mirror of
https://github.com/ClusterCockpit/cc-backend
synced 2024-12-25 12:59:06 +01:00
110 lines
2.7 KiB
Go
110 lines
2.7 KiB
Go
// Copyright (C) 2022 NHR@FAU, University Erlangen-Nuremberg.
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// All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"errors"
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"io"
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"math"
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"strconv"
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)
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// A custom float type is used so that (Un)MarshalJSON and
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// (Un)MarshalGQL can be overloaded and NaN/null can be used.
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// The default behaviour of putting every nullable value behind
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// a pointer has a bigger overhead.
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type Float float64
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var NaN Float = Float(math.NaN())
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var nullAsBytes []byte = []byte("null")
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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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// NaN will be serialized to `null`.
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func (f Float) MarshalJSON() ([]byte, error) {
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if f.IsNaN() {
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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', 2, 64), nil
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}
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// `null` will be unserialized to NaN.
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func (f *Float) UnmarshalJSON(input []byte) error {
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s := string(input)
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if s == "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(s, 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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// UnmarshalGQL implements the graphql.Unmarshaler interface.
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func (f *Float) UnmarshalGQL(v interface{}) error {
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f64, ok := v.(float64)
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if !ok {
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return errors.New("invalid Float scalar")
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}
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*f = Float(f64)
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return nil
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}
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// MarshalGQL implements the graphql.Marshaler interface.
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// NaN will be serialized to `null`.
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func (f Float) MarshalGQL(w io.Writer) {
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if f.IsNaN() {
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w.Write(nullAsBytes)
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} else {
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w.Write(strconv.AppendFloat(make([]byte, 0, 10), float64(f), 'f', 2, 64))
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}
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}
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// Only used via REST-API, not via GraphQL.
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// This uses a lot less allocations per series,
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// but it turns out that the performance increase
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// from using this is not that big.
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func (s *Series) MarshalJSON() ([]byte, error) {
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buf := make([]byte, 0, 512+len(s.Data)*8)
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buf = append(buf, `{"hostname":"`...)
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buf = append(buf, s.Hostname...)
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buf = append(buf, '"')
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if s.Id != nil {
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buf = append(buf, `,"id":`...)
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buf = strconv.AppendInt(buf, int64(*s.Id), 10)
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}
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if s.Statistics != nil {
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buf = append(buf, `,"statistics":{"min":`...)
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buf = strconv.AppendFloat(buf, s.Statistics.Min, 'f', 2, 64)
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buf = append(buf, `,"avg":`...)
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buf = strconv.AppendFloat(buf, s.Statistics.Avg, 'f', 2, 64)
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buf = append(buf, `,"max":`...)
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buf = strconv.AppendFloat(buf, s.Statistics.Max, 'f', 2, 64)
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buf = append(buf, '}')
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}
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buf = append(buf, `,"data":[`...)
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for i := 0; i < len(s.Data); i++ {
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if i != 0 {
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buf = append(buf, ',')
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}
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if s.Data[i].IsNaN() {
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buf = append(buf, `null`...)
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} else {
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buf = strconv.AppendFloat(buf, float64(s.Data[i]), 'f', 2, 32)
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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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