From 9f8a4be2cdd9633f68065c592460570a30594c46 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 3 Mar 2010 16:40:19 +0000
Subject: [PATCH] Refactored DatabasePager so that it nolonger takes
 ref_ptr<PagedLOD>, but instead uses a custom version of observer_ptr<>. This
 change should make it possible to delete PagedLOD's independantly from the
 DatabasePager, and also prevent issues of consistency of the pager when
 subgraphs when are cached elsewhere in the application such as in the
 Registry filecache.

---
 include/osgDB/DatabasePager |  39 ++--
 src/osgDB/DatabasePager.cpp | 451 +++++++++++++++---------------------
 2 files changed, 210 insertions(+), 280 deletions(-)

diff --git a/include/osgDB/DatabasePager b/include/osgDB/DatabasePager
index fb9bb5304..63f17846e 100644
--- a/include/osgDB/DatabasePager
+++ b/include/osgDB/DatabasePager
@@ -21,6 +21,7 @@
 #include <osg/GraphicsThread>
 #include <osg/FrameStamp>
 #include <osg/ObserverNodePath>
+#include <osg/observer_ptr>
 
 #include <OpenThreads/Thread>
 #include <OpenThreads/Mutex>
@@ -279,11 +280,7 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
         
         /** Merge the changes to the scene graph by calling calling removeExpiredSubgraphs then addLoadedDataToSceneGraph.
           * Note, must only be called from single thread update phase. */
-        virtual void updateSceneGraph(const osg::FrameStamp& frameStamp)
-        {
-            removeExpiredSubgraphs(frameStamp);
-            addLoadedDataToSceneGraph(frameStamp);
-        }
+        virtual void updateSceneGraph(const osg::FrameStamp& frameStamp);
                 
         /** Turn the compilation of rendering objects for specified graphics context on (true) or off(false). */
         void setCompileGLObjectsForContextID(unsigned int contextID, bool on);
@@ -332,7 +329,6 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
         /** Reset the Stats variables.*/
         void resetStats();
 
-        typedef std::list< osg::ref_ptr<osg::PagedLOD> >                PagedLODList;
         typedef std::set< osg::ref_ptr<osg::StateSet> >                 StateSetList;
         typedef std::vector< osg::ref_ptr<osg::Drawable> >              DrawableList;
         typedef std::pair<StateSetList,DrawableList>                    DataToCompile;
@@ -349,6 +345,28 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
 
         struct RequestQueue;
 
+        struct PagedLODObserver : public osg::observer_ptr<osg::PagedLOD>
+        {
+            typedef osg::observer_ptr<osg::PagedLOD> BaseClass;
+
+            PagedLODObserver(osg::PagedLOD* plod):BaseClass(plod) {}
+            PagedLODObserver(const PagedLODObserver& plodObserver):BaseClass(plodObserver) {}
+
+            PagedLODObserver& operator = (const PagedLODObserver& rhs)
+            {
+                (*static_cast<BaseClass*>(this)) = rhs;
+                return *this;
+            }
+
+            virtual void objectDeleted(void* ptr)
+            {
+                BaseClass::objectDeleted(ptr);
+            }
+        };
+
+        typedef std::list< PagedLODObserver >                PagedLODList;
+
+
         struct DatabaseRequest : public osg::Referenced
         {
             DatabaseRequest():
@@ -442,8 +460,7 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
         class FindCompileableGLObjectsVisitor;
         friend class FindCompileableGLObjectsVisitor;
         
-        class MarkPagedLODsVisitor;
-        
+        class CountPagedLODsVisitor;
         class FindPagedLODsVisitor;
         friend class FindPagedLODsVisitor;
 
@@ -547,12 +564,6 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
           * note, should be only be called from the update thread. */
         virtual void removeExpiredSubgraphs(const osg::FrameStamp &frameStamp);
 
