Remove State Reconciliation flags and dead code

Summary: Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D23292369

fbshipit-source-id: 6f00070495e9947476f1dbea7776ca85002e078b

ReactCommon/react/renderer/mounting/ShadowTree.cpp

@@ -17,7 +17,6 @@
 #include <react/renderer/mounting/ShadowViewMutation.h>
 
 #include "ShadowTreeDelegate.h"
-#include "TreeStateReconciliation.h"
 
 namespace facebook {
 namespace react {
@@ -303,22 +302,11 @@ bool ShadowTree::tryCommit(
   }
 
   if (enableStateReconciliation) {
-    if (enableNewStateReconciliation_) {
-      auto updatedNewRootShadowNode =
-          progressState(*newRootShadowNode, *oldRootShadowNode);
-      if (updatedNewRootShadowNode) {
-        newRootShadowNode =
-            std::static_pointer_cast<RootShadowNode>(updatedNewRootShadowNode);
-      }
-    } else {
-      // Compare state revisions of old and new root
-      // Children of the root node may be mutated in-place
-      UnsharedShadowNode reconciledNode =
-          reconcileStateWithTree(newRootShadowNode.get(), oldRootShadowNode);
-      if (reconciledNode != nullptr) {
-        newRootShadowNode = std::make_shared<RootShadowNode>(
-            *reconciledNode, ShadowNodeFragment{});
-      }
+    auto updatedNewRootShadowNode =
+        progressState(*newRootShadowNode, *oldRootShadowNode);
+    if (updatedNewRootShadowNode) {
+      newRootShadowNode =
+          std::static_pointer_cast<RootShadowNode>(updatedNewRootShadowNode);
     }
   }
 

ReactCommon/react/renderer/mounting/ShadowTree.h

@@ -81,13 +81,6 @@ class ShadowTree final {
 
   MountingCoordinator::Shared getMountingCoordinator() const;
 
-  /*
-   * Temporary.
-   * Do not use.
-   */
-  void setEnableNewStateReconciliation(bool value) {
-    enableNewStateReconciliation_ = value;
-  }
   void setEnableReparentingDetection(bool value) {
     enableReparentingDetection_ = value;
   }

ReactCommon/react/renderer/mounting/TreeStateReconciliation.cpp

@@ -1,94 +0,0 @@
-/*
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-#include "TreeStateReconciliation.h"
-
-namespace facebook {
-namespace react {
-
-using ChangedShadowNodePairs =
-    std::vector<std::pair<ShadowNode::Shared, ShadowNode::Unshared>>;
-
-/**
- * Clones any children in the subtree that need to be cloned, and adds those to
- * the `changedPairs` vector argument.
- */
-static ChangedShadowNodePairs reconcileStateWithChildren(
-    SharedShadowNodeList const &newChildren,
-    SharedShadowNodeList const &oldChildren) {
-  ChangedShadowNodePairs changedPairs;
-  // Find children that are the same family in both trees.
-  // We only want to find nodes that existing in the new tree - if they
-  // don't exist in the new tree, they're being deleted; if they don't exist
-  // in the old tree, they're new. We don't need to deal with either of those
-  // cases here.
-  // Currently we use a naive double loop - this could be improved, but we need
-  // to be able to handle cases where nodes are entirely reordered, for
-  // instance.
-  for (auto const &child : newChildren) {
-    auto const oldChild = std::find_if(
-        oldChildren.begin(), oldChildren.end(), [&](const auto &el) {
-          return ShadowNode::sameFamily(*child, *el);
-        });
-
-    if (oldChild != oldChildren.end()) {
-      UnsharedShadowNode newChild =
-          reconcileStateWithTree(child.get(), *oldChild);
-      if (newChild != nullptr) {
-        changedPairs.push_back(std::make_pair(child, newChild));
-      }
-    }
-  };
-
-  return changedPairs;
-}
-
-UnsharedShadowNode reconcileStateWithTree(
-    ShadowNode const *newNode,
-    SharedShadowNode committedNode) {
-  // If the revisions on the node are the same, we can finish here.
-  // Subtrees are guaranteed to be identical at this point, too.
-  if (committedNode->getStateRevision() <= newNode->getStateRevision()) {
-    return nullptr;
-  }
-
-  // If we got this fair, we're guaranteed that the state of 1) this node,
-  // and/or 2) some descendant node is out-of-date and must be reconciled.
-  // This requires traversing all children, and we must at *least* clone
-  // this node, whether or not we clone and update any children.
-  auto const &newChildren = newNode->getChildren();
-  auto const &oldChildren = committedNode->getChildren();
-  auto const changedPairs =
-      reconcileStateWithChildren(newChildren, oldChildren);
-
-  ShadowNode::SharedListOfShared clonedChildren =
-      ShadowNodeFragment::childrenPlaceholder();
-
-  // If any children were cloned, we need to recreate the child list.
-  // This won't cause any children to be cloned that weren't already cloned -
-  // it just collects all children, cloned or uncloned, into a new list.
-  if (!changedPairs.empty()) {
-    ShadowNode::UnsharedListOfShared newList =
-        std::make_shared<ShadowNode::ListOfShared>();
-    for (std::size_t i = 0, j = 0; i < newChildren.size(); ++i) {
-      if (j < changedPairs.size() && changedPairs[j].first == newChildren[i]) {
-        newList->push_back(changedPairs[j].second);
-        ++j;
-      } else {
-        newList->push_back(newChildren[i]);
-      }
-    }
-    clonedChildren = newList;
-  }
-
-  return newNode->clone({/* .props = */ ShadowNodeFragment::propsPlaceholder(),
-                         /* .children = */ clonedChildren,
-                         /* .state = */ newNode->getMostRecentState()});
-}
-
-} // namespace react
-} // namespace facebook

