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, 57 insertions, 62 deletions

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index fff6d569753..788701b20fe 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.40 2000/11/08 22:09:57 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.41 2000/11/16 22:30:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,7 +86,6 @@ DefineIndex(char *heapRelationName,
 	Oid			relationId;
 	IndexInfo  *indexInfo;
 	int			numberOfAttributes;
-	HeapTuple	tuple;
 	List	   *cnfPred = NIL;
 	bool		lossy = false;
 	List	   *pl;
@@ -111,13 +110,12 @@ DefineIndex(char *heapRelationName,
 	/*
 	 * compute access method id
 	 */
-	tuple = SearchSysCacheTuple(AMNAME,
-								PointerGetDatum(accessMethodName),
-								0, 0, 0);
-	if (!HeapTupleIsValid(tuple))
+	accessMethodId = GetSysCacheOid(AMNAME,
+									PointerGetDatum(accessMethodName),
+									0, 0, 0);
+	if (!OidIsValid(accessMethodId))
 		elog(ERROR, "DefineIndex: access method \"%s\" not found",
 			 accessMethodName);
-	accessMethodId = tuple->t_data->t_oid;
 
 	/*
 	 * XXX Hardwired hacks to check for limitations on supported index types.
@@ -239,21 +237,22 @@ ExtendIndex(char *indexRelationName, Expr *predicate, List *rangetable)
 	/*
 	 * Get index's relation id and access method id from pg_class
 	 */
-	tuple = SearchSysCacheTuple(RELNAME,
-								PointerGetDatum(indexRelationName),
-								0, 0, 0);
+	tuple = SearchSysCache(RELNAME,
+						   PointerGetDatum(indexRelationName),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "ExtendIndex: index \"%s\" not found",
 			 indexRelationName);
 	indexId = tuple->t_data->t_oid;
 	accessMethodId = ((Form_pg_class) GETSTRUCT(tuple))->relam;
+	ReleaseSysCache(tuple);
 
 	/*
 	 * Extract info from the pg_index tuple for the index
 	 */
-	tuple = SearchSysCacheTuple(INDEXRELID,
-								ObjectIdGetDatum(indexId),
-								0, 0, 0);
+	tuple = SearchSysCache(INDEXRELID,
+						   ObjectIdGetDatum(indexId),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "ExtendIndex: relation \"%s\" is not an index",
 			 indexRelationName);
@@ -262,6 +261,7 @@ ExtendIndex(char *indexRelationName, Expr *predicate, List *rangetable)
 	relationId = index->indrelid;
 	indexInfo = BuildIndexInfo(tuple);
 	oldPred = indexInfo->ii_Predicate;
+	ReleaseSysCache(tuple);
 
 	if (oldPred == NULL)
 		elog(ERROR, "ExtendIndex: \"%s\" is not a partial index",
@@ -391,16 +391,16 @@ FuncIndexArgs(IndexInfo *indexInfo,
 		HeapTuple	tuple;
 		Form_pg_attribute att;
 
-		tuple = SearchSysCacheTuple(ATTNAME,
-									ObjectIdGetDatum(relId),
-									PointerGetDatum(arg),
-									0, 0);
+		tuple = SearchSysCache(ATTNAME,
+							   ObjectIdGetDatum(relId),
+							   PointerGetDatum(arg),
+							   0, 0);
 		if (!HeapTupleIsValid(tuple))
 			elog(ERROR, "DefineIndex: attribute \"%s\" not found", arg);
 		att = (Form_pg_attribute) GETSTRUCT(tuple);
-
 		indexInfo->ii_KeyAttrNumbers[nargs] = att->attnum;
 		argTypes[nargs] = att->atttypid;
+		ReleaseSysCache(tuple);
 		nargs++;
 	}
 
@@ -465,10 +465,10 @@ NormIndexAttrs(IndexInfo *indexInfo,
 		if (attribute->name == NULL)
 			elog(ERROR, "missing attribute for define index");
 
-		atttuple = SearchSysCacheTupleCopy(ATTNAME,
-										   ObjectIdGetDatum(relId),
-										PointerGetDatum(attribute->name),
-										   0, 0);
+		atttuple = SearchSysCache(ATTNAME,
+								  ObjectIdGetDatum(relId),
+								  PointerGetDatum(attribute->name),
+								  0, 0);
 		if (!HeapTupleIsValid(atttuple))
 			elog(ERROR, "DefineIndex: attribute \"%s\" not found",
 				 attribute->name);
@@ -479,7 +479,7 @@ NormIndexAttrs(IndexInfo *indexInfo,
 		classOidP[attn] = GetAttrOpClass(attribute, attform->atttypid,
 										 accessMethodName, accessMethodId);
 
-		heap_freetuple(atttuple);
+		ReleaseSysCache(atttuple);
 		attn++;
 	}
 }
@@ -507,13 +507,12 @@ GetAttrOpClass(IndexElem *attribute, Oid attrType,
 		doTypeCheck = false;
 	}
 
-	tuple = SearchSysCacheTuple(CLANAME,
-								PointerGetDatum(attribute->class),
-								0, 0, 0);
-	if (!HeapTupleIsValid(tuple))
+	opClassId = GetSysCacheOid(CLANAME,
+							   PointerGetDatum(attribute->class),
+							   0, 0, 0);
+	if (!OidIsValid(opClassId))
 		elog(ERROR, "DefineIndex: opclass \"%s\" not found",
 			 attribute->class);
-	opClassId = tuple->t_data->t_oid;
 
