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, 27 insertions, 21 deletions

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 0d32e82ed9a..055cd3788b9 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/plancat.c,v 1.61 2000/09/29 18:21:23 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/plancat.c,v 1.62 2000/11/16 22:30:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -48,9 +48,9 @@ relation_info(Oid relationObjectId,
 	HeapTuple	relationTuple;
 	Form_pg_class relation;
 
-	relationTuple = SearchSysCacheTuple(RELOID,
-										ObjectIdGetDatum(relationObjectId),
-										0, 0, 0);
+	relationTuple = SearchSysCache(RELOID,
+								   ObjectIdGetDatum(relationObjectId),
+								   0, 0, 0);
 	if (!HeapTupleIsValid(relationTuple))
 		elog(ERROR, "relation_info: Relation %u not found",
 			 relationObjectId);
@@ -62,6 +62,7 @@ relation_info(Oid relationObjectId,
 		*hasindex = (relation->relhasindex) ? true : false;
 	*pages = relation->relpages;
 	*tuples = relation->reltuples;
+	ReleaseSysCache(relationTuple);
 }
 
 /*
@@ -100,9 +101,9 @@ find_secondary_indexes(Oid relationObjectId)
 		Oid			relam;
 		uint16		amorderstrategy;
 
-		indexTuple = SearchSysCacheTupleCopy(INDEXRELID,
-											 ObjectIdGetDatum(indexoid),
-											 0, 0, 0);
+		indexTuple = SearchSysCache(INDEXRELID,
+									ObjectIdGetDatum(indexoid),
+									0, 0, 0);
 		if (!HeapTupleIsValid(indexTuple))
 			elog(ERROR, "find_secondary_indexes: index %u not found",
 				 indexoid);
@@ -162,20 +163,22 @@ find_secondary_indexes(Oid relationObjectId)
 				Form_pg_amop amop;
 
 				amopTuple =
-					SearchSysCacheTuple(AMOPSTRATEGY,
-										ObjectIdGetDatum(relam),
-									ObjectIdGetDatum(index->indclass[i]),
-										UInt16GetDatum(amorderstrategy),
-										0);
+					SearchSysCache(AMOPSTRATEGY,
+								   ObjectIdGetDatum(relam),
+								   ObjectIdGetDatum(index->indclass[i]),
+								   UInt16GetDatum(amorderstrategy),
+								   0);
 				if (!HeapTupleIsValid(amopTuple))
 					elog(ERROR, "find_secondary_indexes: no amop %u %u %d",
-					   relam, index->indclass[i], (int) amorderstrategy);
+						 relam, index->indclass[i],
+						 (int) amorderstrategy);
 				amop = (Form_pg_amop) GETSTRUCT(amopTuple);
 				info->ordering[i] = amop->amopopr;
+				ReleaseSysCache(amopTuple);
 			}
 		}
 
-		heap_freetuple(indexTuple);
+		ReleaseSysCache(indexTuple);
 
 		indexinfos = lcons(info, indexinfos);
 	}
@@ -315,13 +318,16 @@ find_inheritance_children(Oid inhparent)
 bool
 has_subclass(Oid relationId)
 {
-	HeapTuple	tuple =
-		SearchSysCacheTuple(RELOID,
-							ObjectIdGetDatum(relationId),
-							0, 0, 0);
+	HeapTuple	tuple;
+	bool		result;
 
+	tuple = SearchSysCache(RELOID,
+						   ObjectIdGetDatum(relationId),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
-		elog(ERROR, "has_subclass: Relation %u not found",
-			 relationId);
-	return ((Form_pg_class) GETSTRUCT(tuple))->relhassubclass;
+		elog(ERROR, "has_subclass: Relation %u not found", relationId);
+
+	result = ((Form_pg_class) GETSTRUCT(tuple))->relhassubclass;
+	ReleaseSysCache(tuple);
+	return result;
 }