ReactCommon/react/renderer/mounting/TreeStateReconciliation.h

@@ -1,33 +0,0 @@
-/*
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-#include <react/renderer/core/ShadowNode.h>
-#include <react/renderer/core/ShadowNodeFragment.h>
-
-namespace facebook {
-namespace react {
-
-/**
- * Problem Description: because of C++ State, the React Native C++ ShadowTree
- * can diverge from the ReactJS ShadowTree; ReactJS communicates all tree
- * changes to C++, but C++ state commits are not propagated to ReactJS (ReactJS
- * may or may not clone nodes with state changes, but it has no way of knowing
- * if it /should/ clone those nodes; so those clones may never happen). This
- * causes a number of problems. This function resolves the problem by taking a
- * candidate tree being committed, and sees if any State changes need to be
- * applied to it. If any changes need to be made, a new ShadowNode is returned;
- * otherwise, nullptr is returned if the node is already consistent with the
- * latest tree, including all state changes.
- *
- * This should be called during the commit phase, pre-layout and pre-diff.
- */
-UnsharedShadowNode reconcileStateWithTree(
-    ShadowNode const *newNode,
-    SharedShadowNode committedNode);
-
-} // namespace react
-} // namespace facebook

ReactCommon/react/renderer/scheduler/Scheduler.cpp

@@ -108,15 +108,11 @@ Scheduler::Scheduler(
 #ifdef ANDROID
   enableReparentingDetection_ = reactNativeConfig_->getBool(
       "react_fabric:enable_reparenting_detection_android");
-  enableNewStateReconciliation_ = reactNativeConfig_->getBool(
-      "react_fabric:enable_new_state_reconciliation_android");
   removeOutstandingSurfacesOnDestruction_ = reactNativeConfig_->getBool(
       "react_fabric:remove_outstanding_surfaces_on_destruction_android");
 #else
   enableReparentingDetection_ = reactNativeConfig_->getBool(
       "react_fabric:enable_reparenting_detection_ios");
-  enableNewStateReconciliation_ = reactNativeConfig_->getBool(
-      "react_fabric:enable_new_state_reconciliation_ios");
   removeOutstandingSurfacesOnDestruction_ = reactNativeConfig_->getBool(
       "react_fabric:remove_outstanding_surfaces_on_destruction_ios");
 #endif
@@ -192,8 +188,6 @@ void Scheduler::startSurface(
       mountingOverrideDelegate,
       enableReparentingDetection_);
 
-  shadowTree->setEnableNewStateReconciliation(enableNewStateReconciliation_);
-
   auto uiManager = uiManager_;
 
   uiManager->getShadowTreeRegistry().add(std::move(shadowTree));

ReactCommon/react/renderer/scheduler/Scheduler.h

@@ -138,7 +138,6 @@ class Scheduler final : public UIManagerDelegate {
    * Temporary flags.
    */
   bool enableReparentingDetection_{false};
-  bool enableNewStateReconciliation_{false};
   bool removeOutstandingSurfacesOnDestruction_{false};
 };