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, 117 insertions, 97 deletions

diff --git a/src/backend/parser/parse_oper.c b/src/backend/parser/parse_oper.c
index 7d3919a1fc6..a44a740dc92 100644
--- a/src/backend/parser/parse_oper.c
+++ b/src/backend/parser/parse_oper.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.43 2000/11/11 19:49:26 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.44 2000/11/16 22:30:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -38,25 +38,21 @@ static void op_error(char *op, Oid arg1, Oid arg2);
 static void unary_op_error(char *op, Oid arg, bool is_left_op);
 
 
+/* Select an ordering operator for the given datatype */
 Oid
 any_ordering_op(Oid restype)
 {
-	Operator	order_op;
 	Oid			order_opid;
 
-	order_op = oper("<", restype, restype, TRUE);
-	if (!HeapTupleIsValid(order_op))
-	{
+	order_opid = oper_oid("<", restype, restype, true);
+	if (!OidIsValid(order_opid))
 		elog(ERROR, "Unable to identify an ordering operator '%s' for type '%s'"
 			 "\n\tUse an explicit ordering operator or modify the query",
 			 "<", typeidTypeName(restype));
-	}
-	order_opid = oprid(order_op);
-
 	return order_opid;
 }
 
-/* given operator, return the operator OID */
+/* given operator tuple, return the operator OID */
 Oid
 oprid(Operator op)
 {
@@ -502,9 +498,10 @@ oper_select_candidate(int nargs,
 
 
 /* oper_exact()
- * Given operator, and arguments, return oper struct or NULL.
- * Inputs:
- * arg1, arg2: Type IDs
+ * Given operator, types of arg1 and arg2, return oper struct or NULL.
+ *
+ * NOTE: on success, the returned object is a syscache entry.  The caller
+ * must ReleaseSysCache() the entry when done with it.
  */
 static Operator
 oper_exact(char *op, Oid arg1, Oid arg2)
@@ -517,20 +514,21 @@ oper_exact(char *op, Oid arg1, Oid arg2)
 	else if ((arg2 == UNKNOWNOID) && (arg1 != InvalidOid))
 		arg2 = arg1;
 
-	tup = SearchSysCacheTuple(OPERNAME,
-							  PointerGetDatum(op),
-							  ObjectIdGetDatum(arg1),
-							  ObjectIdGetDatum(arg2),
-							  CharGetDatum('b'));
+	tup = SearchSysCache(OPERNAME,
+						 PointerGetDatum(op),
+						 ObjectIdGetDatum(arg1),
+						 ObjectIdGetDatum(arg2),
+						 CharGetDatum('b'));
 
 	return (Operator) tup;
-}	/* oper_exact() */
+}
 
 
 /* oper_inexact()
- * Given operator, types of arg1, and arg2, return oper struct or NULL.
- * Inputs:
- * arg1, arg2: Type IDs
+ * Given operator, types of arg1 and arg2, return oper struct or NULL.
+ *
+ * NOTE: on success, the returned object is a syscache entry.  The caller
+ * must ReleaseSysCache() the entry when done with it.
  */
 static Operator
 oper_inexact(char *op, Oid arg1, Oid arg2)
@@ -556,11 +554,11 @@ oper_inexact(char *op, Oid arg1, Oid arg2)
 	/* Or found exactly one? Then proceed... */
 	else if (ncandidates == 1)
 	{
-		tup = SearchSysCacheTuple(OPERNAME,
-								  PointerGetDatum(op),
-								  ObjectIdGetDatum(candidates->args[0]),
-								  ObjectIdGetDatum(candidates->args[1]),
-								  CharGetDatum('b'));
+		tup = SearchSysCache(OPERNAME,
+							 PointerGetDatum(op),
+							 ObjectIdGetDatum(candidates->args[0]),
+							 ObjectIdGetDatum(candidates->args[1]),
+							 CharGetDatum('b'));
 		Assert(HeapTupleIsValid(tup));
 	}
 
@@ -572,43 +570,68 @@ oper_inexact(char *op, Oid arg1, Oid arg2)
 		targetOids = oper_select_candidate(2, inputOids, candidates);
 		if (targetOids != NULL)
 		{
-			tup = SearchSysCacheTuple(OPERNAME,
-									  PointerGetDatum(op),
-									  ObjectIdGetDatum(targetOids[0]),
-									  ObjectIdGetDatum(targetOids[1]),
-									  CharGetDatum('b'));
+			tup = SearchSysCache(OPERNAME,
+								 PointerGetDatum(op),
+								 ObjectIdGetDatum(targetOids[0]),
+								 ObjectIdGetDatum(targetOids[1]),
+								 CharGetDatum('b'));
 		}
 		else
 			tup = NULL;
 	}
 	return (Operator) tup;
-}	/* oper_inexact() */
+}
 
