Re: [Qemu-block] [PATCH v5 2/4] quorum: implement bdrv_add_child() and bdrv_del_child()

[Alberto Garcia]

On Fri 09 Oct 2015 05:51:55 PM CEST, Max Reitz <address@hidden> wrote:
>>>> +        s->bs = g_renew(BlockDriverState *, s->bs, s->max_children + 1);
>>>> +        s->bs[s->num_children] = NULL;
>>>> +        s->max_children++;
>>>> +    }
>>>
>>> Just a suggestion, please feel free to ignore it completely:
>>>
>>> You can drop the s->max_children field and just always call g_renew()
>>> with s->num_children + 1 as the @count parameter. There shouldn't be
>>> any (visible) performance penalty, but it would simplify the code.
>> 
>> If s->num_children has decreased since the previous g_renew() call
>> (because the user called quorum_del_child()) that could actually reduce
>> the array size.
>
> Yes, it could. And that would be just fine. ;-)
>
> We'd just keep the array exactly as big as it needs to be. I find that
> pretty intuitive. It's just counter-intuitive if you think one should
> never use realloc() for reducing the size of a buffer (and I know I
> myself tend to write my code thinking that).

If the goal is to keep the array exactly as big as it needs to be then
we should use g_renew() in quorum_del_child()...

Anyway we're digressing :-) this array is one pointer per Quorum child,
so the amount of memory we're talking about here is probably negligible.
I'm fine with any solution.

Berto