From c05ee846d6d9099642eeeed58933924a00d80262 Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Thu, 27 Jul 2023 15:11:42 -0700
Subject: [PATCH v1 1/3] Transform proconfig for faster execution.

Store function config settings as a list of (name, value) pairs to
avoid the need to parse for each function invocation.
---
 src/backend/utils/fmgr/fmgr.c | 27 ++++++++++------
 src/backend/utils/misc/guc.c  | 58 +++++++++++++++++++++++++++++++++++
 src/include/utils/guc.h       |  1 +
 3 files changed, 77 insertions(+), 9 deletions(-)

diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 9208c31fe0..3b49684991 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -612,7 +612,7 @@ struct fmgr_security_definer_cache
 {
 	FmgrInfo	flinfo;			/* lookup info for target function */
 	Oid			userid;			/* userid to set, or InvalidOid */
-	ArrayType  *proconfig;		/* GUC values to set, or NULL */
+	List	   *configList;		/* GUC values to set, or NULL */
 	Datum		arg;			/* passthrough argument for plugin modules */
 };
 
@@ -634,6 +634,7 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 	FmgrInfo   *save_flinfo;
 	Oid			save_userid;
 	int			save_sec_context;
+	ListCell   *lc;
 	volatile int save_nestlevel;
 	PgStat_FunctionCallUsage fcusage;
 
@@ -666,8 +667,10 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 								&isnull);
 		if (!isnull)
 		{
+			ArrayType *array;
 			oldcxt = MemoryContextSwitchTo(fcinfo->flinfo->fn_mcxt);
-			fcache->proconfig = DatumGetArrayTypePCopy(datum);
+			array = DatumGetArrayTypeP(datum);
+			fcache->configList = TransformGUCArray(array);
 			MemoryContextSwitchTo(oldcxt);
 		}
 
@@ -680,7 +683,7 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 
 	/* GetUserIdAndSecContext is cheap enough that no harm in a wasted call */
 	GetUserIdAndSecContext(&save_userid, &save_sec_context);
-	if (fcache->proconfig)		/* Need a new GUC nesting level */
+	if (fcache->configList != NIL)		/* Need a new GUC nesting level */
 		save_nestlevel = NewGUCNestLevel();
 	else
 		save_nestlevel = 0;		/* keep compiler quiet */
@@ -689,12 +692,18 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 		SetUserIdAndSecContext(fcache->userid,
 							   save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
 
-	if (fcache->proconfig)
+	foreach(lc, fcache->configList)
 	{
-		ProcessGUCArray(fcache->proconfig,
-						(superuser() ? PGC_SUSET : PGC_USERSET),
-						PGC_S_SESSION,
-						GUC_ACTION_SAVE);
+		GucContext	 context = superuser() ? PGC_SUSET : PGC_USERSET;
+		GucSource	 source	 = PGC_S_SESSION;
+		GucAction	 action	 = GUC_ACTION_SAVE;
+		List		*pair	 = lfirst(lc);
+		char		*name	 = linitial(pair);
+		char		*value	 = lsecond(pair);
+
+		(void) set_config_option(name, value,
+								 context, source,
+								 action, true, 0, false);
 	}
 
 	/* function manager hook */
@@ -737,7 +746,7 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 
 	fcinfo->flinfo = save_flinfo;
 
-	if (fcache->proconfig)
+	if (fcache->configList != NIL)
 		AtEOXact_GUC(true, save_nestlevel);
 	if (OidIsValid(fcache->userid))
 		SetUserIdAndSecContext(save_userid, save_sec_context);
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 5308896c87..bb69ebc4d8 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -6213,6 +6213,64 @@ ParseLongOption(const char *string, char **name, char **value)
 			*cp = '_';
 }
 
+/*
+ * Transform array of GUC settings into a list of (name, value) pairs. The
+ * list is faster to process in cases where the settings must be applied
+ * repeatedly (e.g. for each function invocation).
+ */
+List *
+TransformGUCArray(ArrayType *array)
+{
+	List	   *result = NIL;
+	int			i;
+
+	Assert(array != NULL);
+	Assert(ARR_ELEMTYPE(array) == TEXTOID);
+	Assert(ARR_NDIM(array) == 1);
+	Assert(ARR_LBOUND(array)[0] == 1);
+
+	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
+	{
+		Datum		d;
+		bool		isnull;
+		char	   *s;
+		char	   *name;
+		char	   *value;
+		List	   *pair;
+
+		d = array_ref(array, 1, &i,
+					  -1 /* varlenarray */ ,
+					  -1 /* TEXT's typlen */ ,
+					  false /* TEXT's typbyval */ ,
+					  TYPALIGN_INT /* TEXT's typalign */ ,
+					  &isnull);
+
+		if (isnull)
+			continue;
+
+		s = TextDatumGetCString(d);
+
+		ParseLongOption(s, &name, &value);
+		if (!value)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("could not parse setting for parameter \"%s\"",
+							name)));
+			pfree(name);
+			continue;
+		}
+
+		pair = list_make2(pstrdup(name), pstrdup(value));
+		result = lappend(result, pair);
+
+		pfree(name);
+		pfree(value);
+		pfree(s);
+	}
+
+	return result;
+}
 
 /*
  * Handle options fetched from pg_db_role_setting.setconfig,
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 223a19f80d..713a121312 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -391,6 +391,7 @@ extern void AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt);
 extern char *GetConfigOptionByName(const char *name, const char **varname,
 								   bool missing_ok);
 
+extern List *TransformGUCArray(ArrayType *array);
 extern void ProcessGUCArray(ArrayType *array,
 							GucContext context, GucSource source, GucAction action);
 extern ArrayType *GUCArrayAdd(ArrayType *array, const char *name, const char *value);
-- 
2.34.1