mirror of
https://github.com/ClusterCockpit/cc-metric-store.git
synced 2025-11-04 02:35:08 +01:00
65 lines
1.4 KiB
Go
65 lines
1.4 KiB
Go
package util
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import (
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"math"
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"strconv"
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)
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// Go's JSON encoder for floats does not support NaN (https://github.com/golang/go/issues/3480).
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// This program uses NaN as a signal for missing data.
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// For the HTTP JSON API to be able to handle NaN values,
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// we have to use our own type which implements encoding/json.Marshaler itself.
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type Float float64
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var (
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NaN Float = Float(math.NaN())
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nullAsBytes []byte = []byte("null")
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)
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func (f Float) IsNaN() bool {
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return math.IsNaN(float64(f))
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}
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func (f Float) MarshalJSON() ([]byte, error) {
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if math.IsNaN(float64(f)) {
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return nullAsBytes, nil
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}
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return strconv.AppendFloat(make([]byte, 0, 10), float64(f), 'f', 3, 64), nil
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}
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func (f *Float) UnmarshalJSON(input []byte) error {
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if string(input) == "null" {
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*f = NaN
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return nil
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}
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val, err := strconv.ParseFloat(string(input), 64)
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if err != nil {
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return err
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}
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*f = Float(val)
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return nil
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}
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// Same as `[]Float`, but can be marshaled to JSON with less allocations.
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type FloatArray []Float
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func (fa FloatArray) MarshalJSON() ([]byte, error) {
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buf := make([]byte, 0, 2+len(fa)*8)
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buf = append(buf, '[')
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for i := 0; i < len(fa); i++ {
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if i != 0 {
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buf = append(buf, ',')
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}
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if fa[i].IsNaN() {
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buf = append(buf, `null`...)
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} else {
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buf = strconv.AppendFloat(buf, float64(fa[i]), 'f', 3, 64)
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}
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}
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buf = append(buf, ']')
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return buf, nil
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}
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