FrameStatistics.h

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/*  SPDX-License-Identifier: GPL-2.0-or-later */
/*!********************************************************************
 
  Audacity: A Digital Audio Editor
 
  FrameStatistics.h
 
  Dmitry Vedenko
 
**********************************************************************/
 
#pragma once
 
#include <chrono>
#include <cstddef>
#include <functional>
 
#include "Observer.h"
 
 
class GRAPHICS_API FrameStatistics final
{
public:
   using Clock = std::chrono::high_resolution_clock;
   using Duration = Clock::duration;
   using Timepoint = Clock::time_point;
 
   enum class SectionID
   {
      TrackPanel,
      WaveformView,
      WaveDataCache,
      WaveBitmapCachePreprocess,
      WaveBitmapCache,
      Count
   };
 
   struct GRAPHICS_API UpdatePublisher : Observer::Publisher<SectionID>
   {
      void Invoke(SectionID id);
   };
 
   class GRAPHICS_API Stopwatch final
   {
   public:
      ~Stopwatch() noexcept;
   private:
      explicit Stopwatch(SectionID section) noexcept;
 
      SectionID mSection;
      Timepoint mStart;
 
      friend class FrameStatistics;
   };
 
   class GRAPHICS_API Section final
   {
   public:
      Duration GetLastDuration() const noexcept;
      Duration GetMinDuration() const noexcept;
      Duration GetMaxDuration() const noexcept;
      Duration GetAverageDuration() const noexcept;
      size_t   GetEventsCount() const noexcept;
   private:
      void AddEvent(Duration duration) noexcept;
 
      static constexpr size_t KERNEL_SIZE = 16;
 
      Duration mLastDuration {};
      Duration mMinDuration { std::numeric_limits<Duration::rep>::max() };
      Duration mMaxDuration { std::numeric_limits<Duration::rep>::min() };
      Duration mAvgAccum {};
      Duration mAvgDuration {};
 
      Duration mFilteringKernel[KERNEL_SIZE] {};
      size_t mNextIndex { 0 };
      size_t mKernelItems { 0 };
 
      size_t mEventsCount { 0 };
 
      friend class FrameStatistics;
   };
 
   static Stopwatch CreateStopwatch(SectionID section) noexcept;
   static const Section& GetSection(SectionID section) noexcept;
   static Observer::Subscription Subscribe(UpdatePublisher::Callback callback);
private:
   void AddEvent(SectionID section, Duration duration);
 
   Section mSections[size_t(SectionID::Count)];
 
   UpdatePublisher mUpdatePublisher;
};