yii\rbac\DbManager::loadFromCache PHP Method

    public function loadFromCache()
    {
        if ($this->items !== null || !$this->cache instanceof Cache) {
            return;
        }
        $data = $this->cache->get($this->cacheKey);
        if (is_array($data) && isset($data[0], $data[1], $data[2])) {
            list($this->items, $this->rules, $this->parents) = $data;
            return;
        }
        $query = (new Query())->from($this->itemTable);
        $this->items = [];
        foreach ($query->all($this->db) as $row) {
            $this->items[$row['name']] = $this->populateItem($row);
        }
        $query = (new Query())->from($this->ruleTable);
        $this->rules = [];
        foreach ($query->all($this->db) as $row) {
            $this->rules[$row['name']] = unserialize($row['data']);
        }
        $query = (new Query())->from($this->itemChildTable);
        $this->parents = [];
        foreach ($query->all($this->db) as $row) {
            if (isset($this->items[$row['child']])) {
                $this->parents[$row['child']][] = $row['parent'];
            }
        }
        $this->cache->set($this->cacheKey, [$this->items, $this->rules, $this->parents]);
    }