db/storage.go
func (s *LogStorage) CreateAppLogCollection(appName string) (*storage.Collection, error) {
	c := s.AppLogCollection(appName)
	err := c.Create(&logCappedInfo)
	return c, err
}
func (s *LogStorage) CreateAppLogCollection(appName string) (*storage.Collection, error) {
	c := s.AppLogCollection(appName)
	err := c.Create(&logCappedInfo)
	return c, err
}
// CreateAppLogCollection creates a new capped collection to store logs for an app.