func()

in internal/beatcmd/beat.go [202:261]
49 lines of code
12 McCabe index (conditional complexity)

func (b *Beat) loadMeta(metaPath string) error {
	type meta struct {
		UUID       uuid.UUID `json:"uuid"`
		FirstStart time.Time `json:"first_start"`
	}

	b.Info.Logger.Debugf("beat", "Beat metadata path: %v", metaPath)
	f, err := openRegular(metaPath)
	if err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("meta file failed to open: %w", err)
	}
	if err == nil {
		var m meta
		if err := json.NewDecoder(f).Decode(&m); err != nil && err != io.EOF {
			f.Close()
			return fmt.Errorf("Beat meta file reading error: %w", err)
		}
		f.Close()
		b.Info.FirstStart = m.FirstStart
		b.Info.ID = m.UUID
	}

	rewrite := false
	if b.Info.FirstStart.IsZero() {
		b.Info.FirstStart = b.Info.StartTime
		rewrite = true
	}
	if b.Info.ID == uuid.Nil {
		id, err := uuid.NewV4()
		if err != nil {
			return err
		}
		b.Info.ID = id
		rewrite = true
	}
	if !rewrite {
		return nil
	}

	// meta.json does not exist, or the contents are invalid: write a new file.
	//
	// Write a temporary file, and then atomically move it into place in case
	// of errors occurring half way through.

	encodedMeta, err := json.Marshal(meta{
		UUID:       b.Info.ID,
		FirstStart: b.Info.FirstStart,
	})
	if err != nil {
		return fmt.Errorf("failed to encode metadata: %w", err)
	}

	tempFile := metaPath + ".new"
	if err := os.WriteFile(tempFile, encodedMeta, 0600); err != nil {
		return fmt.Errorf("failed to write metadata: %w", err)
	}

	// move temporary file into final location
	return file.SafeFileRotate(metaPath, tempFile)
}