Avoid redundant copy of shared_ptr

Summary:
changelog: [internal]

Making a copy of shared_ptr is order of magnitude more expensive than moving it. This diff avoids two redundant copies in commit phase.

Reviewed By: rubennorte, cipolleschi

Differential Revision: D43306245

fbshipit-source-id: cfa942cc67b1e5c91be47803b80f7c8cda2e32d8

Author: sammy-SC

ReactCommon/react/renderer/mounting/MountingCoordinator.cpp

@@ -33,15 +33,15 @@ SurfaceId MountingCoordinator::getSurfaceId() const {
   return surfaceId_;
 }
 
-void MountingCoordinator::push(ShadowTreeRevision const &revision) const {
+void MountingCoordinator::push(ShadowTreeRevision revision) const {
   {
     std::lock_guard<std::mutex> lock(mutex_);
 
     react_native_assert(
         !lastRevision_.has_value() || revision.number != lastRevision_->number);
 
     if (!lastRevision_.has_value() || lastRevision_->number < revision.number) {
-      lastRevision_ = revision;
+      lastRevision_ = std::move(revision);
     }
   }
 

ReactCommon/react/renderer/mounting/MountingCoordinator.h

@@ -88,7 +88,7 @@ class MountingCoordinator final {
  private:
   friend class ShadowTree;
 
-  void push(ShadowTreeRevision const &revision) const;
+  void push(ShadowTreeRevision revision) const;
 
   /*
    * Revokes the last pushed `ShadowTreeRevision`.

ReactCommon/react/renderer/mounting/ShadowTree.cpp

@@ -393,16 +393,16 @@ CommitStatus ShadowTree::tryCommit(
     telemetry.didCommit();
     telemetry.setRevisionNumber(static_cast<int>(newRevisionNumber));
 
-    newRevision =
-        ShadowTreeRevision{newRootShadowNode, newRevisionNumber, telemetry};
+    newRevision = ShadowTreeRevision{
+        std::move(newRootShadowNode), newRevisionNumber, telemetry};
 
     currentRevision_ = newRevision;
   }
 
   emitLayoutEvents(affectedLayoutableNodes);
 
   if (commitMode == CommitMode::Normal) {
-    mount(newRevision, commitOptions.mountSynchronously);
+    mount(std::move(newRevision), commitOptions.mountSynchronously);
   }
 
   return CommitStatus::Succeeded;
@@ -413,10 +413,9 @@ ShadowTreeRevision ShadowTree::getCurrentRevision() const {
   return currentRevision_;
 }
 
-void ShadowTree::mount(
-    ShadowTreeRevision const &revision,
-    bool mountSynchronously) const {
-  mountingCoordinator_->push(revision);
+void ShadowTree::mount(ShadowTreeRevision revision, bool mountSynchronously)
+    const {
+  mountingCoordinator_->push(std::move(revision));
   delegate_.shadowTreeDidFinishTransaction(
       mountingCoordinator_, mountSynchronously);
 }

ReactCommon/react/renderer/mounting/ShadowTree.h

@@ -134,7 +134,7 @@ class ShadowTree final {
  private:
   constexpr static ShadowTreeRevision::Number INITIAL_REVISION{0};
 
-  void mount(ShadowTreeRevision const &revision, bool mountSynchronously) const;
+  void mount(ShadowTreeRevision revision, bool mountSynchronously) const;
 
   void emitLayoutEvents(
       std::vector<LayoutableShadowNode const *> &affectedLayoutableNodes) const;