perf: memoize a message's CID and encoded length

[LesnyRumcajs]

Summary of changes

Changes introduced in this pull request:

• memoizes the cid and len of messages, nicely improving performance of handling messages in a transparent way. I kept Memo this way, but we might think about promoting it to a generic type Memo<T> if there's a compelling place where to reuse it.

Reference issue to close (if applicable)

Closes #7449

Other information and links

┌──────────────────────────────┬───────────────┬───────────┬───────────┬──────┐
│          benchmark           │ refactor-only │ memoized  │  change   │  p   │
├──────────────────────────────┼───────────────┼───────────┼───────────┼──────┤
│ validation_encode_path/100   │ 545.66 µs     │ 206.45 µs │ −61.8%    │ 0.00 │
├──────────────────────────────┼───────────────┼───────────┼───────────┼──────┤
│ validation_encode_path/1000  │ 5.3735 ms     │ 2.0036 ms │ −62.7%    │ 0.00 │
├──────────────────────────────┼───────────────┼───────────┼───────────┼──────┤
│ validation_encode_path/10000 │ 53.946 ms     │ 20.594 ms │ −61.8%    │ 0.00 │
├──────────────────────────────┼───────────────┼───────────┼───────────┼──────┤
│ compute_msg_root/100         │ 142.14 µs     │ 140.05 µs │ −2.3%     │ 0.02 │
├──────────────────────────────┼───────────────┼───────────┼───────────┼──────┤
│ compute_msg_root/1000        │ 1.3876 ms     │ 1.3962 ms │ no change │ 0.46 │
├──────────────────────────────┼───────────────┼───────────┼───────────┼──────┤
│ compute_msg_root/10000       │ 13.960 ms     │ 14.164 ms │ no change │ 0.29 │
└──────────────────────────────┴───────────────┴───────────┴───────────┴──────┘

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

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Summary by CodeRabbit

• Improvements
  • Message identifiers and encoded sizes are calculated consistently for unsigned and signed messages.
  • Signed message size checks include the signature, so the size limit reflects the complete encoded message.
  • Repeated encoding calculations are reduced, improving efficiency during message processing.
  • Message size reporting now reflects the message’s own encoding, helping keep size checks consistent with the data being processed.

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Walkthrough

The change adds memoized CBOR digests and encoded lengths for unsigned and signed messages. Message consumers use the new methods for CID calculation, VM execution lengths, and message-pool size validation.

Changes

Message encoding

Layer / File(s)	Summary
CBOR encoding and memo primitives src/utils/cid/mod.rs	EncodedCbor computes a DAG-CBOR digest and byte length in one serialization pass. Memo lazily stores the result and supports clearing it.
Unsigned and signed message caches src/shim/message.rs, src/message/signed_message.rs, src/message/chain_message.rs	Message and SignedMessage use memoized encodings for CIDs and lengths. Mutations clear the cache, and signed-message serialization retains its tuple representation. ChainMessage::encoded_len returns the appropriate message length. Tests cover cache behavior, encoding results, and serialization compatibility.
Message length and CID consumers src/chain_sync/validation.rs, src/interpreter/vm.rs, src/message_pool/msgpool/msg_pool.rs	Block validation obtains message CIDs through message methods. VM execution and message-pool size validation use the new encoded-length methods.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Refactor

Suggested reviewers: sudo-shashank

Merge Risk: 🟡 Moderate · up to cd438

Invalid message amounts can now trigger a panic instead of a validation error. Restore error propagation before merging; the impact on externally submitted messages is not yet established.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The PR implements the cache objective in [#7449]. Message and SignedMessage memoize digest and encoded length. The implementation preserves the BLS SignedMessage::cid() rule, invalidates memoize…	Implement the remaining allocation-free length paths from [#7449] with a shared counting-writer helper, or split the cache work from [#7449] and do not close the issue until its remaining coding objectives are complete.
Docstring Coverage	⚠️ Warning	Docstring coverage is 42.42% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 66 functions across 7 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Out of Scope Changes check	✅ Passed	The changes stay within [#7449]. The memo, CID and length methods, mutation invalidation, serialization compatibility, validation integration, VM integration, message-pool integration, and related tes…
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the primary change: memoizing message CIDs and encoded lengths for performance.

Full details: Linked Issues check

Explanation

The PR implements the cache objective in [#7449]. Message and SignedMessage memoize digest and encoded length. The implementation preserves the BLS SignedMessage::cid() rule, invalidates memoized values on mutation, and adds byte-equivalence and memo-behavior tests. CidCborExt::from_cbor_blake2b256 also streams into the hasher. The issue-wide allocation-free length objective is not complete. The supplied change summary shows updates for VM and msg_pool, but no reusable length helper or updates for the other issue-listed to_vec(...).len() paths, including tipset_syncer.rs and the chain-exchange provider.

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Inline comments:
Review comments at @src/utils/cid/mod.rs:
- Around line 37-70: Update EncodedCbor memo access and the Message,
SignedMessage, and ChainMessage encoded-length APIs to propagate encoding
failures as Result instead of panicking; pass errors through chain_length,
VM::apply_message, and message-pool validate_static, while keeping infallible
CID callers explicit.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Essentials

Run ID: 34301264-e82a-4259-a191-2fa263fd51cb

📥 Commits

Reviewing files that changed from the base of the PR and between 999f995 and cd43846.

📒 Files selected for processing (7)

• src/chain_sync/validation.rs
• src/interpreter/vm.rs
• src/message/chain_message.rs
• src/message/signed_message.rs
• src/message_pool/msgpool/msg_pool.rs
• src/shim/message.rs
• src/utils/cid/mod.rs

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• filecoin-project/lotus (manual)

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[codecov]

Codecov Report

❌ Patch coverage is 99.57265% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 67.89%. Comparing base (d9d81d4) to head (fe8ff2f).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/utils/cid/mod.rs	98.78%	0 Missing and 1 partial ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/chain_sync/validation.rs	89.18% <100.00%> (+0.40%)	⬆️
src/interpreter/vm.rs	81.13% <100.00%> (+0.29%)	⬆️
src/message/chain_message.rs	89.74% <100.00%> (+3.69%)	⬆️
src/message/signed_message.rs	96.39% <100.00%> (+2.68%)	⬆️
src/message_pool/msgpool/msg_pool.rs	91.75% <100.00%> (ø)
src/shim/message.rs	93.33% <100.00%> (+2.04%)	⬆️
src/utils/cid/mod.rs	97.97% <98.78%> (+3.86%)	⬆️

... and 8 files with indirect coverage changes

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