add metrics.PrometheusCollectorsFromFields

pkg/api/metrics.go

@@ -2,9 +2,9 @@ package api
 
 import (
 	"net/http"
-	"reflect"
 	"time"
 
+	m "github.com/janos/bee/pkg/metrics"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
@@ -35,17 +35,8 @@ func newMetrics() (m metrics) {
 	}
 }
 
-func (s *server) Metrics() (cs []prometheus.Collector) {
-	v := reflect.Indirect(reflect.ValueOf(s.metrics))
-	for i := 0; i < v.NumField(); i++ {
-		if !v.Field(i).CanInterface() {
-			continue
-		}
-		if u, ok := v.Field(i).Interface().(prometheus.Collector); ok {
-			cs = append(cs, u)
-		}
-	}
-	return cs
+func (s *server) Metrics() []prometheus.Collector {
+	return m.PrometheusCollectorsFromFields(s.metrics)
 }
 
 func (s *server) pageviewMetricsHandler(h http.Handler) http.Handler {

pkg/metrics/metrics.go

+package metrics
+
+import (
+	"reflect"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func PrometheusCollectorsFromFields(i interface{}) (cs []prometheus.Collector) {
+	v := reflect.Indirect(reflect.ValueOf(i))
+	for i := 0; i < v.NumField(); i++ {
+		if !v.Field(i).CanInterface() {
+			continue
+		}
+		if u, ok := v.Field(i).Interface().(prometheus.Collector); ok {
+			cs = append(cs, u)
+		}
+	}
+	return cs
+}

pkg/pingpong/metrics.go

 package pingpong
 
 import (
-	"reflect"
-
+	m "github.com/janos/bee/pkg/metrics"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
@@ -37,15 +36,6 @@ func newMetrics() (m metrics) {
 	}
 }
 
-func (s *Service) Metrics() (cs []prometheus.Collector) {
-	v := reflect.Indirect(reflect.ValueOf(s.metrics))
-	for i := 0; i < v.NumField(); i++ {
-		if !v.Field(i).CanInterface() {
-			continue
-		}
-		if u, ok := v.Field(i).Interface().(prometheus.Collector); ok {
-			cs = append(cs, u)
-		}
-	}
-	return cs
+func (s *Service) Metrics() []prometheus.Collector {
+	return m.PrometheusCollectorsFromFields(s.metrics)
 }