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109 lines
3.5 KiB
Go
109 lines
3.5 KiB
Go
// Copyright 2019 The 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 off
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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 trie
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import (
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"bytes"
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"sort"
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)
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// ResolveSet encapsulates the set of keys that are required to be fully available, or resolved
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// (by using `BRANCH` opcode instead of `HASHER`) after processing of the sequence of key-value
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// pairs
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// DESCRIBED: docs/programmers_guide/guide.md#converting-sequence-of-keys-and-value-into-a-multiproof
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type ResolveSet struct {
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minLength int // Mininum length of prefixes for which `HashOnly` function can return `true`
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hexes sortable
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inited bool // Whether keys are sorted and "LTE" and "GT" indices set
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lteIndex int // Index of the "LTE" key in the keys slice. Next one is "GT"
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}
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// NewResolveSet creates new ResolveSet
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func NewResolveSet(minLength int) *ResolveSet {
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return &ResolveSet{minLength: minLength}
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}
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// AddKey adds a new key (in KEY encoding) to the set
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func (rs *ResolveSet) AddKey(key []byte) {
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rs.hexes = append(rs.hexes, keybytesToHex(key))
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}
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// AddHex adds a new key (in HEX encoding) to the set
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func (rs *ResolveSet) AddHex(hex []byte) {
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rs.hexes = append(rs.hexes, hex)
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}
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func (rs *ResolveSet) ensureInited() {
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if rs.inited {
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return
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}
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if !sort.IsSorted(rs.hexes) {
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sort.Sort(rs.hexes)
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}
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rs.lteIndex = 0
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rs.inited = true
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}
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// HashOnly decides whether to emit `HASHER` or `BRANCH` for a given prefix, by
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// checking if this is prefix of any of the keys added to the set
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// Since keys in the set are sorted, and we expect that the prefixes will
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// come in monotonically ascending order, we optimise for this, though
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// the function would still work if the order is different
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func (rs *ResolveSet) HashOnly(prefix []byte) bool {
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rs.ensureInited()
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if len(prefix) < rs.minLength {
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return false
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}
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// Adjust "GT" if necessary
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var gtAdjusted bool
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for rs.lteIndex < len(rs.hexes)-1 && bytes.Compare(rs.hexes[rs.lteIndex+1], prefix) <= 0 {
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rs.lteIndex++
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gtAdjusted = true
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}
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// Adjust "LTE" if necessary (normally will not be necessary)
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for !gtAdjusted && rs.lteIndex > 0 && bytes.Compare(rs.hexes[rs.lteIndex], prefix) > 0 {
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rs.lteIndex--
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}
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if rs.lteIndex < len(rs.hexes) {
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h := rs.hexes[rs.lteIndex]
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if len(h) > 0 && h[len(h)-1] == 16 {
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h = h[:len(h)-1]
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}
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if bytes.HasPrefix(h, prefix) {
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return false
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}
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}
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if rs.lteIndex < len(rs.hexes)-1 {
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h := rs.hexes[rs.lteIndex+1]
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if len(h) > 0 && h[len(h)-1] == 16 {
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h = h[:len(h)-1]
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}
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if bytes.HasPrefix(h, prefix) {
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return false
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}
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}
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return true
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}
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// Current returns the hex value that has been used for the latest comparison in `HashOnly` function
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// It is only used in one edge case at the moment - to distinguish between the accounts' key
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// and the storage keys of the same account
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func (rs *ResolveSet) Current() []byte {
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return rs.hexes[rs.lteIndex]
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}
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