Method FileControl

vfs.go:2332–2438

FileControl handles file control operations, specifically PRAGMA commands for time travel.

(op int, pragmaName string, pragmaValue *string)

// FileControl handles file control operations, specifically PRAGMA commands for time travel.
func (f *VFSFile) FileControl(op int, pragmaName string, pragmaValue *string) (*string, error) {
	const SQLITE_FCNTL_PRAGMA = 14

	if op != SQLITE_FCNTL_PRAGMA {
		return nil, fmt.Errorf("unsupported file control op: %d", op)
	}

	name := strings.ToLower(pragmaName)

	f.logger.Debug("file control", "pragma", name, "value", pragmaValue)

	switch name {
	case "litestream_txid":
		if pragmaValue != nil {
			return nil, fmt.Errorf("litestream_txid is read-only")
		}
		txid := f.Pos().TXID
		result := txid.String()
		return &result, nil

	case "litestream_lag":
		if pragmaValue != nil {
			return nil, fmt.Errorf("litestream_lag is read-only")
		}
		lastPoll := f.LastPollSuccess()
		if lastPoll.IsZero() {
			result := "-1" // Never polled successfully
			return &result, nil
		}
		lag := int64(time.Since(lastPoll).Seconds())
		result := strconv.FormatInt(lag, 10)
		return &result, nil

	case "litestream_time":
		if pragmaValue == nil {
			result := f.currentTimeString()
			return &result, nil
		}

		if strings.EqualFold(*pragmaValue, "latest") {
			if err := f.ResetTime(context.Background()); err != nil {
				return nil, err
			}
			return nil, nil
		}

		t, err := parseTimeValue(*pragmaValue)
		if err != nil {
			return nil, err
		}
		if err := f.SetTargetTime(context.Background(), t); err != nil {
			return nil, err
		}
		return nil, nil

	case "litestream_hydration_progress":
		if pragmaValue != nil {
			return nil, fmt.Errorf("litestream_hydration_progress is read-only")