Re: Speedup usages of pg_*toa() functions
| От | Ranier Vilela |
|---|---|
| Тема | Re: Speedup usages of pg_*toa() functions |
| Дата | |
| Msg-id | CAEudQAp5o4sp=EoE-LNRneW=RcmQFfVZ0OKRP4RqMOcqJAy92w@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Speedup usages of pg_*toa() functions (Andrew Gierth <andrew@tao11.riddles.org.uk>) |
| Ответы |
Re: Speedup usages of pg_*toa() functions
|
| Список | pgsql-hackers |
Em ter., 9 de jun. de 2020 às 15:53, Andrew Gierth <andrew@tao11.riddles.org.uk> escreveu:
>>>>> "Ranier" == Ranier Vilela <ranier.vf@gmail.com> writes:
Ranier> Where " ends up with two copies of pg_ultoa_n inlined into it",
Ranier> in this simplified example?
The two references to sprintf are both inlined copies of your pg_utoa.
Ranier> (b) I call this tail cut, I believe it saves time, for sure.
You seem to have missed the point that the pg_ultoa_n / pg_ulltoa_n
functions DO NOT ADD A TRAILING NUL. Which means that pg_ltoa / pg_lltoa
can't just tail call them, since they must add the NUL after.
Ranier> Regarding bugs:
Ranier> (c) your version don't check size of a var, when pg_ulltoa_n
Ranier> warning about "least MAXINT8LEN bytes."
Ranier> So in theory, I could blow it up, by calling pg_lltoa.
No. Callers of pg_lltoa are required to provide a buffer of at least
MAXINT8LEN+1 bytes.
Thanks for explanations.
So I would change, just the initialization (var uvalue), even though it is irrelevant.
int
pg_lltoa(int64 value, char *a)
{
int len = 0;
uint64 uvalue;
if (value < 0)
{
uvalue = (uint64) 0 - uvalue;
a[len++] = '-';
}
else
uvalue = value;
len += pg_ulltoa_n(uvalue, a + len);
a[len] = '\0';
return len;
}
pg_lltoa(int64 value, char *a)
{
int len = 0;
uint64 uvalue;
if (value < 0)
{
uvalue = (uint64) 0 - uvalue;
a[len++] = '-';
}
else
uvalue = value;
len += pg_ulltoa_n(uvalue, a + len);
a[len] = '\0';
return len;
}
regards,
Ranier Vilela
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