[consensus/marshal] Abstract over consensus engine

[clabby]

Overview

Note

Do not merge. Stacked on top of #2884

Abstracts marshal over consensus engine variants.

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[codecov]

Codecov Report

❌ Patch coverage is 96.34146% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.78%. Comparing base (91b8d61) to head (a091929).

Files with missing lines	Patch %	Lines
consensus/src/marshal/core/consensus.rs	91.66%	8 Missing ⚠️
consensus/src/marshal/resolver/handler.rs	91.11%	4 Missing ⚠️
consensus/src/marshal/standard/inline.rs	20.00%	4 Missing ⚠️
consensus/src/marshal/standard/variant.rs	40.00%	3 Missing ⚠️
consensus/src/marshal/core/actor.rs	99.04%	1 Missing ⚠️
storage/src/archive/prunable/storage.rs	97.29%	1 Missing ⚠️

@@               Coverage Diff               @@
##           cl/minimmit    #3253      +/-   ##
===============================================
- Coverage        93.87%   93.78%   -0.09%     
===============================================
  Files              440      440              
  Lines           149871   147847    -2024     
===============================================
- Hits            140694   138663    -2031     
- Misses            9177     9184       +7     

Files with missing lines	Coverage Δ
consensus/src/lib.rs	21.42% <100.00%> (+21.42%)	⬆️
consensus/src/marshal/coding/marshaled.rs	64.18% <100.00%> (ø)
consensus/src/marshal/coding/mod.rs	98.30% <100.00%> (ø)
consensus/src/marshal/coding/variant.rs	100.00% <ø> (ø)
consensus/src/marshal/core/cache.rs	97.34% <100.00%> (+1.59%)	⬆️
consensus/src/marshal/core/mailbox.rs	100.00% <100.00%> (ø)
consensus/src/marshal/core/variant.rs	100.00% <ø> (ø)
consensus/src/marshal/mod.rs	54.54% <ø> (ø)
consensus/src/marshal/standard/deferred.rs	91.45% <100.00%> (+0.09%)	⬆️
consensus/src/marshal/standard/mod.rs	99.70% <100.00%> (-0.01%)	⬇️
... and 12 more

... and 30 files with indirect coverage changes

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[clabby]

I was a bit torn about this, but after thinking about it a bit more, I believe this is safe to roll out incrementally. The resolver does not block peers on decode failure, and notarized block backfill is a secondary path in marshal. Finalized block backfill is unchanged.

While a network is rolling out their upgrades to this version, Notarized requests between mixed versions will fail and retry. The fetcher will eventually select a same version peer that can complete their request or cancel the request once a finalized block is processed at a higher view.

We could add in some more complex machinery that allows for nodes to understand the old Notarized(Round) request as well as the new Notarized(Round, Commitment) request temporarily, but it isn't necessary given that the penalty is slightly degraded notarized request availability for a temporary period of time.

[patrick-ogrady]

The resolver does not block peers on decode failure

It does to my knowledge?

[clabby]

In main, it skips:

monorepo/resolver/src/p2p/engine.rs

Lines 350 to 357 in 18fdce5

	// Skip if there is a decoding error
	let msg = match msg {
	Ok(msg) => msg,
	Err(err) => {
	trace!(?err, ?peer, "decode failed");
	continue;
	}
	};

(Note that we did not change the response payload, which would trigger a block. We just changed the key for the Notarized test type.)