Adjust nodeFunctionscan.c to reset transient memory context between calls

to the table function, thus preventing memory leakage accumulation across
calls.  This means that SRFs need to be careful to distinguish permanent
and local storage; adjust code and documentation accordingly.  Patch by
Joe Conway, very minor tweaks by Tom Lane.

1 files changed, 22 insertions, 19 deletions

diff --git a/src/backend/utils/adt/lockfuncs.c b/src/backend/utils/adt/lockfuncs.c
index 83d0d1051df..199efbacd26 100644
--- a/src/backend/utils/adt/lockfuncs.c
+++ b/src/backend/utils/adt/lockfuncs.c
@@ -5,7 +5,7 @@
  * Copyright (c) 2002, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *		$Header: /cvsroot/pgsql/src/backend/utils/adt/lockfuncs.c,v 1.3 2002/08/29 00:17:05 tgl Exp $
+ *		$Header: /cvsroot/pgsql/src/backend/utils/adt/lockfuncs.c,v 1.4 2002/08/29 17:14:33 tgl Exp $
  */
 #include "postgres.h"
 
@@ -24,15 +24,20 @@ static int next_lock(int locks[]);
 Datum
 pg_lock_status(PG_FUNCTION_ARGS)
 {
-	FuncCallContext		*funccxt;
-	LockData			*lockData;
+	FuncCallContext	   *funcctx;
+	LockData		   *lockData;
+	MemoryContext		oldcontext;
 
 	if (SRF_IS_FIRSTCALL())
 	{
-		MemoryContext	oldcxt;
 		TupleDesc		tupdesc;
 
-		funccxt = SRF_FIRSTCALL_INIT();
+		/* create a function context for cross-call persistence */
+		funcctx = SRF_FIRSTCALL_INIT();
+
+		/* switch to memory context appropriate for multiple function calls */
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
 		tupdesc = CreateTemplateTupleDesc(5, WITHOUTOID);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "relation",
 						   OIDOID, -1, 0, false);
@@ -45,10 +50,8 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		TupleDescInitEntry(tupdesc, (AttrNumber) 5, "isgranted",
 						   BOOLOID, -1, 0, false);
 
-		funccxt->slot = TupleDescGetSlot(tupdesc);
-		funccxt->attinmeta = TupleDescGetAttInMetadata(tupdesc);
-
-		oldcxt = MemoryContextSwitchTo(funccxt->fmctx);
+		funcctx->slot = TupleDescGetSlot(tupdesc);
+		funcctx->attinmeta = TupleDescGetAttInMetadata(tupdesc);
 
 		/*
 		 * Preload all the locking information that we will eventually format
@@ -56,15 +59,15 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		 * MemoryContext is reset when the SRF finishes, we don't need to
 		 * free it ourselves.
 		 */
-		funccxt->user_fctx = (LockData *) palloc(sizeof(LockData));
+		funcctx->user_fctx = (LockData *) palloc(sizeof(LockData));
 
-		GetLockStatusData(funccxt->user_fctx);
+		GetLockStatusData(funcctx->user_fctx);
 
-		MemoryContextSwitchTo(oldcxt);
+		MemoryContextSwitchTo(oldcontext);
 	}
 
-	funccxt	= SRF_PERCALL_SETUP();
-	lockData = (LockData *) funccxt->user_fctx;
+	funcctx	= SRF_PERCALL_SETUP();
+	lockData = (LockData *) funcctx->user_fctx;
 
 	while (lockData->currIdx < lockData->nelements)
 	{
@@ -82,7 +85,7 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		holder		= &(lockData->holders[currIdx]);
 		lock		= &(lockData->locks[currIdx]);
 		proc		= &(lockData->procs[currIdx]);
-		num_attrs	= funccxt->attinmeta->tupdesc->natts;
+		num_attrs	= funcctx->attinmeta->tupdesc->natts;
 
 		values = (char **) palloc(sizeof(*values) * num_attrs);
 
@@ -133,12 +136,12 @@ pg_lock_status(PG_FUNCTION_ARGS)
 
 		strncpy(values[3], GetLockmodeName(mode), 32);
 
-		tuple = BuildTupleFromCStrings(funccxt->attinmeta, values);
-		result = TupleGetDatum(funccxt->slot, tuple);
-		SRF_RETURN_NEXT(funccxt, result);
+		tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
+		result = TupleGetDatum(funcctx->slot, tuple);
+		SRF_RETURN_NEXT(funcctx, result);
 	}
 
-	SRF_RETURN_DONE(funccxt);
+	SRF_RETURN_DONE(funcctx);
 }
 
 static LOCKMODE