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, 63 insertions, 35 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index cc25a5a026a..3cd543b5e68 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
  *				back to source text
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.68 2000/11/05 00:15:53 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.69 2000/11/16 22:30:31 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -374,8 +374,9 @@ pg_get_indexdef(PG_FUNCTION_ARGS)
 	 * Fetch the pg_index tuple by the Oid of the index
 	 * ----------
 	 */
-	ht_idx = SearchSysCacheTuple(INDEXRELID,
-								 ObjectIdGetDatum(indexrelid), 0, 0, 0);
+	ht_idx = SearchSysCache(INDEXRELID,
+							ObjectIdGetDatum(indexrelid),
+							0, 0, 0);
 	if (!HeapTupleIsValid(ht_idx))
 		elog(ERROR, "syscache lookup for index %u failed", indexrelid);
 	idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
@@ -384,8 +385,9 @@ pg_get_indexdef(PG_FUNCTION_ARGS)
 	 * Fetch the pg_class tuple of the index relation
 	 * ----------
 	 */
-	ht_idxrel = SearchSysCacheTuple(RELOID,
-						  ObjectIdGetDatum(idxrec->indexrelid), 0, 0, 0);
+	ht_idxrel = SearchSysCache(RELOID,
+							   ObjectIdGetDatum(idxrec->indexrelid),
+							   0, 0, 0);
 	if (!HeapTupleIsValid(ht_idxrel))
 		elog(ERROR, "syscache lookup for relid %u failed", idxrec->indexrelid);
 	idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);
@@ -394,8 +396,9 @@ pg_get_indexdef(PG_FUNCTION_ARGS)
 	 * Fetch the pg_class tuple of the indexed relation
 	 * ----------
 	 */
-	ht_indrel = SearchSysCacheTuple(RELOID,
-							ObjectIdGetDatum(idxrec->indrelid), 0, 0, 0);
+	ht_indrel = SearchSysCache(RELOID,
+							   ObjectIdGetDatum(idxrec->indrelid),
+							   0, 0, 0);
 	if (!HeapTupleIsValid(ht_indrel))
 		elog(ERROR, "syscache lookup for relid %u failed", idxrec->indrelid);
 	indrelrec = (Form_pg_class) GETSTRUCT(ht_indrel);
@@ -484,12 +487,13 @@ pg_get_indexdef(PG_FUNCTION_ARGS)
 		HeapTuple	proctup;
 		Form_pg_proc procStruct;
 
-		proctup = SearchSysCacheTuple(PROCOID,
-							 ObjectIdGetDatum(idxrec->indproc), 0, 0, 0);
+		proctup = SearchSysCache(PROCOID,
+								 ObjectIdGetDatum(idxrec->indproc),
+								 0, 0, 0);
 		if (!HeapTupleIsValid(proctup))
 			elog(ERROR, "cache lookup for proc %u failed", idxrec->indproc);
-
 		procStruct = (Form_pg_proc) GETSTRUCT(proctup);
+
 		appendStringInfo(&buf, "%s(%s) ",
 				 quote_identifier(pstrdup(NameStr(procStruct->proname))),
 						 keybuf.data);
@@ -508,6 +512,7 @@ pg_get_indexdef(PG_FUNCTION_ARGS)
 		appendStringInfo(&buf, "%s",
 						 quote_identifier(SPI_getvalue(spi_tup, spi_ttc,
 													   spi_fno)));
+		ReleaseSysCache(proctup);
 	}
 	else
 		/* ----------
@@ -523,15 +528,19 @@ pg_get_indexdef(PG_FUNCTION_ARGS)
 	appendStringInfo(&buf, ")");
 
 	/* ----------
-	 * Create the result in upper executor memory
+	 * Create the result in upper executor memory, and free objects
 	 * ----------
 	 */
 	len = buf.len + VARHDRSZ;
 	indexdef = SPI_palloc(len);
 	VARATT_SIZEP(indexdef) = len;
 	memcpy(VARDATA(indexdef), buf.data, buf.len);
+
 	pfree(buf.data);
 	pfree(keybuf.data);
+	ReleaseSysCache(ht_idx);
+	ReleaseSysCache(ht_idxrel);
+	ReleaseSysCache(ht_indrel);
 