 
-/* oper()
- * Given operator, types of arg1, and arg2, return oper struct.
- * Inputs:
- * arg1, arg2: Type IDs
+/* oper() -- search for a binary operator
+ * Given operator name, types of arg1 and arg2, return oper struct.
+ *
+ * If no matching operator found, return NULL if noError is true,
+ * raise an error if it is false.
+ *
+ * NOTE: on success, the returned object is a syscache entry.  The caller
+ * must ReleaseSysCache() the entry when done with it.
  */
 Operator
-oper(char *opname, Oid ltypeId, Oid rtypeId, bool noWarnings)
+oper(char *opname, Oid ltypeId, Oid rtypeId, bool noError)
 {
 	HeapTuple	tup;
 
 	/* check for exact match on this operator... */
 	if (HeapTupleIsValid(tup = oper_exact(opname, ltypeId, rtypeId)))
-	{
-	}
+		return (Operator) tup;
+
 	/* try to find a match on likely candidates... */
-	else if (HeapTupleIsValid(tup = oper_inexact(opname, ltypeId, rtypeId)))
-	{
-	}
-	else if (!noWarnings)
+	if (HeapTupleIsValid(tup = oper_inexact(opname, ltypeId, rtypeId)))
+		return (Operator) tup;
+
+	if (!noError)
 		op_error(opname, ltypeId, rtypeId);
 
-	return (Operator) tup;
-}	/* oper() */
+	return (Operator) NULL;
+}
+
+/* oper_oid() -- get OID of a binary operator
+ *
+ * This is a convenience routine that extracts only the operator OID
+ * from the result of oper().  InvalidOid is returned if the lookup
+ * fails and noError is true.
+ */
+Oid
+oper_oid(char *op, Oid arg1, Oid arg2, bool noError)
+{
+	Operator	optup;
+	Oid			result;
 
+	optup = oper(op, arg1, arg2, noError);
+	if (optup != NULL)
+	{
+		result = oprid(optup);
+		ReleaseSysCache(optup);
+		return result;
+	}
+	return InvalidOid;
+}
 
 /* unary_oper_get_candidates()
  *	given opname, find all possible types for which
@@ -671,8 +694,13 @@ unary_oper_get_candidates(char *opname,
 }	/* unary_oper_get_candidates() */
 
 
-/* Given unary right-side operator (operator on right), return oper struct */
-/* arg-- type id */
+/* Given unary right operator (operator on right), return oper struct
+ *
+ * Always raises error on failure.
+ *
+ * NOTE: on success, the returned object is a syscache entry.  The caller
+ * must ReleaseSysCache() the entry when done with it.
+ */
 Operator
 right_oper(char *op, Oid arg)
 {
@@ -682,11 +710,11 @@ right_oper(char *op, Oid arg)
 	Oid		   *targetOid;
 
 	/* Try for exact match */
-	tup = SearchSysCacheTuple(OPERNAME,
-							  PointerGetDatum(op),
-							  ObjectIdGetDatum(arg),
-							  ObjectIdGetDatum(InvalidOid),
-							  CharGetDatum('r'));
+	tup = SearchSysCache(OPERNAME,
+						 PointerGetDatum(op),
+						 ObjectIdGetDatum(arg),
+						 ObjectIdGetDatum(InvalidOid),
+						 CharGetDatum('r'));
 
 	if (!HeapTupleIsValid(tup))
 	{
@@ -696,21 +724,21 @@ right_oper(char *op, Oid arg)
 			unary_op_error(op, arg, FALSE);
 		else if (ncandidates == 1)
 		{
-			tup = SearchSysCacheTuple(OPERNAME,
-									  PointerGetDatum(op),
-								   ObjectIdGetDatum(candidates->args[0]),
-									  ObjectIdGetDatum(InvalidOid),
-									  CharGetDatum('r'));
+			tup = SearchSysCache(OPERNAME,
+								 PointerGetDatum(op),
+								 ObjectIdGetDatum(candidates->args[0]),
+								 ObjectIdGetDatum(InvalidOid),
+								 CharGetDatum('r'));
 		}
 		else
 		{
 			targetOid = oper_select_candidate(1, &arg, candidates);
 			if (targetOid != NULL)
-				tup = SearchSysCacheTuple(OPERNAME,
-										  PointerGetDatum(op),
-										  ObjectIdGetDatum(targetOid[0]),
-										  ObjectIdGetDatum(InvalidOid),
-										  CharGetDatum('r'));
+				tup = SearchSysCache(OPERNAME,
+									 PointerGetDatum(op),
+									 ObjectIdGetDatum(targetOid[0]),
+									 ObjectIdGetDatum(InvalidOid),
+									 CharGetDatum('r'));
 		}
 
 		if (!HeapTupleIsValid(tup))
@@ -721,8 +749,13 @@ right_oper(char *op, Oid arg)
 }	/* right_oper() */
 
