reuse buffer (cosmos#453)

* reuse buffer

* copy bytes

(cherry picked from commit 0568d39)

encoding.go

@@ -10,6 +10,12 @@ import (
 	"sync"
 )
 
+var bufPool = &sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
 var varintPool = &sync.Pool{
 	New: func() interface{} {
 		return &[binary.MaxVarintLen64]byte{}
@@ -93,9 +99,16 @@ func encodeBytes(w io.Writer, bz []byte) error {
 
 // encodeBytesSlice length-prefixes the byte slice and returns it.
 func encodeBytesSlice(bz []byte) ([]byte, error) {
-	var buf bytes.Buffer
-	err := encodeBytes(&buf, bz)
-	return buf.Bytes(), err
+	buf := bufPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufPool.Put(buf)
+
+	err := encodeBytes(buf, bz)
+
+	bytesCopy := make([]byte, buf.Len())
+	copy(bytesCopy, buf.Bytes())
+
+	return bytesCopy, err
 }
 
 // encodeBytesSize returns the byte size of the given slice including length-prefixing.

import.go

@@ -119,13 +119,18 @@ func (i *Importer) Add(exportNode *ExportNode) error {
 		return err
 	}
 
-	var buf bytes.Buffer
-	err = node.writeBytes(&buf)
-	if err != nil {
+	buf := bufPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufPool.Put(buf)
+
+	if err = node.writeBytes(buf); err != nil {
 		return err
 	}
 
-	if err = i.batch.Set(i.tree.ndb.nodeKey(node.hash), buf.Bytes()); err != nil {
+	bytesCopy := make([]byte, buf.Len())
+	copy(bytesCopy, buf.Bytes())
+
+	if err = i.batch.Set(i.tree.ndb.nodeKey(node.hash), bytesCopy); err != nil {
 		return err
 	}
 

proof.go

@@ -55,7 +55,10 @@ func (pin ProofInnerNode) stringIndented(indent string) string {
 
 func (pin ProofInnerNode) Hash(childHash []byte) []byte {
 	hasher := sha256.New()
-	buf := new(bytes.Buffer)
+
+	buf := bufPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufPool.Put(buf)
 
 	err := encodeVarint(buf, int64(pin.Height))
 	if err == nil {
@@ -145,7 +148,10 @@ func (pln ProofLeafNode) stringIndented(indent string) string {
 
 func (pln ProofLeafNode) Hash() []byte {
 	hasher := sha256.New()
-	buf := new(bytes.Buffer)
+
+	buf := bufPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufPool.Put(buf)
 
 	err := encodeVarint(buf, 0)
 	if err == nil {

proof_ics23_test.go

@@ -151,7 +151,6 @@ func GetKey(allkeys [][]byte, loc Where) []byte {
 		return allkeys[len(allkeys)-1]
 	}
 	// select a random index between 1 and allkeys-2
-	// nolint:gosec
 	idx := rand.Int()%(len(allkeys)-2) + 1
 	return allkeys[idx]
 }
@@ -181,7 +180,6 @@ func BuildTree(size int) (itree *ImmutableTree, keys [][]byte, err error) {
 	for i := 0; i < size; i++ {
 		key := make([]byte, 4)
 		// create random 4 byte key
-		// nolint:gosec
 		rand.Read(key)
 		value := "value_for_key:" + string(key)
 		tree.Set(key, []byte(value))

testutils_test.go

@@ -82,7 +82,6 @@ func randBytes(length int) []byte {
 	key := make([]byte, length)
 	// math.rand.Read always returns err=nil
 	// we do not need cryptographic randomness for this test:
-	//nolint:gosec
 	mrand.Read(key)
 	return key
 }

tree_dotgraph.go

@@ -55,7 +55,7 @@ func WriteDOTGraph(w io.Writer, tree *ImmutableTree, paths []PathToLeaf) {
 		}
 		shortHash := graphNode.Hash[:7]
 
-		graphNode.Label = mkLabel(fmt.Sprintf("%s", node.key), 16, "sans-serif")
+		graphNode.Label = mkLabel(string(node.key), 16, "sans-serif")
 		graphNode.Label += mkLabel(shortHash, 10, "monospace")
 		graphNode.Label += mkLabel(fmt.Sprintf("version=%d", node.version), 10, "monospace")