Show detailed CPU load information in a tool-tip (#5970)

* Profiler rework

* Workaround for GCC bug

* Rollback QFile removal

* Use enum instead of a plain index to describe detailed stats

* Use the GCC workaround code for all compilers to avoid redundancy

* Update and fix comments

* Implement suggestions from review

* Split AudioEngine::renderNextBuffer() into separate functions, fix old formatting

* Remove QFile include

* Revert formatting changes

* Apply suggestion from review (remove unnecessary template parameter)

* Revert more formatting changes

* Convert DetailType to enum class

* DetailType enum class improvements suggested in review

* Use std::atomic for m_detailLoad

* RAII-style profiler probes

* Apply suggestions from code review

Co-authored-by: Dominic Clark <mrdomclark@gmail.com>

* Fix namespace comment

* Improve CPU load widget precision and use floats for load computations

* Atomic m_cpuLoad

* Add custom step size support for CPULoadWidget

* Apply suggestions from review (convert the profiler probe into a nested class, other small changes)

* Do not limit stored load averages to 100%

---------

Co-authored-by: sakertooth <sakertooth@gmail.com>
Co-authored-by: Dominic Clark <mrdomclark@gmail.com>

include/AudioEngine.h

@@ -275,6 +275,11 @@ public:
 		return m_profiler.cpuLoad();
 	}
 
+	int detailLoad(const AudioEngineProfiler::DetailType type) const
+	{
+		return m_profiler.detailLoad(type);
+	}
+
 	const qualitySettings & currentQualitySettings() const
 	{
 		return m_qualitySettings;
@@ -401,6 +406,10 @@ private:
 	AudioDevice * tryAudioDevices();
 	MidiClient * tryMidiClients();
 
+	void renderStageNoteSetup();
+	void renderStageInstruments();
+	void renderStageEffects();
+	void renderStageMix();
 
 	const surroundSampleFrame * renderNextBuffer();
 

include/AudioEngineProfiler.h

@@ -25,6 +25,8 @@
 #ifndef LMMS_AUDIO_ENGINE_PROFILER_H
 #define LMMS_AUDIO_ENGINE_PROFILER_H
 
+#include <array>
+#include <atomic>
 #include <QFile>
 
 #include "lmms_basics.h"
@@ -53,11 +55,55 @@ public:
 
 	void setOutputFile( const QString& outputFile );
 
+	enum class DetailType {
+		NoteSetup,
+		Instruments,
+		Effects,
+		Mixing,
+		Count
+	};
+
+	constexpr static auto DetailCount = static_cast<std::size_t>(DetailType::Count);
+
+	int detailLoad(const DetailType type) const
+	{
+		return m_detailLoad[static_cast<std::size_t>(type)].load(std::memory_order_relaxed);
+	}
+
+	class Probe
+	{
+	public:
+		Probe(AudioEngineProfiler& profiler, AudioEngineProfiler::DetailType type)
+			: m_profiler(profiler)
+			, m_type(type)
+		{
+			profiler.startDetail(type);
+		}
+		~Probe() { m_profiler.finishDetail(m_type); }
+		Probe& operator=(const Probe&) = delete;
+		Probe(const Probe&) = delete;
+		Probe(Probe&&) = delete;
+
+	private:
+		AudioEngineProfiler &m_profiler;
+		const AudioEngineProfiler::DetailType m_type;
+	};
 
 private:
+	void startDetail(const DetailType type) { m_detailTimer[static_cast<std::size_t>(type)].reset(); }
+	void finishDetail(const DetailType type)
+	{
+		m_detailTime[static_cast<std::size_t>(type)] = m_detailTimer[static_cast<std::size_t>(type)].elapsed();
+	}
+
 	MicroTimer m_periodTimer;
-	int m_cpuLoad;
+	std::atomic<float> m_cpuLoad;
 	QFile m_outputFile;
+
+	// Use arrays to avoid dynamic allocations in realtime code
+	std::array<MicroTimer, DetailCount> m_detailTimer;
+	std::array<int, DetailCount> m_detailTime{0};
+	std::array<std::atomic<float>, DetailCount> m_detailLoad{0};
 };
 
 } // namespace lmms

include/CPULoadWidget.h

@@ -26,6 +26,7 @@
 #ifndef LMMS_GUI_CPU_LOAD_WIDGET_H
 #define LMMS_GUI_CPU_LOAD_WIDGET_H
 
+#include <algorithm>
 #include <QTimer>
 #include <QPixmap>
 #include <QWidget>
@@ -40,6 +41,7 @@ namespace lmms::gui
 class CPULoadWidget : public QWidget
 {
 	Q_OBJECT
+	Q_PROPERTY(int stepSize MEMBER m_stepSize)
 public:
 	CPULoadWidget( QWidget * _parent );
 	~CPULoadWidget() override = default;
@@ -54,6 +56,8 @@ protected slots:
 
 
 private:
+	int stepSize() const { return std::max(1, m_stepSize); }
+
 	int m_currentLoad;
 
 	QPixmap m_temp;
@@ -64,6 +68,8 @@ private:
 
 	QTimer m_updateTimer;
 
+	int m_stepSize;
+
 } ;