Simplify sampling rate calculation

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 185 matching lines @@
   unsigned next_node_id_;
   ProfileNode* root_;
   double ms_to_ticks_scale_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileTree);
 };
 
 
 class CpuProfile {
  public:
-  CpuProfile(const char* title, unsigned uid, bool record_samples)
-      : title_(title), uid_(uid), record_samples_(record_samples) { }
+  CpuProfile(const char* title, unsigned uid, bool record_samples);
 
   // Add pc -> ... -> main() call path to the profile.
   void AddPath(const Vector<CodeEntry*>& path);
-  void CalculateTotalTicks();
-  void SetActualSamplingRate(double actual_sampling_rate);
+  void CalculateTotalTicksAndSamplingRate();
 
   INLINE(const char* title() const) { return title_; }
   INLINE(unsigned uid() const) { return uid_; }
   INLINE(const ProfileTree* top_down() const) { return &top_down_; }
 
   INLINE(int samples_count() const) { return samples_.length(); }
   INLINE(ProfileNode* sample(int index) const) { return samples_.at(index); }
 
   void UpdateTicksScale();
 
   void ShortPrint();
   void Print();
 
  private:
   const char* title_;
   unsigned uid_;
   bool record_samples_;
+  double start_time_ms_;
+  double end_time_ms_;
   List<ProfileNode*> samples_;
   ProfileTree top_down_;
 
   DISALLOW_COPY_AND_ASSIGN(CpuProfile);
 };
 
 
 class CodeMap {
  public:
   CodeMap() : next_shared_id_(1) { }
@@ skipping 39 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(CodeMap);
 };
 
 
 class CpuProfilesCollection {
  public:
   CpuProfilesCollection();
   ~CpuProfilesCollection();
 
   bool StartProfiling(const char* title, unsigned uid, bool record_samples);
-  CpuProfile* StopProfiling(const char* title, double actual_sampling_rate);
+  CpuProfile* StopProfiling(const char* title);
   List<CpuProfile*>* profiles() { return &finished_profiles_; }
   const char* GetName(Name* name) {
     return function_and_resource_names_.GetName(name);
   }
   const char* GetName(int args_count) {
     return function_and_resource_names_.GetName(args_count);
   }
   const char* GetFunctionName(Name* name) {
     return function_and_resource_names_.GetFunctionName(name);
   }
@@ skipping 22 matching lines @@
   List<CpuProfile*> finished_profiles_;
 
   // Accessed by VM thread and profile generator thread.
   List<CpuProfile*> current_profiles_;
   Semaphore* current_profiles_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(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_;
-
-  DISALLOW_COPY_AND_ASSIGN(SampleRateCalculator);
-};
-
-
 class ProfileGenerator {
  public:
   explicit ProfileGenerator(CpuProfilesCollection* profiles);
 
   void RecordTickSample(const TickSample& sample);
 
   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* const kAnonymousFunctionName;
   static const char* const kProgramEntryName;
   static const char* const kGarbageCollectorEntryName;
   // Used to represent frames for which we have no reliable way to
   // detect function.
   static const char* const kUnresolvedFunctionName;
 
  private:
   INLINE(CodeEntry* EntryForVMState(StateTag tag));
 
   CpuProfilesCollection* profiles_;
   CodeMap code_map_;
   CodeEntry* program_entry_;
   CodeEntry* gc_entry_;
   CodeEntry* unresolved_entry_;
-  SampleRateCalculator sample_rate_calc_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileGenerator);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_