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// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package model
import (
"encoding/json"
"fmt"
"math"
"strconv"
)
var (
// ZeroSamplePair is the pseudo zero-value of SamplePair used to signal a
// non-existing sample pair. It is a SamplePair with timestamp Earliest and
// value 0.0. Note that the natural zero value of SamplePair has a timestamp
// of 0, which is possible to appear in a real SamplePair and thus not
// suitable to signal a non-existing SamplePair.
ZeroSamplePair = SamplePair{Timestamp: Earliest}
)
// A SampleValue is a representation of a value for a given sample at a given
// time.
type SampleValue float64
// MarshalJSON implements json.Marshaler.
func (v SampleValue) MarshalJSON() ([]byte, error) {
return json.Marshal(v.String())
}
// UnmarshalJSON implements json.Unmarshaler.
func (v *SampleValue) UnmarshalJSON(b []byte) error {
if len(b) < 2 || b[0] != '"' || b[len(b)-1] != '"' {
return fmt.Errorf("sample value must be a quoted string")
}
f, err := strconv.ParseFloat(string(b[1:len(b)-1]), 64)
if err != nil {
return err
}
*v = SampleValue(f)
return nil
}
// Equal returns true if the value of v and o is equal or if both are NaN. Note
// that v==o is false if both are NaN. If you want the conventional float
// behavior, use == to compare two SampleValues.
func (v SampleValue) Equal(o SampleValue) bool {
if v == o {
return true
}
return math.IsNaN(float64(v)) && math.IsNaN(float64(o))
}
func (v SampleValue) String() string {
return strconv.FormatFloat(float64(v), 'f', -1, 64)
}
// SamplePair pairs a SampleValue with a Timestamp.
type SamplePair struct {
Timestamp Time
Value SampleValue
}
func (s SamplePair) MarshalJSON() ([]byte, error) {
t, err := json.Marshal(s.Timestamp)
if err != nil {
return nil, err
}
v, err := json.Marshal(s.Value)
if err != nil {
return nil, err
}
return []byte(fmt.Sprintf("[%s,%s]", t, v)), nil
}
// UnmarshalJSON implements json.Unmarshaler.
func (s *SamplePair) UnmarshalJSON(b []byte) error {
v := [...]json.Unmarshaler{&s.Timestamp, &s.Value}
return json.Unmarshal(b, &v)
}
// Equal returns true if this SamplePair and o have equal Values and equal
// Timestamps. The semantics of Value equality is defined by SampleValue.Equal.
func (s *SamplePair) Equal(o *SamplePair) bool {
return s == o || (s.Value.Equal(o.Value) && s.Timestamp.Equal(o.Timestamp))
}
func (s SamplePair) String() string {
return fmt.Sprintf("%s @[%s]", s.Value, s.Timestamp)
}
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