-        /** Old expiry delay based removeExpiredSubgraphs. */
-        virtual void expiry_removeExpiredSubgraphs(const osg::FrameStamp &frameStamp);
-
-        /** New capped based removeExpiredSubgraphs. */
-        virtual void capped_removeExpiredSubgraphs(const osg::FrameStamp &frameStamp);
-
         /** Add the loaded data to the scene graph.*/
         void addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp);
 
diff --git a/src/osgDB/DatabasePager.cpp b/src/osgDB/DatabasePager.cpp
index f1b285f11..b74e0aa13 100644
--- a/src/osgDB/DatabasePager.cpp
+++ b/src/osgDB/DatabasePager.cpp
@@ -217,7 +217,7 @@ public:
         {
         case DatabasePager::DO_NOT_MODIFY_DRAWABLE_SETTINGS: 
              // do nothing, leave settings as they came in from loaded database.
-             // OSG_NOTIFY(osg::NOTICE)<<"DO_NOT_MODIFY_DRAWABLE_SETTINGS"<<std::endl;
+             // OSG_NOTICE<<"DO_NOT_MODIFY_DRAWABLE_SETTINGS"<<std::endl;
              break;
         case DatabasePager::USE_DISPLAY_LISTS: 
              drawable->setUseDisplayList(true);
@@ -226,12 +226,12 @@ public:
         case DatabasePager::USE_VERTEX_BUFFER_OBJECTS:
              drawable->setUseDisplayList(true);
              drawable->setUseVertexBufferObjects(true);
-             // OSG_NOTIFY(osg::NOTICE)<<"USE_VERTEX_BUFFER_OBJECTS"<<std::endl;
+             // OSG_NOTICE<<"USE_VERTEX_BUFFER_OBJECTS"<<std::endl;
              break;
         case DatabasePager::USE_VERTEX_ARRAYS:
              drawable->setUseDisplayList(false);
              drawable->setUseVertexBufferObjects(false);
-             // OSG_NOTIFY(osg::NOTICE)<<"USE_VERTEX_ARRAYS"<<std::endl;
+             // OSG_NOTICE<<"USE_VERTEX_ARRAYS"<<std::endl;
              break;
         }
         // Don't compile if already compiled. This can happen if the
@@ -283,7 +283,7 @@ struct DatabasePager::SortFileRequestFunctor
 //
 void DatabasePager::DatabaseRequest::invalidate()
 {
-    OSG_NOTIFY(osg::INFO)<<"   DatabasePager::DatabaseRequest::invalidate()."<<std::endl;
+    OSG_INFO<<"   DatabasePager::DatabaseRequest::invalidate()."<<std::endl;
     _valid = false;
     _groupForAddingLoadedSubgraph = 0;
     _loadedModel = 0;
@@ -293,7 +293,7 @@ void DatabasePager::DatabaseRequest::invalidate()
 
 DatabasePager::RequestQueue::~RequestQueue()
 {
-    OSG_NOTIFY(osg::INFO)<<"DatabasePager::RequestQueue::~RequestQueue() Destructing queue."<<std::endl;
+    OSG_INFO<<"DatabasePager::RequestQueue::~RequestQueue() Destructing queue."<<std::endl;
     for(RequestList::iterator itr = _requestList.begin();
         itr != _requestList.end();
         ++itr)
@@ -457,7 +457,7 @@ int DatabasePager::DatabaseThread::cancel()
 
 void DatabasePager::DatabaseThread::run()
 {
-    OSG_NOTIFY(osg::INFO)<<_name<<": DatabasePager::DatabaseThread::run"<<std::endl;
+    OSG_INFO<<_name<<": DatabasePager::DatabaseThread::run"<<std::endl;
     
 #if 1
     // need to set the texture object manager to be able to reuse textures
@@ -501,7 +501,7 @@ void DatabasePager::DatabaseThread::run()
 
         _active = true;
 
-        OSG_NOTIFY(osg::INFO)<<_name<<": _pager->_requestList.size()= "<<read_queue->_requestList.size()<<" to delete = "<<read_queue->_childrenToDeleteList.size()<<std::endl;
+        OSG_INFO<<_name<<": _pager->_requestList.size()= "<<read_queue->_requestList.size()<<" to delete = "<<read_queue->_childrenToDeleteList.size()<<std::endl;
 
 
         //
@@ -582,7 +582,7 @@ void DatabasePager::DatabaseThread::run()
                             }
                             else
                             {
-                                OSG_NOTIFY(osg::INFO)<<_name<<": Passing http requests over "<<databaseRequest->_fileName<<std::endl;
+                                OSG_INFO<<_name<<": Passing http requests over "<<databaseRequest->_fileName<<std::endl;
                                 out_queue->add(databaseRequest.get());
                                 databaseRequest = 0;
                             }
@@ -608,7 +608,7 @@ void DatabasePager::DatabaseThread::run()
                        
