maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Monty!

On Apr 02, Michael Widenius wrote:
> revision-id: 405a89353b2 (mariadb-10.5.2-542-g405a89353b2)
> parent(s): 2dd8d472fcc
> author: Michael Widenius <michael.widenius@xxxxxxxxx>
> committer: Michael Widenius <michael.widenius@xxxxxxxxx>
> timestamp: 2021-03-24 19:25:08 +0200
> message:
> 
> Don't reset StringBuffers in loops when not needed
> 
> - Moved out creating StringBuffers in loops and instead create them
>   outside and just reset the buffer if it was not allocated (to avoid
>   a possible malloc/free for every entry)
> 
> diff --git a/sql/sql_string.h b/sql/sql_string.h
> index 29d01779b71..8df50ac5e66 100644
> --- a/sql/sql_string.h
> +++ b/sql/sql_string.h
> @@ -1045,6 +1045,12 @@ class StringBuffer : public String
>    {
>      length(0);
>    }
> +  void set_buffer_if_not_allocated(CHARSET_INFO *cs)
> +  {
> +    if (is_alloced())
> +      Static_binary_string::set(buff, buff_sz);

it seems to be doing exactly the opposite of what the name suggests.
It sets the buffer *if allocated*.

Also, it looks logical to do length(0) here, so that this method
would reset the StringBuffer to its initial state.

> +    set_charset(cs);
> +  }
>  };

Regards,
Sergei
VP of MariaDB Server Engineering
and security@xxxxxxxxxxx