Fix jsonb iterator freeing

Author: Nikita Glukhov

src/backend/access/common/detoast.c

@@ -42,7 +42,7 @@ create_detoast_iterator(struct varlena *attr)
 		iter = (DetoastIterator) palloc0(sizeof(DetoastIteratorData));
 		iter->done = false;
 		iter->nrefs = 1;
-		iter->gen.free = (void (*)(void *)) free_detoast_iterator;
+		iter->gen.free_callback.func = (void (*)(void *)) free_detoast_iterator;
 
 		/* This is an externally stored datum --- initialize fetch datum iterator */
 		iter->fetch_datum_iterator = fetch_iter = create_fetch_datum_iterator(attr);
@@ -87,7 +87,7 @@ create_detoast_iterator(struct varlena *attr)
 		iter = (DetoastIterator) palloc0(sizeof(DetoastIteratorData));
 		iter->done = false;
 		iter->nrefs = 1;
-		iter->gen.free = (void (*)(void *)) free_detoast_iterator;
+		iter->gen.free_callback.func = (void (*)(void *)) free_detoast_iterator;
 
 		iter->fetch_datum_iterator = palloc0(sizeof(*iter->fetch_datum_iterator));
 		iter->fetch_datum_iterator->buf = buf = create_toast_buffer(VARSIZE_ANY(attr), true);

src/backend/utils/adt/jsonb_util.c

@@ -2961,7 +2961,6 @@ jsonbzIteratorInit(JsonContainer *jc)
 	return jsonbIteratorInitExt(jc, jbc, cjb);
 }
 
-#define JSONB_FREE_ITERATORS
 #ifdef JSONB_FREE_ITERATORS
 static struct
 {
@@ -3003,20 +3002,20 @@ jsonbzInitFromDetoastIterator(JsonContainerData *jc, DetoastIterator iter)
 #endif
 }
 
+#ifdef JSONB_FREE_ITERATORS
 void
 jsonbInitIterators(void)
 {
-#ifdef JSONB_FREE_ITERATORS
 	jsonb_detoast_iterators = palloc(sizeof(*jsonb_detoast_iterators));
 	jsonb_detoast_iterators->mcxt = CurrentMemoryContext;
 	jsonb_detoast_iterators->iterators = NIL;
-#endif
 }
+#endif
 
+#ifdef JSONB_FREE_ITERATORS
 void
 jsonbFreeIterators(void)
 {
-#ifdef JSONB_FREE_ITERATORS
 	ListCell *lc;
 
 	if (jsonb_detoast_iterators)
@@ -3031,20 +3030,28 @@ jsonbFreeIterators(void)
 		pfree(jsonb_detoast_iterators);
 		jsonb_detoast_iterators = NULL;
 	}
-#endif
 }
+#endif
 
+#ifdef JSONB_FREE_ITERATORS
 MemoryContext
 jsonbGetIteratorContext(void)
 {
 	return jsonb_detoast_iterators ? jsonb_detoast_iterators->mcxt : NULL;
 }
+#endif
 
 void
 jsonbRegisterIterator(GenericDetoastIterator iter)
 {
+#ifndef JSONB_FREE_ITERATORS
+	//iter->free_callback.func = iter->free;
+	iter->free_callback.arg = iter;
+	MemoryContextRegisterResetCallback(CurrentMemoryContext, &iter->free_callback);
+#else
 	if (jsonb_detoast_iterators)
 		jsonb_detoast_iterators->iterators = lappend(jsonb_detoast_iterators->iterators, iter);
+#endif
 }
 
 static void
@@ -3079,6 +3086,8 @@ jsonbzInit(JsonContainerData *jc, Datum value)
 		jsonbRegisterIterator(&iter->gen);
 		MemoryContextSwitchTo(oldcxt);
 	}
+#else
+	jsonbRegisterIterator(&iter->gen);
 #endif
 
 	jsonbzInitFromDetoastIterator(jc, iter);
@@ -3172,6 +3181,8 @@ DatumGetJsonbPC(Datum datum, Json *tmp, bool copy)
 		jsonbRegisterIterator(&iter->gen);
 		MemoryContextSwitchTo(oldcxt);
 	}
+# else
+	jsonbRegisterIterator(&iter->gen);
 # endif
 #endif
 

src/include/access/detoast.h

@@ -95,7 +95,7 @@ typedef struct FetchDatumIteratorData *FetchDatumIterator;
 
 typedef struct GenericDetoastIteratorData
 {
-	void (*free)(void *iter);
+	MemoryContextCallback free_callback;
 } GenericDetoastIteratorData, *GenericDetoastIterator;
 
 typedef struct DetoastIteratorData

src/include/utils/jsonb.h

@@ -255,9 +255,15 @@ extern bool jsonb_sort_field_values;		/* GUC */
 extern bool jsonb_partial_decompression;	/* GUC */
 extern bool jsonb_partial_detoast;			/* GUC */
 
+//#define JSONB_FREE_ITERATORS
+#ifdef JSONB_FREE_ITERATORS
 extern void jsonbInitIterators(void);
 extern void jsonbFreeIterators(void);
 extern MemoryContext jsonbGetIteratorContext(void);
+#else
+# define jsonbInitIterators() ((void) 0)
+# define jsonbFreeIterators() ((void) 0)
+#endif
 extern void jsonbRegisterIterator(GenericDetoastIterator iter);
 
 #endif							/* __JSONB_H__ */