src: fix AliasedBuffer memory attribution in heap snapshots

Before the AliasedBuffers were represented solely by the TypedArrays
event though they also retain additional memory themselves.
Make the accounting more accurate by implementing MemoryRetainer in
AliasedBuffer.

PR-URL: https://github.com/nodejs/node/pull/46817
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

src/aliased_buffer-inl.h

@@ -206,6 +206,25 @@ void AliasedBufferBase<NativeT, V8T>::reserve(size_t new_capacity) {
   count_ = new_capacity;
 }
 
+template <typename NativeT, typename V8T>
+inline size_t AliasedBufferBase<NativeT, V8T>::SelfSize() const {
+  return sizeof(*this);
+}
+
+#define VM(NativeT, V8T)                                                       \
+  template <>                                                                  \
+  inline const char* AliasedBufferBase<NativeT, v8::V8T>::MemoryInfoName()     \
+      const {                                                                  \
+    return "Aliased" #V8T;                                                     \
+  }                                                                            \
+  template <>                                                                  \
+  inline void AliasedBufferBase<NativeT, v8::V8T>::MemoryInfo(                 \
+      node::MemoryTracker* tracker) const {                                    \
+    tracker->TrackField("js_array", js_array_);                                \
+  }
+ALIASED_BUFFER_LIST(VM)
+#undef VM
+
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

src/aliased_buffer.h

@@ -4,6 +4,7 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include <cinttypes>
+#include "memory_tracker.h"
 #include "v8.h"
 
 namespace node {
@@ -28,7 +29,7 @@ typedef size_t AliasedBufferIndex;
  * observed. Any notification APIs will be left as a future exercise.
  */
 template <class NativeT, class V8T>
-class AliasedBufferBase {
+class AliasedBufferBase : public MemoryRetainer {
  public:
   static_assert(std::is_scalar<NativeT>::value);
 
@@ -157,6 +158,11 @@ class AliasedBufferBase {
   // an owning `AliasedBufferBase`.
   void reserve(size_t new_capacity);
 
+  inline size_t SelfSize() const override;
+
+  inline const char* MemoryInfoName() const override;
+  inline void MemoryInfo(node::MemoryTracker* tracker) const override;
+
  private:
   v8::Isolate* isolate_ = nullptr;
   size_t count_ = 0;

src/memory_tracker-inl.h

@@ -3,8 +3,8 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
-#include "aliased_buffer-inl.h"
 #include "memory_tracker.h"
+#include "util-inl.h"
 
 namespace node {
 
@@ -270,13 +270,6 @@ void MemoryTracker::TrackInlineField(const char* name,
   TrackInlineFieldWithSize(name, sizeof(value), "uv_async_t");
 }
 
-template <class NativeT, class V8T>
-void MemoryTracker::TrackField(const char* name,
-                               const AliasedBufferBase<NativeT, V8T>& value,
-                               const char* node_name) {
-  TrackField(name, value.GetJSArray(), "AliasedBuffer");
-}
-
 void MemoryTracker::Track(const MemoryRetainer* retainer,
                           const char* edge_name) {
   v8::HandleScope handle_scope(isolate_);

src/memory_tracker.h

@@ -2,7 +2,6 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
-#include "aliased_buffer.h"
 #include "v8-profiler.h"
 
 #include <uv.h>
@@ -238,10 +237,6 @@ class MemoryTracker {
   inline void TrackInlineField(const char* edge_name,
                                const uv_async_t& value,
                                const char* node_name = nullptr);
-  template <class NativeT, class V8T>
-  inline void TrackField(const char* edge_name,
-                         const AliasedBufferBase<NativeT, V8T>& value,
-                         const char* node_name = nullptr);
 
   // Put a memory container into the graph, create an edge from
   // the current node if there is one on the stack.

test/pummel/test-heapdump-fs-promise.js

@@ -10,7 +10,7 @@ validateSnapshotNodes('Node / FSReqPromise', [
   {
     children: [
       { node_name: 'FSReqPromise', edge_name: 'native_to_javascript' },
-      { node_name: 'Float64Array', edge_name: 'stats_field_array' },
+      { node_name: 'Node / AliasedFloat64Array', edge_name: 'stats_field_array' },
     ],
   },
 ]);