Re: Replace some cstring_to_text to cstring_to_text_with_len

Andrew Dunstan <andrew(at)dunslane(dot)net> writes:

> On 2023-08-31 Th 07:41, John Naylor wrote:
>>
>> On Thu, Aug 31, 2023 at 6:07 PM Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> wrote:
>> >
>> > Em qui., 31 de ago. de 2023 às 00:22, Michael Paquier
>> <michael(at)paquier(dot)xyz> escreveu:
>> >>
>> >> On Wed, Aug 30, 2023 at 03:00:13PM -0300, Ranier Vilela wrote:
>> >> > cstring_to_text has a small overhead, because call strlen for
>> >> > pointer to char parameter.
>> >> >
>> >> > Is it worth the effort to avoid this, where do we know the size
>> of the
>> >> > parameter?
>> >>
>> >> Are there workloads where this matters?
>> >
>> > None, but note this change has the same spirit of 8b26769bc.
>>
>> - return cstring_to_text("");
>> + return cstring_to_text_with_len("", 0);
>>
>> This looks worse, so we'd better be getting something in return.
>
>
> I agree this is a bit ugly. I wonder if we'd be better off creating a
> function that returned an empty text value, so we'd just avoid
> converting the empty cstring altogether and say:
>
>   return empty_text();

Or we could generalise it for any string literal (of which there are
slightly more¹ non-empty than empty in calls to
cstring_to_text(_with_len)):

#define literal_to_text(str) cstring_to_text_with_len("" str "", sizeof(str)-1)

[1]:

~/src/postgresql $ rg 'cstring_to_text(_with_len)?\("[^"]+"' | wc -l
17
~/src/postgresql $ rg 'cstring_to_text(_with_len)?\(""' | wc -l
15

- ilmari