in log/config.go [171:186]
func (t TimeUnit) RotationGap() time.Duration {
switch t {
case Minute:
return time.Minute
case Hour:
return time.Hour
case Day:
return time.Hour * 24
case Month:
return time.Hour * 24 * 30
case Year:
return time.Hour * 24 * 365
default:
return time.Hour * 24
}
}