src: implement GetDetachedness() in MemoryRetainerNode

This allows us to mark weak/detached references in the heap snapshot. Also mark weak/detached BaseObject with Detachedness::kDetached so that the state of the reference can be displayed by frontend consuming the heap snapshot. PR-URL: #44803 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

Author: joyeecheung

src/base_object-inl.h

@@ -92,6 +92,11 @@ bool BaseObject::IsWeakOrDetached() const {
  return pd->wants_weak_jsobj || pd->is_detached;
 }
 
+v8::EmbedderGraph::Node::Detachedness BaseObject::GetDetachedness() const {
+ return IsWeakOrDetached() ? v8::EmbedderGraph::Node::Detachedness::kDetached
+ : v8::EmbedderGraph::Node::Detachedness::kUnknown;
+}
+
 template <int Field>
 void BaseObject::InternalFieldGet(
  v8::Local<v8::String> property,

src/base_object.h

@@ -85,6 +85,8 @@ class BaseObject : public MemoryRetainer {
  // to it anymore.
  inline bool IsWeakOrDetached() const;
 
+ inline v8::EmbedderGraph::Node::Detachedness GetDetachedness() const override;
+
  // Utility to create a FunctionTemplate with one internal field (used for
  // the `BaseObject*` pointer) and a constructor that initializes that field
  // to `nullptr`.

src/memory_tracker-inl.h

@@ -31,6 +31,7 @@ class MemoryRetainerNode : public v8::EmbedderGraph::Node {
 
  name_ = retainer_->MemoryInfoName();
  size_ = retainer_->SelfSize();
+ detachedness_ = retainer_->GetDetachedness();
  }
 
  inline MemoryRetainerNode(MemoryTracker* tracker,
@@ -57,6 +58,9 @@ class MemoryRetainerNode : public v8::EmbedderGraph::Node {
  }
  return is_root_node_;
  }
+ v8::EmbedderGraph::Node::Detachedness GetDetachedness() override {
+ return detachedness_;
+ }
 
  private:
  friend class MemoryTracker;
@@ -73,6 +77,8 @@ class MemoryRetainerNode : public v8::EmbedderGraph::Node {
  bool is_root_node_ = false;
  std::string name_;
  size_t size_ = 0;
+ v8::EmbedderGraph::Node::Detachedness detachedness_ =
+ v8::EmbedderGraph::Node::Detachedness::kUnknown;
 };
 
 void MemoryTracker::TrackFieldWithSize(const char* edge_name,

src/memory_tracker.h

@@ -127,6 +127,9 @@ class MemoryRetainer {
  }
 
  virtual bool IsRootNode() const { return false; }
+ virtual v8::EmbedderGraph::Node::Detachedness GetDetachedness() const {
+ return v8::EmbedderGraph::Node::Detachedness::kUnknown;
+ }
 };
 
 class MemoryTracker {

test/common/heap.js

@@ -142,6 +142,22 @@ class State {
  }
  }
  }
+
+ if (expectation.detachedness !== undefined) {
+ const matchedNodes = rootNodes.filter(
+ (node) => node.detachedness === expectation.detachedness);
+ if (loose) {
+ assert(matchedNodes.length >= rootNodes.length,
+ `Expect to find at least ${rootNodes.length} with ` +
+ `detachedness ${expectation.detachedness}, ` +
+ `found ${matchedNodes.length}`);
+ } else {
+ assert.strictEqual(
+ matchedNodes.length, rootNodes.length,
+ `Expect to find ${rootNodes.length} with detachedness ` +
+ `${expectation.detachedness}, found ${matchedNodes.length}`);
+ }
+ }
  }
  }
 

test/pummel/test-heapdump-dns.js

@@ -13,6 +13,7 @@ validateSnapshotNodes('Node / ChannelWrap', [
  { node_name: 'Node / NodeAresTask::List', edge_name: 'task_list' },
  // `Node / ChannelWrap` (C++) -> `ChannelWrap` (JS)
  { node_name: 'ChannelWrap', edge_name: 'wrapped' },
- ]
+ ],
+ detachedness: 2
  },
 ]);