Refactor code building relation options

Historically, the code to build relation options has been shaped the
same way in multiple code paths by using a set of datums in input with
the options parsed with a static table which is then filled with the
option values.  This introduces a new common routine in reloptions.c to
do most of the legwork for the in-core code paths.

Author: Amit Langote
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/CA+HiwqGsoSn_uTPPYT19WrtR7oYpYtv4CdS0xuedTKiHHWuk_g@mail.gmail.com

contrib/bloom/blutils.c

@@ -475,18 +475,18 @@ BloomInitMetapage(Relation index)
 bytea *
 bloptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	int			numoptions;
 	BloomOptions *rdopts;
 
 	/* Parse the user-given reloptions */
-	options = parseRelOptions(reloptions, validate, bl_relopt_kind, &numoptions);
-	rdopts = allocateReloptStruct(sizeof(BloomOptions), options, numoptions);
-	fillRelOptions((void *) rdopts, sizeof(BloomOptions), options, numoptions,
-				   validate, bl_relopt_tab, lengthof(bl_relopt_tab));
+	rdopts = (BloomOptions *) build_reloptions(reloptions, validate,
+											   bl_relopt_kind,
+											   sizeof(BloomOptions),
+											   bl_relopt_tab,
+											   lengthof(bl_relopt_tab));
 
 	/* Convert signature length from # of bits to # to words, rounding up */
-	rdopts->bloomLength = (rdopts->bloomLength + SIGNWORDBITS - 1) / SIGNWORDBITS;
+	if (rdopts)
+		rdopts->bloomLength = (rdopts->bloomLength + SIGNWORDBITS - 1) / SIGNWORDBITS;
 
 	return (bytea *) rdopts;
 }

src/backend/access/brin/brin.c

@@ -820,29 +820,15 @@ brinvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
 bytea *
 brinoptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	BrinOptions *rdopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"pages_per_range", RELOPT_TYPE_INT, offsetof(BrinOptions, pagesPerRange)},
 		{"autosummarize", RELOPT_TYPE_BOOL, offsetof(BrinOptions, autosummarize)}
 	};
 
-	options = parseRelOptions(reloptions, validate, RELOPT_KIND_BRIN,
-							  &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	rdopts = allocateReloptStruct(sizeof(BrinOptions), options, numoptions);
-
-	fillRelOptions((void *) rdopts, sizeof(BrinOptions), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) rdopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  RELOPT_KIND_BRIN,
+									  sizeof(BrinOptions),
+									  tab, lengthof(tab));
 }
 
 /*

src/backend/access/common/reloptions.c

@@ -1474,9 +1474,6 @@ fillRelOptions(void *rdopts, Size basesize,
 bytea *
 default_reloptions(Datum reloptions, bool validate, relopt_kind kind)
 {
-	relopt_value *options;
-	StdRdOptions *rdopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"fillfactor", RELOPT_TYPE_INT, offsetof(StdRdOptions, fillfactor)},
 		{"autovacuum_enabled", RELOPT_TYPE_BOOL,
@@ -1521,20 +1518,57 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind)
 		offsetof(StdRdOptions, vacuum_truncate)}
 	};
 
+	return (bytea *) build_reloptions(reloptions, validate, kind,
+									  sizeof(StdRdOptions),
+									  tab, lengthof(tab));
+}
+
+/*
+ * build_reloptions
+ *
+ * Parses "reloptions" provided by the caller, returning them in a
+ * structure containing the parsed options.  The parsing is done with
+ * the help of a parsing table describing the allowed options, defined
+ * by "relopt_elems" of length "num_relopt_elems".
+ *
+ * "validate" must be true if reloptions value is freshly built by
+ * transformRelOptions(), as opposed to being read from the catalog, in which
+ * case the values contained in it must already be valid.
+ *
+ * NULL is returned if the passed-in options did not match any of the options
+ * in the parsing table, unless validate is true in which case an error would
+ * be reported.
+ */
+void *
+build_reloptions(Datum reloptions, bool validate,
+				 relopt_kind kind,
+				 Size relopt_struct_size,
+				 const relopt_parse_elt *relopt_elems,
+				 int num_relopt_elems)
+{
+	int			numoptions;
+	relopt_value *options;
+	void	   *rdopts;
+
+	/* parse options specific to given relation option kind */
 	options = parseRelOptions(reloptions, validate, kind, &numoptions);
+	Assert(numoptions <= num_relopt_elems);
 
 	/* if none set, we're done */
 	if (numoptions == 0)
+	{
+		Assert(options == NULL);
 		return NULL;
+	}
 
-	rdopts = allocateReloptStruct(sizeof(StdRdOptions), options, numoptions);
-
-	fillRelOptions((void *) rdopts, sizeof(StdRdOptions), options, numoptions,
-				   validate, tab, lengthof(tab));
+	/* allocate and fill the structure */
+	rdopts = allocateReloptStruct(relopt_struct_size, options, numoptions);
+	fillRelOptions(rdopts, relopt_struct_size, options, numoptions,
+				   validate, relopt_elems, num_relopt_elems);
 
 	pfree(options);
 
-	return (bytea *) rdopts;
+	return rdopts;
 }
 
 /*
@@ -1543,9 +1577,6 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind)
 bytea *
 view_reloptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	ViewOptions *vopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"security_barrier", RELOPT_TYPE_BOOL,
 		offsetof(ViewOptions, security_barrier)},
@@ -1553,20 +1584,10 @@ view_reloptions(Datum reloptions, bool validate)
 		offsetof(ViewOptions, check_option)}
 	};
 
