From 353c1d3ee0be954b70060e3cf54968cdfb7fb1dc Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Tue, 22 Aug 2023 18:41:31 +0200
Subject: [PATCH] core/types: reduce allocation when decoding typed
 transactions and receipts

---
 core/types/hashing.go     | 17 +++++++++++++++++
 core/types/receipt.go     | 11 +++++++++--
 core/types/transaction.go | 10 ++++++++--
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/core/types/hashing.go b/core/types/hashing.go
index fbdeaf0d07..e127855ca8 100644
--- a/core/types/hashing.go
+++ b/core/types/hashing.go
@@ -18,6 +18,8 @@ package types
 
 import (
 	"bytes"
+	"fmt"
+	"math"
 	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -36,6 +38,21 @@ var encodeBufferPool = sync.Pool{
 	New: func() interface{} { return new(bytes.Buffer) },
 }
 
+// getPooledBuffer retrieves a buffer from the pool and creates a byte slice
+// of the requested size from it.
+//
+// The caller should return the Buffer object back into encodeBufferPool after use!
+func getPooledBuffer(size uint64) ([]byte, *bytes.Buffer, error) {
+	if size > math.MaxInt {
+		return nil, nil, fmt.Errorf("can't get buffer of size %d", size)
+	}
+	buf := encodeBufferPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	buf.Grow(int(size))
+	b := buf.Bytes()[:int(size)]
+	return b, buf, nil
+}
+
 // rlpHash encodes x and hashes the encoded bytes.
 func rlpHash(x interface{}) (h common.Hash) {
 	sha := hasherPool.Get().(crypto.KeccakState)
diff --git a/core/types/receipt.go b/core/types/receipt.go
index a96eb6b8d6..28522f8d07 100644
--- a/core/types/receipt.go
+++ b/core/types/receipt.go
@@ -153,7 +153,7 @@ func (r *Receipt) MarshalBinary() ([]byte, error) {
 // DecodeRLP implements rlp.Decoder, and loads the consensus fields of a receipt
 // from an RLP stream.
 func (r *Receipt) DecodeRLP(s *rlp.Stream) error {
-	kind, _, err := s.Kind()
+	kind, size, err := s.Kind()
 	switch {
 	case err != nil:
 		return err
@@ -167,7 +167,14 @@ func (r *Receipt) DecodeRLP(s *rlp.Stream) error {
 		return r.setFromRLP(dec)
 	default:
 		// It's an EIP-2718 typed tx receipt.
-		b, err := s.Bytes()
+		b, buf, err := getPooledBuffer(size)
+		if err != nil {
+			return err
+		}
+		defer encodeBufferPool.Put(buf)
+		if err := s.ReadBytes(b); err != nil {
+			return err
+		}
 		if err != nil {
 			return err
 		}
diff --git a/core/types/transaction.go b/core/types/transaction.go
index bf6dfb3428..44b588a012 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -147,10 +147,16 @@ func (tx *Transaction) DecodeRLP(s *rlp.Stream) error {
 		return err
 	default:
 		// It's an EIP-2718 typed TX envelope.
-		var b []byte
-		if b, err = s.Bytes(); err != nil {
+		// First read the tx payload bytes into a temporary buffer.
+		b, buf, err := getPooledBuffer(size)
+		if err != nil {
 			return err
 		}
+		defer encodeBufferPool.Put(buf)
+		if err := s.ReadBytes(b); err != nil {
+			return err
+		}
+		// Now decode the inner transaction.
 		inner, err := tx.decodeTyped(b)
 		if err == nil {
 			tx.setDecoded(inner, uint64(len(b)))