metrics: added OperationTiming which is a useful combination of a Meter and a Histogram, intended to track frequency and duration of certain operations

3 files changed, 120 insertions, 1 deletions

diff --git a/zencore/include/zencore/stats.h b/zencore/include/zencore/stats.h
index f61184ced..dfa8dac34 100644
--- a/zencore/include/zencore/stats.h
+++ b/zencore/include/zencore/stats.h
@@ -180,6 +180,46 @@ private:
 	std::atomic<int64_t> m_Count{0};
 };
 
+/** Track timing and frequency of some operation
+
+	Example usage would be to track frequency and duration of network
+	requests, or function calls.
+
+ */
+class OperationTiming
+{
+public:
+	OperationTiming(int32_t SampleCount = 514);
+	~OperationTiming();
+
+	void		   Update(int64_t Duration);
+	int64_t		   Max() const;
+	int64_t		   Min() const;
+	double		   Mean() const;
+	uint64_t	   Count() const;
+	SampleSnapshot Snapshot() const { return m_Histogram.Snapshot(); }
+
+	double Rate1() { return m_Meter.Rate1(); }
+	double Rate5() { return m_Meter.Rate5(); }
+	double Rate15() { return m_Meter.Rate15(); }
+	double MeanRate() const { return m_Meter.MeanRate(); }
+
+	struct Scope
+	{
+		Scope(OperationTiming& Outer);
+		~Scope();
+
+	private:
+		OperationTiming& m_Outer;
+		uint64_t		 m_StartTick;
+	};
+
+private:
+	Meter	  m_Meter;
+	Histogram m_Histogram;
+};
+
+void EmitSnapshot(std::string_view Tag, OperationTiming& Stat, CbObjectWriter& Cbo);
 void EmitSnapshot(std::string_view Tag, const Histogram& Stat, CbObjectWriter& Cbo);
 void EmitSnapshot(std::string_view Tag, Meter& Stat, CbObjectWriter& Cbo);
 
diff --git a/zencore/stats.cpp b/zencore/stats.cpp
index 53086f3ec..34dc2828f 100644
--- a/zencore/stats.cpp
+++ b/zencore/stats.cpp
@@ -353,6 +353,78 @@ SampleSnapshot::GetValues() const
 
 //////////////////////////////////////////////////////////////////////////
 
+OperationTiming::OperationTiming(int32_t SampleCount) : m_Histogram{SampleCount}
+{
+}
+
+OperationTiming::~OperationTiming()
+{
+}
+
+void
+OperationTiming::Update(int64_t Duration)
+{
+	m_Meter.Mark(1);
+	m_Histogram.Update(Duration);
+}
+
+int64_t
+OperationTiming::Max() const
+{
+	return m_Histogram.Max();
+}
+
+int64_t
+OperationTiming::Min() const
+{
+	return m_Histogram.Min();
+}
+
+double
+OperationTiming::Mean() const
+{
+	return m_Histogram.Mean();
+}
+
+uint64_t
+OperationTiming::Count() const
+{
+	return m_Meter.Count();
+}
+
+OperationTiming::Scope::Scope(OperationTiming& Outer) : m_Outer(Outer), m_StartTick(GetHifreqTimerValue())
+{
+}
+
+OperationTiming::Scope::~Scope()
+{
+	m_Outer.Update(GetHifreqTimerValue() - m_StartTick);
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+void
+EmitSnapshot(std::string_view Tag, OperationTiming& Stat, CbObjectWriter& Cbo)
+{
+	Cbo.BeginObject(Tag);
+
+	SampleSnapshot Snap = Stat.Snapshot();
+
+	Cbo << "count" << Stat.Count();
+
+	Cbo << "rate_mean" << Stat.MeanRate();
+	Cbo << "rate_1" << Stat.Rate1() << "rate_5" << Stat.Rate5() << "rate_15" << Stat.Rate15();
+
+	const double ToSeconds = GetHifreqTimerToSeconds();
+
+	Cbo << "t_avg" << Stat.Mean() * ToSeconds;
+	Cbo << "t_min" << Stat.Min() * ToSeconds << "t_max" << Stat.Max() * ToSeconds;
+	Cbo << "t_p75" << Snap.Get75Percentile() * ToSeconds << "t_p95" << Snap.Get95Percentile() * ToSeconds << "t_p99"
+		<< Snap.Get99Percentile() * ToSeconds << "t_p999" << Snap.Get999Percentile() * ToSeconds;
+
+	Cbo.EndObject();
+}
+
 void
 EmitSnapshot(std::string_view Tag, const Histogram& Stat, CbObjectWriter& Cbo)
 {
diff --git a/zencore/timer.cpp b/zencore/timer.cpp
index b2c6cb6a2..5d30d9b29 100644
--- a/zencore/timer.cpp
+++ b/zencore/timer.cpp
@@ -42,7 +42,8 @@ InternalGetHifreqTimerFrequency()
 #endif
 }
 
-static uint64_t QpcFreq = InternalGetHifreqTimerFrequency();
+uint64_t			QpcFreq	  = InternalGetHifreqTimerFrequency();
+static const double QpcFactor = 1.0 / InternalGetHifreqTimerFrequency();
 
 uint64_t
 GetHifreqTimerFrequency()
@@ -50,6 +51,12 @@ GetHifreqTimerFrequency()
 	return QpcFreq;
 }
 
+double
+GetHifreqTimerToSeconds()
+{
+	return QpcFactor;
+}
+
 uint64_t
 GetHifreqTimerFrequencySafe()
 {