Switch PgStat_Kind from an enum to a uint32 type

A follow-up patch is planned to make cumulative statistics pluggable,
and using a type is useful in the internal routines used by pgstats as
PgStat_Kind may have a value that was not originally in the enum removed
here, once made pluggable.

While on it, this commit switches pgstat_is_kind_valid() to use
PgStat_Kind rather than an int, to be more consistent with its existing
callers.  Some loops based on the stats kind IDs are switched to use
PgStat_Kind rather than int, for consistency with the new time.

Author: Michael Paquier
Reviewed-by: Dmitry Dolgov, Bertrand Drouvot
Discussion: https://postgr.es/m/Zmqm9j5EO0I4W8dx@paquier.xyz

src/backend/utils/activity/pgstat.c

@@ -183,7 +183,7 @@ static void pgstat_prep_snapshot(void);
 static void pgstat_build_snapshot(void);
 static void pgstat_build_snapshot_fixed(PgStat_Kind kind);
 
-static inline bool pgstat_is_kind_valid(int ikind);
+static inline bool pgstat_is_kind_valid(PgStat_Kind kind);
 
 
 /* ----------
@@ -1089,7 +1089,7 @@ pgstat_build_snapshot(void)
 	/*
 	 * Build snapshot of all fixed-numbered stats.
 	 */
-	for (int kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
+	for (PgStat_Kind kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
 	{
 		const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
@@ -1286,7 +1286,7 @@ pgstat_flush_pending_entries(bool nowait)
 PgStat_Kind
 pgstat_get_kind_from_str(char *kind_str)
 {
-	for (int kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
+	for (PgStat_Kind kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
 	{
 		if (pg_strcasecmp(kind_str, pgstat_kind_infos[kind].name) == 0)
 			return kind;
@@ -1299,9 +1299,9 @@ pgstat_get_kind_from_str(char *kind_str)
 }
 
 static inline bool
-pgstat_is_kind_valid(int ikind)
+pgstat_is_kind_valid(PgStat_Kind kind)
 {
-	return ikind >= PGSTAT_KIND_FIRST_VALID && ikind <= PGSTAT_KIND_LAST;
+	return kind >= PGSTAT_KIND_FIRST_VALID && kind <= PGSTAT_KIND_LAST;
 }
 
 const PgStat_KindInfo *
@@ -1393,7 +1393,7 @@ pgstat_write_statsfile(XLogRecPtr redo)
 	write_chunk_s(fpout, &redo);
 
 	/* Write various stats structs for fixed number of objects */
-	for (int kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
+	for (PgStat_Kind kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
 	{
 		char	   *ptr;
 		const PgStat_KindInfo *info = pgstat_get_kind_info(kind);
@@ -1777,7 +1777,7 @@ pgstat_reset_after_failure(void)
 	TimestampTz ts = GetCurrentTimestamp();
 
 	/* reset fixed-numbered stats */
-	for (int kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
+	for (PgStat_Kind kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
 	{
 		const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 

src/backend/utils/activity/pgstat_shmem.c

@@ -197,7 +197,7 @@ StatsShmemInit(void)
 		pg_atomic_init_u64(&ctl->gc_request_count, 1);
 
 		/* initialize fixed-numbered stats */
-		for (int kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
+		for (PgStat_Kind kind = PGSTAT_KIND_FIRST_VALID; kind <= PGSTAT_KIND_LAST; kind++)
 		{
 			const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 			char	   *ptr;

src/include/pgstat.h

@@ -33,26 +33,25 @@
 #define PG_STAT_TMP_DIR		"pg_stat_tmp"
 
 /* The types of statistics entries */
-typedef enum PgStat_Kind
+#define PgStat_Kind uint32
-{
+
-	/* use 0 for INVALID, to catch zero-initialized data */
+/* use 0 for INVALID, to catch zero-initialized data */
-	PGSTAT_KIND_INVALID = 0,
+#define PGSTAT_KIND_INVALID 0
-
+
-	/* stats for variable-numbered objects */
+/* stats for variable-numbered objects */
-	PGSTAT_KIND_DATABASE,		/* database-wide statistics */
+#define PGSTAT_KIND_DATABASE	1	/* database-wide statistics */
-	PGSTAT_KIND_RELATION,		/* per-table statistics */
+#define PGSTAT_KIND_RELATION	2	/* per-table statistics */
-	PGSTAT_KIND_FUNCTION,		/* per-function statistics */
+#define PGSTAT_KIND_FUNCTION	3	/* per-function statistics */
-	PGSTAT_KIND_REPLSLOT,		/* per-slot statistics */
+#define PGSTAT_KIND_REPLSLOT	4	/* per-slot statistics */
-	PGSTAT_KIND_SUBSCRIPTION,	/* per-subscription statistics */
+#define PGSTAT_KIND_SUBSCRIPTION	5	/* per-subscription statistics */
-
+
-	/* stats for fixed-numbered objects */
+/* stats for fixed-numbered objects */
-	PGSTAT_KIND_ARCHIVER,
+#define PGSTAT_KIND_ARCHIVER	6
-	PGSTAT_KIND_BGWRITER,
+#define PGSTAT_KIND_BGWRITER	7
-	PGSTAT_KIND_CHECKPOINTER,
+#define PGSTAT_KIND_CHECKPOINTER	8
-	PGSTAT_KIND_IO,
+#define PGSTAT_KIND_IO	9
-	PGSTAT_KIND_SLRU,
+#define PGSTAT_KIND_SLRU	10
-	PGSTAT_KIND_WAL,
+#define PGSTAT_KIND_WAL	11
-} PgStat_Kind;
 
 #define PGSTAT_KIND_FIRST_VALID PGSTAT_KIND_DATABASE
 #define PGSTAT_KIND_LAST PGSTAT_KIND_WAL