From 99822674f329ab765903490df37093c68519e34b Mon Sep 17 00:00:00 2001
From: Quentin McGaw <quentin.mcgaw@gmail.com>
Date: Fri, 8 Jul 2022 14:51:41 +0000
Subject: [PATCH] Fix rebase conflicts

---
 lib/trie/proof/generate.go | 12 +++++++-----
 lib/trie/proof/verify.go   | 21 +++++++++++++++------
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/lib/trie/proof/generate.go b/lib/trie/proof/generate.go
index 157e7dbffd..6638d42707 100644
--- a/lib/trie/proof/generate.go
+++ b/lib/trie/proof/generate.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/ChainSafe/gossamer/internal/trie/codec"
 	"github.com/ChainSafe/gossamer/internal/trie/node"
+	"github.com/ChainSafe/gossamer/internal/trie/pools"
 	"github.com/ChainSafe/gossamer/lib/common"
 	"github.com/ChainSafe/gossamer/lib/trie"
 )
@@ -36,6 +37,9 @@ func Generate(rootHash []byte, fullKeys [][]byte, database Database) (
 	}
 	rootNode := trie.RootNode()
 
+	buffer := pools.DigestBuffers.Get().(*bytes.Buffer)
+	defer pools.DigestBuffers.Put(buffer)
+
 	merkleValuesSeen := make(map[string]struct{})
 	for _, fullKey := range fullKeys {
 		fullKeyNibbles := codec.KeyLEToNibbles(fullKey)
@@ -48,14 +52,12 @@ func Generate(rootHash []byte, fullKeys [][]byte, database Database) (
 		}
 
 		for _, encodedProofNode := range newEncodedProofNodes {
-			// No need to force-hash the root node if it smaller than 32B since
-			// we use this merkle value for deduplication only, so isRoot is false.
-			const isRoot = false
-			merkleValue, err := node.MerkleValue(encodedProofNode, isRoot)
+			buffer.Reset()
+			err := node.MerkleValue(encodedProofNode, buffer)
 			if err != nil {
 				return nil, fmt.Errorf("blake2b hash: %w", err)
 			}
-			merkleValueString := string(merkleValue)
+			merkleValueString := buffer.String()
 
 			_, seen := merkleValuesSeen[merkleValueString]
 			if seen {
diff --git a/lib/trie/proof/verify.go b/lib/trie/proof/verify.go
index f447ba9057..5aab830d12 100644
--- a/lib/trie/proof/verify.go
+++ b/lib/trie/proof/verify.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/ChainSafe/gossamer/internal/trie/node"
+	"github.com/ChainSafe/gossamer/internal/trie/pools"
 	"github.com/ChainSafe/gossamer/lib/common"
 	"github.com/ChainSafe/gossamer/lib/trie"
 )
@@ -58,25 +59,33 @@ func buildTrie(encodedProofNodes [][]byte, rootHash []byte) (t *trie.Trie, err e
 	}
 
 	digestToEncoding := make(map[string][]byte, len(encodedProofNodes))
+	var root *node.Node
+
+	// note we can use a buffer from the pool since
+	// the calculated root hash digest is not used after
+	// the function completes.
+	buffer := pools.DigestBuffers.Get().(*bytes.Buffer)
+	defer pools.DigestBuffers.Put(buffer)
 
 	// This loop does two things:
 	// 1. It finds the root node by comparing it with the root hash and decodes it.
 	// 2. It stores other encoded nodes in a mapping from their encoding digest to
 	//    their encoding. They are only decoded later if the root or one of its
 	//    descendant nodes reference their hash digest.
-	var root *node.Node
 	for _, encodedProofNode := range encodedProofNodes {
 		// Note all encoded proof nodes are one of the following:
 		// - trie root node
 		// - child trie root node
 		// - child node with an encoding larger than 32 bytes
-		// In all cases, their Merkle value is the encoding hash digest.
-		const isRoot = true // force hashing of the node
-		digestHash, err := node.MerkleValue(encodedProofNode, isRoot)
+		// In all cases, their Merkle value is the encoding hash digest,
+		// so we use MerkleValueRoot to force hashing the node in case
+		// it is a root node smaller or equal to 32 bytes.
+		buffer.Reset()
+		err = node.MerkleValueRoot(encodedProofNode, buffer)
 		if err != nil {
-			return nil, fmt.Errorf("blake2b hash: %w", err)
+			return nil, fmt.Errorf("calculating Merkle value: %w", err)
 		}
-		digest := digestHash[:]
+		digest := buffer.Bytes()
 
 		if root != nil || !bytes.Equal(digest, rootHash) {
 			// root node already found or the hash doesn't match the root hash.