load: Update plugin structure

go.mod

@@ -15,7 +15,7 @@ require (
 	github.com/theckman/go-flock v0.7.1
 	github.com/ziutek/telnet v0.0.0-20180329124119-c3b780dc415b
 	golang.org/x/crypto v0.0.0-20190424203555-c05e17bb3b2d // indirect
-	golang.org/x/sys v0.0.0-20190424175732-18eb32c0e2f0 // indirect
+	golang.org/x/sys v0.0.0-20190425045458-9f0b1ff7b46a // indirect
 	google.golang.org/appengine v1.4.0 // indirect
 	google.golang.org/genproto v0.0.0-20190418145605-e7d98fc518a7 // indirect
 	google.golang.org/grpc v1.20.1 // indirect

go.sum

@@ -67,8 +67,8 @@ golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190424175732-18eb32c0e2f0 h1:V+O002es++Mnym06Rj/S6Fl7VCsgRBgVDGb/NoZVHUg=
-golang.org/x/sys v0.0.0-20190424175732-18eb32c0e2f0/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190425045458-9f0b1ff7b46a h1:8cVTj31lbQ2I9z63Y1LjjHVKGisLuXDt12kKR0+r89w=
+golang.org/x/sys v0.0.0-20190425045458-9f0b1ff7b46a/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=

mod-system/load.go

@@ -23,18 +23,26 @@ import (
 	"github.com/snapserv/nagocheck/shared"
 	"github.com/snapserv/nagopher"
 	"math"
-	"runtime"
 )
 
 type loadPlugin struct {
 	shared.Plugin
+
+	stats  loadStats
 	PerCPU bool
 }
 
 type loadSummarizer struct {
 	shared.PluginSummarizer
 }
 
+type loadStats struct {
+	cpuCores      uint
+	loadAverage1  float64
+	loadAverage5  float64
+	loadAverage15 float64
+}
+
 func newLoadPlugin() *loadPlugin {
 	return &loadPlugin{
 		Plugin: shared.NewPlugin(),
@@ -70,23 +78,15 @@ func (p *loadPlugin) Probe(warnings nagopher.WarningCollection) (metrics []nagop
 		return metrics, err
 	}
 
-	loadAverages, err := getLoadAverages()
-	if err != nil {
+	if err := p.stats.Collect(p.PerCPU); err != nil {
 		return metrics, err
 	}
 
-	metricNames := []string{"load1", "load5", "load15"}
-	cpuCount := runtime.NumCPU()
-
-	for key, loadAverage := range loadAverages {
-		if p.PerCPU {
-			loadAverage /= float64(cpuCount)
-		}
-
-		metrics = append(metrics, nagopher.MustNewNumericMetric(
-			metricNames[key], loadAverage, "", &valueRange, "load",
-		))
-	}
+	metrics = append(metrics,
+		nagopher.MustNewNumericMetric("load1", p.stats.loadAverage1, "", &valueRange, "load"),
+		nagopher.MustNewNumericMetric("load5", p.stats.loadAverage5, "", &valueRange, "load"),
+		nagopher.MustNewNumericMetric("load15", p.stats.loadAverage15, "", &valueRange, "load"),
+	)
 
 	return metrics, nil
 }

mod-system/load_linux.go

@@ -21,25 +21,49 @@ package modsystem
 import (
 	"fmt"
 	"io/ioutil"
+	"runtime"
 	"strconv"
 	"strings"
 )
 
-func getLoadAverages() (loadAverages [3]float64, _ error) {
-	bytes, err := ioutil.ReadFile("/proc/loadavg")
+var procLoadavgPath = "/proc/loadavg"
+
+func (s *loadStats) Collect(perCPU bool) error {
+	s.cpuCores = uint(runtime.NumCPU())
+	if err := s.collectLoadAverages(perCPU); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (s *loadStats) collectLoadAverages(perCPU bool) error {
+	bytes, err := ioutil.ReadFile(procLoadavgPath)
 	if err != nil {
-		return loadAverages, fmt.Errorf("load: could not read /proc/loadavg file (%s)", err.Error())
+		return fmt.Errorf("could not read load averages from [%s]: %s", procLoadavgPath, err.Error())
 	}
 
 	values := strings.Split(string(bytes), " ")
+	if len(values) < 3 {
+		return fmt.Errorf("could not parse unknown format from [%s]: expected 3 space-separated values", procLoadavgPath)
+	}
+
+	loadAverages := make([]float64, 0, 3)
 	for i := 0; i < 3; i++ {
 		value, err := strconv.ParseFloat(values[i], strconv.IntSize)
 		if err != nil {
-			return loadAverages, fmt.Errorf("load: could not parse [%s] as float (%s)", values[i], err.Error())
+			return fmt.Errorf("could not parse [%s] as float (%s)", values[i], err.Error())
 		}
 
-		loadAverages[i] = value
+		if perCPU {
+			value /= float64(s.cpuCores)
+		}
+		loadAverages = append(loadAverages, value)
 	}
 
-	return loadAverages, nil
+	s.loadAverage1 = loadAverages[0]
+	s.loadAverage5 = loadAverages[1]
+	s.loadAverage15 = loadAverages[2]
+
+	return nil
 }