Don't fail when a perflib counter isn't found

collector/collector.go

@@ -1,8 +1,12 @@
 package collector
 
 import (
+	"strconv"
+
 	"github.com/leoluk/perflib_exporter/perflib"
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/log"
+	"golang.org/x/sys/windows/registry"
 )
 
 // ...
@@ -15,6 +19,34 @@ const (
 	windowsEpoch              = 116444736000000000
 )
 
+// getWindowsVersion reads the version number of the OS from the Registry
+// See https://docs.microsoft.com/en-us/windows/desktop/sysinfo/operating-system-version
+func getWindowsVersion() float64 {
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+	if err != nil {
+		log.Warn("Couldn't open registry", err)
+		return 0
+	}
+	defer func() {
+		err = k.Close()
+		if err != nil {
+			log.Warnf("Failed to close registry key: %v", err)
+		}
+	}()
+
+	currentv, _, err := k.GetStringValue("CurrentVersion")
+	if err != nil {
+		log.Warn("Couldn't open registry to determine current Windows version:", err)
+		return 0
+	}
+
+	currentv_flt, err := strconv.ParseFloat(currentv, 64)
+
+	log.Debugf("Detected Windows version %f\n", currentv_flt)
+
+	return currentv_flt
+}
+
 // Factories ...
 var Factories = make(map[string]func() (Collector, error))