src: use V8 graph heap snapshot API

common.gypi

@@ -28,7 +28,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.14',
+    'v8_embedder_string': '-node.15',
 
     # Enable disassembler for `--print-code` v8 options
     'v8_enable_disassembler': 1,

deps/v8/include/v8-profiler.h

@@ -636,7 +636,7 @@ class V8_EXPORT AllocationProfile {
  * Usage:
  * 1) Define derived class of EmbedderGraph::Node for embedder objects.
  * 2) Set the build embedder graph callback on the heap profiler using
- *    HeapProfiler::SetBuildEmbedderGraphCallback.
+ *    HeapProfiler::AddBuildEmbedderGraphCallback.
  * 3) In the callback use graph->AddEdge(node1, node2) to add an edge from
  *    node1 to node2.
  * 4) To represent references from/to V8 object, construct V8 nodes using
@@ -736,7 +736,12 @@ class V8_EXPORT HeapProfiler {
    * The callback must not trigger garbage collection in V8.
    */
   typedef void (*BuildEmbedderGraphCallback)(v8::Isolate* isolate,
-                                             v8::EmbedderGraph* graph);
+                                             v8::EmbedderGraph* graph,
+                                             void* data);
+
+  /** TODO(addaleax): Remove */
+  typedef void (*LegacyBuildEmbedderGraphCallback)(v8::Isolate* isolate,
+                                                   v8::EmbedderGraph* graph);
 
   /** Returns the number of snapshots taken. */
   int GetSnapshotCount();
@@ -878,15 +883,22 @@ class V8_EXPORT HeapProfiler {
 
   /** Binds a callback to embedder's class ID. */
   V8_DEPRECATED(
-      "Use SetBuildEmbedderGraphCallback to provide info about embedder nodes",
+      "Use AddBuildEmbedderGraphCallback to provide info about embedder nodes",
       void SetWrapperClassInfoProvider(uint16_t class_id,
                                        WrapperInfoCallback callback));
 
   V8_DEPRECATED(
-      "Use SetBuildEmbedderGraphCallback to provide info about embedder nodes",
+      "Use AddBuildEmbedderGraphCallback to provide info about embedder nodes",
       void SetGetRetainerInfosCallback(GetRetainerInfosCallback callback));
 
-  void SetBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback);
+  V8_DEPRECATE_SOON(
+      "Use AddBuildEmbedderGraphCallback to provide info about embedder nodes",
+      void SetBuildEmbedderGraphCallback(
+          LegacyBuildEmbedderGraphCallback callback));
+  void AddBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback,
+                                     void* data);
+  void RemoveBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback,
+                                        void* data);
 
   /**
    * Default value of persistent handle class ID. Must not be used to

deps/v8/src/api.cc

@@ -10558,9 +10558,25 @@ void HeapProfiler::SetGetRetainerInfosCallback(
 }
 
 void HeapProfiler::SetBuildEmbedderGraphCallback(
-    BuildEmbedderGraphCallback callback) {
-  reinterpret_cast<i::HeapProfiler*>(this)->SetBuildEmbedderGraphCallback(
-      callback);
+    LegacyBuildEmbedderGraphCallback callback) {
+  reinterpret_cast<i::HeapProfiler*>(this)->AddBuildEmbedderGraphCallback(
+      [](v8::Isolate* isolate, v8::EmbedderGraph* graph, void* data) {
+        reinterpret_cast<LegacyBuildEmbedderGraphCallback>(data)(isolate,
+                                                                 graph);
+      },
+      reinterpret_cast<void*>(callback));
+}
+
+void HeapProfiler::AddBuildEmbedderGraphCallback(
+    BuildEmbedderGraphCallback callback, void* data) {
+  reinterpret_cast<i::HeapProfiler*>(this)->AddBuildEmbedderGraphCallback(
+      callback, data);
+}
+
+void HeapProfiler::RemoveBuildEmbedderGraphCallback(
+    BuildEmbedderGraphCallback callback, void* data) {
+  reinterpret_cast<i::HeapProfiler*>(this)->RemoveBuildEmbedderGraphCallback(
+      callback, data);
 }
 
 v8::Testing::StressType internal::Testing::stress_type_ =

deps/v8/src/profiler/heap-profiler.cc

@@ -69,16 +69,25 @@ v8::HeapProfiler::RetainerInfos HeapProfiler::GetRetainerInfos(
   return infos;
 }
 
