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https://github.com/ethereum/go-ethereum.git
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f676f04706
The invariant "mutating a value slot must mark the stem for re-hash and re-flush" was enforced by every caller remembering to set both flags after setValue. Moving the flip into setValue itself makes it structurally impossible to forget, and drops the duplicate flag-sets at each callsite. decodeNode's on-disk load path still writes directly to sn.values because loaded stems must retain whatever mustRecompute/dirty state the caller asked for (typically both false).
109 lines
3.3 KiB
Go
109 lines
3.3 KiB
Go
// Copyright 2025 go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package bintrie
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import (
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"crypto/sha256"
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"github.com/ethereum/go-ethereum/common"
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)
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// StemNode holds up to 256 values sharing a 31-byte stem.
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//
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// Invariant: dirty=false implies mustRecompute=false. Every mutation that
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// invalidates the cached hash MUST also mark the blob for re-flush.
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type StemNode struct {
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Stem [StemSize]byte
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values [StemNodeWidth][]byte // nil == slot absent
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depth uint8
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mustRecompute bool // hash is stale (cleared by Hash)
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dirty bool // on-disk blob is stale (cleared by CollectNodes)
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hash common.Hash // cached hash when mustRecompute == false
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}
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func (sn *StemNode) getValue(suffix byte) []byte {
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return sn.values[suffix]
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}
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func (sn *StemNode) hasValue(suffix byte) bool {
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return sn.values[suffix] != nil
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}
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// allValues returns the underlying slot array as a slice. nil entries mean
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// absent. Callers must treat it as read-only.
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func (sn *StemNode) allValues() [][]byte {
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return sn.values[:]
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}
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// setValue mutates a value slot and marks the stem for re-hash and
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// re-flush. This is the only API for post-load value mutation; direct
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// values[...] writes are reserved for the on-disk load path in
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// decodeNode, which must leave mustRecompute/dirty at their loaded
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// state.
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func (sn *StemNode) setValue(suffix byte, value []byte) {
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sn.values[suffix] = value
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sn.mustRecompute = true
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sn.dirty = true
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}
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func (sn *StemNode) Hash() common.Hash {
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if !sn.mustRecompute {
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return sn.hash
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}
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// Use sha256.Sum256 (returns [32]byte by value) instead of a pooled
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// hash.Hash: feeding data[i][:0] into the interface method Sum forces
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// data to heap (escape analysis is conservative through interfaces).
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// Sum256 takes []byte and returns by value, so data stays on stack.
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var data [StemNodeWidth]common.Hash
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for i, v := range sn.values {
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if v != nil {
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data[i] = sha256.Sum256(v)
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}
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}
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var pair [2 * HashSize]byte
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for level := 1; level <= 8; level++ {
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for i := range StemNodeWidth / (1 << level) {
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if data[i*2] == (common.Hash{}) && data[i*2+1] == (common.Hash{}) {
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data[i] = common.Hash{}
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continue
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}
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copy(pair[:HashSize], data[i*2][:])
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copy(pair[HashSize:], data[i*2+1][:])
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data[i] = sha256.Sum256(pair[:])
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}
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}
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var final [StemSize + 1 + HashSize]byte
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copy(final[:StemSize], sn.Stem[:])
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final[StemSize] = 0
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copy(final[StemSize+1:], data[0][:])
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sn.hash = sha256.Sum256(final[:])
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sn.mustRecompute = false
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return sn.hash
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}
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func (sn *StemNode) Key(i int) []byte {
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var ret [HashSize]byte
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copy(ret[:], sn.Stem[:])
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ret[StemSize] = byte(i)
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return ret[:]
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}
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