Convert filefd collector to use ConstMetrics

This suffers from the same concurrency bug as the netstat one:
https://github.com/prometheus/node_exporter/issues/280

1 files changed, 13 insertions, 22 deletions

diff --git a/collector/filefd_linux.go b/collector/filefd_linux.go
index 190f780..180c642 100644
--- a/collector/filefd_linux.go
+++ b/collector/filefd_linux.go
@@ -18,20 +18,19 @@ package collector
 import (
         "bufio"
         "fmt"
-        "github.com/prometheus/client_golang/prometheus"
         "io"
         "os"
         "strconv"
         "strings"
+
+        "github.com/prometheus/client_golang/prometheus"
 )
 
 const (
         fileFDStatSubsystem = "filefd"
 )
 
-type fileFDStatCollector struct {
-        metrics map[string]prometheus.Gauge
-}
+type fileFDStatCollector struct{}
 
 func init() {
         Factories[fileFDStatSubsystem] = NewFileFDStatCollector
@@ -39,9 +38,7 @@ func init() {
 
 // NewFileFDStatCollector returns a new Collector exposing file-nr stats.
 func NewFileFDStatCollector() (Collector, error) {
-        return &fileFDStatCollector{
-                metrics: map[string]prometheus.Gauge{},
-        }, nil
+        return &fileFDStatCollector{}, nil
 }
 
 func (c *fileFDStatCollector) Update(ch chan<- prometheus.Metric) (err error) {
@@ -50,26 +47,20 @@ func (c *fileFDStatCollector) Update(ch chan<- prometheus.Metric) (err error) {
                 return fmt.Errorf("couldn't get file-nr: %s", err)
         }
         for name, value := range fileFDStat {
-                if _, ok := c.metrics[name]; !ok {
-                        c.metrics[name] = prometheus.NewGauge(
-                                prometheus.GaugeOpts{
-                                        Namespace: Namespace,
-                                        Subsystem: fileFDStatSubsystem,
-                                        Name:      name,
-                                        Help:      fmt.Sprintf("File descriptor statistics: %s.", name),
-                                },
-                        )
-                }
                 v, err := strconv.ParseFloat(value, 64)
                 if err != nil {
                         return fmt.Errorf("invalid value %s in file-nr: %s", value, err)
                 }
-                c.metrics[name].Set(v)
-        }
-        for _, m := range c.metrics {
-                m.Collect(ch)
+                ch <- prometheus.MustNewConstMetric(
+                        prometheus.NewDesc(
+                                prometheus.BuildFQName(Namespace, fileFDStatSubsystem, name),
+                                fmt.Sprintf("File descriptor statistics: %s.", name),
+                                nil, nil,
+                        ),
+                        prometheus.GaugeValue, v,
+                )
         }
-        return err
+        return nil
 }
 
 func getFileFDStats(fileName string) (map[string]string, error) {