Reuse buffer from pool when encoding elements

array.go

@@ -24,6 +24,7 @@ import (
 	"fmt"
 	"math"
 	"strings"
+	"sync"
 
 	"github.com/fxamacker/cbor/v2"
 )
@@ -220,6 +221,23 @@ type Array struct {
 	mutableElementIndex map[ValueID]uint64
 }
 
+var bufferPool = sync.Pool{
+	New: func() interface{} {
+		e := new(bytes.Buffer)
+		e.Grow(int(maxThreshold))
+		return e
+	},
+}
+
+func getBuffer() *bytes.Buffer {
+	return bufferPool.Get().(*bytes.Buffer)
+}
+
+func putBuffer(e *bytes.Buffer) {
+	e.Reset()
+	bufferPool.Put(e)
+}
+
 var _ Value = &Array{}
 var _ mutableValueNotifier = &Array{}
 
@@ -775,9 +793,11 @@ func (a *ArrayDataSlab) Encode(enc *Encoder) error {
 
 	inlinedTypes := newInlinedExtraData()
 
-	// TODO: maybe use a buffer pool
-	var elementBuf bytes.Buffer
-	elementEnc := NewEncoder(&elementBuf, enc.encMode)
+	// Get a buffer from a pool to encode elements.
+	elementBuf := getBuffer()
+	defer putBuffer(elementBuf)
+
+	elementEnc := NewEncoder(elementBuf, enc.encMode)
 
 	err := a.encodeElements(elementEnc, inlinedTypes)
 	if err != nil {

map.go

@@ -19,7 +19,6 @@
 package atree
 
 import (
-	"bytes"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -2683,9 +2682,11 @@ func (m *MapDataSlab) Encode(enc *Encoder) error {
 
 	inlinedTypes := newInlinedExtraData()
 
-	// TODO: maybe use a buffer pool
-	var buf bytes.Buffer
-	elemEnc := NewEncoder(&buf, enc.encMode)
+	// Get a buffer from a pool to encode elements.
+	elementBuf := getBuffer()
+	defer putBuffer(elementBuf)
+
+	elemEnc := NewEncoder(elementBuf, enc.encMode)
 
 	err := m.encodeElements(elemEnc, inlinedTypes)
 	if err != nil {
@@ -2763,7 +2764,7 @@ func (m *MapDataSlab) Encode(enc *Encoder) error {
 	}
 
 	// Encode elements
-	err = enc.CBOR.EncodeRawBytes(buf.Bytes())
+	err = enc.CBOR.EncodeRawBytes(elementBuf.Bytes())
 	if err != nil {
 		return NewEncodingError(err)
 	}