QPACK and naive H3 implementation

[stammw]

Continuing the work of @evolix1, from #20, which is blocking #130.

Features:

• Encoder
• Reference tracking
• Track DynamicTable::fields mutation, update DynamicTable::*_map when constructing DynamicTableEncoder instead of rebuilding HashMaps
• [-] N bit handling
• [-] Encode / decode concurreny (needs to have concurrent shared mutable state...)
• Configuration (may need H/3 impl to start)

Optimization:

• Improve Literal argument passing:
  • LiteralWithPostBaseNameRef::new(index, field.value.clone()): No
  • Look for a solution in https://deterministic.space/elegant-apis-in-rust.html, https://phaazon.net/blog/on-owning-borrowing-pub-interface
• Header fields lifetimes for Cow
• Use Reference count for DynamicTable::fields DynamicTable::*_map

[codecov]

Codecov Report

Merging #136 into master will increase coverage by 6.65%.
The diff coverage is 95.41%.

@@            Coverage Diff             @@
##           master     #136      +/-   ##
==========================================
+ Coverage   60.03%   66.68%   +6.65%     
==========================================
  Files          21       32      +11     
  Lines        5274     6495    +1221     
==========================================
+ Hits         3166     4331    +1165     
- Misses       2108     2164      +56

Impacted Files	Coverage Δ
quinn-h3/src/qpack/table/static_.rs	100% <100%> (ø)
quinn-h3/src/qpack/string/bitwin.rs	100% <100%> (ø)
quinn-h3/src/qpack/table/field.rs	100% <100%> (ø)
quinn-h3/src/qpack/primitive/iocontext.rs	86.2% <86.2%> (ø)
quinn-h3/src/qpack/primitive/dump.rs	90.16% <90.16%> (ø)
quinn-h3/src/qpack/decoder.rs	93.05% <93.05%> (ø)
quinn-h3/src/qpack/vas.rs	94.59% <94.59%> (ø)
quinn-h3/src/qpack/primitive/parser.rs	94.91% <94.91%> (ø)
quinn-h3/src/qpack/table/dynamic.rs	96.61% <96.61%> (ø)
quinn-h3/src/qpack/string/decode.rs	97.76% <97.76%> (ø)
... and 12 more

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[codecov]

Codecov Report

Merging #136 into master will increase coverage by 2.83%.
The diff coverage is 83.39%.

@@            Coverage Diff             @@
##           master     #136      +/-   ##
==========================================
+ Coverage   74.82%   77.66%   +2.83%     
==========================================
  Files          24       41      +17     
  Lines        6150     9197    +3047     
==========================================
+ Hits         4602     7143    +2541     
- Misses       1548     2054     +506

Impacted Files	Coverage Δ
quinn-proto/src/lib.rs	50% <ø> (ø)	⬆️
quinn-h3/src/qpack/mod.rs	0% <0%> (ø)
interop/src/qif.rs	0% <0%> (ø)
quinn-h3/src/qpack/prefix_int.rs	100% <100%> (ø)
quinn-h3/src/qpack/prefix_string/bitwin.rs	100% <100%> (ø)
quinn-h3/src/qpack/static_.rs	100% <100%> (ø)
quinn-h3/src/qpack/field.rs	63.33% <63.33%> (ø)
quinn-h3/src/qpack/stream.rs	84.07% <84.07%> (ø)
quinn-h3/src/frame.rs	85.57% <85.57%> (ø)
quinn-h3/src/qpack/decoder.rs	89.47% <89.47%> (ø)
... and 25 more

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[stammw]

I think we are near the point where it would be nice to plan merging this.

It has been tested against lightspeed's endpoint and there hasn't been necessary modification in the qpack code. I just had to use what's in #130 to achieve this. For the moment, encoder stream hasn't proved to be totally functional, but I'll soon get it tested.

It's now big enough for me to worry about the review, and willing to work with smaller iterations (surely is a beginner thing).

[djc]

There are a few usages of allow(dead_code) in here, why are they needed? Did you investigate reusing parts of HPACK from the h2 implementation?

[stammw]

@djc I did not think of that. I'm not sure the common code surface would be that big. Maybe for the primitive types like prefix_string.

[djc]

I think that's what I was looking at, but I understand if there's not enough overlap. 👍

[stammw]

I think we're ready to merge !

The interop tool has been updated with only a very simple H3 scenario (with no encoder stream, nor receiving anything from server other than the response).

Trying to implement a full-featured client, I started to think it was too much code to write in form of a quick implementation. So it would be better to continue writing a solid code into another PR.

[djc]

So looking at the interop tool additions mainly for now, this looks pretty good. @Ralith, do you want to review this more before it gets merged?

[Ralith]

I'll try to have a look at the futuresy bits tomorrow per @stammw's request, at least.

[djc]

🎉