From d80b2af492ab3aeeec233af08115799cbb036cc3 Mon Sep 17 00:00:00 2001
From: Siavash Safi <siavash.safi@gmail.com>
Date: Wed, 24 Jun 2015 16:38:43 +0430
Subject: [PATCH] loadavg: Split the collector for linux and other platforms.

---
 collector/loadavg.go            |  3 +-
 collector/loadavg_linux.go      | 65 +++++++++++++++++++++++++++++++++
 collector/loadavg_linux_test.go | 14 +++++++
 3 files changed, 81 insertions(+), 1 deletion(-)
 create mode 100644 collector/loadavg_linux.go
 create mode 100644 collector/loadavg_linux_test.go

diff --git a/collector/loadavg.go b/collector/loadavg.go
index 6ecb7edb..7d7611a6 100644
--- a/collector/loadavg.go
+++ b/collector/loadavg.go
@@ -1,4 +1,4 @@
-// +build !noloadavg
+// +build !linux !noloadavg
 
 package collector
 
@@ -21,6 +21,7 @@ func init() {
 	Factories["loadavg"] = NewLoadavgCollector
 }
 
+// Takes a prometheus registry and returns a new Collector exposing
 // load1 stat.
 func NewLoadavgCollector() (Collector, error) {
 	return &loadavgCollector{
diff --git a/collector/loadavg_linux.go b/collector/loadavg_linux.go
new file mode 100644
index 00000000..bdf72988
--- /dev/null
+++ b/collector/loadavg_linux.go
@@ -0,0 +1,65 @@
+// +build !noloadavg
+
+package collector
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/log"
+)
+
+const (
+	procLoad = "/proc/loadavg"
+)
+
+type loadavgCollector struct {
+	metric prometheus.Gauge
+}
+
+func init() {
+	Factories["loadavg"] = NewLoadavgCollector
+}
+
+// Takes a prometheus registry and returns a new Collector exposing
+// load, seconds since last login and a list of tags as specified by config.
+func NewLoadavgCollector() (Collector, error) {
+	return &loadavgCollector{
+		metric: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: Namespace,
+			Name:      "load1",
+			Help:      "1m load average.",
+		}),
+	}, nil
+}
+
+func (c *loadavgCollector) Update(ch chan<- prometheus.Metric) (err error) {
+	load, err := getLoad1()
+	if err != nil {
+		return fmt.Errorf("Couldn't get load: %s", err)
+	}
+	log.Debugf("Set node_load: %f", load)
+	c.metric.Set(load)
+	c.metric.Collect(ch)
+	return err
+}
+
+func getLoad1() (float64, error) {
+	data, err := ioutil.ReadFile(procLoad)
+	if err != nil {
+		return 0, err
+	}
+	return parseLoad(string(data))
+}
+
+func parseLoad(data string) (float64, error) {
+	parts := strings.Fields(data)
+	load, err := strconv.ParseFloat(parts[0], 64)
+	if err != nil {
+		return 0, fmt.Errorf("Could not parse load '%s': %s", parts[0], err)
+	}
+	return load, nil
+}
diff --git a/collector/loadavg_linux_test.go b/collector/loadavg_linux_test.go
new file mode 100644
index 00000000..e83822a6
--- /dev/null
+++ b/collector/loadavg_linux_test.go
@@ -0,0 +1,14 @@
+package collector
+
+import "testing"
+
+func TestLoad(t *testing.T) {
+	load, err := parseLoad("0.21 0.37 0.39 1/719 19737")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want := 0.21; want != load {
+		t.Fatalf("want load %f, got %f", want, load)
+	}
+}