execution/types: reduce typed-transaction Hash() allocations (no []any, no reflection) - #21858
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Pull request overview
Reduces allocations and reflection overhead in EIP-1559 (DynamicFeeTransaction) hashing by hashing the typed-transaction prefix plus the already hand-written RLP payload encoding, avoiding []any boxing and rlp.Encode reflection.
Changes:
- Add
prefixedPayloadHash(prefix, encode)helper to hashkeccak256(prefix || payload)where payload is written directly to the hasher. - Update
DynamicFeeTransaction.Hash()to usepayloadSize()+encodePayload(...)via the new helper instead of constructing a[]anyand calling reflection-basedrlp.Encode.
Reviewed changes
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| File | Description |
|---|---|
| execution/types/hashing.go | Adds prefixedPayloadHash to hash typed-tx prefix + caller-written payload using pooled keccak + pooled RLP scratch buffer. |
| execution/types/dynamic_fee_tx.go | Switches DynamicFeeTransaction.Hash() to hash the existing hand-written payload encoding (no []any, no reflection). |
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Hash() built a []any of the transaction fields and ran it through the reflection-based rlp encoder. Add typed helpers rlpPayloadHash and prefixedPayloadHash that hash into a pooled keccak state and let each transaction encode through its existing hand-written encodePayload, so there is no []any boxing and no reflection. Applied to LegacyTx, AccessListTx, DynamicFeeTransaction, BlobTx, SetCodeTransaction and AccountAbstractionTransaction. For the first five the hash is unchanged, verified byte-for-byte against the old reflection path. BlobTx.encodePayload now encodes To via EncodeOptionalAddress (byte-identical for the always-present To of a valid blob tx), matching its own payloadSize and the reflection path instead of dereferencing a possibly-nil To. AccountAbstractionTransaction's hash changes: its old []any path encoded SenderAddress (accounts.Address = unique.Handle) via reflection, which skips the unexported handle field and dropped the sender from the hash. The encodePayload path matches MarshalBinary, so Hash() now equals keccak256 of the canonical wire bytes. Also fix a pool-leak-on-panic in prefixedRlpHash (return the hasher via defer). Per-call allocations drop to 1 (the cached-hash pointer): e.g. SetCode 22->1, AA 13->1, Blob 10->1.
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awskii
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On Bloatnet i noticed "GC stop-the-world spike"
The win is from not using
[]anycasting and not using reflection:Hash()built a[]any{...}of the tx fields (slice alloc + boxing eachuint64/pointer into an interface), thenrlp.Encode, which walks the values dynamically and allocates as it goes.Applied to
LegacyTx,AccessListTx,DynamicFeeTransaction,BlobTx,SetCodeTransaction,AccountAbstractionTransaction— every tx type that already has anencodePayload.Results (
BenchmarkTxHash, M4 Max — allocs/op)Two behavioral notes
BlobTx.encodePayloadpreviously dereferencedTounconditionally (it had a non-nil-Toprecondition enforced by theErrNilToFieldTxguards inMarshalBinary/EncodeRLP). It now encodesToviaEncodeOptionalAddress— byte-identical for the always-presentToof a valid blob tx, and consistent with its ownpayloadSize(which already sizesTooptionally).MarshalBinary/EncodeRLPkeep theirErrNilToFieldTxguards, so their external contract is unchanged.AccountAbstractionTransaction's hash value changes. Its old[]anypath encodedSenderAddress(accounts.Address=unique.Handle, which has unexported fields) through reflection, which silently dropped the sender from the hash.Hash()now goes throughencodePayloadand equalskeccak256of the canonicalMarshalBinarybytes. AA (RIP-7560) is not live, so this is a latent-bug fix rather than a consensus change.