Replace TupleTableSlot convention for whole-row variables and function

results with tuples as ordinary varlena Datums.  This commit does not
in itself do much for us, except eliminate the horrid memory leak
associated with evaluation of whole-row variables.  However, it lays the
groundwork for allowing composite types as table columns, and perhaps
some other useful features as well.  Per my proposal of a few days ago.

1 files changed, 14 insertions, 31 deletions

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index ac941598be..4a521a0fac 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -447,7 +447,6 @@ dblink_fetch(PG_FUNCTION_ARGS)
 	TupleDesc	tupdesc = NULL;
 	int			call_cntr;
 	int			max_calls;
-	TupleTableSlot *slot;
 	AttInMetadata *attinmeta;
 	char	   *msg;
 	PGresult   *res = NULL;
@@ -566,9 +565,10 @@ dblink_fetch(PG_FUNCTION_ARGS)
 
 		if (functyptype == 'c')
 			tupdesc = TypeGetTupleDesc(functypeid, NIL);
-		else if (functyptype == 'p' && functypeid == RECORDOID)
+		else if (functypeid == RECORDOID)
 		{
-			if (!rsinfo || !IsA(rsinfo, ReturnSetInfo))
+			if (!rsinfo || !IsA(rsinfo, ReturnSetInfo) ||
+				rsinfo->expectedDesc == NULL)
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 						 errmsg("function returning record called in context "
@@ -582,8 +582,6 @@ dblink_fetch(PG_FUNCTION_ARGS)
 			elog(ERROR, "return type must be a row type");
 
 		/* store needed metadata for subsequent calls */
-		slot = TupleDescGetSlot(tupdesc);
-		funcctx->slot = slot;
 		attinmeta = TupleDescGetAttInMetadata(tupdesc);
 		funcctx->attinmeta = attinmeta;
 
@@ -599,8 +597,6 @@ dblink_fetch(PG_FUNCTION_ARGS)
 	call_cntr = funcctx->call_cntr;
 	max_calls = funcctx->max_calls;
 
-	slot = funcctx->slot;
-
 	res = (PGresult *) funcctx->user_fctx;
 	attinmeta = funcctx->attinmeta;
 	tupdesc = attinmeta->tupdesc;
@@ -626,7 +622,7 @@ dblink_fetch(PG_FUNCTION_ARGS)
 		tuple = BuildTupleFromCStrings(attinmeta, values);
 
 		/* make the tuple into a datum */
-		result = TupleGetDatum(slot, tuple);
+		result = HeapTupleGetDatum(tuple);
 
 		SRF_RETURN_NEXT(funcctx, result);
 	}
@@ -649,7 +645,6 @@ dblink_record(PG_FUNCTION_ARGS)
 	TupleDesc	tupdesc = NULL;
 	int			call_cntr;
 	int			max_calls;
-	TupleTableSlot *slot;
 	AttInMetadata *attinmeta;
 	char	   *msg;
 	PGresult   *res = NULL;
@@ -741,7 +736,7 @@ dblink_record(PG_FUNCTION_ARGS)
 			/* need a tuple descriptor representing one TEXT column */
 			tupdesc = CreateTemplateTupleDesc(1, false);
 			TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
-							   TEXTOID, -1, 0, false);
+							   TEXTOID, -1, 0);
 
 			/*
 			 * and save a copy of the command status string to return as
@@ -776,9 +771,10 @@ dblink_record(PG_FUNCTION_ARGS)
 		{
 			if (functyptype == 'c')
 				tupdesc = TypeGetTupleDesc(functypeid, NIL);
-			else if (functyptype == 'p' && functypeid == RECORDOID)
+			else if (functypeid == RECORDOID)
 			{
-				if (!rsinfo || !IsA(rsinfo, ReturnSetInfo))
+				if (!rsinfo || !IsA(rsinfo, ReturnSetInfo) ||
+					rsinfo->expectedDesc == NULL)
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 							 errmsg("function returning record called in context "
@@ -793,8 +789,6 @@ dblink_record(PG_FUNCTION_ARGS)
 		}
 
 		/* store needed metadata for subsequent calls */
-		slot = TupleDescGetSlot(tupdesc);
-		funcctx->slot = slot;
 		attinmeta = TupleDescGetAttInMetadata(tupdesc);
 		funcctx->attinmeta = attinmeta;
 
@@ -810,8 +804,6 @@ dblink_record(PG_FUNCTION_ARGS)
 	call_cntr = funcctx->call_cntr;
 	max_calls = funcctx->max_calls;
 
-	slot = funcctx->slot;
-
 	res = (PGresult *) funcctx->user_fctx;
 	attinmeta = funcctx->attinmeta;
 	tupdesc = attinmeta->tupdesc;
@@ -846,7 +838,7 @@ dblink_record(PG_FUNCTION_ARGS)
 		tuple = BuildTupleFromCStrings(attinmeta, values);
 
 		/* make the tuple into a datum */
-		result = TupleGetDatum(slot, tuple);
+		result = HeapTupleGetDatum(tuple);
 
 		SRF_RETURN_NEXT(funcctx, result);
 	}
@@ -925,7 +917,7 @@ dblink_exec(PG_FUNCTION_ARGS)
 		/* need a tuple descriptor representing one TEXT column */
 		tupdesc = CreateTemplateTupleDesc(1, false);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
-						   TEXTOID, -1, 0, false);
+						   TEXTOID, -1, 0);
 
 		/*
 		 * and save a copy of the command status string to return as our
@@ -939,7 +931,7 @@ dblink_exec(PG_FUNCTION_ARGS)
 		/* need a tuple descriptor representing one TEXT column */
 		tupdesc = CreateTemplateTupleDesc(1, false);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
-						   TEXTOID, -1, 0, false);
+						   TEXTOID, -1, 0);
 
 		/*
 		 * and save a copy of the command status string to return as our
@@ -978,7 +970,6 @@ dblink_get_pkey(PG_FUNCTION_ARGS)
 	FuncCallContext *funcctx;
 	int32		call_cntr;
 	int32		max_calls;
-	TupleTableSlot *slot;
 	AttInMetadata *attinmeta;
 	MemoryContext oldcontext;
 
@@ -1010,15 +1001,9 @@ dblink_get_pkey(PG_FUNCTION_ARGS)
 		 */
 		tupdesc = CreateTemplateTupleDesc(2, false);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "position",
-						   INT4OID, -1, 0, false);
+						   INT4OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "colname",
-						   TEXTOID, -1, 0, false);
-
-		/* allocate a slot for a tuple with this tupdesc */
-		slot = TupleDescGetSlot(tupdesc);
-
-		/* assign slot to function context */
-		funcctx->slot = slot;
+						   TEXTOID, -1, 0);
 
 		/*
 		 * Generate attribute metadata needed later to produce tuples from
@@ -1053,8 +1038,6 @@ dblink_get_pkey(PG_FUNCTION_ARGS)
 	call_cntr = funcctx->call_cntr;
 	max_calls = funcctx->max_calls;
 
-	slot = funcctx->slot;
-
 	results = (char **) funcctx->user_fctx;
 	attinmeta = funcctx->attinmeta;
 
@@ -1075,7 +1058,7 @@ dblink_get_pkey(PG_FUNCTION_ARGS)
 		tuple = BuildTupleFromCStrings(attinmeta, values);
 
 		/* make the tuple into a datum */
-		result = TupleGetDatum(slot, tuple);
+		result = HeapTupleGetDatum(tuple);
 
 		SRF_RETURN_NEXT(funcctx, result);
 	}