mirror of
https://github.com/ClusterCockpit/cc-metric-store.git
synced 2024-11-15 07:27:25 +01:00
65 lines
1.4 KiB
Go
65 lines
1.4 KiB
Go
package util
|
|
|
|
import (
|
|
"math"
|
|
"strconv"
|
|
)
|
|
|
|
// Go's JSON encoder for floats does not support NaN (https://github.com/golang/go/issues/3480).
|
|
// This program uses NaN as a signal for missing data.
|
|
// For the HTTP JSON API to be able to handle NaN values,
|
|
// we have to use our own type which implements encoding/json.Marshaler itself.
|
|
type Float float64
|
|
|
|
var (
|
|
NaN Float = Float(math.NaN())
|
|
nullAsBytes []byte = []byte("null")
|
|
)
|
|
|
|
func (f Float) IsNaN() bool {
|
|
return math.IsNaN(float64(f))
|
|
}
|
|
|
|
func (f Float) MarshalJSON() ([]byte, error) {
|
|
if math.IsNaN(float64(f)) {
|
|
return nullAsBytes, nil
|
|
}
|
|
|
|
return strconv.AppendFloat(make([]byte, 0, 10), float64(f), 'f', 3, 64), nil
|
|
}
|
|
|
|
func (f *Float) UnmarshalJSON(input []byte) error {
|
|
if string(input) == "null" {
|
|
*f = NaN
|
|
return nil
|
|
}
|
|
|
|
val, err := strconv.ParseFloat(string(input), 64)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
*f = Float(val)
|
|
return nil
|
|
}
|
|
|
|
// Same as `[]Float`, but can be marshaled to JSON with less allocations.
|
|
type FloatArray []Float
|
|
|
|
func (fa FloatArray) MarshalJSON() ([]byte, error) {
|
|
buf := make([]byte, 0, 2+len(fa)*8)
|
|
buf = append(buf, '[')
|
|
for i := 0; i < len(fa); i++ {
|
|
if i != 0 {
|
|
buf = append(buf, ',')
|
|
}
|
|
|
|
if fa[i].IsNaN() {
|
|
buf = append(buf, `null`...)
|
|
} else {
|
|
buf = strconv.AppendFloat(buf, float64(fa[i]), 'f', 3, 64)
|
|
}
|
|
}
|
|
buf = append(buf, ']')
|
|
return buf, nil
|
|
}
|