framework/mutex/MysqlMutex.php
protected function releaseLock($name)
    {
        return $this->db->useMaster(function ($db) use ($name) {
            /** @var \yii\db\Connection $db */
            return (bool) $db->createCommand(
                'SELECT RELEASE_LOCK(:name)',
                [':name' => $this->hashLockName($name)]
            )->queryScalar();
        });
    }
protected function releaseLock($name)
    {
        return $this->db->useMaster(function ($db) use ($name) {
            /** @var \yii\db\Connection $db */
            return (bool) $db->createCommand(
                'SELECT RELEASE_LOCK(:name)',
                [':name' => $this->hashLockName($name)]
            )->queryScalar();
        });
    }
Releases lock by given name.
@param string $name of the lock to be released.
@return bool release result.
@see http://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock