[Feature] Redefine stability

Stability (in rev3) is based on whether the standard deviations of the
measurements are within a certain percentage of the average. This commit
adds that functionality.

2 files changed, 56 insertions, 20 deletions

diff --git a/constants/constants.go b/constants/constants.go
index c4f2c20..6934459 100644
--- a/constants/constants.go
+++ b/constants/constants.go
@@ -17,17 +17,21 @@ package constants
 import "time"
 
 var (
-	// The initial number of connections on a LBC.
-	StartingNumberOfLoadGeneratingConnections uint64 = 4
-	// The number of intervals for which to account in a moving-average
-	// calculation.
-	MovingAverageIntervalCount int = 4
-	// The number of intervals across which to consider a moving average stable.
-	MovingAverageStabilitySpan uint64 = 4
-	// The number of connections to add to a LBC when unsaturated.
-	AdditiveNumberOfLoadGeneratingConnections uint64 = 4
-	// The cutoff of the percent difference that defines instability.
-	InstabilityDelta float64 = 5
+	// The initial number of load-generating connections when attempting to saturate the network.
+	StartingNumberOfLoadGeneratingConnections uint64 = 1
+	// The number of load-generating connections to add at each interval while attempting to
+	// saturate the network.
+	AdditiveNumberOfLoadGeneratingConnections uint64 = 1
+
+	// The number of previous instantaneous measurements to consider when generating the so-called
+	// instantaneous moving averages of a measurement.
+	InstantaneousThroughputMeasurementCount int = 4
+	InstantaneousProbeMeasurementCount      int = 1
+	// The number of instantaneous moving averages to consider when determining stability.
+	InstantaneousMovingAverageCount int = 4
+	// The standard deviation cutoff used to determine stability among the K preceding moving averages
+	// of a measurement (as a percentage of the mean).
+	StabilityStandardDeviation float64 = 5.0
 
 	// The amount of time that the client will cooldown if it is in debug mode.
 	CooldownPeriod time.Duration = 4 * time.Second
diff --git a/stabilizer/rev3.go b/stabilizer/rev3.go
index e81fc76..2e29626 100644
--- a/stabilizer/rev3.go
+++ b/stabilizer/rev3.go
@@ -40,8 +40,14 @@ func NewProbeStabilizer(i int, k int, s float64, debugLevel debug.DebugLevel, de
 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())
+
+	// There may be more than one round trip accumulated together. If that is the case,
+	// we will blow them apart in to three separate measurements and each one will just
+	// be 1 / measurement.RoundTripCount of the total length.
+	for range utilities.Iota(0, int(measurement.RoundTripCount)) {
+		// Add this instantaneous measurement to the mix of the I previous instantaneous measurements.
+		r3.instantaneousMeasurements.AddElement(measurement.Duration.Seconds() / float64(measurement.RoundTripCount))
+	}
 	// 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())
@@ -58,14 +64,27 @@ func (r3 *ProbeStabilizer) AddMeasurement(measurement rpm.ProbeDataPoint) {
 
 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)
+	isvalid, stddev := r3.movingAverages.StandardDeviation()
+
+	if !isvalid {
+		// If there are not enough values in the series to be able to calculate a
+		// standard deviation, then we know that we are not yet stable. Vamoose.
+		return false
+	}
+
+	// Stability is determined by whether or not the standard deviation of the values
+	// is within 5% of the average.
+	stabilityCutoff := r3.movingAverages.CalculateAverage() * (r3.stabilityStandardDeviation / 100.0)
+	isStable := stddev <= stabilityCutoff
 
 	if debug.IsDebug(r3.dbgLevel) {
 		fmt.Printf(
-			"%s: Standard Deviation: %f s; Is Normally Distributed? %v).\n",
+			"%s: Is Stable? %v; Standard Deviation: %f s; Is Normally Distributed? %v; Standard Deviation Cutoff: %v s).\n",
 			r3.dbgConfig.String(),
+			isStable,
 			stddev,
 			r3.movingAverages.IsNormallyDistributed(),
+			stabilityCutoff,
 		)
 		fmt.Printf("%s: Values: ", r3.dbgConfig.String())
 		for _, v := range r3.movingAverages.Values() {
@@ -73,7 +92,8 @@ func (r3 *ProbeStabilizer) IsStable() bool {
 		}
 		fmt.Printf("\n")
 	}
-	return islt
+
+	return isStable
 }
 
 func NewThroughputStabilizer(i int, k int, s float64, debugLevel debug.DebugLevel, debug *debug.DebugWithPrefix) ThroughputStabilizer {
@@ -104,15 +124,27 @@ func (r3 *ThroughputStabilizer) AddMeasurement(measurement rpm.ThroughputDataPoi
 }
 
 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)
+	isvalid, stddev := r3.movingAverages.StandardDeviation()
+
+	if !isvalid {
+		// If there are not enough values in the series to be able to calculate a
+		// standard deviation, then we know that we are not yet stable. Vamoose.
+		return false
+	}
+
+	// Stability is determined by whether or not the standard deviation of the values
+	// is within 5% of the average.
+	stabilityCutoff := r3.movingAverages.CalculateAverage() * (r3.stabilityStandardDeviation / 100.0)
+	isStable := stddev <= stabilityCutoff
 
 	if debug.IsDebug(r3.dbgLevel) {
 		fmt.Printf(
-			"%s: Standard Deviation: %f Mbps; Is Normally Distributed? %v).\n",
+			"%s: Is Stable? %v; Standard Deviation: %f Mbps; Is Normally Distributed? %v; Standard Deviation Cutoff: %v Mbps).\n",
 			r3.dbgConfig.String(),
+			isStable,
 			stddev,
 			r3.movingAverages.IsNormallyDistributed(),
+			stabilityCutoff,
 		)
 		fmt.Printf("%s: Values: ", r3.dbgConfig.String())
 		for _, v := range r3.movingAverages.Values() {
@@ -120,5 +152,5 @@ func (r3 *ThroughputStabilizer) IsStable() bool {
 		}
 		fmt.Printf("\n")
 	}
-	return islt
+	return isStable
 }