             // load the data, note safe to write to the databaseRequest since once 
             // it is created this thread is the only one to write to the _loadedModel pointer.
-            //OSG_NOTIFY(osg::NOTICE)<<"In DatabasePager thread readNodeFile("<<databaseRequest->_fileName<<")"<<std::endl;
+            //OSG_NOTICE<<"In DatabasePager thread readNodeFile("<<databaseRequest->_fileName<<")"<<std::endl;
             //osg::Timer_t before = osg::Timer::instance()->tick();
 
 
@@ -630,7 +630,7 @@ void DatabasePager::DatabaseThread::run()
 
             if ((_pager->_frameNumber-databaseRequest->_frameNumberLastRequest)>1)
             {
-                OSG_NOTIFY(osg::INFO)<<_name<<": Warning DatabaseRquest no longer required."<<std::endl;
+                OSG_INFO<<_name<<": Warning DatabaseRquest no longer required."<<std::endl;
                 databaseRequest->_loadedModel = 0;
             }
 
@@ -638,12 +638,12 @@ void DatabasePager::DatabaseThread::run()
             osg::RefNodePath refNodePath;
             if (!databaseRequest->_observerNodePath.getRefNodePath(refNodePath))
             {
-                OSG_NOTICE<<_name<<": Warning node in parental chain has been deleted, discarding load."<<std::endl;
+                OSG_INFO<<_name<<": Warning node in parental chain has been deleted, discarding load."<<std::endl;
                 databaseRequest->_loadedModel = 0;
             }
 
 
-            //OSG_NOTIFY(osg::NOTICE)<<"     node read in "<<osg::Timer::instance()->delta_m(before,osg::Timer::instance()->tick())<<" ms"<<std::endl;
+            //OSG_NOTICE<<"     node read in "<<osg::Timer::instance()->delta_m(before,osg::Timer::instance()->tick())<<" ms"<<std::endl;
 
             bool loadedObjectsNeedToBeCompiled = false;
 
@@ -743,7 +743,7 @@ void DatabasePager::DatabaseThread::run()
                     citr != _pager->_dataToCompileList->_requestList.end();
                     ++citr)
                 {
-                    OSG_NOTIFY(osg::INFO)<<_name<<": pruning from compile list"<<std::endl;
+                    OSG_INFO<<_name<<": pruning from compile list"<<std::endl;
                     (*citr)->_loadedModel = 0;
                     (*citr)->_requestQueue = 0;
                 }
@@ -778,7 +778,7 @@ void DatabasePager::DatabaseThread::run()
                     }
                 }
 
-                // OSG_NOTIFY(osg::NOTICE)<<"Done compiling in paging thread"<<std::endl;
+                // OSG_NOTICE<<"Done compiling in paging thread"<<std::endl;
             }
         }
         else
@@ -803,7 +803,7 @@ void DatabasePager::DatabaseThread::run()
 
 DatabasePager::DatabasePager()
 {
-    //OSG_NOTIFY(osg::INFO)<<"Constructing DatabasePager()"<<std::endl;
+    //OSG_INFO<<"Constructing DatabasePager()"<<std::endl;
     
     _startThreadCalled = false;
 
@@ -893,14 +893,14 @@ DatabasePager::DatabasePager()
     if( (ptr = getenv("OSG_EXPIRY_DELAY")) != 0)
     {
         _expiryDelay = osg::asciiToDouble(ptr);
-        OSG_NOTIFY(osg::NOTICE)<<"DatabasePager: Expiry delay = "<<_expiryDelay<<std::endl;
+        OSG_NOTICE<<"DatabasePager: Expiry delay = "<<_expiryDelay<<std::endl;
     }
 
     _expiryFrames = 1; // Last frame will not be expired
     if( (ptr = getenv("OSG_EXPIRY_FRAMES")) != 0)
     {
         _expiryFrames = atoi(ptr);
-        OSG_NOTIFY(osg::NOTICE)<<"DatabasePager: Expiry frames = "<<_expiryFrames<<std::endl;
+        OSG_NOTICE<<"DatabasePager: Expiry frames = "<<_expiryFrames<<std::endl;
     }
 
     if( (ptr = getenv("OSG_RELEASE_DELAY")) != 0)
@@ -914,7 +914,7 @@ DatabasePager::DatabasePager()
             setReleaseDelay(osg::asciiToDouble(ptr));
         }
             