 	/* ----------
 	 * Disconnect from SPI manager
@@ -568,13 +577,14 @@ pg_get_userbyid(PG_FUNCTION_ARGS)
 	 * Get the pg_shadow entry and print the result
 	 * ----------
 	 */
-	usertup = SearchSysCacheTuple(SHADOWSYSID,
-								  ObjectIdGetDatum(uid),
-								  0, 0, 0);
+	usertup = SearchSysCache(SHADOWSYSID,
+							 ObjectIdGetDatum(uid),
+							 0, 0, 0);
 	if (HeapTupleIsValid(usertup))
 	{
 		user_rec = (Form_pg_shadow) GETSTRUCT(usertup);
 		StrNCpy(NameStr(*result), NameStr(user_rec->usename), NAMEDATALEN);
+		ReleaseSysCache(usertup);
 	}
 	else
 		sprintf(NameStr(*result), "unknown (UID=%d)", uid);
@@ -1392,10 +1402,11 @@ get_rule_expr(Node *node, deparse_context *context)
 							HeapTuple	tp;
 							Form_pg_operator optup;
 
-							tp = SearchSysCacheTuple(OPEROID,
-												  ObjectIdGetDatum(opno),
-													 0, 0, 0);
-							Assert(HeapTupleIsValid(tp));
+							tp = SearchSysCache(OPEROID,
+												ObjectIdGetDatum(opno),
+												0, 0, 0);
+							if (!HeapTupleIsValid(tp))
+								elog(ERROR, "cache lookup for operator %u failed", opno);
 							optup = (Form_pg_operator) GETSTRUCT(tp);
 							switch (optup->oprkind)
 							{
@@ -1414,6 +1425,7 @@ get_rule_expr(Node *node, deparse_context *context)
 								default:
 									elog(ERROR, "get_rule_expr: bogus oprkind");
 							}
+							ReleaseSysCache(tp);
 						}
 						appendStringInfoChar(buf, ')');
 						break;
@@ -1524,9 +1536,9 @@ get_rule_expr(Node *node, deparse_context *context)
 
 				/* we do NOT parenthesize the arg expression, for now */
 				get_rule_expr(fselect->arg, context);
-				typetup = SearchSysCacheTuple(TYPEOID,
-								   ObjectIdGetDatum(exprType(fselect->arg)),
-											  0, 0, 0);
+				typetup = SearchSysCache(TYPEOID,
+										 ObjectIdGetDatum(exprType(fselect->arg)),
+										 0, 0, 0);
 				if (!HeapTupleIsValid(typetup))
 					elog(ERROR, "cache lookup of type %u failed",
 						 exprType(fselect->arg));
@@ -1538,6 +1550,7 @@ get_rule_expr(Node *node, deparse_context *context)
 				fieldname = get_relid_attribute_name(typrelid,
 													 fselect->fieldnum);
 				appendStringInfo(buf, ".%s", quote_identifier(fieldname));
+				ReleaseSysCache(typetup);
 			}
 			break;
 
@@ -1550,9 +1563,9 @@ get_rule_expr(Node *node, deparse_context *context)
 
 				appendStringInfoChar(buf, '(');
 				get_rule_expr(relabel->arg, context);
-				typetup = SearchSysCacheTuple(TYPEOID,
+				typetup = SearchSysCache(TYPEOID,
 								   ObjectIdGetDatum(relabel->resulttype),
-											  0, 0, 0);
+										 0, 0, 0);
 				if (!HeapTupleIsValid(typetup))
 					elog(ERROR, "cache lookup of type %u failed",
 						 relabel->resulttype);
@@ -1560,6 +1573,7 @@ get_rule_expr(Node *node, deparse_context *context)
 				extval = pstrdup(NameStr(typeStruct->typname));
 				appendStringInfo(buf, ")::%s", quote_identifier(extval));
 				pfree(extval);
+				ReleaseSysCache(typetup);
 			}
 			break;
 
@@ -1616,14 +1630,14 @@ get_func_expr(Expr *expr, deparse_context *context)
 	/*
 	 * Get the functions pg_proc tuple
 	 */
-	proctup = SearchSysCacheTuple(PROCOID,
-								  ObjectIdGetDatum(func->funcid),
-								  0, 0, 0);
+	proctup = SearchSysCache(PROCOID,
+							 ObjectIdGetDatum(func->funcid),
+							 0, 0, 0);
 	if (!HeapTupleIsValid(proctup))
 		elog(ERROR, "cache lookup for proc %u failed", func->funcid);
 
 	procStruct = (Form_pg_proc) GETSTRUCT(proctup);
-	proname = pstrdup(NameStr(procStruct->proname));
+	proname = NameStr(procStruct->proname);
 
