codec: remove unnecessary allocations in ProtoCodec.MarshalBinaryLengthPrefixed (#6877)

* codec: remove unnecessary allocations in ProtoCodec.MarshalBinaryLengthPrefixed

Improve ProtoCodec.MarshalBinaryLengthPrefixed by removing the need
to use a *bytes.Buffer and instead use an array and invoke
binary.PutUvarint, and directly create the respective length prefixed
concatentation.

With this change we get the following improvement in all dimenions
of throughput, bytes allocated, number of allocations per operation.

```shell
$ benchstat before.txt after.txt
name                                     old time/op    new time/op    delta
ProtoCodecMarshalBinaryLengthPrefixed-8     295ns ± 2%     177ns ± 3%  -39.92%  (p=0.000 n=20+20)

name                                     old speed      new speed      delta
ProtoCodecMarshalBinaryLengthPrefixed-8   505MB/s ± 2%   841MB/s ± 3%  +66.44%  (p=0.000 n=20+20)

name                                     old alloc/op   new alloc/op   delta
ProtoCodecMarshalBinaryLengthPrefixed-8      576B ± 0%      336B ± 0%  -41.67%  (p=0.000 n=20+20)

name                                     old allocs/op  new allocs/op  delta
ProtoCodecMarshalBinaryLengthPrefixed-8      5.00 ± 0%      3.00 ± 0%  -40.00%  (p=0.000 n=20+20)
```

Fixes #6875

* Address @marbar3778's feedback

Use binary.MaxVarintLen64 instead of 10

Co-authored-by: Marko <marbar3778@yahoo.com>

Co-authored-by: Marko <marbar3778@yahoo.com>
Co-authored-by: Aaron Craelius <aaron@regen.network>

codec/codec.go

@@ -1,12 +1,9 @@
 package codec
 
 import (
-	"encoding/binary"
-	"io"
+	"github.com/gogo/protobuf/proto"
 
 	"github.com/cosmos/cosmos-sdk/codec/types"
-
-	"github.com/gogo/protobuf/proto"
 )
 
 type (
@@ -58,12 +55,3 @@ type (
 		Unmarshal(data []byte) error
 	}
 )
-
-func encodeUvarint(w io.Writer, u uint64) (err error) {
-	var buf [10]byte
-
-	n := binary.PutUvarint(buf[:], u)
-	_, err = w.Write(buf[0:n])
-
-	return err
-}

codec/proto_codec.go

@@ -1,7 +1,6 @@
 package codec
 
 import (
-	"bytes"
 	"encoding/binary"
 	"fmt"
 	"strings"
@@ -40,16 +39,9 @@ func (pc *ProtoCodec) MarshalBinaryLengthPrefixed(o ProtoMarshaler) ([]byte, err
 		return nil, err
 	}
 
-	buf := new(bytes.Buffer)
-	if err := encodeUvarint(buf, uint64(o.Size())); err != nil {
-		return nil, err
-	}
-
-	if _, err := buf.Write(bz); err != nil {
-		return nil, err
-	}
-
-	return buf.Bytes(), nil
+	var sizeBuf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(sizeBuf[:], uint64(o.Size()))
+	return append(sizeBuf[:n], bz...), nil
 }
 
 func (pc *ProtoCodec) MustMarshalBinaryLengthPrefixed(o ProtoMarshaler) []byte {

codec/proto_codec_test.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"testing"
 
+	"github.com/gogo/protobuf/proto"
 	"github.com/stretchr/testify/require"
 
 	"github.com/cosmos/cosmos-sdk/codec"
@@ -193,3 +194,45 @@ func TestProtoCodecUnmarshalBinaryLengthPrefixedChecks(t *testing.T) {
 		require.Panics(t, func() { cdc.MustUnmarshalBinaryLengthPrefixed(crafted, recv) })
 	})
 }
+
+func mustAny(msg proto.Message) *types.Any {
+	any, err := types.NewAnyWithValue(msg)
+	if err != nil {
+		panic(err)
+	}
+	return any
+}
+
+func BenchmarkProtoCodecMarshalBinaryLengthPrefixed(b *testing.B) {
+	var pCdc = codec.NewProtoCodec(types.NewInterfaceRegistry()).(*codec.ProtoCodec)
+	var msg = &testdata.HasAnimal{
+		X: 1000,
+		Animal: mustAny(&testdata.HasAnimal{
+			X: 2000,
+			Animal: mustAny(&testdata.HasAnimal{
+				X: 3000,
+				Animal: mustAny(&testdata.HasAnimal{
+					X: 4000,
+					Animal: mustAny(&testdata.HasAnimal{
+						X: 5000,
+						Animal: mustAny(&testdata.Cat{
+							Moniker: "Garfield",
+							Lives:   6,
+						}),
+					}),
+				}),
+			}),
+		}),
+	}
+
+	b.ResetTimer()
+	b.ReportAllocs()
+
+	for i := 0; i < b.N; i++ {
+		blob, err := pCdc.MarshalBinaryLengthPrefixed(msg)
+		if err != nil {
+			b.Fatal(err)
+		}
+		b.SetBytes(int64(len(blob)))
+	}
+}