-        OSG_NOTIFY(osg::NOTICE)<<"DatabasePager: Release delay = "<<_releaseDelay<<std::endl;
+        OSG_NOTICE<<"DatabasePager: Release delay = "<<_releaseDelay<<std::endl;
     }
     else
     {
@@ -926,7 +926,7 @@ DatabasePager::DatabasePager()
     if( (ptr = getenv("OSG_RELEASE_FRAMES")) != 0)
     {
         _releaseFrames = atoi(ptr);
-        OSG_NOTIFY(osg::NOTICE)<<"Release frames = "<<_releaseFrames<<std::endl;
+        OSG_NOTICE<<"Release frames = "<<_releaseFrames<<std::endl;
     }
 
 
@@ -934,7 +934,7 @@ DatabasePager::DatabasePager()
     if( (ptr = getenv("OSG_MAX_PAGEDLOD")) != 0)
     {
         _targetMaximumNumberOfPageLOD = atoi(ptr);
-        OSG_NOTIFY(osg::NOTICE)<<"_targetMaximumNumberOfPageLOD = "<<_targetMaximumNumberOfPageLOD<<std::endl;
+        OSG_NOTICE<<"_targetMaximumNumberOfPageLOD = "<<_targetMaximumNumberOfPageLOD<<std::endl;
     }
 
 
@@ -981,7 +981,7 @@ DatabasePager::DatabasePager()
 
 DatabasePager::DatabasePager(const DatabasePager& rhs)
 {
-    //OSG_NOTIFY(osg::INFO)<<"Constructing DatabasePager(const DatabasePager& )"<<std::endl;
+    //OSG_INFO<<"Constructing DatabasePager(const DatabasePager& )"<<std::endl;
     
     _startThreadCalled = false;
 
@@ -1082,7 +1082,7 @@ void DatabasePager::setUpThreads(unsigned int totalNumThreads, unsigned int numH
 
 unsigned int DatabasePager::addDatabaseThread(DatabaseThread::Mode mode, const std::string& name)
 {
-    OSG_NOTIFY(osg::INFO)<<"DatabasePager::addDatabaseThread() "<<name<<std::endl;
+    OSG_INFO<<"DatabasePager::addDatabaseThread() "<<name<<std::endl;
 
     unsigned int pos = _databaseThreads.size();
     
@@ -1245,11 +1245,11 @@ void DatabasePager::requestNodeFile(const std::string& fileName,osg::Group* grou
     {
        loadOptions = Registry::instance()->getOptions();
 
-        // OSG_NOTIFY(osg::NOTICE)<<"Using options from Registry "<<std::endl;
+        // OSG_NOTICE<<"Using options from Registry "<<std::endl;
     }
     else
     {
-        // OSG_NOTIFY(osg::NOTICE)<<"options from requestNodeFile "<<std::endl;
+        // OSG_NOTICE<<"options from requestNodeFile "<<std::endl;
     }
 
 
@@ -1267,7 +1267,7 @@ void DatabasePager::requestNodeFile(const std::string& fileName,osg::Group* grou
     
     if (previousFrame!=frameNumber)
     {
-        OSG_NOTIFY(osg::NOTICE)<<"requestNodeFiles for "<<previousFrame<<" time = "<<totalTime<<std::endl;
+        OSG_NOTICE<<"requestNodeFiles for "<<previousFrame<<" time = "<<totalTime<<std::endl;
 
         previousFrame = frameNumber;
         totalTime = 0.0;
@@ -1282,13 +1282,13 @@ void DatabasePager::requestNodeFile(const std::string& fileName,osg::Group* grou
         DatabaseRequest* databaseRequest = dynamic_cast<DatabaseRequest*>(databaseRequestRef.get());
         if (databaseRequest && databaseRequest->valid())
         {
-            OSG_NOTIFY(osg::NOTICE)<<"DatabaseRequest has been previously invalidated whilst still attached to scene graph."<<std::endl;
+            OSG_NOTICE<<"DatabaseRequest has been previously invalidated whilst still attached to scene graph."<<std::endl;
             databaseRequest = 0;
         }
 
         if (databaseRequest)
         {
-            OSG_NOTIFY(osg::INFO)<<"DatabasePager::requestNodeFile("<<fileName<<") updating already assigned."<<std::endl;
+            OSG_INFO<<"DatabasePager::requestNodeFile("<<fileName<<") updating already assigned."<<std::endl;
 