-	options = parseRelOptions(reloptions, validate, RELOPT_KIND_VIEW, &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	vopts = allocateReloptStruct(sizeof(ViewOptions), options, numoptions);
-
-	fillRelOptions((void *) vopts, sizeof(ViewOptions), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) vopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  RELOPT_KIND_VIEW,
+									  sizeof(ViewOptions),
+									  tab, lengthof(tab));
 }
 
 /*
@@ -1628,29 +1649,15 @@ index_reloptions(amoptions_function amoptions, Datum reloptions, bool validate)
 bytea *
 attribute_reloptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	AttributeOpts *aopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"n_distinct", RELOPT_TYPE_REAL, offsetof(AttributeOpts, n_distinct)},
 		{"n_distinct_inherited", RELOPT_TYPE_REAL, offsetof(AttributeOpts, n_distinct_inherited)}
 	};
 
-	options = parseRelOptions(reloptions, validate, RELOPT_KIND_ATTRIBUTE,
-							  &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	aopts = allocateReloptStruct(sizeof(AttributeOpts), options, numoptions);
-
-	fillRelOptions((void *) aopts, sizeof(AttributeOpts), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) aopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  RELOPT_KIND_ATTRIBUTE,
+									  sizeof(AttributeOpts),
+									  tab, lengthof(tab));
 }
 
 /*
@@ -1659,30 +1666,16 @@ attribute_reloptions(Datum reloptions, bool validate)
 bytea *
 tablespace_reloptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	TableSpaceOpts *tsopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"random_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, random_page_cost)},
 		{"seq_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, seq_page_cost)},
 		{"effective_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, effective_io_concurrency)}
 	};
 
-	options = parseRelOptions(reloptions, validate, RELOPT_KIND_TABLESPACE,
-							  &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	tsopts = allocateReloptStruct(sizeof(TableSpaceOpts), options, numoptions);
-
-	fillRelOptions((void *) tsopts, sizeof(TableSpaceOpts), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) tsopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  RELOPT_KIND_TABLESPACE,
+									  sizeof(TableSpaceOpts),
+									  tab, lengthof(tab));
 }
 
 /*

src/backend/access/gin/ginutil.c

@@ -602,30 +602,16 @@ ginExtractEntries(GinState *ginstate, OffsetNumber attnum,
 bytea *
 ginoptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	GinOptions *rdopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"fastupdate", RELOPT_TYPE_BOOL, offsetof(GinOptions, useFastUpdate)},
 		{"gin_pending_list_limit", RELOPT_TYPE_INT, offsetof(GinOptions,
 															 pendingListCleanupSize)}
 	};
 
-	options = parseRelOptions(reloptions, validate, RELOPT_KIND_GIN,
-							  &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	rdopts = allocateReloptStruct(sizeof(GinOptions), options, numoptions);
-
-	fillRelOptions((void *) rdopts, sizeof(GinOptions), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) rdopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  RELOPT_KIND_GIN,
+									  sizeof(GinOptions),
+									  tab, lengthof(tab));
 }
 
 /*

src/backend/access/gist/gistutil.c

@@ -908,29 +908,15 @@ gistPageRecyclable(Page page)
 bytea *
 gistoptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	GiSTOptions *rdopts;
-	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"fillfactor", RELOPT_TYPE_INT, offsetof(GiSTOptions, fillfactor)},
 		{"buffering", RELOPT_TYPE_ENUM, offsetof(GiSTOptions, buffering_mode)}
 	};
 
-	options = parseRelOptions(reloptions, validate, RELOPT_KIND_GIST,
-							  &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	rdopts = allocateReloptStruct(sizeof(GiSTOptions), options, numoptions);
-
-	fillRelOptions((void *) rdopts, sizeof(GiSTOptions), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) rdopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  RELOPT_KIND_GIST,
+									  sizeof(GiSTOptions),
+									  tab, lengthof(tab));
 }
 
 /*

src/include/access/reloptions.h

@@ -296,6 +296,11 @@ extern void fillRelOptions(void *rdopts, Size basesize,
 						   relopt_value *options, int numoptions,
 						   bool validate,
 						   const relopt_parse_elt *elems, int nelems);
+extern void *build_reloptions(Datum reloptions, bool validate,
+							  relopt_kind kind,
+							  Size relopt_struct_size,
+							  const relopt_parse_elt *relopt_elems,
+							  int num_relopt_elems);
 
 extern bytea *default_reloptions(Datum reloptions, bool validate,
 								 relopt_kind kind);

src/test/modules/dummy_index_am/dummy_index_am.c

@@ -222,17 +222,10 @@ dicostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 static bytea *
 dioptions(Datum reloptions, bool validate)
 {
-	relopt_value *options;
-	int			numoptions;
-	DummyIndexOptions *rdopts;
-
-	/* Parse the user-given reloptions */
-	options = parseRelOptions(reloptions, validate, di_relopt_kind, &numoptions);
-	rdopts = allocateReloptStruct(sizeof(DummyIndexOptions), options, numoptions);
-	fillRelOptions((void *) rdopts, sizeof(DummyIndexOptions), options, numoptions,
-				   validate, di_relopt_tab, lengthof(di_relopt_tab));
-
-	return (bytea *) rdopts;
+	return (bytea *) build_reloptions(reloptions, validate,
+									  di_relopt_kind,
+									  sizeof(DummyIndexOptions),
+									  di_relopt_tab, lengthof(di_relopt_tab));
 }
 
 /*