meter: fast path for only one label

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

meter/meter.go

@@ -105,18 +105,20 @@ func BuildName(name string, labels ...string) string {
 		labels = labels[:len(labels)-1]
 	}
 
-	sort.Sort(byKey(labels))
+	if len(labels) > 2 {
+		sort.Sort(byKey(labels))
 
-	idx := 0
-	for {
-		if labels[idx] == labels[idx+2] {
-			copy(labels[idx:], labels[idx+2:])
-			labels = labels[:len(labels)-2]
-		} else {
-			idx += 2
-		}
-		if idx+2 >= len(labels) {
-			break
+		idx := 0
+		for {
+			if labels[idx] == labels[idx+2] {
+				copy(labels[idx:], labels[idx+2:])
+				labels = labels[:len(labels)-2]
+			} else {
+				idx += 2
+			}
+			if idx+2 >= len(labels) {
+				break
+			}
 		}
 	}
 

meter/meter_test.go

@@ -56,6 +56,10 @@ func TestBuildName(t *testing.T) {
 			"my_metric",
 			"broker", "broker1", "broker", "broker2", "server", "http", "server", "tcp", "register", "mdns",
 		},
+		`my_metric{aaa="aaa"}`: []string{
+			"my_metric",
+			"aaa", "aaa",
+		},
 	}
 
 	for e, d := range data {