From a46593fa7418caaa078656fd89a565b016f789c3 Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Thu, 9 Feb 2017 01:08:07 +0100
Subject: [PATCH] Add PreloadItem::abort() to avoid no longer required cells
 from blocking the work thread

---
 apps/openmw/mwworld/cellpreloader.cpp | 23 +++++++++++++++++++++++
 components/sceneutil/workqueue.hpp    |  3 +++
 2 files changed, 26 insertions(+)

diff --git a/apps/openmw/mwworld/cellpreloader.cpp b/apps/openmw/mwworld/cellpreloader.cpp
index d76e5ddcb..3608699fb 100644
--- a/apps/openmw/mwworld/cellpreloader.cpp
+++ b/apps/openmw/mwworld/cellpreloader.cpp
@@ -55,6 +55,7 @@ namespace MWWorld
             , mKeyframeManager(keyframeManager)
             , mTerrain(terrain)
             , mPreloadInstances(preloadInstances)
+            , mAbort(false)
         {
             ListModelsVisitor visitor (mMeshes);
             if (cell->getState() == MWWorld::CellStore::State_Loaded)
@@ -76,6 +77,11 @@ namespace MWWorld
             }
         }
 
+        virtual void abort()
+        {
+            mAbort = true;
+        }
+
         /// Preload work to be called from the worker thread.
         virtual void doWork()
         {
@@ -92,6 +98,9 @@ namespace MWWorld
 
             for (MeshList::const_iterator it = mMeshes.begin(); it != mMeshes.end(); ++it)
             {
+                if (mAbort)
+                    break;
+
                 try
                 {
                     std::string mesh  = *it;
@@ -144,6 +153,8 @@ namespace MWWorld
         Terrain::World* mTerrain;
         bool mPreloadInstances;
 
+        volatile bool mAbort;
+
         // keep a ref to the loaded objects to make sure it stays loaded as long as this cell is in the preloaded state
         std::vector<osg::ref_ptr<const osg::Object> > mPreloadedObjects;
     };
@@ -187,7 +198,10 @@ namespace MWWorld
     CellPreloader::~CellPreloader()
     {
         for (PreloadMap::iterator it = mPreloadCells.begin(); it != mPreloadCells.end();++it)
+        {
+            it->second.mWorkItem->abort();
             it->second.mWorkItem->waitTillDone();
+        }
         mPreloadCells.clear();
     }
 
@@ -228,7 +242,10 @@ namespace MWWorld
             }
 
             if (oldestTimestamp + threshold < timestamp)
+            {
+                oldestCell->second.mWorkItem->abort();
                 mPreloadCells.erase(oldestCell);
+            }
             else
                 return;
         }
@@ -246,7 +263,10 @@ namespace MWWorld
         {
             // do the deletion in the background thread
             if (found->second.mWorkItem)
+            {
+                found->second.mWorkItem->abort();
                 mUnrefQueue->push(mPreloadCells[cell].mWorkItem);
+            }
 
             mPreloadCells.erase(found);
         }
@@ -257,7 +277,10 @@ namespace MWWorld
         for (PreloadMap::iterator it = mPreloadCells.begin(); it != mPreloadCells.end();)
         {
             if (mPreloadCells.size() >= mMinCacheSize && it->second.mTimeStamp < timestamp - mExpiryDelay)
+            {
+                it->second.mWorkItem->abort();
                 mPreloadCells.erase(it++);
+            }
             else
                 ++it;
         }
diff --git a/components/sceneutil/workqueue.hpp b/components/sceneutil/workqueue.hpp
index e7b0151dd..1b0e30be9 100644
--- a/components/sceneutil/workqueue.hpp
+++ b/components/sceneutil/workqueue.hpp
@@ -31,6 +31,9 @@ namespace SceneUtil
         /// Internal use by the WorkQueue.
         void signalDone();
 
+        /// Set abort flag in order to return from doWork() as soon as possible. May not be respected by all WorkItems.
+        virtual void abort() {}
+
     protected:
         OpenThreads::Atomic mDone;
         OpenThreads::Mutex mMutex;