storage/driver.go
func GetCurrentDbDriver() (*DbDriver, error) {
	driverLock.RLock()
	if currentDbDriver != nil {
		driverLock.RUnlock()
		return currentDbDriver, nil
	}
	driverLock.RUnlock()
	driverLock.Lock()
	defer driverLock.Unlock()
	if currentDbDriver != nil {
		return currentDbDriver, nil
	}
	dbDriverName, err := config.GetString("database:driver")
	if err != nil || dbDriverName == "" {
		dbDriverName = DefaultDbDriverName
	}
	currentDbDriver, err = GetDbDriver(dbDriverName)
	if err != nil {
		return nil, err
	}
	return currentDbDriver, nil
}
func GetCurrentDbDriver() (*DbDriver, error) {
	driverLock.RLock()
	if currentDbDriver != nil {
		driverLock.RUnlock()
		return currentDbDriver, nil
	}
	driverLock.RUnlock()
	driverLock.Lock()
	defer driverLock.Unlock()
	if currentDbDriver != nil {
		return currentDbDriver, nil
	}
	dbDriverName, err := config.GetString("database:driver")
	if err != nil || dbDriverName == "" {
		dbDriverName = DefaultDbDriverName
	}
	currentDbDriver, err = GetDbDriver(dbDriverName)
	if err != nil {
		return nil, err
	}
	return currentDbDriver, nil
}
// GetCurrentDbDriver returns the DB driver specified in the configuration file.
// If this configuration was omitted, it returns the default DB driver