From e4186762ffaa4188e16702e8f4f299ea70988b96 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 29 Aug 2002 17:14:33 +0000
Subject: 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.

---
 src/backend/utils/adt/lockfuncs.c | 41 +++++++++++++++++++++------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

(limited to 'src/backend/utils/adt/lockfuncs.c')

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
-- 
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