Fabric: ShadowNode::getCommitedState() now returns by value

Summary: Returning a shared pointer by const reference in this context is not correct/safe because the object (the ShadowNode) doesn't own the object, so the caller cannot reason about the lifetime (esp. in a multithreaded environment).

Reviewed By: mdvacca

Differential Revision: D15958737

fbshipit-source-id: 8f03e6530d07d63ece5f955055c5c67c204b8223

ReactCommon/fabric/core/shadownode/ShadowNode.cpp

@@ -120,7 +120,7 @@ const State::Shared &ShadowNode::getState() const {
   return state_;
 }
 
-const State::Shared &ShadowNode::getCommitedState() const {
+State::Shared ShadowNode::getCommitedState() const {
   return state_ ? state_->getCommitedState()
                 : ShadowNodeFragment::statePlaceholder();
 }

ReactCommon/fabric/core/shadownode/ShadowNode.h

@@ -115,7 +115,7 @@ class ShadowNode : public virtual Sealable,
    * Returns a momentary value of currently committed state associated with a
    * family of nodes which this node belongs to.
    */
-  const State::Shared &getCommitedState() const;
+  State::Shared getCommitedState() const;
 
   /*
    * Returns a local data associated with the node.

ReactCommon/fabric/core/state/State.cpp

@@ -29,7 +29,7 @@ void State::commit(const ShadowNode &shadowNode) const {
   stateCoordinator_->setTarget(StateTarget{shadowNode});
 }
 
-const State::Shared &State::getCommitedState() const {
+State::Shared State::getCommitedState() const {
   return stateCoordinator_->getTarget().getShadowNode().getState();
 }
 

ReactCommon/fabric/core/state/State.h

@@ -48,7 +48,7 @@ class State {
   /*
    * Must be used by `ShadowNode` *only*.
    */
-  const State::Shared &getCommitedState() const;
+  State::Shared getCommitedState() const;
 };
 
 } // namespace react