 	/*
 	 * Assume the opclass is supported by this index access method
@@ -532,10 +531,8 @@ GetAttrOpClass(IndexElem *attribute, Oid attrType,
 	scan = heap_beginscan(relation, false, SnapshotNow, 2, entry);
 
 	if (! HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
-	{
 		elog(ERROR, "DefineIndex: opclass \"%s\" not supported by access method \"%s\"",
 			 attribute->class, accessMethodName);
-	}
 
 	oprId = ((Form_pg_amop) GETSTRUCT(tuple))->amopopr;
 
@@ -557,9 +554,9 @@ GetAttrOpClass(IndexElem *attribute, Oid attrType,
 	 */
 	if (doTypeCheck)
 	{
-		tuple = SearchSysCacheTuple(OPEROID,
-									ObjectIdGetDatum(oprId),
-									0, 0, 0);
+		tuple = SearchSysCache(OPEROID,
+							   ObjectIdGetDatum(oprId),
+							   0, 0, 0);
 		if (HeapTupleIsValid(tuple))
 		{
 			Form_pg_operator optup = (Form_pg_operator) GETSTRUCT(tuple);
@@ -570,6 +567,7 @@ GetAttrOpClass(IndexElem *attribute, Oid attrType,
 				! IS_BINARY_COMPATIBLE(attrType, opInputType))
 				elog(ERROR, "DefineIndex: opclass \"%s\" does not accept datatype \"%s\"",
 					 attribute->class, typeidTypeName(attrType));
+			ReleaseSysCache(tuple);
 		}
 	}
 
@@ -580,15 +578,18 @@ static char *
 GetDefaultOpClass(Oid atttypid)
 {
 	HeapTuple	tuple;
+	char	   *result;
 
-	tuple = SearchSysCacheTuple(CLADEFTYPE,
-								ObjectIdGetDatum(atttypid),
-								0, 0, 0);
+	tuple = SearchSysCache(CLADEFTYPE,
+						   ObjectIdGetDatum(atttypid),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		return NULL;
 
-	return DatumGetCString(DirectFunctionCall1(nameout,
-			NameGetDatum(&((Form_pg_opclass) GETSTRUCT(tuple))->opcname)));
+	result = pstrdup(NameStr(((Form_pg_opclass) GETSTRUCT(tuple))->opcname));
+
+	ReleaseSysCache(tuple);
+	return result;
 }
 
 /*
@@ -605,21 +606,19 @@ RemoveIndex(char *name)
 {
 	HeapTuple	tuple;
 
-	tuple = SearchSysCacheTuple(RELNAME,
-								PointerGetDatum(name),
-								0, 0, 0);
-
+	tuple = SearchSysCache(RELNAME,
+						   PointerGetDatum(name),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "index \"%s\" does not exist", name);
 
 	if (((Form_pg_class) GETSTRUCT(tuple))->relkind != RELKIND_INDEX)
-	{
 		elog(ERROR, "relation \"%s\" is of type \"%c\"",
-			 name,
-			 ((Form_pg_class) GETSTRUCT(tuple))->relkind);
-	}
+			 name, ((Form_pg_class) GETSTRUCT(tuple))->relkind);
 
 	index_drop(tuple->t_data->t_oid);
+
+	ReleaseSysCache(tuple);
 }
 
 /*
@@ -644,22 +643,20 @@ ReindexIndex(const char *name, bool force /* currently unused */ )
 	if (IsTransactionBlock())
 		elog(ERROR, "REINDEX cannot run inside a BEGIN/END block");
 
-	tuple = SearchSysCacheTuple(RELNAME,
-								PointerGetDatum(name),
-								0, 0, 0);
-
+	tuple = SearchSysCache(RELNAME,
+						   PointerGetDatum(name),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "index \"%s\" does not exist", name);
 
 	if (((Form_pg_class) GETSTRUCT(tuple))->relkind != RELKIND_INDEX)
-	{
 		elog(ERROR, "relation \"%s\" is of type \"%c\"",
-			 name,
-			 ((Form_pg_class) GETSTRUCT(tuple))->relkind);
-	}
+			 name, ((Form_pg_class) GETSTRUCT(tuple))->relkind);
 
 	if (!reindex_index(tuple->t_data->t_oid, force))
 		elog(NOTICE, "index \"%s\" wasn't reindexed", name);
+
+	ReleaseSysCache(tuple);
 }
 
 /*
@@ -684,22 +681,20 @@ ReindexTable(const char *name, bool force)
 	if (IsTransactionBlock())
 		elog(ERROR, "REINDEX cannot run inside a BEGIN/END block");
 
-	tuple = SearchSysCacheTuple(RELNAME,
-								PointerGetDatum(name),
-								0, 0, 0);
-
+	tuple = SearchSysCache(RELNAME,
+						   PointerGetDatum(name),
+						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "table \"%s\" does not exist", name);
 
 	if (((Form_pg_class) GETSTRUCT(tuple))->relkind != RELKIND_RELATION)
-	{
 		elog(ERROR, "relation \"%s\" is of type \"%c\"",
-			 name,
-			 ((Form_pg_class) GETSTRUCT(tuple))->relkind);
-	}
+			 name, ((Form_pg_class) GETSTRUCT(tuple))->relkind);
 
 	if (!reindex_relation(tuple->t_data->t_oid, force))
 		elog(NOTICE, "table \"%s\" wasn't reindexed", name);
+
+	ReleaseSysCache(tuple);
 }
 
 /*