 
-/* Given unary left-side operator (operator on left), return oper struct */
-/* arg--type id */
+/* Given unary left operator (operator on left), return oper struct
+ *
+ * Always raises error on failure.
+ *
+ * NOTE: on success, the returned object is a syscache entry.  The caller
+ * must ReleaseSysCache() the entry when done with it.
+ */
 Operator
 left_oper(char *op, Oid arg)
 {
@@ -732,11 +765,11 @@ left_oper(char *op, Oid arg)
 	Oid		   *targetOid;
 
 	/* Try for exact match */
-	tup = SearchSysCacheTuple(OPERNAME,
-							  PointerGetDatum(op),
-							  ObjectIdGetDatum(InvalidOid),
-							  ObjectIdGetDatum(arg),
-							  CharGetDatum('l'));
+	tup = SearchSysCache(OPERNAME,
+						 PointerGetDatum(op),
+						 ObjectIdGetDatum(InvalidOid),
+						 ObjectIdGetDatum(arg),
+						 CharGetDatum('l'));
 
 	if (!HeapTupleIsValid(tup))
 	{
@@ -746,21 +779,21 @@ left_oper(char *op, Oid arg)
 			unary_op_error(op, arg, TRUE);
 		else if (ncandidates == 1)
 		{
-			tup = SearchSysCacheTuple(OPERNAME,
-									  PointerGetDatum(op),
-									  ObjectIdGetDatum(InvalidOid),
-								   ObjectIdGetDatum(candidates->args[0]),
-									  CharGetDatum('l'));
+			tup = SearchSysCache(OPERNAME,
+								 PointerGetDatum(op),
+								 ObjectIdGetDatum(InvalidOid),
+								 ObjectIdGetDatum(candidates->args[0]),
+								 CharGetDatum('l'));
 		}
 		else
 		{
 			targetOid = oper_select_candidate(1, &arg, candidates);
 			if (targetOid != NULL)
-				tup = SearchSysCacheTuple(OPERNAME,
-										  PointerGetDatum(op),
-										  ObjectIdGetDatum(InvalidOid),
-										  ObjectIdGetDatum(targetOid[0]),
-										  CharGetDatum('l'));
+				tup = SearchSysCache(OPERNAME,
+									 PointerGetDatum(op),
+									 ObjectIdGetDatum(InvalidOid),
+									 ObjectIdGetDatum(targetOid[0]),
+									 CharGetDatum('l'));
 		}
 
 		if (!HeapTupleIsValid(tup))
@@ -778,24 +811,17 @@ left_oper(char *op, Oid arg)
 static void
 op_error(char *op, Oid arg1, Oid arg2)
 {
-	Type		tp1 = NULL,
-				tp2 = NULL;
-
-	if (typeidIsValid(arg1))
-		tp1 = typeidType(arg1);
-	else
+	if (!typeidIsValid(arg1))
 		elog(ERROR, "Left hand side of operator '%s' has an unknown type"
 			 "\n\tProbably a bad attribute name", op);
 
-	if (typeidIsValid(arg2))
-		tp2 = typeidType(arg2);
-	else
+	if (!typeidIsValid(arg2))
 		elog(ERROR, "Right hand side of operator %s has an unknown type"
 			 "\n\tProbably a bad attribute name", op);
 
 	elog(ERROR, "Unable to identify an operator '%s' for types '%s' and '%s'"
 		 "\n\tYou will have to retype this query using an explicit cast",
-		 op, typeTypeName(tp1), typeTypeName(tp2));
+		 op, typeidTypeName(arg1), typeidTypeName(arg2));
 }
 
 /* unary_op_error()
@@ -805,20 +831,14 @@ op_error(char *op, Oid arg1, Oid arg2)
 static void
 unary_op_error(char *op, Oid arg, bool is_left_op)
 {
-	Type		tp1 = NULL;
-
-	if (typeidIsValid(arg))
-		tp1 = typeidType(arg);
-	else
-	{
+	if (!typeidIsValid(arg))
 		elog(ERROR, "Argument of %s operator '%s' has an unknown type"
 			 "\n\tProbably a bad attribute name",
 			 (is_left_op ? "left" : "right"),
 			 op);
-	}
 
 	elog(ERROR, "Unable to identify a %s operator '%s' for type '%s'"
 		 "\n\tYou may need to add parentheses or an explicit cast",
 		 (is_left_op ? "left" : "right"),
-		 op, typeTypeName(tp1));
+		 op, typeidTypeName(arg));
 }