<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\mutex;

use Yii;
use yii\db\Connection;
use yii\base\InvalidConfigException;

/**
 * @author resurtm <resurtm@gmail.com>
 * @since 2.0
 */
abstract class DbMutex extends Mutex
{
    /**
     * @var Connection|string the DB connection object or the application component ID of the DB connection.
     * After the Mutex object is created, if you want to change this property, you should only assign
     * it with a DB connection object.
     */
    public $db = 'db';

    /**
     * Initializes generic database table based mutex implementation.
     * @throws InvalidConfigException if [[db]] is invalid.
     */
    public function init()
    {
        parent::init();
        if (is_string($this->db)) {
            $this->db = Yii::$app->get($this->db);
        }
        if (!$this->db instanceof Connection) {
            throw new InvalidConfigException('Mutex::db must be either a DB connection instance or the application component ID of a DB connection.');
        }
    }
}
