public function init()
    {
        $valid = null;

        if ($this->cache->has(self::CACHE_KEY)) {
            $cached = $this->cache->get(self::CACHE_KEY);
            $valid  = $cached && isset($cached['hosts']) && count($cached['hosts']);
        }


        if ($valid) {
            $this->map = $cached;
        } else {
            $this->build();
        }
    }