-void HeapProfiler::SetBuildEmbedderGraphCallback(
-    v8::HeapProfiler::BuildEmbedderGraphCallback callback) {
-  build_embedder_graph_callback_ = callback;
+void HeapProfiler::AddBuildEmbedderGraphCallback(
+    v8::HeapProfiler::BuildEmbedderGraphCallback callback, void* data) {
+  build_embedder_graph_callbacks_.push_back({callback, data});
+}
+
+void HeapProfiler::RemoveBuildEmbedderGraphCallback(
+    v8::HeapProfiler::BuildEmbedderGraphCallback callback, void* data) {
+  auto it = std::find(build_embedder_graph_callbacks_.begin(),
+                      build_embedder_graph_callbacks_.end(),
+                      std::make_pair(callback, data));
+  if (it != build_embedder_graph_callbacks_.end())
+    build_embedder_graph_callbacks_.erase(it);
 }
 
 void HeapProfiler::BuildEmbedderGraph(Isolate* isolate,
                                       v8::EmbedderGraph* graph) {
-  if (build_embedder_graph_callback_ != nullptr)
-    build_embedder_graph_callback_(reinterpret_cast<v8::Isolate*>(isolate),
-                                   graph);
+  for (const auto& cb : build_embedder_graph_callbacks_) {
+    cb.first(reinterpret_cast<v8::Isolate*>(isolate), graph, cb.second);
+  }
 }
 
 HeapSnapshot* HeapProfiler::TakeSnapshot(

deps/v8/src/profiler/heap-profiler.h

@@ -71,11 +71,13 @@ class HeapProfiler : public HeapObjectAllocationTracker {
       v8::HeapProfiler::GetRetainerInfosCallback callback);
   v8::HeapProfiler::RetainerInfos GetRetainerInfos(Isolate* isolate);
 
-  void SetBuildEmbedderGraphCallback(
-      v8::HeapProfiler::BuildEmbedderGraphCallback callback);
+  void AddBuildEmbedderGraphCallback(
+      v8::HeapProfiler::BuildEmbedderGraphCallback callback, void* data);
+  void RemoveBuildEmbedderGraphCallback(
+      v8::HeapProfiler::BuildEmbedderGraphCallback callback, void* data);
   void BuildEmbedderGraph(Isolate* isolate, v8::EmbedderGraph* graph);
   bool HasBuildEmbedderGraphCallback() {
-    return build_embedder_graph_callback_ != nullptr;
+    return !build_embedder_graph_callbacks_.empty();
   }
 
   bool is_tracking_object_moves() const { return is_tracking_object_moves_; }
@@ -103,8 +105,8 @@ class HeapProfiler : public HeapObjectAllocationTracker {
   std::unique_ptr<SamplingHeapProfiler> sampling_heap_profiler_;
   v8::HeapProfiler::GetRetainerInfosCallback get_retainer_infos_callback_ =
       nullptr;
-  v8::HeapProfiler::BuildEmbedderGraphCallback build_embedder_graph_callback_ =
-      nullptr;
+  std::vector<std::pair<v8::HeapProfiler::BuildEmbedderGraphCallback, void*>>
+      build_embedder_graph_callbacks_;
 
   DISALLOW_COPY_AND_ASSIGN(HeapProfiler);
 };

deps/v8/test/cctest/test-heap-profiler.cc

@@ -1541,8 +1541,8 @@ class EmbedderGraphBuilder : public v8::PersistentHandleVisitor {
         graph->AddNode(std::unique_ptr<Group>(new Group("ccc-group")));
   }
 
-  static void BuildEmbedderGraph(v8::Isolate* isolate,
-                                 v8::EmbedderGraph* graph) {
+  static void BuildEmbedderGraph(v8::Isolate* isolate, v8::EmbedderGraph* graph,
+                                 void* data) {
     EmbedderGraphBuilder builder(isolate, graph);
     isolate->VisitHandlesWithClassIds(&builder);
   }
@@ -1604,8 +1604,8 @@ TEST(HeapSnapshotRetainedObjectInfo) {
   v8::HandleScope scope(isolate);
   v8::HeapProfiler* heap_profiler = isolate->GetHeapProfiler();
 
-  heap_profiler->SetBuildEmbedderGraphCallback(
-      EmbedderGraphBuilder::BuildEmbedderGraph);
+  heap_profiler->AddBuildEmbedderGraphCallback(
+      EmbedderGraphBuilder::BuildEmbedderGraph, nullptr);
   v8::Persistent<v8::String> p_AAA(isolate, v8_str("AAA"));
   p_AAA.SetWrapperClassId(1);
   v8::Persistent<v8::String> p_BBB(isolate, v8_str("BBB"));
@@ -2932,7 +2932,8 @@ class EmbedderRootNode : public EmbedderNode {
 // global object.
 v8::Local<v8::Value>* global_object_pointer;
 
