+++ /dev/null
-// Copyright (c) 2015-2016 The btcsuite developers
-// Use of this source code is governed by an ISC
-// license that can be found in the LICENSE file.
-
-package ffldb
-
-import (
- "fmt"
- "hash/crc32"
-
- "github.com/btcsuite/btcd/database"
-)
-
-// The serialized write cursor location format is:
-//
-// [0:4] Block file (4 bytes)
-// [4:8] File offset (4 bytes)
-// [8:12] Castagnoli CRC-32 checksum (4 bytes)
-
-// serializeWriteRow serialize the current block file and offset where new
-// will be written into a format suitable for storage into the metadata.
-func serializeWriteRow(curBlockFileNum, curFileOffset uint32) []byte {
- var serializedRow [12]byte
- byteOrder.PutUint32(serializedRow[0:4], curBlockFileNum)
- byteOrder.PutUint32(serializedRow[4:8], curFileOffset)
- checksum := crc32.Checksum(serializedRow[:8], castagnoli)
- byteOrder.PutUint32(serializedRow[8:12], checksum)
- return serializedRow[:]
-}
-
-// deserializeWriteRow deserializes the write cursor location stored in the
-// metadata. Returns ErrCorruption if the checksum of the entry doesn't match.
-func deserializeWriteRow(writeRow []byte) (uint32, uint32, error) {
- // Ensure the checksum matches. The checksum is at the end.
- gotChecksum := crc32.Checksum(writeRow[:8], castagnoli)
- wantChecksumBytes := writeRow[8:12]
- wantChecksum := byteOrder.Uint32(wantChecksumBytes)
- if gotChecksum != wantChecksum {
- str := fmt.Sprintf("metadata for write cursor does not match "+
- "the expected checksum - got %d, want %d", gotChecksum,
- wantChecksum)
- return 0, 0, makeDbErr(database.ErrCorruption, str, nil)
- }
-
- fileNum := byteOrder.Uint32(writeRow[0:4])
- fileOffset := byteOrder.Uint32(writeRow[4:8])
- return fileNum, fileOffset, nil
-}
-
-// reconcileDB reconciles the metadata with the flat block files on disk. It
-// will also initialize the underlying database if the create flag is set.
-func reconcileDB(pdb *db, create bool) (database.DB, error) {
- // Perform initial internal bucket and value creation during database
- // creation.
- if create {
- if err := initDB(pdb.cache.ldb); err != nil {
- return nil, err
- }
- }
-
- // Load the current write cursor position from the metadata.
- var curFileNum, curOffset uint32
- err := pdb.View(func(tx database.Tx) error {
- writeRow := tx.Metadata().Get(writeLocKeyName)
- if writeRow == nil {
- str := "write cursor does not exist"
- return makeDbErr(database.ErrCorruption, str, nil)
- }
-
- var err error
- curFileNum, curOffset, err = deserializeWriteRow(writeRow)
- return err
- })
- if err != nil {
- return nil, err
- }
-
- // When the write cursor position found by scanning the block files on
- // disk is AFTER the position the metadata believes to be true, truncate
- // the files on disk to match the metadata. This can be a fairly common
- // occurrence in unclean shutdown scenarios while the block files are in
- // the middle of being written. Since the metadata isn't updated until
- // after the block data is written, this is effectively just a rollback
- // to the known good point before the unclean shutdown.
- wc := pdb.store.writeCursor
- if wc.curFileNum > curFileNum || (wc.curFileNum == curFileNum &&
- wc.curOffset > curOffset) {
-
- log.Info("Detected unclean shutdown - Repairing...")
- log.Debugf("Metadata claims file %d, offset %d. Block data is "+
- "at file %d, offset %d", curFileNum, curOffset,
- wc.curFileNum, wc.curOffset)
- pdb.store.handleRollback(curFileNum, curOffset)
- log.Infof("Database sync complete")
- }
-
- // When the write cursor position found by scanning the block files on
- // disk is BEFORE the position the metadata believes to be true, return
- // a corruption error. Since sync is called after each block is written
- // and before the metadata is updated, this should only happen in the
- // case of missing, deleted, or truncated block files, which generally
- // is not an easily recoverable scenario. In the future, it might be
- // possible to rescan and rebuild the metadata from the block files,
- // however, that would need to happen with coordination from a higher
- // layer since it could invalidate other metadata.
- if wc.curFileNum < curFileNum || (wc.curFileNum == curFileNum &&
- wc.curOffset < curOffset) {
-
- str := fmt.Sprintf("metadata claims file %d, offset %d, but "+
- "block data is at file %d, offset %d", curFileNum,
- curOffset, wc.curFileNum, wc.curOffset)
- log.Warnf("***Database corruption detected***: %v", str)
- return nil, makeDbErr(database.ErrCorruption, str, nil)
- }
-
- return pdb, nil
-}
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