v4-0003-Optimize-GUC-functions-for-simple-hash.patch
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Filename: v4-0003-Optimize-GUC-functions-for-simple-hash.patch
Type: text/x-patch
Part: 1
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Format: format-patch
Series: patch v4-0003
Subject: Optimize GUC functions for simple hash
| File | + | − |
|---|---|---|
| src/backend/utils/misc/guc.c | 36 | 4 |
From 01b053b473d897c71725a7bb09a3127fc78140dc Mon Sep 17 00:00:00 2001
From: John Naylor <john.naylor@postgresql.org>
Date: Wed, 22 Nov 2023 18:45:48 +0700
Subject: [PATCH v4 3/3] Optimize GUC functions for simple hash
Only downcase a character when an equality check fails,
since we expect most names to be lower case. Also simplify
downcasing in the hash function.
---
src/backend/utils/misc/guc.c | 40 ++++++++++++++++++++++++++++++++----
1 file changed, 36 insertions(+), 4 deletions(-)
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index bf05b022c3..7896deb63b 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -229,6 +229,7 @@ static int GUCNestLevel = 0; /* 1 when in main transaction */
static int guc_var_compare(const void *a, const void *b);
+static bool guc_name_eq(const char *namea, const char *nameb);
static uint32 guc_name_hash(const char *name);
static void InitializeGUCOptionsFromEnvironment(void);
static void InitializeOneGUCOption(struct config_generic *gconf);
@@ -271,7 +272,7 @@ static bool call_enum_check_hook(struct config_enum *conf, int *newval,
#define SH_KEY_TYPE const char *
#define SH_KEY gucname
#define SH_HASH_KEY(tb, key) guc_name_hash(key)
-#define SH_EQUAL(tb, a, b) (guc_name_compare(a, b) == 0)
+#define SH_EQUAL(tb, a, b) (guc_name_eq(a, b))
#define SH_SCOPE static inline
#define SH_DECLARE
#define SH_DEFINE
@@ -1308,6 +1309,38 @@ guc_name_compare(const char *namea, const char *nameb)
return 0;
}
+static bool
+guc_name_eq(const char *namea, const char *nameb)
+{
+ char cha;
+ char chb;
+
+ while (*namea && *nameb)
+ {
+ cha = *namea++;
+ chb = *nameb++;
+
+ if (cha != chb)
+ {
+ /* Casefold lazily since we expect lower case */
+ if (cha >= 'A' && cha <= 'Z')
+ cha += 'a' - 'A';
+ if (chb >= 'A' && chb <= 'Z')
+ chb += 'a' - 'A';
+
+ if (cha != chb)
+ return false;
+ }
+ }
+
+ if (*namea == *nameb)
+ return true;
+ else
+ return false;
+
+ //Assert(guc_name_compare(namea, nameb) == 0);
+}
+
/*
* Hash function that's compatible with guc_name_compare
*/
@@ -1320,9 +1353,8 @@ guc_name_hash(const char *name)
{
char ch = *name++;
- /* Case-fold in the same way as guc_name_compare */
- if (ch >= 'A' && ch <= 'Z')
- ch += 'a' - 'A';
+ /* quick and dirty casefolding suitable for hashing */
+ ch |= 0x20;
/* Merge into hash ... not very bright, but it needn't be */
result = pg_rotate_left32(result, 5);
--
2.42.0