Add a syscache for pg_resgroup

This commit is a modified version of 8286b61f76014d1f3d58176ec3f12bb2dc9a9dcc,
the only difference is we put new entries to the end of cacheinfo array, so extensions
like madlib, plcontainer who linked with syscache.h can still have the same cache
identifier value.

src/backend/commands/resgroupcmds.c

@@ -380,7 +380,7 @@ AlterResourceGroup(AlterResourceGroupStmt *stmt)
 	 * Check the pg_resgroup relation to be certain the resource group already
 	 * exists.
 	 */
-	groupid = GetResGroupIdForName(stmt->name, RowExclusiveLock);
+	groupid = GetResGroupIdForName(stmt->name);
 	if (groupid == InvalidOid)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
@@ -612,32 +612,27 @@ GetResGroupIdForRole(Oid roleid)
  *	to Oid.
  */
 Oid
-GetResGroupIdForName(const char *name, LOCKMODE lockmode)
+GetResGroupIdForName(const char *name)
 {
-	Relation	rel;
-	ScanKeyData scankey;
-	SysScanDesc scan;
 	HeapTuple	tuple;
 	Oid			rsgid;
 
-	rel = heap_open(ResGroupRelationId, lockmode);
+	tuple = SearchSysCache1(WRESGROUPNAME,
+							CStringGetDatum(name));
 
-	/* SELECT oid FROM pg_resgroup WHERE rsgname = :1 */
-	ScanKeyInit(&scankey,
-				Anum_pg_resgroup_rsgname,
-				BTEqualStrategyNumber, F_NAMEEQ,
-				CStringGetDatum(name));
-	scan = systable_beginscan(rel, ResGroupRsgnameIndexId, true,
-							  SnapshotNow, 1, &scankey);
-
-	tuple = systable_getnext(scan);
 	if (HeapTupleIsValid(tuple))
-		rsgid = HeapTupleGetOid(tuple);
+	{
+		bool isnull;
+		Datum oidDatum = SysCacheGetAttr(WRESGROUPNAME, tuple,
+										  ObjectIdAttributeNumber,
+										  &isnull);
+		Assert (!isnull);
+		rsgid = DatumGetObjectId(oidDatum);
+	}
 	else
-		rsgid = InvalidOid;
+		return InvalidOid;
 
-	systable_endscan(scan);
-	heap_close(rel, lockmode);
+	ReleaseSysCache(tuple);
 
 	return rsgid;
 }
@@ -646,37 +641,28 @@ GetResGroupIdForName(const char *name, LOCKMODE lockmode)
  * GetResGroupNameForId -- Return the resource group name for an Oid
  */
 char *
-GetResGroupNameForId(Oid oid, LOCKMODE lockmode)
+GetResGroupNameForId(Oid oid)
 {
-	Relation	rel;
-	ScanKeyData scankey;
-	SysScanDesc scan;
 	HeapTuple	tuple;
 	char		*name = NULL;
 
-	rel = heap_open(ResGroupRelationId, lockmode);
-
-	/* SELECT rsgname FROM pg_resgroup WHERE oid = :1 */
-	ScanKeyInit(&scankey,
-				ObjectIdAttributeNumber,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(oid));
-	scan = systable_beginscan(rel, ResGroupOidIndexId, true,
-							  SnapshotNow, 1, &scankey);
+	tuple = SearchSysCache1(WRESGROUPOID,
+							ObjectIdGetDatum(oid));
 
-	tuple = systable_getnext(scan);
 	if (HeapTupleIsValid(tuple))
 	{
 		bool isnull;
-		Datum nameDatum = heap_getattr(tuple, Anum_pg_resgroup_rsgname,
-									   rel->rd_att, &isnull);
+		Datum nameDatum = SysCacheGetAttr(WRESGROUPOID, tuple,
+										  Anum_pg_resgroup_rsgname,
+										  &isnull);
 		Assert (!isnull);
 		Name resGroupName = DatumGetName(nameDatum);
 		name = pstrdup(NameStr(*resGroupName));
 	}
+	else
+		return "unknow";
 
-	systable_endscan(scan);
-	heap_close(rel, lockmode);
+	ReleaseSysCache(tuple);
 
 	return name;
 }

src/backend/commands/user.c

@@ -533,7 +533,7 @@ CreateRole(CreateRoleStmt *stmt)
 	{
 		Oid rsgid;
 
-		rsgid = GetResGroupIdForName(resgroup, ShareLock);
+		rsgid = GetResGroupIdForName(resgroup);
 		if (rsgid == InvalidOid)
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_OBJECT),
@@ -1195,7 +1195,7 @@ AlterRole(AlterRoleStmt *stmt)
 								resgroup)));
 		}
 
-		rsgid = GetResGroupIdForName(resgroup, ShareLock);
+		rsgid = GetResGroupIdForName(resgroup);
 		if (rsgid == InvalidOid)
 			ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),

src/backend/utils/adt/pgstatfuncs.c

@@ -633,7 +633,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			if (funcctx->tuple_desc->natts > 13)
 			{
 				Datum now = TimestampTzGetDatum(GetCurrentTimestamp());
-				char *groupName = GetResGroupNameForId(beentry->st_rsgid, AccessShareLock);
+				char *groupName = GetResGroupNameForId(beentry->st_rsgid);
 
 				values[13] = ObjectIdGetDatum(beentry->st_rsgid);
 

src/backend/utils/cache/syscache.c

@@ -54,6 +54,7 @@
 #include "catalog/pg_ts_template.h"
 #include "catalog/pg_type.h"
 #include "catalog/pg_window.h"
+#include "catalog/pg_resgroup.h"
 #include "utils/syscache.h"
 
 
@@ -662,6 +663,28 @@ static const struct cachedesc cacheinfo[] = {
 			0
 		},
 		32
+	},
+	{ResGroupRelationId,		/* WRESGROUPNAME */
+		ResGroupRsgnameIndexId,
+		1,
+		{
+			Anum_pg_resgroup_rsgname,
+			0,
+			0,
+			0
+		},
+		128
+	},
+	{ResGroupRelationId,		/* WRESGROUPOID */
+		ResGroupOidIndexId,
+		1,
+		{
+			ObjectIdAttributeNumber,
+			0,
+			0,
+			0
+		},
+		128
 	}
 };
 

src/include/commands/resgroupcmds.h

@@ -32,8 +32,8 @@ extern void DropResourceGroup(DropResourceGroupStmt *stmt);
 extern void AlterResourceGroup(AlterResourceGroupStmt *stmt);
 
 /* catalog access function */
-extern Oid GetResGroupIdForName(const char *name, LOCKMODE lockmode);
-extern char *GetResGroupNameForId(Oid oid, LOCKMODE lockmode);
+extern Oid GetResGroupIdForName(const char *name);
+extern char *GetResGroupNameForId(Oid oid);
 extern Oid GetResGroupIdForRole(Oid roleid);
 extern void GetResGroupCapabilities(Relation rel,
 									Oid groupId,

src/include/utils/syscache.h

@@ -79,7 +79,9 @@ enum SysCacheIdentifier
 	TSTEMPLATEOID,
 	TYPENAMENSP,
 	TYPEOID,
-	WINFNOID
+	WINFNOID,
+	WRESGROUPNAME,
+	WRESGROUPOID
 };
 
 extern void InitCatalogCache(void);