemented like it is shown in Executor trait docs.

[seanmonstar]

Good point, more docs would help people. Here's some thoughts of what to put where (anyone is free to suggest differently!):

• http2::Builder::new - Can explain briefly what the argument is, linking to the Http2ConnExec trait (or bounds module, perhaps).
• serve_connection - Briefly explain, like above.
• Http2ConnExec - Explain that this trait is for bounds, and that any desire to implement the trait should be done by implementing an Executor, linking to it.
• bounds - Explain that the module contains traits that ease setting bounds, but that traits within that module likely can be implemented automatically by implementing a different trait. I can't say bounds will only ever be for Executor, so that's what I'm slightly generic here. But there can be a subheading for the bounds docs about Executor.