perf(rsema1d): reuse SHA256 hasher in coefficient derivation#7064
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perf(rsema1d): reuse SHA256 hasher in coefficient derivation#7064
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Reuse a single sha256 hasher with Reset() between iterations in deriveCoefficients instead of calling sha256.Sum256() per symbol. This avoids re-initializing the internal digest state from scratch each time, yielding ~12% speedup on the SHA256 portion of coefficient derivation. Also add verify_breakdown_bench_test.go that isolates each component of VerifyRowWithContext for profiling. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Reminded me of https://github.com/celestiaorg/rsema1d-private/pull/16/ |
Handle unchecked error returns from rand.Read and merkle.ComputeRootFromProof, and fix gofumpt comment alignment to satisfy CI golangci-lint checks. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Wondertan
reviewed
Apr 14, 2026
Existing BenchmarkDeriveCoefficients already covers the optimized path. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Wondertan
approved these changes
Apr 14, 2026
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Summary
Reuses a single
sha256hasher withReset()between iterations inderiveCoefficients, instead of callingsha256.Sum256()(which re-initializes from scratch each time).Motivation
Benchmarking the verification hot path shows
deriveCoefficientsis the most expensive component ofVerifyRowWithContext— 65% of total time for 128MB blobs. It calls SHA256 once per GF16 symbol: 65,536 hashes for 128KB rows.Component breakdown (128MB blob, per-row):
Reusing the hasher saves ~12% on the SHA256 portion (~0.6ms for 128MB blobs).
Changes
pkg/rsema1d/commitment.go:deriveCoefficientsnow usesh.Reset()+h.Write()+h.Sum(digest[:0])instead ofsha256.Sum256()pkg/rsema1d/verify_breakdown_bench_test.go: New benchmark breaking down each component ofVerifyRowWithContextat 1MB/8MB/128MB blob sizesBenchmarks
Note: a further 55% reduction is possible by deriving 2 coefficients per hash (using both 16-byte halves independently instead of XOR-folding), but that requires a protocol/spec change.
Test plan
go test ./pkg/rsema1d/...passesCloses https://linear.app/celestia/issue/PROTOCO-1497
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