From c4296b65fd467cac4df36021059c53865ef1ca05 Mon Sep 17 00:00:00 2001
From: Vilius Pranckaitis <vpranckaitis@gmail.com>
Date: Mon, 18 Jan 2021 15:35:04 +0200
Subject: [PATCH] benchmark TagValueFromEncodedTagsFast

---
 .../convert/decoder_fast_benchmark_test.go    | 74 +++++++++++++++++++
 src/x/serialize/decoder_fast.go               | 50 +++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 src/dbnode/storage/index/convert/decoder_fast_benchmark_test.go

diff --git a/src/dbnode/storage/index/convert/decoder_fast_benchmark_test.go b/src/dbnode/storage/index/convert/decoder_fast_benchmark_test.go
new file mode 100644
index 0000000000..88efae2d7d
--- /dev/null
+++ b/src/dbnode/storage/index/convert/decoder_fast_benchmark_test.go
@@ -0,0 +1,74 @@
+package convert
+
+import (
+	"github.com/m3db/m3/src/x/checked"
+	"github.com/m3db/m3/src/x/pool"
+	"github.com/m3db/m3/src/x/serialize"
+	"github.com/stretchr/testify/require"
+	"math/rand"
+	"testing"
+)
+
+type encodedTagsWithTagName struct {
+	encodedTags, tagName []byte
+}
+
+func BenchmarkTagValueFromEncodedTagsFast(b *testing.B) {
+	testData, err := prepareData(b)
+	require.NoError(b, err)
+
+	b.ResetTimer()
+	for i := range testData {
+		_, _, err := serialize.TagValueFromEncodedTagsFast(testData[i].encodedTags,
+			testData[i].tagName)
+		require.NoError(b, err)
+	}
+}
+
+func BenchmarkTagValueFromEncodedTagsFast2(b *testing.B) {
+	testData, err := prepareData(b)
+	require.NoError(b, err)
+
+	b.ResetTimer()
+	for i := range testData {
+		_, _, err := serialize.TagValueFromEncodedTagsFast2(testData[i].encodedTags,
+			testData[i].tagName)
+		require.NoError(b, err)
+	}
+}
+
+func prepareData(b *testing.B) ([]encodedTagsWithTagName, error) {
+	data, err := prepareIDAndEncodedTags(b)
+	if err != nil {
+		return nil, err
+	}
+
+	decoderPool := serialize.NewTagDecoderPool(
+		serialize.NewTagDecoderOptions(serialize.TagDecoderOptionsConfig{}),
+		pool.NewObjectPoolOptions(),
+	)
+	decoderPool.Init()
+	decoder := decoderPool.Get()
+	defer decoder.Close()
+
+	var tagNames [][]byte
+	decoder.Reset(checked.NewBytes(data[0].encodedTags, nil))
+	for decoder.Next() {
+		tagNames = append(tagNames, clone(decoder.Current().Name.Bytes()))
+	}
+	tagNames = append(tagNames, []byte("not_exist"))
+
+	var (
+		result = make([]encodedTagsWithTagName, 0, b.N)
+		rnd    = rand.New(rand.NewSource(42))
+	)
+
+	for i := 0; i < b.N; i++ {
+		result = append(result, encodedTagsWithTagName{
+			encodedTags: data[i].encodedTags,
+			tagName:     tagNames[rnd.Intn(len(tagNames))],
+		})
+	}
+
+	return result, nil
+}
diff --git a/src/x/serialize/decoder_fast.go b/src/x/serialize/decoder_fast.go
index f73cf9c131..60d8bb053d 100644
--- a/src/x/serialize/decoder_fast.go
+++ b/src/x/serialize/decoder_fast.go
@@ -30,6 +30,56 @@ import (
 func TagValueFromEncodedTagsFast(
 	encodedTags []byte,
 	tagName []byte,
+) ([]byte, bool, error) {
+	total := len(encodedTags)
+	if total < 4 {
+		return nil, false, fmt.Errorf(
+			"encoded tags too short: size=%d, need=%d", total, 4)
+	}
+
+	header := byteOrder.Uint16(encodedTags[:2])
+	encodedTags = encodedTags[2:]
+	if header != headerMagicNumber {
+		return nil, false, errIncorrectHeader
+	}
+
+	length := int(byteOrder.Uint16(encodedTags[:2]))
+	encodedTags = encodedTags[2:]
+
+	for i := 0; i < length; i++ {
+		if len(encodedTags) < 2 {
+			return nil, false, fmt.Errorf("missing size for tag name: index=%d", i)
+		}
+		numBytesName := int(byteOrder.Uint16(encodedTags[:2]))
+		if numBytesName == 0 {
+			return nil, false, errEmptyTagNameLiteral
+		}
+		encodedTags = encodedTags[2:]
+
+		bytesName := encodedTags[:numBytesName]
+		encodedTags = encodedTags[numBytesName:]
+
+		if len(encodedTags) < 2 {
+			return nil, false, fmt.Errorf("missing size for tag value: index=%d", i)
+		}
+
+		numBytesValue := int(byteOrder.Uint16(encodedTags[:2]))
+		encodedTags = encodedTags[2:]
+
+		bytesValue := encodedTags[:numBytesValue]
+		encodedTags = encodedTags[numBytesValue:]
+
+		if bytes.Equal(bytesName, tagName) {
+			return bytesValue, true, nil
+		}
+	}
+
+	return nil, false, nil
+}
+
+func TagValueFromEncodedTagsFast2(
+	encodedTags []byte,
+	tagName []byte,
 ) ([]byte, bool, error) {
 	var (
 		length int