Introduce a way to grab heap stats.

src/profile-generator.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 692 matching lines @@
   HeapObjectsMap();
   ~HeapObjectsMap();
 
   void SnapshotGenerationFinished();
   SnapshotObjectId FindObject(Address addr);
   void MoveObject(Address from, Address to);
   SnapshotObjectId last_assigned_id() const {
     return next_id_ - kObjectIdStep;
   }
 
+  void StopHeapObjectsTracking();
+  void PushHeapObjectsStats(OutputStream* stream);
+
   static SnapshotObjectId GenerateId(v8::RetainedObjectInfo* info);
   static inline SnapshotObjectId GetNthGcSubrootId(int delta);
 
   static const int kObjectIdStep = 2;
   static const SnapshotObjectId kInternalRootObjectId;
   static const SnapshotObjectId kGcRootsObjectId;
   static const SnapshotObjectId kNativesRootObjectId;
   static const SnapshotObjectId kGcRootsFirstSubrootId;
   static const SnapshotObjectId kFirstAvailableObjectId;
 
  private:
   struct EntryInfo {
     EntryInfo(SnapshotObjectId id, Address addr)
       : id(id), addr(addr), accessed(true) { }
     EntryInfo(SnapshotObjectId id, Address addr, bool accessed)
       : id(id), addr(addr), accessed(accessed) { }
     SnapshotObjectId id;
     Address addr;
     bool accessed;
   };
+  struct TimeInterval {
+    explicit TimeInterval(SnapshotObjectId id) : id(id), count(0) { }
+    SnapshotObjectId id;
+    uint32_t count;
+  };
 
   void AddEntry(Address addr, SnapshotObjectId id);
   SnapshotObjectId FindEntry(Address addr);
+  SnapshotObjectId FindOrAddEntry(Address addr);
+  void UpdateHeapObjectsMap();
   void RemoveDeadEntries();
 
   static bool AddressesMatch(void* key1, void* key2) {
     return key1 == key2;
   }
 
   static uint32_t AddressHash(Address addr) {
     return ComputeIntegerHash(
         static_cast<uint32_t>(reinterpret_cast<uintptr_t>(addr)),
         v8::internal::kZeroHashSeed);
   }
 
   bool initial_fill_mode_;
   SnapshotObjectId next_id_;
   HashMap entries_map_;
   List<EntryInfo>* entries_;
+  List<TimeInterval> time_intervals_;
 
   DISALLOW_COPY_AND_ASSIGN(HeapObjectsMap);
 };
 
 
 class HeapSnapshotsCollection {
  public:
   HeapSnapshotsCollection();
   ~HeapSnapshotsCollection();
 
   bool is_tracking_objects() { return is_tracking_objects_; }
+  void PushHeapObjectsStats(OutputStream* stream) {
+    return ids_.PushHeapObjectsStats(stream);
+  }
+  void StartHeapObjectsTracking() { is_tracking_objects_ = true; }
+  void StopHeapObjectsTracking() { ids_.StopHeapObjectsTracking(); }
 
   HeapSnapshot* NewSnapshot(
       HeapSnapshot::Type type, const char* name, unsigned uid);
   void SnapshotGenerationFinished(HeapSnapshot* snapshot);
   List<HeapSnapshot*>* snapshots() { return &snapshots_; }
   HeapSnapshot* GetSnapshot(unsigned uid);
   void RemoveSnapshot(HeapSnapshot* snapshot);
 
   StringsStorage* names() { return &names_; }
   TokenEnumerator* token_enumerator() { return token_enumerator_; }
@@ skipping 392 matching lines @@
 
   friend class HeapSnapshotJSONSerializerEnumerator;
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_