Report approximated duration in milliseconds for profile nodes.

src/profile-generator.h

Index: src/profile-generator.h
diff --git a/src/profile-generator.h b/src/profile-generator.h
index b02ba8575ef94e5e3e2c20cceb35fede20a50c13..bd5b0cd24f64fba67eaf68a5c2ed805810072391 100644
--- a/src/profile-generator.h
+++ b/src/profile-generator.h
@@ -70,9 +70,11 @@ class CodeEntry {
 };
 
 
+class ProfileTree;
+
 class ProfileNode {
  public:
-  INLINE(explicit ProfileNode(CodeEntry* entry));
+  INLINE(ProfileNode(ProfileTree* tree, CodeEntry* entry));
 
   ProfileNode* FindChild(CodeEntry* entry);
   ProfileNode* FindOrAddChild(CodeEntry* entry);
@@ -80,9 +82,11 @@ class ProfileNode {
   INLINE(void IncreaseTotalTicks(unsigned amount)) { total_ticks_ += amount; }
 
   INLINE(CodeEntry* entry() const) { return entry_; }
-  INLINE(unsigned total_ticks() const) { return total_ticks_; }
   INLINE(unsigned self_ticks() const) { return self_ticks_; }
+  INLINE(unsigned total_ticks() const) { return total_ticks_; }
   INLINE(const List<ProfileNode*>* children() const) { return &children_list_; }
+  double GetSelfMillis() const;
+  double GetTotalMillis() const;
 
   void Print(int indent);
 
@@ -95,6 +99,7 @@ class ProfileNode {
     return static_cast<int32_t>(reinterpret_cast<intptr_t>(entry));
   }
 
+  ProfileTree* tree_;
   CodeEntry* entry_;
   unsigned total_ticks_;
   unsigned self_ticks_;
@@ -115,7 +120,11 @@ class ProfileTree {
   void AddPathFromStart(const Vector<CodeEntry*>& path);
   void CalculateTotalTicks();
 
+  double TicksToMillis(unsigned ticks) const {
+    return ticks * ms_to_ticks_scale_;
+  }
   ProfileNode* root() const { return root_; }
+  void SetTickRatePerMs(double ticks_per_ms);
 
   void ShortPrint();
   void Print() {
@@ -124,10 +133,11 @@ class ProfileTree {
 
  private:
   template <typename Callback>
-  void TraverseBreadthFirstPostOrder(Callback* callback);
+  void TraverseDepthFirstPostOrder(Callback* callback);
 
   CodeEntry root_entry_;
   ProfileNode* root_;
+  double ms_to_ticks_scale_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileTree);
 };
@@ -141,12 +151,15 @@ class CpuProfile {
   // Add pc -> ... -> main() call path to the profile.
   void AddPath(const Vector<CodeEntry*>& path);
   void CalculateTotalTicks();
+  void SetActualSamplingRate(double actual_sampling_rate);
 
   INLINE(const char* title() const) { return title_; }
   INLINE(unsigned uid() const) { return uid_; }
   INLINE(const ProfileTree* top_down() const) { return &top_down_; }
   INLINE(const ProfileTree* bottom_up() const) { return &bottom_up_; }
 
+  void UpdateTicksScale();
+
   void ShortPrint();
   void Print();
 
@@ -208,8 +221,8 @@ class CpuProfilesCollection {
 
   bool StartProfiling(const char* title, unsigned uid);
   bool StartProfiling(String* title, unsigned uid);
-  CpuProfile* StopProfiling(const char* title);
-  CpuProfile* StopProfiling(String* title);
+  CpuProfile* StopProfiling(const char* title, double actual_sampling_rate);
+  CpuProfile* StopProfiling(String* title, double actual_sampling_rate);
   INLINE(List<CpuProfile*>* profiles()) { return &profiles_; }
   CpuProfile* GetProfile(unsigned uid);
   inline bool is_last_profile();
@@ -256,6 +269,42 @@ class CpuProfilesCollection {
 };
 
 
+class SampleRateCalculator {
+ public:
+  SampleRateCalculator()
+      : result_(Logger::kSamplingIntervalMs * kResultScale),
+        ticks_per_ms_(Logger::kSamplingIntervalMs),
+        measurements_count_(0),
+        wall_time_query_countdown_(1) {
+  }
+
+  double ticks_per_ms() {
+    return result_ / static_cast<double>(kResultScale);
+  }
+  void Tick();
+  void UpdateMeasurements(double current_time);
+
+  // Instead of querying current wall time each tick,
+  // we use this constant to control query intervals.
+  static const unsigned kWallTimeQueryIntervalMs = 100;
+
+ private:
+  // As the result needs to be accessed from a different thread, we
+  // use type that guarantees atomic writes to memory.  There should
+  // be <= 1000 ticks per second, thus storing a value of a 10 ** 5
+  // order should provide enough precision while keeping away from a
+  // potential overflow.
+  static const int kResultScale = 100000;
+
+  AtomicWord result_;
+  // All other fields are accessed only from the sampler thread.
+  double ticks_per_ms_;
+  unsigned measurements_count_;
+  unsigned wall_time_query_countdown_;
+  double last_wall_time_;
+};
+
+
 class ProfileGenerator {
  public:
   explicit ProfileGenerator(CpuProfilesCollection* profiles);
@@ -287,6 +336,11 @@ class ProfileGenerator {
 
   INLINE(CodeMap* code_map()) { return &code_map_; }
 
+  INLINE(void Tick()) { sample_rate_calc_.Tick(); }
+  INLINE(double actual_sampling_rate()) {
+    return sample_rate_calc_.ticks_per_ms();
+  }
+
   static const char* kAnonymousFunctionName;
   static const char* kProgramEntryName;
   static const char* kGarbageCollectorEntryName;
@@ -298,6 +352,7 @@ class ProfileGenerator {
   CodeMap code_map_;
   CodeEntry* program_entry_;
   CodeEntry* gc_entry_;
+  SampleRateCalculator sample_rate_calc_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileGenerator);
 };