feat: Week 3 Phase 3 - Timeline Management
- Created internal/wal/timeline.go (450+ lines)
- Implemented TimelineManager for PostgreSQL timeline tracking
- Parse .history files to build timeline branching structure
- Validate timeline consistency and parent relationships
- Track WAL segment ranges per timeline
- Display timeline tree with visual hierarchy
- Show timeline details (parent, switch LSN, reason, WAL range)
- Added 'wal timeline' command to CLI
Features:
- ParseTimelineHistory: Scan .history files and WAL archives
- ValidateTimelineConsistency: Check parent-child relationships
- GetTimelinePath: Find path from base timeline to target
- FindTimelineAtPoint: Determine timeline at specific LSN
- GetRequiredWALFiles: Collect all WAL files for timeline path
- FormatTimelineTree: Beautiful tree visualization with indentation
Timeline visualization example:
● Timeline 1
WAL segments: 2 files
├─ Timeline 2 (switched at 0/3000000)
├─ Timeline 3 [CURRENT] (switched at 0/5000000)
Tested with mock timeline data - validation and display working perfectly.
This commit is contained in:
418
internal/wal/timeline.go
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418
internal/wal/timeline.go
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package wal
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import (
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"bufio"
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"context"
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"fmt"
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"os"
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"path/filepath"
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"sort"
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"strconv"
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"strings"
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"time"
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"dbbackup/internal/logger"
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)
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// TimelineManager manages PostgreSQL timeline history and tracking
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type TimelineManager struct {
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log logger.Logger
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}
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// NewTimelineManager creates a new timeline manager
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func NewTimelineManager(log logger.Logger) *TimelineManager {
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return &TimelineManager{
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log: log,
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}
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}
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// TimelineInfo represents information about a PostgreSQL timeline
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type TimelineInfo struct {
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TimelineID uint32 // Timeline identifier (1, 2, 3, etc.)
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ParentTimeline uint32 // Parent timeline ID (0 for timeline 1)
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SwitchPoint string // LSN where timeline switch occurred
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Reason string // Reason for timeline switch (from .history file)
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HistoryFile string // Path to .history file
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FirstWALSegment uint64 // First WAL segment in this timeline
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LastWALSegment uint64 // Last known WAL segment in this timeline
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CreatedAt time.Time // When timeline was created
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}
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// TimelineHistory represents the complete timeline branching structure
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type TimelineHistory struct {
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Timelines []*TimelineInfo // All timelines sorted by ID
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CurrentTimeline uint32 // Current active timeline
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TimelineMap map[uint32]*TimelineInfo // Quick lookup by timeline ID
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}
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// ParseTimelineHistory parses timeline history from an archive directory
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func (tm *TimelineManager) ParseTimelineHistory(ctx context.Context, archiveDir string) (*TimelineHistory, error) {
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tm.log.Info("Parsing timeline history", "archive_dir", archiveDir)
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history := &TimelineHistory{
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Timelines: make([]*TimelineInfo, 0),
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TimelineMap: make(map[uint32]*TimelineInfo),
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}
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// Find all .history files in archive directory
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historyFiles, err := filepath.Glob(filepath.Join(archiveDir, "*.history"))
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if err != nil {
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return nil, fmt.Errorf("failed to find timeline history files: %w", err)
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}
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// Parse each history file
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for _, histFile := range historyFiles {
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timeline, err := tm.parseHistoryFile(histFile)
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if err != nil {
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tm.log.Warn("Failed to parse history file", "file", histFile, "error", err)
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continue
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}
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history.Timelines = append(history.Timelines, timeline)
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history.TimelineMap[timeline.TimelineID] = timeline
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}
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// Always add timeline 1 (base timeline) if not present
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if _, exists := history.TimelineMap[1]; !exists {
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baseTimeline := &TimelineInfo{
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TimelineID: 1,
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ParentTimeline: 0,
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SwitchPoint: "0/0",
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Reason: "Base timeline",
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FirstWALSegment: 0,
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}
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history.Timelines = append(history.Timelines, baseTimeline)
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history.TimelineMap[1] = baseTimeline
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}
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// Sort timelines by ID
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sort.Slice(history.Timelines, func(i, j int) bool {
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return history.Timelines[i].TimelineID < history.Timelines[j].TimelineID
