forked from cerc-io/plugeth
110 lines
3.3 KiB
Go
110 lines
3.3 KiB
Go
// Copyright 2022 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 rawdb
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import (
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"io"
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"os"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/rlp"
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)
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const freezerVersion = 1 // The initial version tag of freezer table metadata
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// freezerTableMeta wraps all the metadata of the freezer table.
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type freezerTableMeta struct {
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// Version is the versioning descriptor of the freezer table.
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Version uint16
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// VirtualTail indicates how many items have been marked as deleted.
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// Its value is equal to the number of items removed from the table
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// plus the number of items hidden in the table, so it should never
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// be lower than the "actual tail".
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VirtualTail uint64
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}
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// newMetadata initializes the metadata object with the given virtual tail.
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func newMetadata(tail uint64) *freezerTableMeta {
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return &freezerTableMeta{
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Version: freezerVersion,
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VirtualTail: tail,
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}
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}
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// readMetadata reads the metadata of the freezer table from the
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// given metadata file.
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func readMetadata(file *os.File) (*freezerTableMeta, error) {
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_, err := file.Seek(0, io.SeekStart)
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if err != nil {
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return nil, err
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}
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var meta freezerTableMeta
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if err := rlp.Decode(file, &meta); err != nil {
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return nil, err
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}
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return &meta, nil
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}
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// writeMetadata writes the metadata of the freezer table into the
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// given metadata file.
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func writeMetadata(file *os.File, meta *freezerTableMeta) error {
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_, err := file.Seek(0, io.SeekStart)
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if err != nil {
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return err
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}
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return rlp.Encode(file, meta)
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}
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// loadMetadata loads the metadata from the given metadata file.
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// Initializes the metadata file with the given "actual tail" if
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// it's empty.
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func loadMetadata(file *os.File, tail uint64) (*freezerTableMeta, error) {
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stat, err := file.Stat()
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if err != nil {
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return nil, err
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}
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// Write the metadata with the given actual tail into metadata file
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// if it's non-existent. There are two possible scenarios here:
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// - the freezer table is empty
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// - the freezer table is legacy
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// In both cases, write the meta into the file with the actual tail
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// as the virtual tail.
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if stat.Size() == 0 {
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m := newMetadata(tail)
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if err := writeMetadata(file, m); err != nil {
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return nil, err
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}
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return m, nil
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}
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m, err := readMetadata(file)
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if err != nil {
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return nil, err
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}
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// Update the virtual tail with the given actual tail if it's even
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// lower than it. Theoretically it shouldn't happen at all, print
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// a warning here.
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if m.VirtualTail < tail {
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log.Warn("Updated virtual tail", "have", m.VirtualTail, "now", tail)
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m.VirtualTail = tail
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if err := writeMetadata(file, m); err != nil {
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return nil, err
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}
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}
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return m, nil
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}
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