[CherryPick][LYN-3398][LYN-3399] Let EditorEntityModel always use the optimized algorithm even in Slice mode (#585)

* [LYN-3398][LYN-3399] Let EditorEntityModel always use the optimized algorithm even in Slice mode (#490)

Code/Framework/AzToolsFramework/AzToolsFramework/Entity/EditorEntityModel.cpp

@@ -117,8 +117,6 @@ namespace AzToolsFramework
 {
     EditorEntityModel::EditorEntityModel()
     {
-        AzFramework::ApplicationRequests::Bus::BroadcastResult(m_isPrefabEnabled, &AzFramework::ApplicationRequests::IsPrefabSystemEnabled);
-
         EntityCompositionNotificationBus::Handler::BusConnect();
         EditorOnlyEntityComponentNotificationBus::Handler::BusConnect();
         EditorEntityRuntimeActivationChangeNotificationBus::Handler::BusConnect();
@@ -565,7 +563,7 @@ namespace AzToolsFramework
     {
         //retrieve or add an entity entry to the table
         //the entry must exist, even if not connected, so children and other data can be assigned
-        [[maybe_unused]] auto [it, inserted] = m_entityInfoTable.try_emplace(entityId, m_isPrefabEnabled);
+        [[maybe_unused]] auto [it, inserted] = m_entityInfoTable.try_emplace(entityId);
         auto& entityInfo = it->second;
 
         //the entity id defaults to invalid and must be set to match the requested id
@@ -882,11 +880,6 @@ namespace AzToolsFramework
         }
     }
 
-    EditorEntityModel::EditorEntityModelEntry::EditorEntityModelEntry(bool isPrefabEnabled)
-        : m_isPrefabEnabled(isPrefabEnabled)
-    {
-    }
-
     EditorEntityModel::EditorEntityModelEntry::~EditorEntityModelEntry()
     {
         Disconnect();
@@ -1213,29 +1206,15 @@ namespace AzToolsFramework
         auto childItr = m_childIndexCache.find(childId);
         if (childItr != m_childIndexCache.end())
         {
-            if (m_isPrefabEnabled)
-            {
-                // Take the last entry and move it into the removed spot instead of deleting the entry and having to move all
-                // following entries one step down.
-                AZ::EntityId backEntity = m_children.back();
-                m_children[childItr->second] = backEntity;
-                // Update cached index for the moved id to the new index.
-                m_childIndexCache[backEntity] = childItr->second;
-                // Now remove the deleted id from the children and cache.
-                m_childIndexCache.erase(childId);
-                m_children.erase(m_children.end() - 1);
-            }
-            else
-            {
-                m_children.erase(m_children.begin() + childItr->second);
-
-                // rebuild index cache for faster lookup
-                m_childIndexCache.clear();
-                for (auto childIdToCache : m_children)
-                {
-                    m_childIndexCache[childIdToCache] = static_cast<AZ::u64>(m_childIndexCache.size());
-                }
-            }
+            // Take the last entry and move it into the removed spot instead of deleting the entry and having to move all
+            // following entries one step down.
+            AZ::EntityId backEntity = m_children.back();
+            m_children[childItr->second] = backEntity;
+            // Update cached index for the moved id to the new index.
+            m_childIndexCache[backEntity] = childItr->second;
+            // Now remove the deleted id from the children and cache.
+            m_childIndexCache.erase(childId);
+            m_children.erase(m_children.end() - 1);
         }
     }
 

Code/Framework/AzToolsFramework/AzToolsFramework/Entity/EditorEntityModel.h

@@ -171,7 +171,6 @@ namespace AzToolsFramework
             , public PropertyEditorEntityChangeNotificationBus::Handler
         {
         public:
-            explicit EditorEntityModelEntry(bool isPrefabEnabled);
             ~EditorEntityModelEntry();
 
             // Separately connect to EditorEntityInfoRequestBus and refresh Entity
@@ -336,7 +335,6 @@ namespace AzToolsFramework
             bool m_visible = true;
             bool m_locked = false;
             bool m_connected = false;
-            bool m_isPrefabEnabled = false;
             AZStd::string m_name;
             AZStd::string m_sliceAssetName;
             AZStd::unordered_map<AZ::EntityId, AZ::u64> m_childIndexCache;
@@ -375,6 +373,5 @@ namespace AzToolsFramework
         AZ::EntityId m_postInstantiateBeforeEntity;
         AZ::EntityId m_postInstantiateSliceParent;
         bool m_gotInstantiateSliceDetails = false;
-        bool m_isPrefabEnabled = false;
     };
 }

Code/Framework/AzToolsFramework/Tests/Prefab/Benchmark/PrefabUpdateInstancesBenchmarks.cpp

@@ -78,7 +78,7 @@ namespace Benchmark
     }
     BENCHMARK_REGISTER_F(BM_PrefabUpdateInstances, UpdateInstances_SingeEntityInstances)
         ->RangeMultiplier(10)
-        ->Range(100, 1000)
+        ->Range(100, 10000)
         ->Unit(benchmark::kMillisecond)
         ->Complexity();
 

Code/Sandbox/Plugins/ComponentEntityEditorPlugin/UI/Outliner/OutlinerListModel.cpp

@@ -1473,13 +1473,14 @@ void OutlinerListModel::OnEntityInfoUpdatedRemoveChildBegin(AZ::EntityId parentI
     emit EnableSelectionUpdates(false);
     auto parentIndex = GetIndexFromEntity(parentId);
     auto childIndex = GetIndexFromEntity(childId);
-    beginRemoveRows(parentIndex, childIndex.row(), childIndex.row());
+    beginResetModel();
 }
 
 void OutlinerListModel::OnEntityInfoUpdatedRemoveChildEnd(AZ::EntityId parentId, AZ::EntityId childId)
 {
     (void)childId;
     AZ_PROFILE_FUNCTION(AZ::Debug::ProfileCategory::AzToolsFramework);
+
     endRemoveRows();
 
     //must refresh partial lock/visibility of parents