src: use V8 graph heap snapshot API

Transition to a newer, more flexible API for
heap snapshot creation.

This addresses a currently pending deprecation in the V8 API.

PR-URL: #21741
Fixes: #21633
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>

Author: addaleax

src/async_wrap.cc

@@ -32,7 +32,6 @@ using v8::Function;
 using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
 using v8::HandleScope;
-using v8::HeapProfiler;
 using v8::Integer;
 using v8::Isolate;
 using v8::Local;
@@ -43,7 +42,6 @@ using v8::ObjectTemplate;
 using v8::Promise;
 using v8::PromiseHookType;
 using v8::PropertyCallbackInfo;
-using v8::RetainedObjectInfo;
 using v8::String;
 using v8::Uint32;
 using v8::Undefined;
@@ -61,87 +59,6 @@ static const char* const provider_names[] = {
 };
 
 
-// Report correct information in a heapdump.
-
-class RetainedAsyncInfo: public RetainedObjectInfo {
- public:
-  explicit RetainedAsyncInfo(uint16_t class_id, AsyncWrap* wrap);
-
-  void Dispose() override;
-  bool IsEquivalent(RetainedObjectInfo* other) override;
-  intptr_t GetHash() override;
-  const char* GetLabel() override;
-  intptr_t GetSizeInBytes() override;
-
- private:
-  const char* label_;
-  const AsyncWrap* wrap_;
-  const size_t length_;
-};
-
-
-static int OwnMemory(AsyncWrap* async_wrap) {
-  MemoryTracker tracker;
-  tracker.set_track_only_self(true);
-  tracker.Track(async_wrap);
-  return tracker.accumulated_size();
-}
-
-
-RetainedAsyncInfo::RetainedAsyncInfo(uint16_t class_id, AsyncWrap* wrap)
-    : label_(provider_names[class_id - NODE_ASYNC_ID_OFFSET]),
-      wrap_(wrap),
-      length_(OwnMemory(wrap)) {
-}
-
-
-void RetainedAsyncInfo::Dispose() {
-  delete this;
-}
-
-
-bool RetainedAsyncInfo::IsEquivalent(RetainedObjectInfo* other) {
-  return label_ == other->GetLabel() &&
-          wrap_ == static_cast<RetainedAsyncInfo*>(other)->wrap_;
-}
-
-
-intptr_t RetainedAsyncInfo::GetHash() {
-  return reinterpret_cast<intptr_t>(wrap_);
-}
-
-
-const char* RetainedAsyncInfo::GetLabel() {
-  return label_;
-}
-
-
-intptr_t RetainedAsyncInfo::GetSizeInBytes() {
-  return length_;
-}
-
-
-RetainedObjectInfo* WrapperInfo(uint16_t class_id, Local<Value> wrapper) {
-  // No class_id should be the provider type of NONE.
-  CHECK_GT(class_id, NODE_ASYNC_ID_OFFSET);
-  // And make sure the class_id doesn't extend past the last provider.
-  CHECK_LE(class_id - NODE_ASYNC_ID_OFFSET, AsyncWrap::PROVIDERS_LENGTH);
-  CHECK(wrapper->IsObject());
-  CHECK(!wrapper.IsEmpty());
-
-  Local<Object> object = wrapper.As<Object>();
-  CHECK_GT(object->InternalFieldCount(), 0);
-
-  AsyncWrap* wrap;
-  ASSIGN_OR_RETURN_UNWRAP(&wrap, object, nullptr);
-
-  return new RetainedAsyncInfo(class_id, wrap);
-}
-
-
-// end RetainedAsyncInfo
-
-
 struct AsyncWrapObject : public AsyncWrap {
   static inline void New(const FunctionCallbackInfo<Value>& args) {
     Environment* env = Environment::GetCurrent(args);
@@ -616,16 +533,6 @@ void AsyncWrap::Initialize(Local<Object> target,
 }
 
 
-void LoadAsyncWrapperInfo(Environment* env) {
-  HeapProfiler* heap_profiler = env->isolate()->GetHeapProfiler();
-#define V(PROVIDER)                                                           \
-  heap_profiler->SetWrapperClassInfoProvider(                                 \
-      (NODE_ASYNC_ID_OFFSET + AsyncWrap::PROVIDER_ ## PROVIDER), WrapperInfo);
-  NODE_ASYNC_PROVIDER_TYPES(V)
-#undef V
-}
-
-
 AsyncWrap::AsyncWrap(Environment* env,
                      Local<Object> object,
                      ProviderType provider,
@@ -814,9 +721,12 @@ void EmitAsyncDestroy(Isolate* isolate, async_context asyncContext) {
       Environment::GetCurrent(isolate), asyncContext.async_id);
 }
 
