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package decor
import (
"sort"
"sync"
"github.com/VividCortex/ewma"
)
var (
_ ewma.MovingAverage = (*threadSafeMovingAverage)(nil)
_ ewma.MovingAverage = (*medianWindow)(nil)
_ sort.Interface = (*medianWindow)(nil)
)
type threadSafeMovingAverage struct {
ewma.MovingAverage
mu sync.Mutex
}
func (s *threadSafeMovingAverage) Add(value float64) {
s.mu.Lock()
s.MovingAverage.Add(value)
s.mu.Unlock()
}
func (s *threadSafeMovingAverage) Value() float64 {
s.mu.Lock()
defer s.mu.Unlock()
return s.MovingAverage.Value()
}
func (s *threadSafeMovingAverage) Set(value float64) {
s.mu.Lock()
s.MovingAverage.Set(value)
s.mu.Unlock()
}
// NewThreadSafeMovingAverage converts provided ewma.MovingAverage
// into thread safe ewma.MovingAverage.
func NewThreadSafeMovingAverage(average ewma.MovingAverage) ewma.MovingAverage {
if tsma, ok := average.(*threadSafeMovingAverage); ok {
return tsma
}
return &threadSafeMovingAverage{MovingAverage: average}
}
type medianWindow [3]float64
func (s *medianWindow) Len() int { return len(s) }
func (s *medianWindow) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s *medianWindow) Less(i, j int) bool { return s[i] < s[j] }
func (s *medianWindow) Add(value float64) {
s[0], s[1] = s[1], s[2]
s[2] = value
}
func (s *medianWindow) Value() float64 {
tmp := *s
sort.Sort(&tmp)
return tmp[1]
}
func (s *medianWindow) Set(value float64) {
for i := 0; i < len(s); i++ {
s[i] = value
}
}
// NewMedian is fixed last 3 samples median MovingAverage.
func NewMedian() ewma.MovingAverage {
return new(medianWindow)
}
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