Refactor collectors

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

pkg/perflib/perflib_test.go

@@ -0,0 +1,41 @@
+package perflib
+
+import (
+	"fmt"
+	"testing"
+)
+
+func ExampleQueryPerformanceData() {
+	objects, err := QueryPerformanceData("2")
+
+	if err != nil {
+		panic(err)
+	}
+
+	for _, object := range objects {
+		fmt.Printf("%d %s [%d counters, %d instances]\n",
+			object.NameIndex, object.Name, len(object.CounterDefs), len(object.Instances))
+
+		for _, instance := range object.Instances {
+			if !((instance.Name == "_Total") || (instance.Name == "")) {
+				continue
+			}
+
+			if instance.Name == "" {
+				fmt.Println("No instance.", instance.Name)
+			} else {
+				fmt.Println("Instance:", instance.Name)
+			}
+
+			for _, counter := range instance.Counters {
+				fmt.Printf("  -> %s %d\n", counter.Def.Name, counter.Def.NameIndex)
+			}
+		}
+	}
+}
+
+func BenchmarkQueryPerformanceData(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		_, _ = QueryPerformanceData("Global")
+	}
+}