mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2024-12-21 08:29:39 +08:00
Code Issues Packages Projects Releases Wiki Activity

Reduce need for palloc/pfree overhead in varstr_cmp() by using fixed-size

Browse Source 
buffers on stack for short strings.
This commit is contained in:
Tom Lane 2002-11-17 23:01:30 +00:00
parent 35223af057
commit 8fbef3b55d
1 changed files with 25 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
src/backend/utils/adt/varlena.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.92 2002/09/04 20:31:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.93 2002/11/17 23:01:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -736,36 +736,47 @@ int
varstr_cmp(char *arg1, int len1, char *arg2, int len2)
{
int result;
char *a1p,
*a2p;
/*
* Unfortunately, there is no strncoll(), so in the non-C locale case
* we have to do some memory copying. This turns out to be
* significantly slower, so we optimize the case where LC_COLLATE is
* C.
* C. We also try to optimize relatively-short strings by avoiding
* palloc/pfree overhead.
*/
#define STACKBUFLEN 1024
if (!lc_collate_is_c())
{
a1p = (char *) palloc(len1 + 1);
a2p = (char *) palloc(len2 + 1);
char a1buf[STACKBUFLEN];
char a2buf[STACKBUFLEN];
char *a1p,
*a2p;
if (len1 >= STACKBUFLEN)
a1p = (char *) palloc(len1 + 1);
else
a1p = a1buf;
if (len2 >= STACKBUFLEN)
a2p = (char *) palloc(len2 + 1);
else
a2p = a2buf;
memcpy(a1p, arg1, len1);
*(a1p + len1) = '\0';
a1p[len1] = '\0';
memcpy(a2p, arg2, len2);
*(a2p + len2) = '\0';
a2p[len2] = '\0';
result = strcoll(a1p, a2p);
pfree(a1p);
pfree(a2p);
if (len1 >= STACKBUFLEN)
pfree(a1p);
if (len2 >= STACKBUFLEN)
pfree(a2p);
}
else
{
a1p = arg1;
a2p = arg2;
result = strncmp(a1p, a2p, Min(len1, len2));
result = strncmp(arg1, arg2, Min(len1, len2));
if ((result == 0) && (len1 != len2))
result = (len1 < len2) ? -1 : 1;
}