Scraping: Add benchmark for protobuf format

Extract helper function textToProto().

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

scrape/scrape_test.go

@@ -1295,6 +1295,45 @@ func BenchmarkScrapeLoopAppendOM(b *testing.B) {
 	}
 }
 
+func BenchmarkScrapeLoopAppendProto(b *testing.B) {
+	ctx, sl := simpleTestScrapeLoop(b)
+
+	slApp := sl.appender(ctx)
+
+	// Construct a metrics string to parse
+	sb := bytes.Buffer{}
+	fmt.Fprintf(&sb, "type: GAUGE\n")
+	fmt.Fprintf(&sb, "help: \"metric_a help text\"\n")
+	fmt.Fprintf(&sb, "name: \"metric_a\"\n")
+	for i := 0; i < 100; i++ {
+		fmt.Fprintf(&sb, `metric: <
+  label: <
+    name: "foo"
+    value: "%d"
+  >
+  label: <
+    name: "bar"
+    value: "%d"
+  >
+  gauge: <
+    value: 1
+  >
+>
+`, i, i*100)
+	}
+	// From text to proto message.
+	pb := bytes.Buffer{}
+	require.NoError(b, textToProto(sb.String(), &pb))
+	ts := time.Time{}
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		ts = ts.Add(time.Second)
+		_, _, _, _ = sl.append(slApp, pb.Bytes(), "application/vnd.google.protobuf", ts)
+	}
+}
+
 func TestSetOptionsHandlingStaleness(t *testing.T) {
 	s := teststorage.New(t, 600000)
 	defer s.Close()
@@ -2454,18 +2493,7 @@ metric: <
 
 			buf := &bytes.Buffer{}
 			if test.contentType == "application/vnd.google.protobuf" {
-				// In case of protobuf, we have to create the binary representation.
+				require.NoError(t, textToProto(test.scrapeText, buf))
-				pb := &dto.MetricFamily{}
-				// From text to proto message.
-				require.NoError(t, proto.UnmarshalText(test.scrapeText, pb))
-				// From proto message to binary protobuf.
-				protoBuf, err := proto.Marshal(pb)
-				require.NoError(t, err)
-
-				// Write first length, then binary protobuf.
-				varintBuf := binary.AppendUvarint(nil, uint64(len(protoBuf)))
-				buf.Write(varintBuf)
-				buf.Write(protoBuf)
 			} else {
 				buf.WriteString(test.scrapeText)
 			}
@@ -2480,6 +2508,26 @@ metric: <
 	}
 }
 
+func textToProto(text string, buf *bytes.Buffer) error {
+	// In case of protobuf, we have to create the binary representation.
+	pb := &dto.MetricFamily{}
+	// From text to proto message.
+	err := proto.UnmarshalText(text, pb)
+	if err != nil {
+		return err
+	}
+	// From proto message to binary protobuf.
+	protoBuf, err := proto.Marshal(pb)
+	if err != nil {
+		return err
+	}
+	// Write first length, then binary protobuf.
+	varintBuf := binary.AppendUvarint(nil, uint64(len(protoBuf)))
+	buf.Write(varintBuf)
+	buf.Write(protoBuf)
+	return nil
+}
+
 func TestScrapeLoopAppendExemplarSeries(t *testing.T) {
 	scrapeText := []string{`metric_total{n="1"} 1 # {t="1"} 1.0 10000
 # EOF`, `metric_total{n="1"} 2 # {t="2"} 2.0 20000