 	/*
 	 * nullvalue() and nonnullvalue() should get turned into special
@@ -1636,6 +1650,7 @@ get_func_expr(Expr *expr, deparse_context *context)
 			appendStringInfoChar(buf, '(');
 			get_rule_expr((Node *) lfirst(expr->args), context);
 			appendStringInfo(buf, " ISNULL)");
+			ReleaseSysCache(proctup);
 			return;
 		}
 		if (strcmp(proname, "nonnullvalue") == 0)
@@ -1643,6 +1658,7 @@ get_func_expr(Expr *expr, deparse_context *context)
 			appendStringInfoChar(buf, '(');
 			get_rule_expr((Node *) lfirst(expr->args), context);
 			appendStringInfo(buf, " NOTNULL)");
+			ReleaseSysCache(proctup);
 			return;
 		}
 	}
@@ -1657,8 +1673,9 @@ get_func_expr(Expr *expr, deparse_context *context)
 
 		/*
 		 * Strip off any RelabelType on the input, so we don't print
-		 * redundancies like x::bpchar::char(8). XXX Are there any cases
-		 * where this is a bad idea?
+		 * redundancies like x::bpchar::char(8).
+		 *
+		 * XXX Are there any cases where this is a bad idea?
 		 */
 		if (IsA(arg, RelabelType))
 			arg = ((RelabelType *) arg)->arg;
@@ -1696,6 +1713,8 @@ get_func_expr(Expr *expr, deparse_context *context)
 		}
 		else
 			appendStringInfo(buf, "%s", quote_identifier(proname));
+
+		ReleaseSysCache(proctup);
 		return;
 	}
 
@@ -1711,6 +1730,8 @@ get_func_expr(Expr *expr, deparse_context *context)
 		get_rule_expr((Node *) lfirst(l), context);
 	}
 	appendStringInfoChar(buf, ')');
+
+	ReleaseSysCache(proctup);
 }
 
 
@@ -1766,9 +1787,9 @@ get_const_expr(Const *constval, deparse_context *context)
 	char	   *extval;
 	char	   *valptr;
 
-	typetup = SearchSysCacheTuple(TYPEOID,
-								  ObjectIdGetDatum(constval->consttype),
-								  0, 0, 0);
+	typetup = SearchSysCache(TYPEOID,
+							 ObjectIdGetDatum(constval->consttype),
+							 0, 0, 0);
 	if (!HeapTupleIsValid(typetup))
 		elog(ERROR, "cache lookup of type %u failed", constval->consttype);
 
@@ -1785,6 +1806,7 @@ get_const_expr(Const *constval, deparse_context *context)
 		extval = pstrdup(NameStr(typeStruct->typname));
 		appendStringInfo(buf, "NULL::%s", quote_identifier(extval));
 		pfree(extval);
+		ReleaseSysCache(typetup);
 		return;
 	}
 
@@ -1843,6 +1865,8 @@ get_const_expr(Const *constval, deparse_context *context)
 			pfree(extval);
 			break;
 	}
+
+	ReleaseSysCache(typetup);
 }
 
 
@@ -2198,14 +2222,18 @@ get_relation_name(Oid relid)
 {
 	HeapTuple	classtup;
 	Form_pg_class classStruct;
+	char	   *result;
 
-	classtup = SearchSysCacheTuple(RELOID,
-								   ObjectIdGetDatum(relid), 0, 0, 0);
+	classtup = SearchSysCache(RELOID,
+							  ObjectIdGetDatum(relid),
+							  0, 0, 0);
 	if (!HeapTupleIsValid(classtup))
 		elog(ERROR, "cache lookup of relation %u failed", relid);
 
 	classStruct = (Form_pg_class) GETSTRUCT(classtup);
-	return pstrdup(NameStr(classStruct->relname));
+	result = pstrdup(NameStr(classStruct->relname));
+	ReleaseSysCache(classtup);
+	return result;
 }