src/M6Web/Component/Redis/Manager.php
protected function getServerId($key, $servers = null)
    {
        if (is_null($servers)) {
            $servers = $this->getServerConfig();
        }
        $serverKeys = array_keys($servers);

        return $serverKeys[(int) (crc32($key) % count($serverKeys))];
    }
protected function getServerId($key, $servers = null)
    {
        if (is_null($servers)) {
            $servers = $this->getServerConfig();
        }
        $serverKeys = array_keys($servers);

        return $serverKeys[(int) (crc32($key) % count($serverKeys))];
    }
return a server according to the redis key passed
@param string $key     server name
@param array  $servers array of servers

@return mixed