+std::string AsyncWrap::MemoryInfoName() const {
+  return provider_names[provider_type()];
+}
+
 std::string AsyncWrap::diagnostic_name() const {
-  return std::string(provider_names[provider_type()]) +
-      " (" + std::to_string(env()->thread_id()) + ":" +
+  return MemoryInfoName() + " (" + std::to_string(env()->thread_id()) + ":" +
       std::to_string(static_cast<int64_t>(async_id_)) + ")";
 }
 

src/async_wrap.h

@@ -175,6 +175,7 @@ class AsyncWrap : public BaseObject {
       v8::Local<v8::Value>* argv);
 
   virtual std::string diagnostic_name() const;
+  std::string MemoryInfoName() const override;
 
   static void WeakCallback(const v8::WeakCallbackInfo<DestroyParam> &info);
 
@@ -205,8 +206,6 @@ class AsyncWrap : public BaseObject {
   double trigger_async_id_;
 };
 
-void LoadAsyncWrapperInfo(Environment* env);
-
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

src/env.cc

@@ -142,9 +142,15 @@ Environment::Environment(IsolateData* isolate_data,
   std::string debug_cats;
   SafeGetenv("NODE_DEBUG_NATIVE", &debug_cats);
   set_debug_categories(debug_cats, true);
+
+  isolate()->GetHeapProfiler()->AddBuildEmbedderGraphCallback(
+      BuildEmbedderGraph, this);
 }
 
 Environment::~Environment() {
+  isolate()->GetHeapProfiler()->RemoveBuildEmbedderGraphCallback(
+      BuildEmbedderGraph, this);
+
   // Make sure there are no re-used libuv wrapper objects.
   // CleanupHandles() should have removed all of them.
   CHECK(file_handle_read_wrap_freelist_.empty());
@@ -212,7 +218,6 @@ void Environment::Start(int argc,
   set_process_object(process_object);
 
   SetupProcessObject(this, argc, argv, exec_argc, exec_argv);
-  LoadAsyncWrapperInfo(this);
 
   static uv_once_t init_once = UV_ONCE_INIT;
   uv_once(&init_once, InitThreadLocalOnce);
@@ -653,6 +658,16 @@ void Environment::stop_sub_worker_contexts() {
   }
 }
 
+void Environment::BuildEmbedderGraph(v8::Isolate* isolate,
+                                     v8::EmbedderGraph* graph,
+                                     void* data) {
+  MemoryTracker tracker(isolate, graph);
+  static_cast<Environment*>(data)->ForEachBaseObject([&](BaseObject* obj) {
+    tracker.Track(obj);
+  });
+}
+
+
 // Not really any better place than env.cc at this moment.
 void BaseObject::DeleteMe(void* data) {
   BaseObject* self = static_cast<BaseObject*>(data);

src/env.h

@@ -859,6 +859,10 @@ class Environment {
   inline void RemoveCleanupHook(void (*fn)(void*), void* arg);
   void RunCleanup();
 
+  static void BuildEmbedderGraph(v8::Isolate* isolate,
+                                 v8::EmbedderGraph* graph,
+                                 void* data);
+
  private:
   inline void CreateImmediate(native_immediate_callback cb,
                               void* data,

src/memory_tracker-inl.h

@@ -7,23 +7,68 @@
 
 namespace node {
 
+class MemoryRetainerNode : public v8::EmbedderGraph::Node {
+ public:
+  explicit inline MemoryRetainerNode(MemoryTracker* tracker,
+                                     const MemoryRetainer* retainer,
+                                     const char* name)
+     : retainer_(retainer) {
+    if (retainer_ != nullptr) {
+      v8::HandleScope handle_scope(tracker->isolate());
+      v8::Local<v8::Object> obj = retainer_->WrappedObject();
+      if (!obj.IsEmpty())
+        wrapper_node_ = tracker->graph()->V8Node(obj);
+
+      name_ = retainer_->MemoryInfoName();
+    }
+    if (name_.empty() && name != nullptr) {
+      name_ = name;
+    }
+  }
+
+  const char* Name() override { return name_.c_str(); }
+  const char* NamePrefix() override { return "Node /"; }
+  size_t SizeInBytes() override { return size_; }
+  // TODO(addaleax): Merging this with the "official" WrapperNode() method
+  // seems to lose accuracy, e.g. SizeInBytes() is disregarded.
+  // Figure out whether to do anything about that.
+  Node* JSWrapperNode() { return wrapper_node_; }
+
+  bool IsRootNode() override {
+    return retainer_ != nullptr && retainer_->IsRootNode();
+  }
+
+ private:
+  friend class MemoryTracker;
+
+  Node* wrapper_node_ = nullptr;
+  const MemoryRetainer* retainer_;
+  std::string name_;
+  size_t size_ = 0;
+};
+
 template <typename T>
 void MemoryTracker::TrackThis(const T* obj) {
-  accumulated_size_ += sizeof(T);
+  CurrentNode()->size_ = sizeof(T);
 }
 
