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

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[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 4, 2026, 10:11 AM

[claude]

Claude finished @tac0turtle's task in 3m 42s —— View job

---

PR Review: perf: use autoresearch to reduce allocations

• Read changed files
• Review code quality & architecture
• Review performance & correctness
• Review testing
• Post final feedback

---

Summary

This PR introduces sync.Pool for protobuf message structs and unsafe.Slice reinterpretation of []Tx → [][]byte across several hot serialization paths. The approach is sound, well-commented, and delivers real allocation reductions per block. A few issues worth addressing before merge:

---

Issues

1. &pb.Signer{} allocation in SignedHeader.MarshalBinary nil-pubkey path

types/serialization.go:247 — when sh.Signer.PubKey == nil, the code allocates a fresh &pb.Signer{} instead of using pbSignerPool:

if sh.Signer.PubKey == nil {
    psh.Signer = &pb.Signer{}   // ← new allocation, inconsistent with pool strategy
    ...
}

This is the common case for nodes that haven't set a signer. Should use pbSignerPool.Get() / pbSignerPool.Put() here, just like the non-nil branch.

Fix this →

2. timestamppb.Timestamp not pooled in State.MarshalBinary

types/serialization.go:540-543:

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

This allocates a new Timestamp on every call despite the function comment saying "pooled protobuf messages". Either pool it or remove the claim from the docstring. Timestamp is a small allocation but leaving it as-is makes the comment misleading.

3. defer in Data.MarshalBinary — inconsistent cleanup style

types/serialization.go:135-138: All other functions in this file use explicit cleanup before return. The defer here is the only exception and adds a defer frame (minor cost on a hot path). Consider making it explicit like the rest:

// Instead of defer, call explicitly before return:
pm.Reset()
pbMetadataPool.Put(pm)

4. Missing test coverage for State.MarshalBinary

TestStateRoundTrip in serialization_test.go calls state.ToProto() + proto.Marshal() directly — it does not exercise the new State.MarshalBinary() path. The new method should have at least a round-trip test that calls s.MarshalBinary() then proto.Unmarshal() + s.FromProto() (or a dedicated UnmarshalBinary if it exists) with multiple state values, including zero state and a fully-populated state.

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Observations / Praise

unsafe.Slice reinterpretation (types/serialization.go:142, hashing.go:135, executor.go:799): The Tx = []byte type alias means []Tx and [][]byte are layout-identical. The unsafe.Slice((*[]byte)(unsafe.SliceData(...)), n) pattern is idiomatic for this in Go and avoids a make + copy. All call sites correctly guard against nil and empty slices (or handle them via len == 0). Well done.

sha256Pool in hashing.go: leafHashOpt calls s.Reset() as its first operation, so pooled hashers returned in any state are safe to reuse. Correct.

Pool cleanup on all early-return paths: SignedHeader.MarshalBinary has two early returns (nil pubkey, marshalling error). Both correctly return all three acquired pool objects before returning. Good defensive code.

Pool objects are Reset before Put: Every Put is preceded by the corresponding Reset(), preventing stale byte-slice references in pooled objects from keeping GC roots alive. Correct.

Data.ToProto() inlining of Metadata.ToProto(): The promoted field d.LastDataHash correctly accesses d.Metadata.LastDataHash through the embedded *Metadata pointer. No semantic change.

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Minor Nits

• types/hash_memo_bench_test.go:13,28,40 — uses b.Loop() which is the Go 1.24+ benchmarking API. Ensure the project's minimum Go version supports this; otherwise use the classic for i := 0; i < b.N; i++ form.
• BenchmarkHeaderHash_Single measures a fully cold (never-memoized) hash. The benchmark name could clarify it is "no memo, single call" vs BenchmarkHeaderHash_NoMemo which is "no memo, 3 calls". As-is the distinction is slightly confusing.

[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 78.75000% with 34 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.62%. Comparing base (022b565) to head (2438dc0).

Files with missing lines	Patch %	Lines
types/serialization.go	77.39%	32 Missing and 1 partial ⚠️
pkg/store/batch.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3225      +/-   ##
==========================================
+ Coverage   61.43%   61.62%   +0.18%     
==========================================
  Files         120      120              
  Lines       12504    12645     +141     
==========================================
+ Hits         7682     7792     +110     
- Misses       3960     3991      +31     
  Partials      862      862              

Flag	Coverage Δ
combined	61.62% <78.75%> (+0.18%)	⬆️

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