public function onOneKeyServer($key)
    {
        $this->selectedRedis[] = $this->getRedis($key);
        $this->multiRedis = false;

        return $this;
    }
public function onOneKeyServer($key)
    {
        $this->selectedRedis[] = $this->getRedis($key);
        $this->multiRedis = false;

        return $this;
    }
public function onOneKeyServer ( $ key ) { $ this -> selectedRedis [ ] = $ this -> getRedis ( $ key ) ; $ this -> multiRedis = false ; return $ this ; }
select one server according to the key

@param string $key cache key

@return $this
@throws Exception when no redis server available
select one server according to the key