perf: use autoresearch to reduce allocations

[tac0turtle]

Overview

This pr used autoresearch to run a loop on reducing allocations

3 a8b6352 78allocs 22,996 33,091 keep Unsafe reinterpret cast of Txs to [][]byte in ApplyBlock — eliminates make([][]byte, n) allocation
4 823aa62 77allocs 20,276 32,480 keep Direct pb.Data serialization in DACommitment — avoids pruned Data wrapper and txsToByteSlices allocations
5 0720b44 74allocs 12,192 31,624 keep unsafe.Slice in Data.ToProto() — eliminates txsToByteSlices [][]byte allocation
6 — 74allocs 12,187 31,217 discard Reverted hand-written HashSlim wire encoder — produced different hashes than MarshalBinary
7 ccbc2e4 64allocs 11,130 31,570 keep sync.Pool for protobuf message structs in MarshalBinary — eliminates 10 allocs per block
8 805672e 56allocs 10,217 31,037 keep Pooled SignedHeader.MarshalBinary — reuse pb.SignedHeader/pb.Header/pb.Signer/pb.Version structs

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 9dc826f3-3e21-4e32-a93d-1955b346a0ba

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch autoresearch/block-perf-2026-04-04

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[github-actions]

The latest Buf updates on your PR. Results from workflow CI / buf-check (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	⏩ skipped	✅ passed	✅ passed	Apr 7, 2026, 6:39 PM

[claude]

Claude finished @tac0turtle's task in 4m 39s —— View job

---

Code Review: perf: use autoresearch to reduce allocations

• Gather context
• Read changed files
• Review unsafe operations
• Review sync.Pool usage
• Review serialization changes
• Post comprehensive review

---

Good optimization work overall — the allocation reductions are real and the compile-time layout guards in tx.go are a nice touch. A few correctness concerns worth addressing before merge.

Critical / Correctness

1. ApplyBlock: aliasing between rawTxs and data.Txs (executor.go:799–801)

rawTxs = unsafe.Slice((*[]byte)(unsafe.SliceData(data.Txs)), n)

rawTxs and data.Txs now share the same backing array. If any Executor.ExecuteTxs implementation mutates elements of the passed [][]byte (e.g. appends to a transaction, trims it, or reassigns elements), it will silently corrupt data.Txs. The coreexecutor.Executor interface carries no documentation prohibiting mutation.

This is the riskiest change in the PR. Either:

• document the no-mutation contract on coreexecutor.Executor.ExecuteTxs, and add a //nolint:govet or godoc note on the call site, or
• add a //go:noescape wrapper / restrict to a clearly owned temporary scope.

Fix this →

---

2. Pool escape on panic in SignedHeader.MarshalBinary (serialization.go:223–291)

Pool cleanup is done inline (not via defer) in three separate code paths. If proto.Marshal panics (rare, but possible with corrupt internal state), psh, ph, pv, and psi are never returned to their pools. The pool will create new instances on demand so correctness is maintained, but it creates a subtle invariant. The same concern applies to Header.MarshalBinary.

Consider extracting the cleanup into a single defer:

defer func() {
    ph.Reset(); pbHeaderPool.Put(ph)
    pv.Reset(); pbVersionPool.Put(pv)
    psi.Reset(); pbSignerPool.Put(psi)
    psh.Reset(); pbSignedHeaderPool.Put(psh)
}()

The overhead of one defer vs. three inlined cleanup sites is negligible relative to proto.Marshal.

Fix this →

---

Medium

3. Inconsistent nil guard for Txs unsafe cast (hashing.go:130 vs serialization.go:143)

Data.MarshalBinary guards:

if d.Txs != nil {
    pd.Txs = unsafe.Slice(...)
}

DACommitment does not guard:

pbData := pb.Data{Txs: unsafe.Slice((*[]byte)(unsafe.SliceData(d.Txs)), len(d.Txs))}

Both are actually safe per the Go spec (unsafe.SliceData(nil) == nil, unsafe.Slice(nil, 0) == nil), but the inconsistency is confusing to readers. Either add the nil guard to DACommitment or remove it from MarshalBinary with a comment explaining why it's unnecessary.

---

4. timestamppb.Timestamp still allocates in State.MarshalBinary (serialization.go:539)

pts := &timestamppb.Timestamp{
    Seconds: s.LastBlockTime.Unix(),
    Nanos:   int32(s.LastBlockTime.Nanosecond()),
}

A *timestamppb.Timestamp is allocated on every State.MarshalBinary call. Since you've pooled pbStatePool, pooling the timestamp too would be consistent (though Timestamp is a small fixed struct so the escape analysis may already stack-allocate it — worth checking with -gcflags="-m").

---

5. sync.Pool returns interface{} — missed type assertion on sha256Pool (hashing.go:123)

s := sha256Pool.Get().(hash.Hash)

The sha256Pool.New returns sha256.New() which implements hash.Hash. The type assertion will panic if the pool ever returns a non-hash.Hash value — which can't happen with the current code, but is fragile. Storing *sha256.digest directly (using sha256.New().(*sha256.digest)) is not publicly accessible, so the interface approach is acceptable; just make sure there are no //go:linkname tricks pulling the wrong type in.

---

Low / Informational

6. Compile-time guards check size, not layout (tx.go:13–16)

The zero-array trick proves sizeof(Tx) == sizeof([]byte), which is necessary but not strictly sufficient for a pointer reinterpret cast. In practice this is fine because type Tx []byte shares the same underlying type, guaranteeing identical slice-header layout. A comment noting this distinction would help future readers.

7. defer pbMetadataPool.Put(pm) called after pbDataPool.Put(pd) on same path (serialization.go:136–140)

pd is returned to pbDataPool at line 148, then the deferred pm cleanup runs. Between those two moments, pd (with pd.Metadata = nil after Reset()) is back in the pool and could be grabbed by another goroutine before pm is returned. This is technically safe since pd.Metadata is already nil after Reset(), but the interleaved pool lifecycle is subtle. Adding an explicit pm.Reset(); pbMetadataPool.Put(pm) before the pd.Reset() (and removing the defer) would make the ordering unambiguous.

---

Testing

• The new TestDataMarshalBinary_Pooled / concurrent test is absent. A TestDataMarshalBinaryRoundTrip with t.Parallel() plus a concurrent stress path exercising the pools would strengthen confidence (especially under -race).
• Codecov flags 32 missing lines in types/serialization.go — the legacy-field encoding paths and the State.MarshalBinary pool path appear uncovered. Worth adding tests for marshalLegacyHeader round-trip and the pooled State.MarshalBinary directly.
• The new benchmark file hash_memo_bench_test.go is clean and useful.

---

Summary

Category	Count
Critical (correctness)	2
Medium	3
Low/Informational	2

The ApplyBlock aliasing issue (#1) and pool escape on panic (#2) are the most important to resolve before merge. The rest are polish.

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://evstack.github.io/docs-preview/pr-3225/
Built to branch main at 2026-04-04 10:13 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[codecov]

Codecov Report

❌ Patch coverage is 93.16770% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.06%. Comparing base (ff88b95) to head (636ce24).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
types/serialization.go	93.19%	9 Missing and 1 partial ⚠️
pkg/store/batch.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3225      +/-   ##
==========================================
+ Coverage   61.45%   62.06%   +0.61%     
==========================================
  Files         120      120              
  Lines       12504    12778     +274     
==========================================
+ Hits         7684     7931     +247     
- Misses       3959     3975      +16     
- Partials      861      872      +11     

Flag	Coverage Δ
combined	62.06% <93.16%> (+0.61%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.