[api,profiler] Introduce GetRetainerInfos callback for profiling

BUG=679724

Review-Url: https://codereview.chromium.org/2631063003
Cr-Commit-Position: refs/heads/master@{#42506}

include/v8-profiler.h

@@ -5,6 +5,7 @@
 #ifndef V8_V8_PROFILER_H_
 #define V8_V8_PROFILER_H_
 
+#include <unordered_set>
 #include <vector>
 #include "v8.h"  // NOLINT(build/include)
 
@@ -630,6 +631,24 @@ class V8_EXPORT HeapProfiler {
     kSamplingForceGC = 1 << 0,
   };
 
+  typedef std::unordered_set<const v8::PersistentBase<v8::Value>*>
+      RetainerChildren;
+  typedef std::vector<std::pair<v8::RetainedObjectInfo*, RetainerChildren>>
+      RetainerGroups;
+  typedef std::vector<std::pair<const v8::PersistentBase<v8::Value>*,
+                                const v8::PersistentBase<v8::Value>*>>
+      RetainerEdges;
+
+  struct RetainerInfos {
+    RetainerGroups groups;
+    RetainerEdges edges;
+  };
+
+  /**
+   * Callback function invoked to retrieve all RetainerInfos from the embedder.
+   */
+  typedef RetainerInfos (*GetRetainerInfosCallback)(v8::Isolate* isolate);
+
   /**
    * Callback function invoked for obtaining RetainedObjectInfo for
    * the given JavaScript wrapper object. It is prohibited to enter V8
@@ -782,6 +801,8 @@ class V8_EXPORT HeapProfiler {
       uint16_t class_id,
       WrapperInfoCallback callback);
 
+  void SetGetRetainerInfosCallback(GetRetainerInfosCallback callback);
+
   /**
    * Default value of persistent handle class ID. Must not be used to
    * define a class. Can be used to reset a class of a persistent

src/api.cc

@@ -9755,6 +9755,11 @@ void HeapProfiler::SetWrapperClassInfoProvider(uint16_t class_id,
                                                                callback);
 }
 
+void HeapProfiler::SetGetRetainerInfosCallback(
+    GetRetainerInfosCallback callback) {
+  reinterpret_cast<i::HeapProfiler*>(this)->SetGetRetainerInfosCallback(
+      callback);
+}
 
 size_t HeapProfiler::GetProfilerMemorySize() {
   return reinterpret_cast<i::HeapProfiler*>(this)->

src/profiler/heap-profiler.cc

@@ -16,9 +16,8 @@ namespace internal {
 HeapProfiler::HeapProfiler(Heap* heap)
     : ids_(new HeapObjectsMap(heap)),
       names_(new StringsStorage(heap)),
-      is_tracking_object_moves_(false) {
-}
-
+      is_tracking_object_moves_(false),
+      get_retainer_infos_callback_(nullptr) {}
 
 static void DeleteHeapSnapshot(HeapSnapshot** snapshot_ptr) {
   delete *snapshot_ptr;
@@ -61,6 +60,19 @@ v8::RetainedObjectInfo* HeapProfiler::ExecuteWrapperClassCallback(
       class_id, Utils::ToLocal(Handle<Object>(wrapper)));
 }
 
+void HeapProfiler::SetGetRetainerInfosCallback(
+    v8::HeapProfiler::GetRetainerInfosCallback callback) {
+  get_retainer_infos_callback_ = callback;
+}
+
+v8::HeapProfiler::RetainerInfos HeapProfiler::GetRetainerInfos(
+    Isolate* isolate) {
+  v8::HeapProfiler::RetainerInfos infos;
+  if (get_retainer_infos_callback_ != nullptr)
+    infos =
+        get_retainer_infos_callback_(reinterpret_cast<v8::Isolate*>(isolate));
+  return infos;
+}
 
 HeapSnapshot* HeapProfiler::TakeSnapshot(
     v8::ActivityControl* control,

src/profiler/heap-profiler.h

@@ -66,6 +66,11 @@ class HeapProfiler {
                                                       Object** wrapper);
   void SetRetainedObjectInfo(UniqueId id, RetainedObjectInfo* info);
 
+  void SetGetRetainerInfosCallback(
+      v8::HeapProfiler::GetRetainerInfosCallback callback);
+
+  v8::HeapProfiler::RetainerInfos GetRetainerInfos(Isolate* isolate);
+
   bool is_tracking_object_moves() const { return is_tracking_object_moves_; }
   bool is_tracking_allocations() const { return !!allocation_tracker_; }
 
@@ -86,6 +91,7 @@ class HeapProfiler {
   bool is_tracking_object_moves_;
   base::Mutex profiler_mutex_;
   std::unique_ptr<SamplingHeapProfiler> sampling_heap_profiler_;
+  v8::HeapProfiler::GetRetainerInfosCallback get_retainer_infos_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(HeapProfiler);
 };