Fabric: Using unique_ptr for storing YGNode inside YogaLayoutableShad…

…owNode

Summary:
I recently realized (Thanks David!) that we should not use `shared_ptr` for storing YGNode*
because ShadowNode does not share ownership of the Yoga node with anybody.
So the lifecycle of shadow node and yoga node must be synchronized (this is already the case but changing to unique_ptr makes this explicit and a bit more performant).

Reviewed By: fkgozali

Differential Revision: D8030417

fbshipit-source-id: c7f85ea309598d2a5ebfed55b1d182d3fe1336ae

ReactCommon/fabric/view/yoga/YogaLayoutableShadowNode.cpp

@@ -37,35 +37,32 @@ YogaLayoutableShadowNode::YogaLayoutableShadowNode(
   assert(props);
   assert(children);
 
-  auto yogaNode = std::make_shared<YGNode>();
-  yogaNode->setConfig(suitableYogaConfig().get());
-  yogaNode->setStyle(props->yogaStyle);
-  yogaNode->setContext(this);
-  yogaNode->setDirty(true);
-  YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(*yogaNode, children);
-  yogaNode_ = yogaNode;
+  yogaNode_ = std::make_unique<YGNode>();
+  yogaNode_->setConfig(suitableYogaConfig().get());
+  yogaNode_->setStyle(props->yogaStyle);
+  yogaNode_->setContext(this);
+  yogaNode_->setDirty(true);
+  YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(yogaNode_.get(), children);
 }
 
 YogaLayoutableShadowNode::YogaLayoutableShadowNode(
   const SharedYogaLayoutableShadowNode &shadowNode,
   const SharedYogaStylableProps &props,
   const SharedShadowNodeSharedList &children
 ) {
-  auto yogaNode = std::make_shared<YGNode>(*shadowNode->yogaNode_);
-  yogaNode->setConfig(suitableYogaConfig().get());
-  yogaNode->setContext(this);
-  yogaNode->setOwner(nullptr);
-  yogaNode->setDirty(true);
+  yogaNode_ = std::make_unique<YGNode>(*shadowNode->yogaNode_);
+  yogaNode_->setConfig(suitableYogaConfig().get());
+  yogaNode_->setContext(this);
+  yogaNode_->setOwner(nullptr);
+  yogaNode_->setDirty(true);
 
   if (props) {
-    yogaNode->setStyle(props->yogaStyle);
+    yogaNode_->setStyle(props->yogaStyle);
   }
 
   if (children) {
-    YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(*yogaNode, children);
+    YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(yogaNode_.get(), children);
   }
-
-  yogaNode_ = yogaNode;
 }
 
 void YogaLayoutableShadowNode::cleanLayout() {
@@ -99,21 +96,20 @@ void YogaLayoutableShadowNode::enableMeasurement() {
 void YogaLayoutableShadowNode::appendChild(SharedYogaLayoutableShadowNode child) {
   ensureUnsealed();
 
-  auto nonConstYogaNode = std::const_pointer_cast<YGNode>(yogaNode_);
-  auto nonConstChildYogaNode = std::const_pointer_cast<YGNode>(child->yogaNode_);
-  nonConstYogaNode->insertChild(nonConstChildYogaNode.get(), nonConstYogaNode->getChildrenCount());
+  auto yogaNodeRawPtr = yogaNode_.get();
+  auto childYogaNodeRawPtr = child->yogaNode_.get();
+  yogaNodeRawPtr->insertChild(childYogaNodeRawPtr, yogaNodeRawPtr->getChildrenCount());
 
-  if (nonConstChildYogaNode->getOwner() == nullptr) {
+  if (childYogaNodeRawPtr->getOwner() == nullptr) {
     child->ensureUnsealed();
-    nonConstChildYogaNode->setOwner(nonConstYogaNode.get());
+    childYogaNodeRawPtr->setOwner(yogaNodeRawPtr);
   }
 }
 
 void YogaLayoutableShadowNode::layout(LayoutContext layoutContext) {
   if (!getIsLayoutClean()) {
     ensureUnsealed();
-    YGNode *yogaNode = const_cast<YGNode *>(yogaNode_.get());
-    YGNodeCalculateLayout(yogaNode, YGUndefined, YGUndefined, YGDirectionInherit);
+    YGNodeCalculateLayout(yogaNode_.get(), YGUndefined, YGUndefined, YGDirectionInherit);
   }
 
   LayoutableShadowNode::layout(layoutContext);
@@ -206,7 +202,7 @@ YGSize YogaLayoutableShadowNode::yogaNodeMeasureCallbackConnector(YGNode *yogaNo
   };
 }
 
-void YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(YGNode &yogaNode, const SharedShadowNodeSharedList &children) {
+void YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(YGNode *yogaNodeRawPtr, const SharedShadowNodeSharedList &children) {
   auto yogaNodeChildren = YGVector();
 
   for (const SharedShadowNode &shadowNode : *children) {
@@ -216,17 +212,17 @@ void YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(YGNo
       continue;
     }
 
-    YGNode *yogaNodeChild = (YGNode *)yogaLayoutableShadowNode->yogaNode_.get();
+    auto &&childYogaNodeRawPtr = (YGNode *)yogaLayoutableShadowNode->yogaNode_.get();
 
-    yogaNodeChildren.push_back(yogaNodeChild);
+    yogaNodeChildren.push_back(childYogaNodeRawPtr);
 
-    if (yogaNodeChild->getOwner() == nullptr) {
+    if (childYogaNodeRawPtr->getOwner() == nullptr) {
       yogaLayoutableShadowNode->ensureUnsealed();
-      yogaNodeChild->setOwner(&yogaNode);
+      childYogaNodeRawPtr->setOwner(yogaNodeRawPtr);
     }
   }
 
-  yogaNode.setChildren(yogaNodeChildren);
+  yogaNodeRawPtr->setChildren(yogaNodeChildren);
 }
 
 } // namespace react

ReactCommon/fabric/view/yoga/YogaLayoutableShadowNode.h

@@ -23,9 +23,6 @@ namespace react {
 
 class YogaLayoutableShadowNode;
 
-// We accept that Yoga node is highly mutable thing and we don't try to enforce immutability,
-// so it does not have `const` qualifier (and we mark it as `mutable` in the class).
-using SharedYogaNode = std::shared_ptr<YGNode>;
 using SharedYogaConfig = std::shared_ptr<YGConfig>;
 
 using SharedYogaLayoutableShadowNode = std::shared_ptr<const YogaLayoutableShadowNode>;
@@ -83,11 +80,11 @@ class YogaLayoutableShadowNode:
   void layoutChildren(LayoutContext layoutContext) override;
 
 protected:
-  mutable SharedYogaNode yogaNode_;
+  std::unique_ptr<YGNode> yogaNode_;
 
 private:
   static SharedYogaConfig suitableYogaConfig();
-  static void setYogaNodeChildrenBasedOnShadowNodeChildren(YGNode &yogaNode, const SharedShadowNodeSharedList &children);
+  static void setYogaNodeChildrenBasedOnShadowNodeChildren(YGNode *yogaNodeRawPtr, const SharedShadowNodeSharedList &children);
   static YGNode *yogaNodeCloneCallbackConnector(YGNode *oldYogaNode, YGNode *parentYogaNode, int childIndex);
   static YGSize yogaNodeMeasureCallbackConnector(YGNode *yogaNode, float width, YGMeasureMode widthMode, float height, YGMeasureMode heightMode);
 };