async def cursor_async(self):
        """Acquire async cursor.
        """
        await self.connect_async(loop=self._loop)

        if self.transaction_depth_async() > 0:
            conn = self.transaction_conn_async()
        else:
            conn = None

        try:
            return (await self._async_conn.cursor(conn=conn))
        except:
            await self.close_async()
            raise
Acquire async cursor.