-void BuildEmbedderGraph(v8::Isolate* v8_isolate, v8::EmbedderGraph* graph) {
+void BuildEmbedderGraph(v8::Isolate* v8_isolate, v8::EmbedderGraph* graph,
+                        void* data) {
   using Node = v8::EmbedderGraph::Node;
   Node* global_node = graph->V8Node(*global_object_pointer);
   Node* embedder_node_A = graph->AddNode(
@@ -2979,12 +2980,92 @@ TEST(EmbedderGraph) {
           (isolate->context()->native_context()->global_object())));
   global_object_pointer = &global_object;
   v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();
-  heap_profiler->SetBuildEmbedderGraphCallback(BuildEmbedderGraph);
+  heap_profiler->AddBuildEmbedderGraphCallback(BuildEmbedderGraph, nullptr);
   const v8::HeapSnapshot* snapshot = heap_profiler->TakeHeapSnapshot();
   CHECK(ValidateSnapshot(snapshot));
   CheckEmbedderGraphSnapshot(env->GetIsolate(), snapshot);
 }
 
+struct GraphBuildingContext {
+  int counter = 0;
+};
+
+void CheckEmbedderGraphSnapshotWithContext(
+    v8::Isolate* isolate, const v8::HeapSnapshot* snapshot,
+    const GraphBuildingContext* context) {
+  const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
+  CHECK_GE(context->counter, 1);
+  CHECK_LE(context->counter, 2);
+
+  const v8::HeapGraphNode* embedder_node_A =
+      GetChildByName(global, "EmbedderNodeA");
+  CHECK_EQ(10, GetSize(embedder_node_A));
+
+  const v8::HeapGraphNode* embedder_node_B =
+      GetChildByName(global, "EmbedderNodeB");
+  if (context->counter == 2) {
+    CHECK_NOT_NULL(embedder_node_B);
+    CHECK_EQ(20, GetSize(embedder_node_B));
+  } else {
+    CHECK_NULL(embedder_node_B);
+  }
+}
+
+void BuildEmbedderGraphWithContext(v8::Isolate* v8_isolate,
+                                   v8::EmbedderGraph* graph, void* data) {
+  using Node = v8::EmbedderGraph::Node;
+  GraphBuildingContext* context = static_cast<GraphBuildingContext*>(data);
+  Node* global_node = graph->V8Node(*global_object_pointer);
+
+  CHECK_GE(context->counter, 0);
+  CHECK_LE(context->counter, 1);
+  switch (context->counter++) {
+    case 0: {
+      Node* embedder_node_A = graph->AddNode(
+          std::unique_ptr<Node>(new EmbedderNode("EmbedderNodeA", 10)));
+      graph->AddEdge(global_node, embedder_node_A);
+      break;
+    }
+    case 1: {
+      Node* embedder_node_B = graph->AddNode(
+          std::unique_ptr<Node>(new EmbedderNode("EmbedderNodeB", 20)));
+      graph->AddEdge(global_node, embedder_node_B);
+      break;
+    }
+  }
+}
+
+TEST(EmbedderGraphMultipleCallbacks) {
+  i::FLAG_heap_profiler_use_embedder_graph = true;
+  LocalContext env;
+  v8::HandleScope scope(env->GetIsolate());
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(env->GetIsolate());
+  v8::Local<v8::Value> global_object =
+      v8::Utils::ToLocal(i::Handle<i::JSObject>(
+          (isolate->context()->native_context()->global_object())));
+  global_object_pointer = &global_object;
+  v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();
+  GraphBuildingContext context;
+
+  heap_profiler->AddBuildEmbedderGraphCallback(BuildEmbedderGraphWithContext,
+                                               &context);
+  heap_profiler->AddBuildEmbedderGraphCallback(BuildEmbedderGraphWithContext,
+                                               &context);
+  const v8::HeapSnapshot* snapshot = heap_profiler->TakeHeapSnapshot();
+  CHECK_EQ(context.counter, 2);
+  CHECK(ValidateSnapshot(snapshot));
+  CheckEmbedderGraphSnapshotWithContext(env->GetIsolate(), snapshot, &context);
+
+  heap_profiler->RemoveBuildEmbedderGraphCallback(BuildEmbedderGraphWithContext,
+                                                  &context);
+  context.counter = 0;
+
+  snapshot = heap_profiler->TakeHeapSnapshot();
+  CHECK_EQ(context.counter, 1);
+  CHECK(ValidateSnapshot(snapshot));
+  CheckEmbedderGraphSnapshotWithContext(env->GetIsolate(), snapshot, &context);
+}
+
 TEST(StrongHandleAnnotation) {
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());
@@ -3010,7 +3091,7 @@ TEST(StrongHandleAnnotation) {
 }
 
