From 3f3d00ffc92644acd0f7d99db5bdb9e5e01f2581 Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Thu, 9 Feb 2017 04:03:38 +0100
Subject: [PATCH] Add CellPreloader::clear to avoid potential dangling
 CellStore pointer and to more aggressively clear preload state from a
 previous game

---
 apps/openmw/mwworld/cellpreloader.cpp | 20 +++++++++++++++++++-
 apps/openmw/mwworld/cellpreloader.hpp |  2 ++
 apps/openmw/mwworld/scene.cpp         |  4 +++-
 apps/openmw/mwworld/scene.hpp         |  2 +-
 apps/openmw/mwworld/worldimp.cpp      |  2 +-
 5 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/apps/openmw/mwworld/cellpreloader.cpp b/apps/openmw/mwworld/cellpreloader.cpp
index 3608699fb..7b90da43b 100644
--- a/apps/openmw/mwworld/cellpreloader.cpp
+++ b/apps/openmw/mwworld/cellpreloader.cpp
@@ -272,13 +272,31 @@ namespace MWWorld
         }
     }
 
+    void CellPreloader::clear()
+    {
+        for (PreloadMap::iterator it = mPreloadCells.begin(); it != mPreloadCells.end();)
+        {
+            if (it->second.mWorkItem)
+            {
+                it->second.mWorkItem->abort();
+                mUnrefQueue->push(it->second.mWorkItem);
+            }
+
+            mPreloadCells.erase(it++);
+        }
+    }
+
     void CellPreloader::updateCache(double timestamp)
     {
         for (PreloadMap::iterator it = mPreloadCells.begin(); it != mPreloadCells.end();)
         {
             if (mPreloadCells.size() >= mMinCacheSize && it->second.mTimeStamp < timestamp - mExpiryDelay)
             {
-                it->second.mWorkItem->abort();
+                if (it->second.mWorkItem)
+                {
+                    it->second.mWorkItem->abort();
+                    mUnrefQueue->push(it->second.mWorkItem);
+                }
                 mPreloadCells.erase(it++);
             }
             else
diff --git a/apps/openmw/mwworld/cellpreloader.hpp b/apps/openmw/mwworld/cellpreloader.hpp
index 3836b6869..e8e59a3a2 100644
--- a/apps/openmw/mwworld/cellpreloader.hpp
+++ b/apps/openmw/mwworld/cellpreloader.hpp
@@ -37,6 +37,8 @@ namespace MWWorld
 
         void notifyLoaded(MWWorld::CellStore* cell);
 
+        void clear();
+
         /// Removes preloaded cells that have not had a preload request for a while.
         void updateCache(double timestamp);
 
diff --git a/apps/openmw/mwworld/scene.cpp b/apps/openmw/mwworld/scene.cpp
index 30d021bfd..3917518a2 100644
--- a/apps/openmw/mwworld/scene.cpp
+++ b/apps/openmw/mwworld/scene.cpp
@@ -315,13 +315,15 @@ namespace MWWorld
         mPreloader->notifyLoaded(cell);
     }
 
-    void Scene::changeToVoid()
+    void Scene::clear()
     {
         CellStoreCollection::iterator active = mActiveCells.begin();
         while (active!=mActiveCells.end())
             unloadCell (active++);
         assert(mActiveCells.empty());
         mCurrentCell = NULL;
+
+        mPreloader->clear();
     }
 
     void Scene::playerMoved(const osg::Vec3f &pos)
diff --git a/apps/openmw/mwworld/scene.hpp b/apps/openmw/mwworld/scene.hpp
index b8cbf49b9..328538076 100644
--- a/apps/openmw/mwworld/scene.hpp
+++ b/apps/openmw/mwworld/scene.hpp
@@ -113,7 +113,7 @@ namespace MWWorld
             ///< Move to exterior cell.
             /// @param changeEvent Set cellChanged flag?
 
-            void changeToVoid();
+            void clear();
             ///< Change into a void
 
             void markCellAsUnchanged();
diff --git a/apps/openmw/mwworld/worldimp.cpp b/apps/openmw/mwworld/worldimp.cpp
index 06e9856e2..0229f1f93 100644
--- a/apps/openmw/mwworld/worldimp.cpp
+++ b/apps/openmw/mwworld/worldimp.cpp
@@ -290,7 +290,7 @@ namespace MWWorld
         mProjectileManager->clear();
         mLocalScripts.clear();
 
-        mWorldScene->changeToVoid();
+        mWorldScene->clear();
 
         mStore.clearDynamic();
         mStore.setUp();