Previous fix for temporary file management broke returning a set from

PL/pgSQL function within an exception handler. Make sure we use the right
resource owner when we create the tuplestore to hold returned tuples.

Simplify tuplestore API so that the caller doesn't need to be in the right
memory context when calling tuplestore_put* functions. tuplestore.c
automatically switches to the memory context used when the tuplestore was
created. Tuplesort was already modified like this earlier. This patch also
removes the now useless MemoryContextSwitch calls from callers.

Report by Aleksei on pgsql-bugs on Dec 22 2009. Backpatch to 8.1, like
the previous patch that broke this.

3 files changed, 28 insertions, 23 deletions

diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index f999495c87..4fe30bba27 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -1,7 +1,7 @@
 /**********************************************************************
  * plperl.c - perl as a procedural language for PostgreSQL
  *
- *	  $PostgreSQL: pgsql/src/pl/plperl/plperl.c,v 1.155 2009/11/29 21:02:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plperl/plperl.c,v 1.156 2009/12/29 17:40:59 heikki Exp $
  *
  **********************************************************************/
 
@@ -2107,11 +2107,7 @@ plperl_return_next(SV *sv)
 
 		tuple = plperl_build_tuple_result((HV *) SvRV(sv),
 										  current_call_data->attinmeta);
-
-		/* Make sure to store the tuple in a long-lived memory context */
-		MemoryContextSwitchTo(rsi->econtext->ecxt_per_query_memory);
 		tuplestore_puttuple(current_call_data->tuple_store, tuple);
-		MemoryContextSwitchTo(old_cxt);
 	}
 	else
 	{
@@ -2141,14 +2137,12 @@ plperl_return_next(SV *sv)
 			isNull = true;
 		}
 
-		/* Make sure to store the tuple in a long-lived memory context */
-		MemoryContextSwitchTo(rsi->econtext->ecxt_per_query_memory);
 		tuplestore_putvalues(current_call_data->tuple_store,
 							 current_call_data->ret_tdesc,
 							 &ret, &isNull);
-		MemoryContextSwitchTo(old_cxt);
 	}
 
+	MemoryContextSwitchTo(old_cxt);
 	MemoryContextReset(current_call_data->tmp_cxt);
 }
 
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 117da74eb0..823cdbea47 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.251 2009/11/09 00:26:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.252 2009/12/29 17:40:59 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2172,7 +2172,6 @@ exec_stmt_return_next(PLpgSQL_execstate *estate,
 {
 	TupleDesc	tupdesc;
 	int			natts;
-	MemoryContext oldcxt;
 	HeapTuple	tuple = NULL;
 	bool		free_tuple = false;
 
@@ -2212,10 +2211,8 @@ exec_stmt_return_next(PLpgSQL_execstate *estate,
 												tupdesc->attrs[0]->atttypmod,
 													isNull);
 
-					oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
 					tuplestore_putvalues(estate->tuple_store, tupdesc,
 										 &retval, &isNull);
-					MemoryContextSwitchTo(oldcxt);
 				}
 				break;
 
@@ -2285,10 +2282,8 @@ exec_stmt_return_next(PLpgSQL_execstate *estate,
 										tupdesc->attrs[0]->atttypmod,
 										isNull);
 
-		oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
 		tuplestore_putvalues(estate->tuple_store, tupdesc,
 							 &retval, &isNull);
-		MemoryContextSwitchTo(oldcxt);
 
 		exec_eval_cleanup(estate);
 	}
@@ -2301,9 +2296,7 @@ exec_stmt_return_next(PLpgSQL_execstate *estate,
 
 	if (HeapTupleIsValid(tuple))
 	{
-		oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
 		tuplestore_puttuple(estate->tuple_store, tuple);
-		MemoryContextSwitchTo(oldcxt);
 
 		if (free_tuple)
 			heap_freetuple(tuple);
@@ -2353,14 +2346,12 @@ exec_stmt_return_query(PLpgSQL_execstate *estate,
 
 	while (true)
 	{
-		MemoryContext old_cxt;
 		int			i;
 
 		SPI_cursor_fetch(portal, true, 50);
 		if (SPI_processed == 0)
 			break;
 
-		old_cxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
 		for (i = 0; i < SPI_processed; i++)
 		{
 			HeapTuple	tuple = SPI_tuptable->vals[i];
@@ -2372,7 +2363,6 @@ exec_stmt_return_query(PLpgSQL_execstate *estate,
 				heap_freetuple(tuple);
 			processed++;
 		}
-		MemoryContextSwitchTo(old_cxt);
 
 		SPI_freetuptable(SPI_tuptable);
 	}
@@ -2394,6 +2384,7 @@ exec_init_tuple_store(PLpgSQL_execstate *estate)
 {
 	ReturnSetInfo *rsi = estate->rsi;
 	MemoryContext oldcxt;
+	ResourceOwner oldowner;
 
 	/*
 	 * Check caller can handle a set result in the way we want
@@ -2405,12 +2396,22 @@ exec_init_tuple_store(PLpgSQL_execstate *estate)
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("set-valued function called in context that cannot accept a set")));
 
-	estate->tuple_store_cxt = rsi->econtext->ecxt_per_query_memory;
-
+	/*
+	 * Switch to the right memory context and resource owner for storing
+	 * the tuplestore for return set. If we're within a subtransaction opened
+	 * for an exception-block, for example, we must still create the
+	 * tuplestore in the resource owner that was active when this function was
+	 * entered, and not in the subtransaction resource owner.
+	 */
 	oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
+	oldowner = CurrentResourceOwner;
+	CurrentResourceOwner = estate->tuple_store_owner;
+
 	estate->tuple_store =
 		tuplestore_begin_heap(rsi->allowedModes & SFRM_Materialize_Random,
 							  false, work_mem);
+
+	CurrentResourceOwner = oldowner;
 	MemoryContextSwitchTo(oldcxt);
 
 	estate->rettupdesc = rsi->expectedDesc;
@@ -2635,7 +2636,16 @@ plpgsql_estate_setup(PLpgSQL_execstate *estate,
 	estate->exitlabel = NULL;
 
 	estate->tuple_store = NULL;
-	estate->tuple_store_cxt = NULL;
+	if (rsi)
+	{
+		estate->tuple_store_cxt = rsi->econtext->ecxt_per_query_memory;
+		estate->tuple_store_owner = CurrentResourceOwner;
+	}
+	else
+	{
+		estate->tuple_store_cxt = NULL;
+		estate->tuple_store_owner = NULL;
+	}
 	estate->rsi = rsi;
 
 	estate->found_varno = func->found_varno;
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 25d1c03699..b0813ba33e 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.125 2009/11/13 22:43:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.126 2009/12/29 17:40:59 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -701,6 +701,7 @@ typedef struct PLpgSQL_execstate
 
 	Tuplestorestate *tuple_store;		/* SRFs accumulate results here */
 	MemoryContext tuple_store_cxt;
+	ResourceOwner tuple_store_owner;
 	ReturnSetInfo *rsi;
 
 	int			found_varno;