From f3adcab9c54a71a4e5f91d0db9b46fa504796210 Mon Sep 17 00:00:00 2001
From: Petr Mikheev <ptmikheev@gmail.com>
Date: Thu, 11 May 2023 01:00:50 +0200
Subject: [PATCH] Update CellStore::mMergedRefs lazily.

---
 apps/openmw/mwworld/cellstore.cpp | 26 +++++++++++++++-----------
 apps/openmw/mwworld/cellstore.hpp | 15 ++++++++++++---
 2 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/apps/openmw/mwworld/cellstore.cpp b/apps/openmw/mwworld/cellstore.cpp
index 00be811137..2c5ab8d3ea 100644
--- a/apps/openmw/mwworld/cellstore.cpp
+++ b/apps/openmw/mwworld/cellstore.cpp
@@ -430,7 +430,7 @@ namespace MWWorld
         {
             mMovedHere.insert(std::make_pair(object.getBase(), from));
         }
-        updateMergedRefs();
+        requestMergedRefsUpdate();
     }
 
     MWWorld::Ptr CellStore::moveTo(const Ptr& object, CellStore* cellToMoveTo)
@@ -462,14 +462,14 @@ namespace MWWorld
                 originalCell->moveTo(object, cellToMoveTo);
             }
 
-            updateMergedRefs();
+            requestMergedRefsUpdate();
             return MWWorld::Ptr(object.getBase(), cellToMoveTo);
         }
 
         cellToMoveTo->moveFrom(object, this);
         mMovedToAnotherCell.insert(std::make_pair(object.getBase(), cellToMoveTo));
 
-        updateMergedRefs();
+        requestMergedRefsUpdate();
         MWWorld::Ptr ptr(object.getBase(), cellToMoveTo);
         const Class& cls = ptr.getClass();
         if (cls.hasInventoryStore(ptr))
@@ -509,13 +509,19 @@ namespace MWWorld
         const std::map<LiveCellRefBase*, MWWorld::CellStore*>& mMovedToAnotherCell;
     };
 
-    void CellStore::updateMergedRefs()
+    void CellStore::requestMergedRefsUpdate()
+    {
+        mRechargingItemsUpToDate = false;
+        mMergedRefsNeedsUpdate = true;
+    }
+
+    void CellStore::updateMergedRefs() const
     {
         mMergedRefs.clear();
-        mRechargingItemsUpToDate = false;
         MergeVisitor visitor(mMergedRefs, mMovedHere, mMovedToAnotherCell);
-        CellStoreImp::forEachInternal(visitor, *this);
+        CellStoreImp::forEachInternal(visitor, const_cast<CellStore&>(*this));
         visitor.merge();
+        mMergedRefsNeedsUpdate = false;
     }
 
     bool CellStore::movedHere(const MWWorld::Ptr& ptr) const
@@ -670,6 +676,8 @@ namespace MWWorld
 
     std::size_t CellStore::count() const
     {
+        if (mMergedRefsNeedsUpdate)
+            updateMergedRefs();
         return mMergedRefs.size();
     }
 
@@ -836,7 +844,7 @@ namespace MWWorld
 
         ESM::visit([&](auto&& cell) { loadRefs(cell, refNumToID); }, mCellVariant);
 
-        updateMergedRefs();
+        requestMergedRefsUpdate();
     }
 
     bool CellStore::isExterior() const
@@ -1022,10 +1030,6 @@ namespace MWWorld
             }
         }
 
-        // Do another update here to make sure objects referred to by MVRF tags can be found
-        // This update is only needed for old saves that used the old copy&delete way of moving objects
-        updateMergedRefs();
-
         while (reader.isNextSub("MVRF"))
         {
             reader.cacheSubName();
diff --git a/apps/openmw/mwworld/cellstore.hpp b/apps/openmw/mwworld/cellstore.hpp
index 47c15edfee..7bbdf0c4cd 100644
--- a/apps/openmw/mwworld/cellstore.hpp
+++ b/apps/openmw/mwworld/cellstore.hpp
@@ -128,7 +128,7 @@ namespace MWWorld
             mHasState = true;
             CellRefList<T>& list = get<T>();
             LiveCellRefBase* ret = &list.insert(*ref);
-            updateMergedRefs();
+            requestMergedRefsUpdate();
             return ret;
         }
 
@@ -198,6 +198,8 @@ namespace MWWorld
             if (mState != State_Loaded)
                 return false;
 
+            if (mMergedRefsNeedsUpdate)
+                updateMergedRefs();
             if (mMergedRefs.empty())
                 return true;
 
@@ -225,6 +227,9 @@ namespace MWWorld
             if (mState != State_Loaded)
                 return false;
 
+            if (mMergedRefsNeedsUpdate)
+                updateMergedRefs();
+
             for (unsigned int i = 0; i < mMergedRefs.size(); ++i)
             {
                 if (!isAccessible(mMergedRefs[i]->mData, mMergedRefs[i]->mRef))
@@ -247,6 +252,8 @@ namespace MWWorld
             if (mState != State_Loaded)
                 return false;
 
+            if (mMergedRefsNeedsUpdate)
+                updateMergedRefs();
             if (mMergedRefs.empty())
                 return true;
 
@@ -368,7 +375,8 @@ namespace MWWorld
 
         // Merged list of ref's currently in this cell - i.e. with added refs from mMovedHere, removed refs from
         // mMovedToAnotherCell
-        std::vector<LiveCellRefBase*> mMergedRefs;
+        mutable std::vector<LiveCellRefBase*> mMergedRefs;
+        mutable bool mMergedRefsNeedsUpdate = false;
 
         // Get the Ptr for the given ref which originated from this cell (possibly moved to another cell at this point).
         Ptr getCurrentPtr(MWWorld::LiveCellRefBase* ref);
@@ -377,7 +385,8 @@ namespace MWWorld
         void moveFrom(const MWWorld::Ptr& object, MWWorld::CellStore* from);
 
         /// Repopulate mMergedRefs.
-        void updateMergedRefs();
+        void requestMergedRefsUpdate();
+        void updateMergedRefs() const;
 
         // (item, max charge)
         typedef std::vector<std::pair<LiveCellRefBase*, float>> TRechargingItems;