 void MemoryTracker::TrackFieldWithSize(const char* name, size_t size) {
-  accumulated_size_ += size;
+  if (size > 0)
+    AddNode(name)->size_ = size;
 }
 
 void MemoryTracker::TrackField(const char* name, const MemoryRetainer& value) {
   TrackField(name, &value);
 }
 
 void MemoryTracker::TrackField(const char* name, const MemoryRetainer* value) {
-  if (track_only_self_ || value == nullptr || seen_.count(value) > 0) return;
-  seen_.insert(value);
-  Track(value);
+  if (track_only_self_ || value == nullptr) return;
+  auto it = seen_.find(value);
+  if (it != seen_.end()) {
+    graph_->AddEdge(CurrentNode(), it->second);
+  } else {
+    Track(value, name);
+  }
 }
 
 template <typename T>
@@ -36,8 +81,10 @@ template <typename T, typename Iterator>
 void MemoryTracker::TrackField(const char* name, const T& value) {
   if (value.begin() == value.end()) return;
   size_t index = 0;
+  PushNode(name);
   for (Iterator it = value.begin(); it != value.end(); ++it)
     TrackField(std::to_string(index++).c_str(), *it);
+  PopNode();
 }
 
 template <typename T>
@@ -56,13 +103,15 @@ void MemoryTracker::TrackField(const char* name, const std::queue<T>& value) {
 template <typename T, typename test_for_number, typename dummy>
 void MemoryTracker::TrackField(const char* name, const T& value) {
   // For numbers, creating new nodes is not worth the overhead.
-  TrackFieldWithSize(name, sizeof(T));
+  CurrentNode()->size_ += sizeof(T);
 }
 
 template <typename T, typename U>
 void MemoryTracker::TrackField(const char* name, const std::pair<T, U>& value) {
+  PushNode(name);
   TrackField("first", value.first);
   TrackField("second", value.second);
+  PopNode();
 }
 
 template <typename T>
@@ -74,10 +123,13 @@ void MemoryTracker::TrackField(const char* name,
 template <typename T, typename Traits>
 void MemoryTracker::TrackField(const char* name,
                                const v8::Persistent<T, Traits>& value) {
+  TrackField(name, value.Get(isolate_));
 }
 
 template <typename T>
 void MemoryTracker::TrackField(const char* name, const v8::Local<T>& value) {
+  if (!value.IsEmpty())
+    graph_->AddEdge(CurrentNode(), graph_->V8Node(value));
 }
 
 template <typename T>
@@ -96,8 +148,47 @@ void MemoryTracker::TrackField(const char* name,
   TrackField(name, value.GetJSArray());
 }
 
-void MemoryTracker::Track(const MemoryRetainer* value) {
+void MemoryTracker::Track(const MemoryRetainer* value, const char* name) {
+  v8::HandleScope handle_scope(isolate_);
+  MemoryRetainerNode* n = PushNode(name, value);
   value->MemoryInfo(this);
+  CHECK_EQ(CurrentNode(), n);
+  CHECK_NE(n->size_, 0);
+  PopNode();
+}
+
+MemoryRetainerNode* MemoryTracker::CurrentNode() const {
+  if (node_stack_.empty()) return nullptr;
+  return node_stack_.top();
+}
+
+MemoryRetainerNode* MemoryTracker::AddNode(
+    const char* name, const MemoryRetainer* retainer) {
+  MemoryRetainerNode* n = new MemoryRetainerNode(this, retainer, name);
+  graph_->AddNode(std::unique_ptr<v8::EmbedderGraph::Node>(n));
+  if (retainer != nullptr)
+    seen_[retainer] = n;
+
+  if (CurrentNode() != nullptr)
+    graph_->AddEdge(CurrentNode(), n);
+
+  if (n->JSWrapperNode() != nullptr) {
+    graph_->AddEdge(n, n->JSWrapperNode());
+    graph_->AddEdge(n->JSWrapperNode(), n);
+  }
+
+  return n;
+}
+
+MemoryRetainerNode* MemoryTracker::PushNode(
+    const char* name, const MemoryRetainer* retainer) {
+  MemoryRetainerNode* n = AddNode(name, retainer);
+  node_stack_.push(n);
+  return n;
+}
+
+void MemoryTracker::PopNode() {
+  node_stack_.pop();
 }
 
 }  // namespace node