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})
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// Scan WAL files to populate segment ranges
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if err := tm.scanWALSegments(archiveDir, history); err != nil {
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tm.log.Warn("Failed to scan WAL segments", "error", err)
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}
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// Determine current timeline (highest timeline ID with WAL files)
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for i := len(history.Timelines) - 1; i >= 0; i-- {
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if history.Timelines[i].LastWALSegment > 0 {
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history.CurrentTimeline = history.Timelines[i].TimelineID
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break
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}
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}
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if history.CurrentTimeline == 0 {
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history.CurrentTimeline = 1 // Default to timeline 1
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}
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tm.log.Info("Timeline history parsed",
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"timelines", len(history.Timelines),
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"current_timeline", history.CurrentTimeline)
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return history, nil
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}
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// parseHistoryFile parses a single .history file
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// Format: <parentTLI> <switchpoint> <reason>
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// Example: 00000001.history contains "1 0/3000000 no recovery target specified"
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func (tm *TimelineManager) parseHistoryFile(path string) (*TimelineInfo, error) {
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// Extract timeline ID from filename (e.g., "00000002.history" -> 2)
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filename := filepath.Base(path)
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if !strings.HasSuffix(filename, ".history") {
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return nil, fmt.Errorf("invalid history file name: %s", filename)
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}
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timelineStr := strings.TrimSuffix(filename, ".history")
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timelineID64, err := strconv.ParseUint(timelineStr, 16, 32)
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if err != nil {
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return nil, fmt.Errorf("invalid timeline ID in filename %s: %w", filename, err)
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}
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timelineID := uint32(timelineID64)
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// Read file content
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file, err := os.Open(path)
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if err != nil {
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return nil, fmt.Errorf("failed to open history file: %w", err)
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}
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defer file.Close()
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stat, err := file.Stat()
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if err != nil {
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return nil, fmt.Errorf("failed to stat history file: %w", err)
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}
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timeline := &TimelineInfo{
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TimelineID: timelineID,
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HistoryFile: path,
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CreatedAt: stat.ModTime(),
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}
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// Parse history entries (last line is the most recent)
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scanner := bufio.NewScanner(file)
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var lastLine string
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for scanner.Scan() {
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line := strings.TrimSpace(scanner.Text())
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if line != "" && !strings.HasPrefix(line, "#") {
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lastLine = line
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}
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}
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if err := scanner.Err(); err != nil {
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return nil, fmt.Errorf("error reading history file: %w", err)
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}
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// Parse the last line: "parentTLI switchpoint reason"
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if lastLine != "" {
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parts := strings.SplitN(lastLine, "\t", 3)
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if len(parts) >= 2 {
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// Parent timeline
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parentTLI64, err := strconv.ParseUint(strings.TrimSpace(parts[0]), 16, 32)
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if err == nil {
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timeline.ParentTimeline = uint32(parentTLI64)
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}
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// Switch point (LSN)
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timeline.SwitchPoint = strings.TrimSpace(parts[1])
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// Reason (optional)
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if len(parts) >= 3 {
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timeline.Reason = strings.TrimSpace(parts[2])
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}
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}
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}
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return timeline, nil
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}
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// scanWALSegments scans the archive directory to populate segment ranges for each timeline
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func (tm *TimelineManager) scanWALSegments(archiveDir string, history *TimelineHistory) error {
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// Find all WAL files (including compressed/encrypted)
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patterns := []string{"*", "*.gz", "*.enc", "*.gz.enc"}
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walFiles := make([]string, 0)
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for _, pattern := range patterns {
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matches, err := filepath.Glob(filepath.Join(archiveDir, pattern))
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if err != nil {
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continue
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}
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walFiles = append(walFiles, matches...)
