Change SearchSysCache coding conventions so that a reference count is

maintained for each cache entry.  A cache entry will not be freed until
the matching ReleaseSysCache call has been executed.  This eliminates
worries about cache entries getting dropped while still in use.  See
my posting to pg-hackers of even date for more info.

1 files changed, 29 insertions, 33 deletions

diff --git a/src/backend/commands/rename.c b/src/backend/commands/rename.c
index 6a9de4abf00..3722948047b 100644
--- a/src/backend/commands/rename.c
+++ b/src/backend/commands/rename.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/Attic/rename.c,v 1.52 2000/11/08 22:09:57 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/Attic/rename.c,v 1.53 2000/11/16 22:30:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -58,8 +58,7 @@ renameatt(char *relname,
 	Relation	targetrelation;
 	Relation	attrelation;
 	HeapTuple	reltup,
-				oldatttup,
-				newatttup;
+				atttup;
 	Oid			relid;
 
 	/*
@@ -113,9 +112,9 @@ renameatt(char *relname,
 
 			if (childrelid == relid)
 				continue;
-			reltup = SearchSysCacheTuple(RELOID,
-										 ObjectIdGetDatum(childrelid),
-										 0, 0, 0);
+			reltup = SearchSysCache(RELOID,
+									ObjectIdGetDatum(childrelid),
+									0, 0, 0);
 			if (!HeapTupleIsValid(reltup))
 			{
 				elog(ERROR, "renameatt: can't find catalog entry for inheriting class with oid %u",
@@ -125,6 +124,7 @@ renameatt(char *relname,
 			StrNCpy(childname,
 					NameStr(((Form_pg_class) GETSTRUCT(reltup))->relname),
 					NAMEDATALEN);
+			ReleaseSysCache(reltup);
 			/* note we need not recurse again! */
 			renameatt(childname, oldattname, newattname, 0);
 		}
@@ -132,42 +132,38 @@ renameatt(char *relname,
 
 	attrelation = heap_openr(AttributeRelationName, RowExclusiveLock);
 
-	oldatttup = SearchSysCacheTupleCopy(ATTNAME,
-										ObjectIdGetDatum(relid),
-										PointerGetDatum(oldattname),
-										0, 0);
-	if (!HeapTupleIsValid(oldatttup))
+	atttup = SearchSysCacheCopy(ATTNAME,
+								ObjectIdGetDatum(relid),
+								PointerGetDatum(oldattname),
+								0, 0);
+	if (!HeapTupleIsValid(atttup))
 		elog(ERROR, "renameatt: attribute \"%s\" does not exist", oldattname);
 
-	if (((Form_pg_attribute) GETSTRUCT(oldatttup))->attnum < 0)
+	if (((Form_pg_attribute) GETSTRUCT(atttup))->attnum < 0)
 		elog(ERROR, "renameatt: system attribute \"%s\" not renamed", oldattname);
 
-	newatttup = SearchSysCacheTuple(ATTNAME,
-									ObjectIdGetDatum(relid),
-									PointerGetDatum(newattname),
-									0, 0);
 	/* should not already exist */
-	if (HeapTupleIsValid(newatttup))
-	{
-		heap_freetuple(oldatttup);
+	if (SearchSysCacheExists(ATTNAME,
+							 ObjectIdGetDatum(relid),
+							 PointerGetDatum(newattname),
+							 0, 0))
 		elog(ERROR, "renameatt: attribute \"%s\" exists", newattname);
-	}
 
-	StrNCpy(NameStr(((Form_pg_attribute) GETSTRUCT(oldatttup))->attname),
+	StrNCpy(NameStr(((Form_pg_attribute) GETSTRUCT(atttup))->attname),
 			newattname, NAMEDATALEN);
 
-	heap_update(attrelation, &oldatttup->t_self, oldatttup, NULL);
+	heap_update(attrelation, &atttup->t_self, atttup, NULL);
 
 	/* keep system catalog indices current */
 	{
 		Relation	irelations[Num_pg_attr_indices];
 
 		CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, irelations);
-		CatalogIndexInsert(irelations, Num_pg_attr_indices, attrelation, oldatttup);
+		CatalogIndexInsert(irelations, Num_pg_attr_indices, attrelation, atttup);
 		CatalogCloseIndices(Num_pg_attr_indices, irelations);
 	}
 
-	heap_freetuple(oldatttup);
+	heap_freetuple(atttup);
 	heap_close(attrelation, RowExclusiveLock);
 }
 
@@ -179,7 +175,7 @@ renamerel(const char *oldrelname, const char *newrelname)
 {
 	Relation	targetrelation;
 	Relation	relrelation;	/* for RELATION relation */
-	HeapTuple	oldreltup;
+	HeapTuple	reltup;
 	Oid			reloid;
 	char		relkind;
 	Relation	irelations[Num_pg_class_indices];
@@ -238,27 +234,27 @@ renamerel(const char *oldrelname, const char *newrelname)
 	 */
 	relrelation = heap_openr(RelationRelationName, RowExclusiveLock);
 
-	oldreltup = SearchSysCacheTupleCopy(RELNAME,
-										PointerGetDatum(oldrelname),
-										0, 0, 0);
-	if (!HeapTupleIsValid(oldreltup))
+	reltup = SearchSysCacheCopy(RELNAME,
+								PointerGetDatum(oldrelname),
+								0, 0, 0);
+	if (!HeapTupleIsValid(reltup))
 		elog(ERROR, "renamerel: relation \"%s\" does not exist", oldrelname);
 
 	if (RelnameFindRelid(newrelname) != InvalidOid)
 		elog(ERROR, "renamerel: relation \"%s\" exists", newrelname);
 
 	/*
-	 * Update pg_class tuple with new relname.  (Scribbling on oldreltup
+	 * Update pg_class tuple with new relname.  (Scribbling on reltup
 	 * is OK because it's a copy...)
 	 */
-	StrNCpy(NameStr(((Form_pg_class) GETSTRUCT(oldreltup))->relname),
+	StrNCpy(NameStr(((Form_pg_class) GETSTRUCT(reltup))->relname),
 			newrelname, NAMEDATALEN);
 
-	heap_update(relrelation, &oldreltup->t_self, oldreltup, NULL);
+	heap_update(relrelation, &reltup->t_self, reltup, NULL);
 
 	/* keep the system catalog indices current */
 	CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, irelations);
-	CatalogIndexInsert(irelations, Num_pg_class_indices, relrelation, oldreltup);
+	CatalogIndexInsert(irelations, Num_pg_class_indices, relrelation, reltup);
 	CatalogCloseIndices(Num_pg_class_indices, irelations);
 
 	heap_close(relrelation, NoLock);