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package ma
import (
"github.com/hawkinsw/goresponsiveness/saturating"
"github.com/hawkinsw/goresponsiveness/utilities"
)
// Convert this to a Type Parameterized interface when they are available
// in Go (1.18).
type MovingAverage struct {
intervals int
instants []float64
index int
divisor *saturating.SaturatingInt
}
func NewMovingAverage(intervals int) *MovingAverage {
return &MovingAverage{instants: make([]float64, intervals), intervals: intervals, divisor: saturating.NewSaturatingInt(intervals)}
}
func (ma *MovingAverage) AddMeasurement(measurement float64) {
ma.instants[ma.index] = measurement
ma.divisor.Add(1)
// Invariant: ma.index always points to the oldest measurement
ma.index = (ma.index + 1) % ma.intervals
}
func (ma *MovingAverage) CalculateAverage() float64 {
total := float64(0)
for i := 0; i < ma.intervals; i++ {
total += ma.instants[i]
}
return float64(total) / float64(ma.divisor.Value())
}
func (ma *MovingAverage) AllSequentialIncreasesLessThan(limit float64) bool {
// If we have not yet accumulated a complete set of intervals,
// this is false.
if ma.divisor.Value() != ma.intervals {
return false
}
// Invariant: ma.index always points to the oldest (see AddMeasurement above)
oldestIndex := ma.index
previous := ma.instants[oldestIndex]
for i := 1; i < ma.intervals; i++ {
currentIndex := (oldestIndex + i) % ma.intervals
current := ma.instants[currentIndex]
percentChange := utilities.SignedPercentDifference(current, previous)
previous = current
if percentChange > limit {
return false
}
}
return true
}
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