From fe37280ff8ab84b863ca11fa9eccbbc1be28a29c Mon Sep 17 00:00:00 2001
From: zubeyralmaho <zubeyralmaho@users.noreply.github.com>
Date: Mon, 2 Mar 2026 10:08:00 +0300
Subject: [PATCH] feat(yoga): Add cache miss tracking to LayoutData for hit
 rate metrics

## Summary
Add layoutCacheMisses and measureCacheMisses fields to LayoutData struct
to enable cache hit rate calculation in layout performance analysis.

## Motivation
Currently Yoga tracks cache hits but not misses, making it impossible
to calculate cache efficiency. This change enables:

  hitRate = cachedLayouts / (cachedLayouts + layoutCacheMisses)

## Changes
- Added layoutCacheMisses and measureCacheMisses to LayoutData struct
- Track cache misses in calculateLayoutInternal() when cache lookup fails

## Test Plan
- Built Yoga library successfully
- Verified first layout has cache misses
- Verified second layout (same dimensions) has cache hits
- Cache hit rate is now calculable
---
 .../ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp       | 4 ++++
 packages/react-native/ReactCommon/yoga/yoga/event/event.h     | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp b/packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp
index 81a5f3b8a0b6..3f7416d6711f 100644
--- a/packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp
+++ b/packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp
@@ -2266,6 +2266,10 @@ bool calculateLayoutInternal(
     (performLayout ? layoutMarkerData.cachedLayouts
                    : layoutMarkerData.cachedMeasures) += 1;
   } else {
+    // Track cache misses for computing hit rates
+    (performLayout ? layoutMarkerData.layoutCacheMisses
+                   : layoutMarkerData.measureCacheMisses) += 1;
+
     calculateLayoutImpl(
         node,
         availableWidth,
diff --git a/packages/react-native/ReactCommon/yoga/yoga/event/event.h b/packages/react-native/ReactCommon/yoga/yoga/event/event.h
index 587c1cd06367..d9f5a63bca58 100644
--- a/packages/react-native/ReactCommon/yoga/yoga/event/event.h
+++ b/packages/react-native/ReactCommon/yoga/yoga/event/event.h
@@ -41,6 +41,10 @@ struct LayoutData {
   uint32_t maxMeasureCache = 0;
   int cachedLayouts = 0;
   int cachedMeasures = 0;
+  // Cache misses occur when a cached result is not found and layout must be
+  // recalculated. Track these to compute cache hit rates.
+  int layoutCacheMisses = 0;
+  int measureCacheMisses = 0;
   int measureCallbacks = 0;
   std::array<int, static_cast<uint8_t>(LayoutPassReason::COUNT)>
       measureCallbackReasonsCount;