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reducer.go
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reducer.go
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package conditions
import (
"math"
"sort"
"github.com/grafana/grafana/pkg/components/null"
"github.com/grafana/grafana/pkg/tsdb"
)
type QueryReducer interface {
Reduce(timeSeries *tsdb.TimeSeries) null.Float
}
type SimpleReducer struct {
Type string
}
func (s *SimpleReducer) Reduce(series *tsdb.TimeSeries) null.Float {
if len(series.Points) == 0 {
return null.FloatFromPtr(nil)
}
value := float64(0)
allNull := true
switch s.Type {
case "avg":
validPointsCount := 0
for _, point := range series.Points {
if point[0].Valid {
value += point[0].Float64
validPointsCount += 1
allNull = false
}
}
if validPointsCount > 0 {
value = value / float64(validPointsCount)
}
case "sum":
for _, point := range series.Points {
if point[0].Valid {
value += point[0].Float64
allNull = false
}
}
case "min":
value = math.MaxFloat64
for _, point := range series.Points {
if point[0].Valid {
allNull = false
if value > point[0].Float64 {
value = point[0].Float64
}
}
}
case "max":
value = -math.MaxFloat64
for _, point := range series.Points {
if point[0].Valid {
allNull = false
if value < point[0].Float64 {
value = point[0].Float64
}
}
}
case "count":
value = float64(len(series.Points))
allNull = false
case "last":
points := series.Points
for i := len(points) - 1; i >= 0; i-- {
if points[i][0].Valid {
value = points[i][0].Float64
allNull = false
break
}
}
case "median":
var values []float64
for _, v := range series.Points {
if v[0].Valid {
allNull = false
values = append(values, v[0].Float64)
}
}
if len(values) >= 1 {
sort.Float64s(values)
length := len(values)
if length%2 == 1 {
value = values[(length-1)/2]
} else {
value = (values[(length/2)-1] + values[length/2]) / 2
}
}
case "diff":
allNull, value = calculateDiff(series, allNull, value, diff)
case "percent_diff":
allNull, value = calculateDiff(series, allNull, value, percentDiff)
case "count_non_null":
for _, v := range series.Points {
if v[0].Valid {
value++
}
}
if value > 0 {
allNull = false
}
}
if allNull {
return null.FloatFromPtr(nil)
}
return null.FloatFrom(value)
}
func NewSimpleReducer(typ string) *SimpleReducer {
return &SimpleReducer{Type: typ}
}
func calculateDiff(series *tsdb.TimeSeries, allNull bool, value float64, fn func(float64, float64) float64) (bool, float64) {
var (
points = series.Points
first float64
i int
)
// get the newest point
for i = len(points) - 1; i >= 0; i-- {
if points[i][0].Valid {
allNull = false
first = points[i][0].Float64
break
}
}
if i >= 1 {
// get the oldest point
points = points[0:i]
for i := 0; i < len(points); i++ {
if points[i][0].Valid {
allNull = false
val := fn(first, points[i][0].Float64)
value = math.Abs(val)
break
}
}
}
return allNull, value
}
var diff = func(newest, oldest float64) float64 {
return newest - oldest
}
var percentDiff = func(newest, oldest float64) float64 {
return (newest - oldest) / oldest * 100
}