Slider component - cache measurements, don't create measure manager on iOS

Summary: Small perf wins for both iOS and Android.

Reviewed By: PeteTheHeat

Differential Revision: D14237532

fbshipit-source-id: 2be114d36adfa6e8540cb8cbca5412782791d8ce

ReactCommon/fabric/components/slider/SliderComponentDescriptor.h

@@ -36,7 +36,9 @@ class SliderComponentDescriptor final
         imageManager_(nullptr),
 #endif
         measurementsManager_(
-            std::make_shared<SliderMeasurementsManager>(contextContainer)) {
+            SliderMeasurementsManager::shouldMeasureSlider()
+                ? std::make_shared<SliderMeasurementsManager>(contextContainer)
+                : nullptr) {
   }
 
   void adopt(UnsharedShadowNode shadowNode) const override {
@@ -50,13 +52,15 @@ class SliderComponentDescriptor final
     // communicate the loading state and results to mounting layer.
     sliderShadowNode->setImageManager(imageManager_);
 
-    // `SliderShadowNode` uses `SliderMeasurementsManager` to
-    // provide measurements to Yoga.
-    sliderShadowNode->setSliderMeasurementsManager(measurementsManager_);
+    if (measurementsManager_) {
+      // `SliderShadowNode` uses `SliderMeasurementsManager` to
+      // provide measurements to Yoga.
+      sliderShadowNode->setSliderMeasurementsManager(measurementsManager_);
 
-    // All `SliderShadowNode`s must have leaf Yoga nodes with properly
-    // setup measure function.
-    sliderShadowNode->enableMeasurement();
+      // All `SliderShadowNode`s must have leaf Yoga nodes with properly
+      // setup measure function.
+      sliderShadowNode->enableMeasurement();
+    }
   }
 
  private:

ReactCommon/fabric/components/slider/SliderShadowNode.cpp

@@ -93,7 +93,7 @@ ImageSource SliderShadowNode::getThumbImageSource() const {
 #pragma mark - LayoutableShadowNode
 
 Size SliderShadowNode::measure(LayoutConstraints layoutConstraints) const {
-  if (measurementsManager_->shouldMeasureSlider()) {
+  if (SliderMeasurementsManager::shouldMeasureSlider()) {
     return measurementsManager_->measure(layoutConstraints);
   }
 

ReactCommon/fabric/components/slider/platform/android/SliderMeasurementsManager.cpp

@@ -16,12 +16,15 @@ using namespace facebook::jni;
 namespace facebook {
 namespace react {
 
-const bool SliderMeasurementsManager::shouldMeasureSlider() const {
-  return true;
-}
-
 Size SliderMeasurementsManager::measure(
     LayoutConstraints layoutConstraints) const {
+  {
+    std::lock_guard<std::mutex> lock(mutex_);
+    if (hasBeenMeasured_) {
+      return cachedMeasurement_;
+    }
+  }
+
   const jni::global_ref<jobject> &fabricUIManager =
       contextContainer_->getInstance<jni::global_ref<jobject>>(
           "FabricUIManager");
@@ -46,7 +49,7 @@ Size SliderMeasurementsManager::measure(
 
   local_ref<JString> componentName = make_jstring("RCTSlider");
 
-  return yogaMeassureToSize(measure(
+  auto measurement = yogaMeassureToSize(measure(
       fabricUIManager,
       componentName.get(),
       nullptr,
@@ -55,6 +58,10 @@ Size SliderMeasurementsManager::measure(
       maxWidth,
       minHeight,
       maxHeight));
+
+  std::lock_guard<std::mutex> lock(mutex_);
+  cachedMeasurement_ = measurement;
+  return measurement;
 }
 
 } // namespace react

ReactCommon/fabric/components/slider/platform/android/SliderMeasurementsManager.h

@@ -22,11 +22,18 @@ class SliderMeasurementsManager {
  public:
   SliderMeasurementsManager(const SharedContextContainer &contextContainer)
       : contextContainer_(contextContainer) {}
-  const bool shouldMeasureSlider() const;
+
+  static inline bool shouldMeasureSlider() {
+    return true;
+  }
+
   Size measure(LayoutConstraints layoutConstraints) const;
 
  private:
   const SharedContextContainer contextContainer_;
+  mutable std::mutex mutex_;
+  mutable bool hasBeenMeasured_ = false;
+  mutable Size cachedMeasurement_{};
 };
 
 } // namespace react

ReactCommon/fabric/components/slider/platform/ios/SliderMeasurementsManager.cpp

@@ -10,10 +10,6 @@
 namespace facebook {
 namespace react {
 
-const bool SliderMeasurementsManager::shouldMeasureSlider() const {
-  return false;
-}
-
 Size SliderMeasurementsManager::measure(
     LayoutConstraints layoutConstraints) const {
   assert(false); // should never reach this point

ReactCommon/fabric/components/slider/platform/ios/SliderMeasurementsManager.h

@@ -21,7 +21,11 @@ namespace react {
 class SliderMeasurementsManager {
  public:
   SliderMeasurementsManager(const SharedContextContainer &contextContainer) {}
-  const bool shouldMeasureSlider() const;
+
+  static inline bool shouldMeasureSlider() {
+    return false;
+  }
+
   Size measure(LayoutConstraints layoutConstraints) const;
 };