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https://github.com/ethereum/go-ethereum.git
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859312d1f5
Implement crash-safe persistence for the Bitbox hash table: - wal.go: WAL format with START/CLEAR/UPDATE/END entries, builder/reader - sync.go: 3-phase sync protocol (BeginSync → WriteWAL → CommitSync) - recover.go: WAL replay for crash recovery The WAL records page diffs (not full pages) for compact logging. The 3-phase protocol ensures: WAL fsynced before HT modification, HT fsynced before WAL truncation, providing at-least-once delivery of page updates. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
73 lines
1.8 KiB
Go
73 lines
1.8 KiB
Go
package bitbox
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import (
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"fmt"
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"github.com/ethereum/go-ethereum/nomt/core"
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)
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// Recover replays the WAL file to restore the database to a consistent state.
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// Returns the sync sequence number from the WAL, or 0 if no recovery was
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// needed.
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func (db *DB) Recover(walPath string) (uint32, error) {
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data, err := ReadWALFile(walPath)
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if err != nil {
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return 0, fmt.Errorf("bitbox/recover: %w", err)
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}
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if len(data) == 0 {
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return 0, nil // No recovery needed.
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}
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syncSeqn, entries, err := ReadWAL(data)
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if err != nil {
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return 0, fmt.Errorf("bitbox/recover: parse: %w", err)
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}
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for _, entry := range entries {
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switch entry.Kind {
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case WALEntryClear:
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db.metaMap.Set(entry.ClearBucket, MetaTombstone)
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case WALEntryUpdate:
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// Read the existing data page at this bucket (or use a fresh one).
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page, readErr := db.readDataPage(entry.UpdateBucket)
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if readErr != nil {
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page = new(core.RawPage)
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}
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// Apply the diff: unpack changed nodes into the page.
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entry.Diff.UnpackChangedNodes(entry.ChangedNodes, page)
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// Set elided children and page ID.
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page.SetElidedChildren(entry.ElidedChildren)
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page.SetPageIDBytes(entry.PageID)
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// Write data page.
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if err := db.writeDataPage(entry.UpdateBucket, page); err != nil {
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return 0, fmt.Errorf("bitbox/recover: write page: %w", err)
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}
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// Update meta byte.
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hash := HashPageIDBytes(db.seed, entry.PageID)
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db.metaMap.Set(entry.UpdateBucket, MakeOccupied(hash))
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}
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}
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// Write dirty meta pages.
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if err := db.FlushMeta(); err != nil {
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return 0, fmt.Errorf("bitbox/recover: flush meta: %w", err)
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}
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// fsync HT file.
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if err := db.file.Sync(); err != nil {
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return 0, fmt.Errorf("bitbox/recover: fsync: %w", err)
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}
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// Truncate WAL.
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if err := TruncateWALFile(walPath); err != nil {
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return 0, fmt.Errorf("bitbox/recover: truncate WAL: %w", err)
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}
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return syncSeqn, nil
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}
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