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mosquitto_counter.go
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/
mosquitto_counter.go
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package main
import (
"errors"
"github.com/prometheus/client_golang/prometheus"
)
// MosquittoCounter exports all counter metrics are already added by mosquitto
type MosquittoCounter struct {
Desc *prometheus.Desc
counter
// ... many more fields
}
// NewMosquittoCounter get a new one
func NewMosquittoCounter(desc *prometheus.Desc) *MosquittoCounter {
return &MosquittoCounter{
Desc: desc,
}
}
// Set sets the value
func (c *MosquittoCounter) Set(v float64) {
c.counter.Set(v)
}
// Describe simply sends the two Descs in the struct to the channel.
func (c *MosquittoCounter) Describe(ch chan<- *prometheus.Desc) {
ch <- c.Desc
}
// Collect already added counter values
func (c *MosquittoCounter) Collect(ch chan<- prometheus.Metric) {
ch <- prometheus.MustNewConstMetric(
c.Desc,
prometheus.CounterValue,
c.counter.value,
)
}
type counter struct {
value float64
}
func (c *counter) Set(v float64) {
if v < 0 {
panic(errors.New("counter cannot decrease in value"))
}
c.value = v
}