Re: Micro-optimizations to avoid some strlen calls. - Mailing list pgsql-hackers

From Ranier Vilela
Subject Re: Micro-optimizations to avoid some strlen calls.
Date
Msg-id CAEudQAqMnBYMYw9-BwiTym=cAhuDzdMyUWbOP_XEYqRDgaDQWg@mail.gmail.com
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In response to Re: Micro-optimizations to avoid some strlen calls.  (Ranier Vilela <ranier.vf@gmail.com>)
List pgsql-hackers
Em qua., 21 de jul. de 2021 às 09:28, Ranier Vilela <ranier.vf@gmail.com> escreveu:
Em qua., 21 de jul. de 2021 às 07:44, David Rowley <dgrowleyml@gmail.com> escreveu:
On Tue, 20 Jul 2021 at 10:49, Ranier Vilela <ranier.vf@gmail.com> wrote:
> There are some places, where strlen can have an overhead.
> This patch tries to fix this.

I'm with Michael and David on this.

I don't really feel like doing;

- snprintf(buffer, sizeof(buffer), "E%s%s\n",
+ buflen = snprintf(buffer, sizeof(buffer), "E%s%s\n",
  _("could not fork new process for connection: "),

is a good idea.  I'm unsure if you're either not aware of the value
that snprintf() returns or just happen to think an overflow is
unlikely enough because you're convinced that 1000 chars are always
enough to fit this translatable string.   I'd say if we were 100%
certain of that then it might as well become sprintf() instead.
However, I imagine you'll struggle to get people to side with you that
taking this overflow risk would be worthwhile given your lack of any
evidence that anything actually has become meaningfully faster as a
result of any of these changes.
I got your point.
Really getting only the result of snprintf is a bad idea.
In this case, the right way would be:

snprintf(buffer, sizeof(buffer), "E%s%s\n",
  _("could not fork new process for connection: "),
buflen = strlen(buffer);

Thus doesn't have to recount buffer over, if rc fails.
Thanks for the tip about snprintf, even though it's not the intention.
This is what I call a bad interface.
Here the v1 version, with fix to snprintf trap.

regards,
Ranier Vilela
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