library/Rediska/Zend/Cache/Backend/Redis.php
protected function _getTransactionByKey($key)
    {
        $connection = $this->getRediska()->getConnectionByKeyName($key);
        if(!$this->_transaction[$connection->getAlias()]){
            $this->_transaction[$connection->getAlias()] = $this->getRediska()
                ->transaction($connection);
        }
        return $this->_transaction[$connection->getAlias()];
    }
protected function _getTransactionByKey($key)
    {
        $connection = $this->getRediska()->getConnectionByKeyName($key);
        if(!$this->_transaction[$connection->getAlias()]){
            $this->_transaction[$connection->getAlias()] = $this->getRediska()
                ->transaction($connection);
        }
        return $this->_transaction[$connection->getAlias()];
    }
@param string $key

@return Rediska_Transaction