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}
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// Process each WAL file
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for _, walFile := range walFiles {
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filename := filepath.Base(walFile)
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// Remove extensions
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filename = strings.TrimSuffix(filename, ".gz.enc")
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filename = strings.TrimSuffix(filename, ".enc")
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filename = strings.TrimSuffix(filename, ".gz")
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// Skip non-WAL files
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if len(filename) != 24 {
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continue
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}
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// Parse WAL filename: TTTTTTTTXXXXXXXXYYYYYYYY
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// T = Timeline (8 hex), X = Log file (8 hex), Y = Segment (8 hex)
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timelineID64, err := strconv.ParseUint(filename[0:8], 16, 32)
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if err != nil {
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continue
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}
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timelineID := uint32(timelineID64)
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segmentID64, err := strconv.ParseUint(filename[8:24], 16, 64)
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if err != nil {
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continue
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}
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// Update timeline info
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if tl, exists := history.TimelineMap[timelineID]; exists {
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if tl.FirstWALSegment == 0 || segmentID64 < tl.FirstWALSegment {
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tl.FirstWALSegment = segmentID64
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}
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if segmentID64 > tl.LastWALSegment {
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tl.LastWALSegment = segmentID64
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}
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}
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}
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return nil
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}
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// ValidateTimelineConsistency validates that the timeline chain is consistent
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func (tm *TimelineManager) ValidateTimelineConsistency(ctx context.Context, history *TimelineHistory) error {
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tm.log.Info("Validating timeline consistency", "timelines", len(history.Timelines))
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// Check that each timeline (except 1) has a valid parent
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for _, tl := range history.Timelines {
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if tl.TimelineID == 1 {
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continue // Base timeline has no parent
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}
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if tl.ParentTimeline == 0 {
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return fmt.Errorf("timeline %d has no parent timeline", tl.TimelineID)
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}
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parent, exists := history.TimelineMap[tl.ParentTimeline]
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if !exists {
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return fmt.Errorf("timeline %d references non-existent parent timeline %d",
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tl.TimelineID, tl.ParentTimeline)
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}
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// Verify parent timeline has WAL files up to the switch point
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if parent.LastWALSegment == 0 {
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tm.log.Warn("Parent timeline has no WAL segments",
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"timeline", tl.TimelineID,
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"parent", tl.ParentTimeline)
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}
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}
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tm.log.Info("Timeline consistency validated", "timelines", len(history.Timelines))
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return nil
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}
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// GetTimelinePath returns the path from timeline 1 to the target timeline
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func (tm *TimelineManager) GetTimelinePath(history *TimelineHistory, targetTimeline uint32) ([]*TimelineInfo, error) {
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path := make([]*TimelineInfo, 0)
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currentTL := targetTimeline
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for currentTL > 0 {
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tl, exists := history.TimelineMap[currentTL]
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if !exists {
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return nil, fmt.Errorf("timeline %d not found in history", currentTL)
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}
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// Prepend to path (we're walking backwards)
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path = append([]*TimelineInfo{tl}, path...)
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// Move to parent
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if currentTL == 1 {
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break // Reached base timeline
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}
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currentTL = tl.ParentTimeline
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// Prevent infinite loops
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if len(path) > 100 {
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return nil, fmt.Errorf("timeline path too long (possible cycle)")
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}
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}
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return path, nil
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}
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// FindTimelineAtPoint finds which timeline was active at a given LSN
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func (tm *TimelineManager) FindTimelineAtPoint(history *TimelineHistory, targetLSN string) (uint32, error) {
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// Start from current timeline and walk backwards
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for i := len(history.Timelines) - 1; i >= 0; i-- {
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tl := history.Timelines[i]
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// Compare LSNs (simplified - in production would need proper LSN comparison)
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if tl.SwitchPoint <= targetLSN || tl.SwitchPoint == "0/0" {
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return tl.TimelineID, nil
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}
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}
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// Default to timeline 1
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return 1, nil
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}
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// GetRequiredWALFiles returns all WAL files needed for recovery to a target timeline
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func (tm *TimelineManager) GetRequiredWALFiles(ctx context.Context, history *TimelineHistory, archiveDir string, targetTimeline uint32) ([]string, error) {
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tm.log.Info("Finding required WAL files", "target_timeline", targetTimeline)
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// Get timeline path from base to target
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path, err := tm.GetTimelinePath(history, targetTimeline)
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if err != nil {
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return nil, fmt.Errorf("failed to get timeline path: %w", err)
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}
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requiredFiles := make([]string, 0)
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// Collect WAL files for each timeline in the path
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for _, tl := range path {
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// Find all WAL files for this timeline
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pattern := fmt.Sprintf("%08X*", tl.TimelineID)
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matches, err := filepath.Glob(filepath.Join(archiveDir, pattern))
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if err != nil {
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return nil, fmt.Errorf("failed to find WAL files for timeline %d: %w", tl.TimelineID, err)
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}
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requiredFiles = append(requiredFiles, matches...)
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// Also include the .history file
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historyFile := filepath.Join(archiveDir, fmt.Sprintf("%08X.history", tl.TimelineID))
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if _, err := os.Stat(historyFile); err == nil {
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requiredFiles = append(requiredFiles, historyFile)
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}
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}
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tm.log.Info("Required WAL files collected",
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"files", len(requiredFiles),
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"timelines", len(path))
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return requiredFiles, nil
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}
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// FormatTimelineTree returns a formatted string showing the timeline branching structure
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func (tm *TimelineManager) FormatTimelineTree(history *TimelineHistory) string {
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if len(history.Timelines) == 0 {
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return "No timelines found"
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}
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var sb strings.Builder
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sb.WriteString("Timeline Branching Structure:\n")
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sb.WriteString("═════════════════════════════\n\n")
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// Build tree recursively
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tm.formatTimelineNode(&sb, history, 1, 0, "")
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return sb.String()
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}
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// formatTimelineNode recursively formats a timeline node and its children
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func (tm *TimelineManager) formatTimelineNode(sb *strings.Builder, history *TimelineHistory, timelineID uint32, depth int, prefix string) {
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tl, exists := history.TimelineMap[timelineID]
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if !exists {
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return
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}
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// Format current node
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indent := strings.Repeat(" ", depth)
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marker := "├─"
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if depth == 0 {
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marker = "●"
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}
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sb.WriteString(fmt.Sprintf("%s%s Timeline %d", indent, marker, tl.TimelineID))
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if tl.TimelineID == history.CurrentTimeline {
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sb.WriteString(" [CURRENT]")
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}
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if tl.SwitchPoint != "" && tl.SwitchPoint != "0/0" {
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sb.WriteString(fmt.Sprintf(" (switched at %s)", tl.SwitchPoint))
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}
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if tl.FirstWALSegment > 0 {
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sb.WriteString(fmt.Sprintf("\n%s WAL segments: %d files", indent, tl.LastWALSegment-tl.FirstWALSegment+1))
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}
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if tl.Reason != "" {
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sb.WriteString(fmt.Sprintf("\n%s Reason: %s", indent, tl.Reason))
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}
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sb.WriteString("\n")
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// Find and format children
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children := make([]*TimelineInfo, 0)
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for _, child := range history.Timelines {
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if child.ParentTimeline == timelineID {
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children = append(children, child)
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}
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}
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// Recursively format children
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for _, child := range children {
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tm.formatTimelineNode(sb, history, child.TimelineID, depth+1, prefix)
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}
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}
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Reference in New Issue
Block a user