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, 25 insertions, 27 deletions

diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index d23c5c1e7c7..1d846bd4bba 100644
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_node.c,v 1.48 2000/10/31 10:22:11 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_node.c,v 1.49 2000/11/16 22:30:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -67,7 +67,6 @@ make_operand(char *opname,
 			 Oid target_typeId)
 {
 	Node	   *result;
-	Type		target_type = typeidType(target_typeId);
 
 	if (tree != NULL)
 	{
@@ -80,15 +79,7 @@ make_operand(char *opname,
 	else
 	{
 		/* otherwise, this is a NULL value */
-		Const	   *con = makeNode(Const);
-
-		con->consttype = target_typeId;
-		con->constlen = typeLen(target_type);
-		con->constvalue = (Datum) NULL;
-		con->constisnull = true;
-		con->constbyval = typeByVal(target_type);
-		con->constisset = false;
-		result = (Node *) con;
+		result = (Node *) makeNullConst(target_typeId);
 	}
 
 	return result;
@@ -137,7 +128,7 @@ make_op(char *opname, Node *ltree, Node *rtree)
 	/* otherwise, binary operator */
 	else
 	{
-		tup = oper(opname, ltypeId, rtypeId, FALSE);
+		tup = oper(opname, ltypeId, rtypeId, false);
 		opform = (Form_pg_operator) GETSTRUCT(tup);
 		left = make_operand(opname, ltree, ltypeId, opform->oprleft);
 		right = make_operand(opname, rtree, rtypeId, opform->oprright);
@@ -159,6 +150,8 @@ make_op(char *opname, Node *ltree, Node *rtree)
 	else
 		result->args = makeList2(left, right);
 
+	ReleaseSysCache(tup);
+
 	return result;
 }	/* make_op() */
 
@@ -183,10 +176,10 @@ make_var(ParseState *pstate, RangeTblEntry *rte, int attrno)
 		HeapTuple	tp;
 		Form_pg_attribute att_tup;
 
-		tp = SearchSysCacheTuple(ATTNUM,
-								 ObjectIdGetDatum(rte->relid),
-								 Int16GetDatum(attrno),
-								 0, 0);
+		tp = SearchSysCache(ATTNUM,
+							ObjectIdGetDatum(rte->relid),
+							Int16GetDatum(attrno),
+							0, 0);
 		/* this shouldn't happen... */
 		if (!HeapTupleIsValid(tp))
 			elog(ERROR, "Relation %s does not have attribute %d",
@@ -194,6 +187,7 @@ make_var(ParseState *pstate, RangeTblEntry *rte, int attrno)
 		att_tup = (Form_pg_attribute) GETSTRUCT(tp);
 		vartypeid = att_tup->atttypid;
 		type_mod = att_tup->atttypmod;
+		ReleaseSysCache(tp);
 	}
 	else
 	{
@@ -249,7 +243,8 @@ transformArraySubscripts(ParseState *pstate,
 	Oid			typearray,
 				typeelement,
 				typeresult;
-	HeapTuple	type_tuple;
+	HeapTuple	type_tuple_array,
+				type_tuple_element;
 	Form_pg_type type_struct_array,
 				type_struct_element;
 	bool		isSlice = forceSlice;
@@ -261,13 +256,13 @@ transformArraySubscripts(ParseState *pstate,
 	/* Get the type tuple for the array */
 	typearray = exprType(arrayBase);
 
-	type_tuple = SearchSysCacheTuple(TYPEOID,
-									 ObjectIdGetDatum(typearray),
-									 0, 0, 0);
-	if (!HeapTupleIsValid(type_tuple))
+	type_tuple_array = SearchSysCache(TYPEOID,
+									  ObjectIdGetDatum(typearray),
+									  0, 0, 0);
+	if (!HeapTupleIsValid(type_tuple_array))
 		elog(ERROR, "transformArraySubscripts: Cache lookup failed for array type %u",
 			 typearray);
-	type_struct_array = (Form_pg_type) GETSTRUCT(type_tuple);
+	type_struct_array = (Form_pg_type) GETSTRUCT(type_tuple_array);
 
 	typeelement = type_struct_array->typelem;
 	if (typeelement == InvalidOid)
@@ -275,13 +270,13 @@ transformArraySubscripts(ParseState *pstate,
 			 NameStr(type_struct_array->typname));
 
 	/* Get the type tuple for the array element type */
-	type_tuple = SearchSysCacheTuple(TYPEOID,
-									 ObjectIdGetDatum(typeelement),
-									 0, 0, 0);
-	if (!HeapTupleIsValid(type_tuple))
+	type_tuple_element = SearchSysCache(TYPEOID,
+										ObjectIdGetDatum(typeelement),
+										0, 0, 0);
+	if (!HeapTupleIsValid(type_tuple_element))
 		elog(ERROR, "transformArraySubscripts: Cache lookup failed for array element type %u",
 			 typeelement);
-	type_struct_element = (Form_pg_type) GETSTRUCT(type_tuple);
+	type_struct_element = (Form_pg_type) GETSTRUCT(type_tuple_element);
 
 	/*
 	 * A list containing only single subscripts refers to a single array
@@ -398,6 +393,9 @@ transformArraySubscripts(ParseState *pstate,
 	aref->refexpr = arrayBase;
 	aref->refassgnexpr = assignFrom;
 
+	ReleaseSysCache(type_tuple_array);
+	ReleaseSysCache(type_tuple_element);
+
 	return aref;
 }