func New(
	lg *zap.Logger,
	mode string,
	retention time.Duration,
	rg RevGetter,
	c Compactable,
) (Compactor, error) {
	switch mode {
	case ModePeriodic:
		return newPeriodic(lg, clockwork.NewRealClock(), retention, rg, c), nil
	case ModeRevision:
		return newRevision(lg, clockwork.NewRealClock(), int64(retention), rg, c), nil
	default:
		return nil, fmt.Errorf("unsupported compaction mode %s", mode)
	}
}
func New(
	lg *zap.Logger,
	mode string,
	retention time.Duration,
	rg RevGetter,
	c Compactable,
) (Compactor, error) {
	switch mode {
	case ModePeriodic:
		return newPeriodic(lg, clockwork.NewRealClock(), retention, rg, c), nil
	case ModeRevision:
		return newRevision(lg, clockwork.NewRealClock(), int64(retention), rg, c), nil
	default:
		return nil, fmt.Errorf("unsupported compaction mode %s", mode)
	}
}
// New returns a new Compactor based on given "mode".