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, 28 insertions, 16 deletions

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index ecf88ceea7e..97ed8123f67 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.87 2000/11/16 17:27:10 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.88 2000/11/16 22:30:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -386,7 +386,7 @@ transformExpr(ParseState *pstate, Node *expr, int precedence)
 						optup = oper(op,
 									 exprType(lexpr),
 									 exprType(tent->expr),
-									 FALSE);
+									 false);
 						opform = (Form_pg_operator) GETSTRUCT(optup);
 
 						if (opform->oprresult != BOOLOID)
@@ -399,6 +399,7 @@ transformExpr(ParseState *pstate, Node *expr, int precedence)
 										 InvalidOid,	/* opid */
 										 opform->oprresult);
 						sublink->oper = lappend(sublink->oper, newop);
+						ReleaseSysCache(optup);
 					}
 					if (left_list != NIL)
 						elog(ERROR, "Subselect has too few fields");
@@ -740,7 +741,8 @@ exprIsLengthCoercion(Node *expr, int32 *coercedTypmod)
 {
 	Func	   *func;
 	Const	   *second_arg;
-	HeapTuple	tup;
+	HeapTuple	procTuple;
+	HeapTuple	typeTuple;
 	Form_pg_proc procStruct;
 	Form_pg_type typeStruct;
 
@@ -771,12 +773,12 @@ exprIsLengthCoercion(Node *expr, int32 *coercedTypmod)
 	/*
 	 * Lookup the function in pg_proc
 	 */
-	tup = SearchSysCacheTuple(PROCOID,
-							  ObjectIdGetDatum(func->funcid),
-							  0, 0, 0);
-	if (!HeapTupleIsValid(tup))
+	procTuple = SearchSysCache(PROCOID,
+							   ObjectIdGetDatum(func->funcid),
+							   0, 0, 0);
+	if (!HeapTupleIsValid(procTuple))
 		elog(ERROR, "cache lookup for proc %u failed", func->funcid);
-	procStruct = (Form_pg_proc) GETSTRUCT(tup);
+	procStruct = (Form_pg_proc) GETSTRUCT(procTuple);
 
 	/*
 	 * It must be a function with two arguments where the first is of the
@@ -787,29 +789,39 @@ exprIsLengthCoercion(Node *expr, int32 *coercedTypmod)
 		procStruct->prorettype != procStruct->proargtypes[0] ||
 		procStruct->proargtypes[1] != INT4OID ||
 		procStruct->prorettype != ((Expr *) expr)->typeOid)
+	{
+		ReleaseSysCache(procTuple);
 		return false;
+	}
 
 	/*
 	 * Furthermore, the name of the function must be the same as the
 	 * argument/result type's name.
 	 */
-	tup = SearchSysCacheTuple(TYPEOID,
-							  ObjectIdGetDatum(procStruct->prorettype),
-							  0, 0, 0);
-	if (!HeapTupleIsValid(tup))
+	typeTuple = SearchSysCache(TYPEOID,
+							   ObjectIdGetDatum(procStruct->prorettype),
+							   0, 0, 0);
+	if (!HeapTupleIsValid(typeTuple))
 		elog(ERROR, "cache lookup for type %u failed",
 			 procStruct->prorettype);
-	typeStruct = (Form_pg_type) GETSTRUCT(tup);
+	typeStruct = (Form_pg_type) GETSTRUCT(typeTuple);
 	if (strncmp(NameStr(procStruct->proname),
 				NameStr(typeStruct->typname),
 				NAMEDATALEN) != 0)
+	{
+		ReleaseSysCache(procTuple);
+		ReleaseSysCache(typeTuple);
 		return false;
+	}
 
 	/*
 	 * OK, it is indeed a length-coercion function.
 	 */
 	if (coercedTypmod != NULL)
 		*coercedTypmod = DatumGetInt32(second_arg->constvalue);
+
+	ReleaseSysCache(procTuple);
+	ReleaseSysCache(typeTuple);
 	return true;
 }
 
@@ -865,6 +877,8 @@ parser_typecast_constant(Value *expr, TypeName *typename)
 	if (string_palloced)
 		pfree(const_string);
 
+	ReleaseSysCache(tp);
+
 	return (Node *) con;
 }
 
@@ -881,11 +895,9 @@ parser_typecast_expression(ParseState *pstate,
 						   Node *expr, TypeName *typename)
 {
 	Oid			inputType = exprType(expr);
-	Type		tp;
 	Oid			targetType;
 
-	tp = typenameType(TypeNameToInternalName(typename));
-	targetType = typeTypeId(tp);
+	targetType = typenameTypeId(TypeNameToInternalName(typename));
 
 	if (inputType == InvalidOid)
 		return expr;			/* do nothing if NULL input */