From fffd7620218db9f1b8f3cadf305975ad68aac004 Mon Sep 17 00:00:00 2001
From: Tuyen Nguyen <twoeths@users.noreply.github.com>
Date: Wed, 12 Mar 2025 15:53:34 +0700
Subject: [PATCH] fix: do not rebind node if unchanged child ViewDUs

---
 packages/ssz/src/viewDU/arrayComposite.ts       | 9 ++++++---
 packages/ssz/src/viewDU/container.ts            | 9 ++++++---
 packages/ssz/test/unit/unchangedViewDUs.test.ts | 2 +-
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/packages/ssz/src/viewDU/arrayComposite.ts b/packages/ssz/src/viewDU/arrayComposite.ts
index aa7e2be4..e2374cd1 100644
--- a/packages/ssz/src/viewDU/arrayComposite.ts
+++ b/packages/ssz/src/viewDU/arrayComposite.ts
@@ -195,9 +195,12 @@ export class ArrayCompositeTreeViewDU<
 
     for (const [index, view] of this.viewsChanged) {
       const node = this.type.elementType.commitViewDU(view, offsetView, byLevelView);
-      // Set new node in nodes array to ensure data represented in the tree and fast nodes access is equal
-      this.nodes[index] = node;
-      nodesChanged.push({index, node});
+      // there's a chance the view is not changed, no need to rebind nodes in that case
+      if (this.nodes[index] !== node) {
+        // Set new node in nodes array to ensure data represented in the tree and fast nodes access is equal
+        this.nodes[index] = node;
+        nodesChanged.push({index, node});
+      }
 
       // Cache the view's caches to preserve it's data after 'this.viewsChanged.clear()'
       const cache = this.type.elementType.cacheOfViewDU(view);
diff --git a/packages/ssz/src/viewDU/container.ts b/packages/ssz/src/viewDU/container.ts
index ab71749c..f38c1925 100644
--- a/packages/ssz/src/viewDU/container.ts
+++ b/packages/ssz/src/viewDU/container.ts
@@ -101,9 +101,12 @@ export class BasicContainerTreeViewDU<Fields extends Record<string, Type<unknown
     for (const [index, view] of this.viewsChanged) {
       const fieldType = this.type.fieldsEntries[index].fieldType as unknown as CompositeTypeAny;
       const node = fieldType.commitViewDU(view, offsetView, byLevelView);
-      // Set new node in nodes array to ensure data represented in the tree and fast nodes access is equal
-      this.nodes[index] = node;
-      nodesChanged.push({index, node});
+      // there's a chance the view is not changed, no need to rebind nodes in that case
+      if (this.nodes[index] !== node) {
+        // Set new node in nodes array to ensure data represented in the tree and fast nodes access is equal
+        this.nodes[index] = node;
+        nodesChanged.push({index, node});
+      }
 
       // Cache the view's caches to preserve it's data after 'this.viewsChanged.clear()'
       const cache = fieldType.cacheOfViewDU(view);
diff --git a/packages/ssz/test/unit/unchangedViewDUs.test.ts b/packages/ssz/test/unit/unchangedViewDUs.test.ts
index c580db9f..e7733be0 100644
--- a/packages/ssz/test/unit/unchangedViewDUs.test.ts
+++ b/packages/ssz/test/unit/unchangedViewDUs.test.ts
@@ -5,7 +5,7 @@ import {getRandomState} from "../utils/generateEth2Objs.js";
 describe("Unchanged ViewDUs", () => {
   const state = sszAltair.BeaconState.toViewDU(getRandomState(100));
 
-  it.skip("should not recompute batchHashTreeRoot() when no fields is changed", () => {
+  it("should not recompute batchHashTreeRoot() when no fields is changed", () => {
     const root = state.batchHashTreeRoot();
     // this causes viewsChanged inside BeaconState container
     state.validators.length;