Collector-specific configuration. LIKWID collector derives metrics itself, Run once CLI option

collectors/topprocsMetric.go

@@ -7,29 +7,50 @@ import (
 	"os/exec"
 	"strings"
 	"time"
+	"encoding/json"
+	"errors"
 )
 
-const NUM_PROCS = 5
+const MAX_NUM_PROCS = 10
+
+type TopProcsCollectorConfig struct {
+    num_procs int                 `json:"num_procs"`
+}
 
 type TopProcsCollector struct {
 	MetricCollector
 	tags map[string]string
+	config TopProcsCollectorConfig
 }
 
-func (m *TopProcsCollector) Init() error {
+func (m *TopProcsCollector) Init(config []byte) error {
+    var err error
 	m.name = "TopProcsCollector"
 	m.tags = map[string]string{"type": "node"}
+	if len(config) > 0 {
+	    err = json.Unmarshal(config, &m.config)
+	    if err != nil {
+	        return err
+	    }
+	}
+	if m.config.num_procs <= 0 || m.config.num_procs > MAX_NUM_PROCS {
+	    return errors.New(fmt.Sprintf("num_procs option must be set in 'topprocs' config (range: 1-%d)", MAX_NUM_PROCS))
+	}
 	m.setup()
 	command := exec.Command("ps", "-Ao", "comm", "--sort=-pcpu")
 	command.Wait()
-	_, err := command.Output()
-	if err == nil {
-		m.init = true
+	_, err = command.Output()
+	if err != nil {
+		return errors.New("Failed to execute command")
 	}
+	m.init = true
 	return nil
 }
 
 func (m *TopProcsCollector) Read(interval time.Duration, out *[]lp.MutableMetric) {
+    if !m.init {
+        return
+    }
 	command := exec.Command("ps", "-Ao", "comm", "--sort=-pcpu")
 	command.Wait()
 	stdout, err := command.Output()
@@ -39,7 +60,7 @@ func (m *TopProcsCollector) Read(interval time.Duration, out *[]lp.MutableMetric
 	}
 
 	lines := strings.Split(string(stdout), "\n")
-	for i := 1; i < NUM_PROCS+1; i++ {
+	for i := 1; i < m.config.num_procs+1; i++ {
 		name := fmt.Sprintf("topproc%d", i)
 		y, err := lp.New(name, m.tags, map[string]interface{}{"value": string(lines[i])}, time.Now())
 		if err == nil {