mirror of
https://gitlab.com/pulsechaincom/erigon-pulse.git
synced 2024-12-22 19:50:36 +00:00
92 lines
2.8 KiB
Go
92 lines
2.8 KiB
Go
// Copyright 2018 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 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 ethdb
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import (
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"bytes"
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"github.com/ledgerwatch/erigon-lib/kv"
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)
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// splitCursor implements cursor with two keys
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// it is used to ignore incarnations in the middle
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// of composite storage key, but without
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// reconstructing the key
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// Instead, the key is split into two parts and
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// functions `Seek` and `Next` deliver both
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// parts as well as the corresponding value
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type splitCursor struct {
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c kv.Cursor // Unlerlying cursor
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startkey []byte // Starting key (also contains bits that need to be preserved)
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matchBytes int
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mask uint8
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part1end int // Position in the key where the first part ends
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part2start int // Position in the key where the second part starts
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part3start int // Position in the key where the third part starts
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}
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func NewSplitCursor(c kv.Cursor, startkey []byte, matchBits int, part1end, part2start, part3start int) *splitCursor {
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var sc splitCursor
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sc.c = c
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sc.startkey = startkey
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sc.part1end = part1end
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sc.part2start = part2start
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sc.part3start = part3start
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sc.matchBytes, sc.mask = Bytesmask(matchBits)
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return &sc
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}
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func (sc *splitCursor) matchKey(k []byte) bool {
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if k == nil {
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return false
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}
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if sc.matchBytes == 0 {
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return true
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}
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if len(k) < sc.matchBytes {
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return false
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}
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if !bytes.Equal(k[:sc.matchBytes-1], sc.startkey[:sc.matchBytes-1]) {
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return false
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}
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return (k[sc.matchBytes-1] & sc.mask) == (sc.startkey[sc.matchBytes-1] & sc.mask)
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}
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func (sc *splitCursor) Seek() (key1, key2, key3, val []byte, err error) {
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k, v, err1 := sc.c.Seek(sc.startkey)
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if err1 != nil {
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return nil, nil, nil, nil, err1
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}
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if !sc.matchKey(k) {
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return nil, nil, nil, nil, nil
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}
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return k[:sc.part1end], k[sc.part2start:sc.part3start], k[sc.part3start:], v, nil
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}
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func (sc *splitCursor) Next() (key1, key2, key3, val []byte, err error) {
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k, v, err1 := sc.c.Next()
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if err1 != nil {
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return nil, nil, nil, nil, err1
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}
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if !sc.matchKey(k) {
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return nil, nil, nil, nil, nil
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}
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return k[:sc.part1end], k[sc.part2start:sc.part3start], k[sc.part3start:], v, nil
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}
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var EndSuffix = []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}
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