client_golang/metrics/gauge.go

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/*
Copyright (c) 2012, Matt T. Proud
All rights reserved.
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Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file.
*/
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package metrics
import (
"fmt"
"github.com/prometheus/client_golang/utility"
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"sync"
)
/*
A gauge metric merely provides an instantaneous representation of a scalar
value or an accumulation. For instance, if one wants to expose the current
temperature or the hitherto bandwidth used, this would be the metric for such
circumstances.
*/
type Gauge interface {
AsMarshallable() map[string]interface{}
ResetAll()
Set(labels map[string]string, value float64) float64
String() string
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}
type gaugeValue struct {
labels map[string]string
value float64
}
func NewGauge() Gauge {
return &gauge{
values: map[string]*gaugeValue{},
}
}
type gauge struct {
mutex sync.RWMutex
values map[string]*gaugeValue
}
func (metric *gauge) String() string {
formatString := "[Gauge %s]"
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metric.mutex.RLock()
defer metric.mutex.RUnlock()
return fmt.Sprintf(formatString, metric.values)
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}
func (metric *gauge) Set(labels map[string]string, value float64) float64 {
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metric.mutex.Lock()
defer metric.mutex.Unlock()
if labels == nil {
labels = map[string]string{}
}
signature := utility.LabelsToSignature(labels)
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if original, ok := metric.values[signature]; ok {
original.value = value
} else {
metric.values[signature] = &gaugeValue{
labels: labels,
value: value,
}
}
return value
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}
func (metric *gauge) ResetAll() {
metric.mutex.Lock()
defer metric.mutex.Unlock()
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for key, value := range metric.values {
for label := range value.labels {
delete(value.labels, label)
}
delete(metric.values, key)
}
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}
func (metric *gauge) AsMarshallable() map[string]interface{} {
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metric.mutex.RLock()
defer metric.mutex.RUnlock()
values := make([]map[string]interface{}, 0, len(metric.values))
for _, value := range metric.values {
values = append(values, map[string]interface{}{
labelsKey: value.labels,
valueKey: value.value,
})
}
return map[string]interface{}{
typeKey: gaugeTypeValue,
valueKey: values,
}
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}