private function removeTag($tag)
    {
        try {
            if (isset($this->_hashmap[$tag])) {
                foreach (array_keys($this->_hashmap[$tag]) as $key) {
                    if (\apc_delete($key)) {
                        unset($this->_hashmap[$tag][$key]);
                    }
                }

                return $this->saveHashmap();
            }
        } catch (\Exception $e) {
            $this->log('warning', \sprintf('Unable to delete cache for tag %s : %s', $tag, $e->getMessage()));

            return false;
        }

        return true;
    }