plugeth/core/rawdb/freezer_meta.go
rjl493456442 538a868384
core/rawdb, cmd, ethdb, eth: implement freezer tail deletion (#23954)
* core/rawdb, cmd, ethdb, eth: implement freezer tail deletion

* core/rawdb: address comments from martin and sina

* core/rawdb: fixes cornercase in tail deletion

* core/rawdb: separate metadata into a standalone file

* core/rawdb: remove unused code

* core/rawdb: add random test

* core/rawdb: polish code

* core/rawdb: fsync meta file before manipulating the index

* core/rawdb: fix typo

* core/rawdb: address comments
2022-03-10 09:37:23 +01:00

110 lines
3.3 KiB
Go

// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>
package rawdb
import (
"io"
"os"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
)
const freezerVersion = 1 // The initial version tag of freezer table metadata
// freezerTableMeta wraps all the metadata of the freezer table.
type freezerTableMeta struct {
// Version is the versioning descriptor of the freezer table.
Version uint16
// VirtualTail indicates how many items have been marked as deleted.
// Its value is equal to the number of items removed from the table
// plus the number of items hidden in the table, so it should never
// be lower than the "actual tail".
VirtualTail uint64
}
// newMetadata initializes the metadata object with the given virtual tail.
func newMetadata(tail uint64) *freezerTableMeta {
return &freezerTableMeta{
Version: freezerVersion,
VirtualTail: tail,
}
}
// readMetadata reads the metadata of the freezer table from the
// given metadata file.
func readMetadata(file *os.File) (*freezerTableMeta, error) {
_, err := file.Seek(0, io.SeekStart)
if err != nil {
return nil, err
}
var meta freezerTableMeta
if err := rlp.Decode(file, &meta); err != nil {
return nil, err
}
return &meta, nil
}
// writeMetadata writes the metadata of the freezer table into the
// given metadata file.
func writeMetadata(file *os.File, meta *freezerTableMeta) error {
_, err := file.Seek(0, io.SeekStart)
if err != nil {
return err
}
return rlp.Encode(file, meta)
}
// loadMetadata loads the metadata from the given metadata file.
// Initializes the metadata file with the given "actual tail" if
// it's empty.
func loadMetadata(file *os.File, tail uint64) (*freezerTableMeta, error) {
stat, err := file.Stat()
if err != nil {
return nil, err
}
// Write the metadata with the given actual tail into metadata file
// if it's non-existent. There are two possible scenarios here:
// - the freezer table is empty
// - the freezer table is legacy
// In both cases, write the meta into the file with the actual tail
// as the virtual tail.
if stat.Size() == 0 {
m := newMetadata(tail)
if err := writeMetadata(file, m); err != nil {
return nil, err
}
return m, nil
}
m, err := readMetadata(file)
if err != nil {
return nil, err
}
// Update the virtual tail with the given actual tail if it's even
// lower than it. Theoretically it shouldn't happen at all, print
// a warning here.
if m.VirtualTail < tail {
log.Warn("Updated virtual tail", "have", m.VirtualTail, "now", tail)
m.VirtualTail = tail
if err := writeMetadata(file, m); err != nil {
return nil, err
}
}
return m, nil
}