yii\rbac\DbManager::getItem PHP Method

    protected function getItem($name)
    {
        if (empty($name)) {
            return null;
        }
        if (!empty($this->items[$name])) {
            return $this->items[$name];
        }
        $row = (new Query())->from($this->itemTable)->where(['name' => $name])->one($this->db);
        if ($row === false) {
            return null;
        }
        return $this->populateItem($row);
    }

 /**
  * @inheritdoc
  */
 protected function getItem($name)
 {
     $cacheKey = 'Item:' . $name;
     $cached = $this->getCache($cacheKey);
     if (empty($cached)) {
         $cached = parent::getItem($name);
         $this->setCache($cacheKey, $cached);
     }
     return $cached;
 }