Doctrine\DBAL\Connections\MasterSlaveConnection::__construct PHP Method

    public function __construct(array $params, Driver $driver, Configuration $config = null, EventManager $eventManager = null)
    {
        if (!isset($params['slaves']) || !isset($params['master'])) {
            throw new \InvalidArgumentException('master or slaves configuration missing');
        }
        if (count($params['slaves']) == 0) {
            throw new \InvalidArgumentException('You have to configure at least one slaves.');
        }
        $params['master']['driver'] = $params['driver'];
        foreach ($params['slaves'] as $slaveKey => $slave) {
            $params['slaves'][$slaveKey]['driver'] = $params['driver'];
        }
        $this->keepSlave = isset($params['keepSlave']) ? (bool) $params['keepSlave'] : false;
        parent::__construct($params, $driver, $config, $eventManager);
    }