 void BuildEmbedderGraphWithWrapperNode(v8::Isolate* v8_isolate,
-                                       v8::EmbedderGraph* graph) {
+                                       v8::EmbedderGraph* graph, void* data) {
   using Node = v8::EmbedderGraph::Node;
   Node* global_node = graph->V8Node(*global_object_pointer);
   Node* wrapper_node = graph->AddNode(
@@ -3041,8 +3122,8 @@ TEST(EmbedderGraphWithWrapperNode) {
           (isolate->context()->native_context()->global_object())));
   global_object_pointer = &global_object;
   v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();
-  heap_profiler->SetBuildEmbedderGraphCallback(
-      BuildEmbedderGraphWithWrapperNode);
+  heap_profiler->AddBuildEmbedderGraphCallback(
+      BuildEmbedderGraphWithWrapperNode, nullptr);
   const v8::HeapSnapshot* snapshot = heap_profiler->TakeHeapSnapshot();
   CHECK(ValidateSnapshot(snapshot));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
@@ -3080,7 +3161,7 @@ class EmbedderNodeWithPrefix : public v8::EmbedderGraph::Node {
 };
 
 void BuildEmbedderGraphWithPrefix(v8::Isolate* v8_isolate,
-                                  v8::EmbedderGraph* graph) {
+                                  v8::EmbedderGraph* graph, void* data) {
   using Node = v8::EmbedderGraph::Node;
   Node* global_node = graph->V8Node(*global_object_pointer);
   Node* node = graph->AddNode(
@@ -3098,7 +3179,8 @@ TEST(EmbedderGraphWithPrefix) {
           (isolate->context()->native_context()->global_object())));
   global_object_pointer = &global_object;
   v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();
-  heap_profiler->SetBuildEmbedderGraphCallback(BuildEmbedderGraphWithPrefix);
+  heap_profiler->AddBuildEmbedderGraphCallback(BuildEmbedderGraphWithPrefix,
+                                               nullptr);
   const v8::HeapSnapshot* snapshot = heap_profiler->TakeHeapSnapshot();
   CHECK(ValidateSnapshot(snapshot));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);

lib/internal/test/heap.js

@@ -0,0 +1,87 @@
+'use strict';
+
+process.emitWarning(
+  'These APIs are exposed only for testing and are not ' +
+  'tracked by any versioning system or deprecation process.',
+  'internal/test/heap');
+
+const { internalBinding } = require('internal/bootstrap/loaders');
+const { createHeapDump, buildEmbedderGraph } = internalBinding('heap_utils');
+const assert = require('assert');
+
+// This is not suitable for production code. It creates a full V8 heap dump,
+// parses it as JSON, and then creates complex objects from it, leading
+// to significantly increased memory usage.
+function createJSHeapDump() {
+  const dump = createHeapDump();
+  const meta = dump.snapshot.meta;
+
+  const nodes =
+    readHeapInfo(dump.nodes, meta.node_fields, meta.node_types, dump.strings);
+  const edges =
+    readHeapInfo(dump.edges, meta.edge_fields, meta.edge_types, dump.strings);
+
+  for (const node of nodes) {
+    node.incomingEdges = [];
+    node.outgoingEdges = [];
+  }
+
+  let fromNodeIndex = 0;
+  let edgeIndex = 0;
+  for (const { type, name_or_index, to_node } of edges) {
+    while (edgeIndex === nodes[fromNodeIndex].edge_count) {
+      edgeIndex = 0;
+      fromNodeIndex++;
+    }
+    const toNode = nodes[to_node / meta.node_fields.length];
+    const fromNode = nodes[fromNodeIndex];
+    const edge = {
+      type,
+      toNode,
+      fromNode,
+      name: typeof name_or_index === 'string' ? name_or_index : null
+    };
+    toNode.incomingEdges.push(edge);
+    fromNode.outgoingEdges.push(edge);
+    edgeIndex++;
+  }
+
+  for (const node of nodes)
+    assert.strictEqual(node.edge_count, node.outgoingEdges.length);
+
+  return nodes;
+}
+
+function readHeapInfo(raw, fields, types, strings) {
+  const items = [];
+
+  for (var i = 0; i < raw.length; i += fields.length) {
+    const item = {};
+    for (var j = 0; j < fields.length; j++) {
+      const name = fields[j];
+      let type = types[j];
+      if (Array.isArray(type)) {
+        item[name] = type[raw[i + j]];
+      } else if (name === 'name_or_index') {  // type === 'string_or_number'
+        if (item.type === 'element' || item.type === 'hidden')
+          type = 'number';
+        else
+          type = 'string';
+      }
+
+      if (type === 'string') {
+        item[name] = strings[raw[i + j]];
+      } else if (type === 'number' || type === 'node') {
+        item[name] = raw[i + j];
+      }
+    }
+    items.push(item);
+  }
+
+  return items;
+}
+
+module.exports = {
+  createJSHeapDump,
+  buildEmbedderGraph
+};