protected function process($extraConf = null)
    {
        if (null === $extraConf && count($this->config) <= 0) {
            return null;
        }

        $processor = new Processor();
        $configuration = new PropelConfiguration();

        if (is_array($extraConf)) {
            $this->config = array_replace_recursive($this->config, $extraConf);
        }

        $this->config = $processor->processConfiguration($configuration, $this->config);

        $this->cleanupSlaveConnections();
        $this->cleanupConnections();
    }