[consensus/marshal] Integrate commonware-coding into marshal

[clabby]

Overview

Warning

WIP; Open for early review, but not feature complete - See TODOs.

Integrates commonware-coding as a default within commonware-consensus' marshal by adding a new shim between consensus and the marshal::Actor. This layer is responsible for broadcasting the erasure coded chunks of Blocks sent by the proposer as well as reconstructing them as they arrive.

Example usage of the new API in alto: commonwarexyz/alto#149

TODO

• test_finalize_good_links test seems to be pseudo-passing; all validators are eventually reconstructing the proposed blocks & receiving the same finalized chain, but it’s failing the determinism check. Need to investigate that.
• When notarization / finalization votes are received by marshal, we need some way to self-identify as the submitter of these votes - right now I’m just naively sending all of the chunks that the validator has locally, which is inefficient.
• Take a second look at the method for mapping of block digest <> coding commitment; Right now we wait for enough chunks to arrive before anything (since we must have the digest,) which seems right, but there could be a better method.
• Use durable / prunable stores in the ShardLayer, prune when Orchestrator reports.
• Support subscriptions in ShardLayer
• Support subscriptions to individual chunks; The Automaton needs this in order to verify individual chunks prior to sending notarization votes.
• Wait to receive minimum amount of valid shards - currently only waiting for the minimum amount of shards w/o checks.
• Consider eager reconstruction for performance. Right now, blocks are reconstructed on-demand. If the ShardMailbox had a way of being notified when its buffered::Mailbox received shards, it could register a listener when Automaton::verify initially verifies the local shard for the notarization vote. This would (hopefully) mean that by the time a proposer wanted to build on the notarized parent, the block is already present for them.
• Handle "couldn't reconstruct" case. Will require marshal to store chunks for blocks that cannot be reconstructed to convince peers. CodingAdapter will need to ensure that it never asks the application to build on a "bad" parent; The application should not need to know this detail about the consensus chain. (e: or, a more elegant solution: [consensus::simplex] Allow for a second, post-notarization-certificate, verify(...) hook to the Automaton, called finalizable(...) #1767)

Viz

sequenceDiagram
    participant P as Proposer / App
    participant E as Erasure Encoder
    participant N1 as Participant 1
    participant N2 as Participant 2
    participant N3 as Participant 3
    participant Nr as Participant r
    participant V as Consensus
    participant S as Shard Layer
    participant M as Marshal
    
    Note over P,M: Block Proposal & Encoding Phase
    P->>E: Original block data
    E->>E: Split into k chunks + generate r parity chunks
    E->>P: Return k+r encoded chunks
    
    Note over P,M: Distribution Phase
    P->>N1: Send chunk 1 + merkle proof
    P->>N2: Send chunk 2 + merkle proof  
    P->>N3: Send chunk 3 + merkle proof
    P->>Nr: Send chunk k+r + merkle proof
    
    Note over P,M: Notarization Phase
    N1->>N1: Validate chunk integrity
    
    N2->>N2: Validate chunk integrity
    N3->>N3: Validate chunk integrity
    Nr->>Nr: Validate chunk integrity
    
    N1->>V: Attest chunk validity + vote
    N2->>V: Attest chunk validity + vote
    N3->>V: Attest chunk validity + vote
    Nr->>V: Attest chunk validity + vote
    V->>V: Notarization
    
    Note over P,M: Reconstruction Phase (parallel w/ finalization)
    S->>S: Collect ≥k valid chunks
    S->>S: Reconstruct original block
    S->>S: Verify commitment
    S->>M: Send block

    Note over P,M: Finalization Phase (parallel w/ reconstruction)
    N1->>V: Vote
    N2->>V: Vote
    N3->>V: Vote
    Nr->>V: Vote
    V->>V: Finalization

    Note over P,M: Reporting Phase
    M->>P: Send finalized block

Loading

honest validator shard distribution

Meta

closes #1520

[patrick-ogrady]

Right now we wait for enough chunks to arrive before anything (since we must have the digest,) which seems right, but there could be a better method.

In this case, you are referring to marshal right? If so, yes. In consensus, we should send a notarize as soon as we observe our fragment is correctly placed in the BMT.

[codecov]

Codecov Report

❌ Patch coverage is 23.62768% with 640 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.53%. Comparing base (87fff07) to head (3a1bf45).

Files with missing lines	Patch %	Lines
consensus/src/marshal/coding/actor.rs	0.00%	244 Missing ⚠️
consensus/src/marshal/coding/application.rs	0.00%	136 Missing ⚠️
consensus/src/marshal/coding/types.rs	60.80%	98 Missing ⚠️
consensus/src/marshal/actor.rs	0.00%	74 Missing ⚠️
consensus/src/marshal/coding/mailbox.rs	0.00%	57 Missing ⚠️
consensus/src/types.rs	51.11%	22 Missing ⚠️
consensus/src/marshal/ingress/orchestrator.rs	0.00%	4 Missing ⚠️
consensus/src/marshal/mocks/block.rs	78.57%	3 Missing ⚠️
consensus/src/marshal/finalizer.rs	0.00%	2 Missing ⚠️

@@            Coverage Diff             @@
##             main    #1680      +/-   ##
==========================================
- Coverage   92.28%   90.53%   -1.76%     
==========================================
  Files         304      307       +3     
  Lines       79179    79315     +136     
==========================================
- Hits        73072    71807    -1265     
- Misses       6107     7508    +1401     

Files with missing lines	Coverage Δ
coding/src/lib.rs	98.26% <ø> (+4.62%)	⬆️
consensus/src/marshal/cache.rs	0.00% <ø> (-94.10%)	⬇️
consensus/src/marshal/ingress/handler.rs	82.19% <100.00%> (-10.96%)	⬇️
consensus/src/marshal/ingress/mailbox.rs	0.00% <ø> (-84.00%)	⬇️
consensus/src/marshal/finalizer.rs	0.00% <0.00%> (-88.64%)	⬇️
consensus/src/marshal/mocks/block.rs	80.00% <78.57%> (-20.00%)	⬇️
consensus/src/marshal/ingress/orchestrator.rs	0.00% <0.00%> (-88.89%)	⬇️
consensus/src/types.rs	72.52% <51.11%> (-20.96%)	⬇️
consensus/src/marshal/coding/mailbox.rs	0.00% <0.00%> (ø)
consensus/src/marshal/actor.rs	0.00% <0.00%> (-88.71%)	⬇️
... and 3 more

... and 15 files with indirect coverage changes

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