From ea39f3e0ddd0b35bf649477f628fabbc0c1ca424 Mon Sep 17 00:00:00 2001
From: Will Hawkins <hawkinsw@obs.cr>
Date: Mon, 7 Nov 2022 10:09:26 -0500
Subject: [Refactor] Add Stabilizer Interface/Package

Add an interface (and an implementation) for a generic stabilizer. This
functionality will allow us to easily redefine/experiment with stability
algorithms without having to revamp the entire code base all the time.
---
 stabilizer/rev3.go       | 124 +++++++++++++++++++++++++++++++++++++++++++++++
 stabilizer/stabilizer.go |   6 +++
 2 files changed, 130 insertions(+)
 create mode 100644 stabilizer/rev3.go
 create mode 100644 stabilizer/stabilizer.go

diff --git a/stabilizer/rev3.go b/stabilizer/rev3.go
new file mode 100644
index 0000000..e81fc76
--- /dev/null
+++ b/stabilizer/rev3.go
@@ -0,0 +1,124 @@
+package stabilizer
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/network-quality/goresponsiveness/debug"
+	"github.com/network-quality/goresponsiveness/ms"
+	"github.com/network-quality/goresponsiveness/rpm"
+	"github.com/network-quality/goresponsiveness/utilities"
+)
+
+type DataPointStabilizer struct {
+	instantaneousMeasurements  *ms.MathematicalSeries[float64]
+	movingAverages             *ms.MathematicalSeries[float64]
+	stabilityStandardDeviation float64
+	m                          sync.Mutex
+	dbgLevel                   debug.DebugLevel
+	dbgConfig                  *debug.DebugWithPrefix
+}
+
+type ProbeStabilizer DataPointStabilizer
+type ThroughputStabilizer DataPointStabilizer
+
+// Stabilizer parameters:
+// 1. I: The number of previous instantaneous measurements to consider when generating
+//       the so-called instantaneous moving averages.
+// 2. K: The number of instantaneous moving averages to consider when determining stability.
+// 3: S: The standard deviation cutoff used to determine stability among the K preceding
+//       moving averages of a measurement.
+
+func NewProbeStabilizer(i int, k int, s float64, debugLevel debug.DebugLevel, debug *debug.DebugWithPrefix) ProbeStabilizer {
+	return ProbeStabilizer{instantaneousMeasurements: ms.NewMathematicalSeries[float64](i),
+		movingAverages:             ms.NewMathematicalSeries[float64](k),
+		stabilityStandardDeviation: s,
+		dbgConfig:                  debug,
+		dbgLevel:                   debugLevel}
+}
+
+func (r3 *ProbeStabilizer) AddMeasurement(measurement rpm.ProbeDataPoint) {
+	r3.m.Lock()
+	defer r3.m.Unlock()
+	// Add this instantaneous measurement to the mix of the I previous instantaneous measurements.
+	r3.instantaneousMeasurements.AddElement(measurement.Duration.Seconds())
+	// Calculate the moving average of the I previous instantaneous measurements and add it to
+	// the mix of K previous moving averages.
+	r3.movingAverages.AddElement(r3.instantaneousMeasurements.CalculateAverage())
+
+	if debug.IsDebug(r3.dbgLevel) {
+		fmt.Printf(
+			"%s: MA: %f ns (previous %d intervals).\n",
+			r3.dbgConfig.String(),
+			r3.movingAverages.CalculateAverage(),
+			r3.movingAverages.Size(),
+		)
+	}
+}
+
+func (r3 *ProbeStabilizer) IsStable() bool {
+	// calculate whether the standard deviation of the K previous moving averages falls below S.
+	islt, stddev := r3.movingAverages.StandardDeviationLessThan(r3.stabilityStandardDeviation)
+
+	if debug.IsDebug(r3.dbgLevel) {
+		fmt.Printf(
+			"%s: Standard Deviation: %f s; Is Normally Distributed? %v).\n",
+			r3.dbgConfig.String(),
+			stddev,
+			r3.movingAverages.IsNormallyDistributed(),
+		)
+		fmt.Printf("%s: Values: ", r3.dbgConfig.String())
+		for _, v := range r3.movingAverages.Values() {
+			fmt.Printf("%v, ", v)
+		}
+		fmt.Printf("\n")
+	}
+	return islt
+}
+
+func NewThroughputStabilizer(i int, k int, s float64, debugLevel debug.DebugLevel, debug *debug.DebugWithPrefix) ThroughputStabilizer {
+	return ThroughputStabilizer{instantaneousMeasurements: ms.NewMathematicalSeries[float64](i),
+		movingAverages:             ms.NewMathematicalSeries[float64](k),
+		stabilityStandardDeviation: s,
+		dbgConfig:                  debug,
+		dbgLevel:                   debugLevel}
+}
+
+func (r3 *ThroughputStabilizer) AddMeasurement(measurement rpm.ThroughputDataPoint) {
+	r3.m.Lock()
+	defer r3.m.Unlock()
+	// Add this instantaneous measurement to the mix of the I previous instantaneous measurements.
+	r3.instantaneousMeasurements.AddElement(utilities.ToMbps(measurement.Throughput))
+	// Calculate the moving average of the I previous instantaneous measurements and add it to
+	// the mix of K previous moving averages.
+	r3.movingAverages.AddElement(r3.instantaneousMeasurements.CalculateAverage())
+
+	if debug.IsDebug(r3.dbgLevel) {
+		fmt.Printf(
+			"%s: MA: %f Mbps (previous %d intervals).\n",
+			r3.dbgConfig.String(),
+			r3.movingAverages.CalculateAverage(),
+			r3.movingAverages.Size(),
+		)
+	}
+}
+
+func (r3 *ThroughputStabilizer) IsStable() bool {
+	// calculate whether the standard deviation of the K previous moving averages falls below S.
+	islt, stddev := r3.movingAverages.StandardDeviationLessThan(r3.stabilityStandardDeviation)
+
+	if debug.IsDebug(r3.dbgLevel) {
+		fmt.Printf(
+			"%s: Standard Deviation: %f Mbps; Is Normally Distributed? %v).\n",
+			r3.dbgConfig.String(),
+			stddev,
+			r3.movingAverages.IsNormallyDistributed(),
+		)
+		fmt.Printf("%s: Values: ", r3.dbgConfig.String())
+		for _, v := range r3.movingAverages.Values() {
+			fmt.Printf("%v, ", v)
+		}
+		fmt.Printf("\n")
+	}
+	return islt
+}
diff --git a/stabilizer/stabilizer.go b/stabilizer/stabilizer.go
new file mode 100644
index 0000000..d85cedc
--- /dev/null
+++ b/stabilizer/stabilizer.go
@@ -0,0 +1,6 @@
+package stabilizer
+
+type Stabilizer[T any] interface {
+	AddMeasurement(T)
+	IsStable() bool
+}
-- 
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