             RequestQueue* requestQueue = databaseRequest->_requestQueue;
             if (requestQueue)
@@ -1312,7 +1312,7 @@ void DatabasePager::requestNodeFile(const std::string& fileName,osg::Group* grou
 
             if (databaseRequestRef->referenceCount()==1)
             {
-                OSG_NOTIFY(osg::INFO)<<"DatabasePager::requestNodeFile("<<fileName<<") orphaned, resubmitting."<<std::endl;
+                OSG_INFO<<"DatabasePager::requestNodeFile("<<fileName<<") orphaned, resubmitting."<<std::endl;
 
                 databaseRequest->_frameNumberFirstRequest = frameNumber;
                 databaseRequest->_timestampFirstRequest = timestamp;
@@ -1333,7 +1333,7 @@ void DatabasePager::requestNodeFile(const std::string& fileName,osg::Group* grou
 
     if (!foundEntry)
     {
-        OSG_NOTIFY(osg::INFO)<<"In DatabasePager::requestNodeFile("<<fileName<<")"<<std::endl;
+        OSG_INFO<<"In DatabasePager::requestNodeFile("<<fileName<<")"<<std::endl;
         
         OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_fileRequestQueue->_requestMutex);
         
@@ -1397,15 +1397,15 @@ void DatabasePager::signalBeginFrame(const osg::FrameStamp* framestamp)
 {
     if (framestamp)
     {
-        //OSG_NOTIFY(osg::INFO) << "signalBeginFrame "<<framestamp->getFrameNumber()<<">>>>>>>>>>>>>>>>"<<std::endl;
+        //OSG_INFO << "signalBeginFrame "<<framestamp->getFrameNumber()<<">>>>>>>>>>>>>>>>"<<std::endl;
         _frameNumber = framestamp->getFrameNumber();
         
-    } //else OSG_NOTIFY(osg::INFO) << "signalBeginFrame >>>>>>>>>>>>>>>>"<<std::endl;
+    } //else OSG_INFO << "signalBeginFrame >>>>>>>>>>>>>>>>"<<std::endl;
 }
 
 void DatabasePager::signalEndFrame()
 {
-    //OSG_NOTIFY(osg::INFO) << "signalEndFrame <<<<<<<<<<<<<<<<<<<< "<<std::endl;
+    //OSG_INFO << "signalEndFrame <<<<<<<<<<<<<<<<<<<< "<<std::endl;
 }
 
 void DatabasePager::setDatabasePagerThreadPause(bool pause)
@@ -1428,14 +1428,50 @@ bool DatabasePager::requiresUpdateSceneGraph() const
     return false;
     
 }
- 
+
+// #define UPDATE_TIMING 1
+void DatabasePager::updateSceneGraph(const osg::FrameStamp& frameStamp)
+{
+#ifdef UPDATE_TIMING
+    osg::ElapsedTime timer;
+    double timeFor_removeExpiredSubgraphs, timeFor_addLoadedDataToSceneGraph;
+#endif
+
+    {
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(*osg::Observer::getGlobalObserverMutex());
+
+        removeExpiredSubgraphs(frameStamp);
+
+#ifdef UPDATE_TIMING
+        timeFor_removeExpiredSubgraphs = timer.elapsedTime_m();
+#endif
+
+        addLoadedDataToSceneGraph(frameStamp);
+
+#ifdef UPDATE_TIMING
+        timeFor_addLoadedDataToSceneGraph = timer.elapsedTime_m() - timeFor_removeExpiredSubgraphs;
+#endif
+
+    }
+
+#ifdef UPDATE_TIMING
+    double elapsedTime = timer.elapsedTime_m();
+    if (elapsedTime>0.2)
+    {
+        OSG_NOTICE<<"DatabasePager::updateSceneGraph() total time = "<<elapsedTime<<"ms"<<std::endl;
+        OSG_NOTICE<<"   timeFor_removeExpiredSubgraphs    = "<<timeFor_removeExpiredSubgraphs<<"ms"<<std::endl;
+        OSG_NOTICE<<"   timeFor_addLoadedDataToSceneGraph = "<<timeFor_addLoadedDataToSceneGraph<<"ms"<<std::endl;
+    }
+#endif
+}
+
 
 void DatabasePager::addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp)
 {
     double timeStamp = frameStamp.getReferenceTime();
     int frameNumber = frameStamp.getFrameNumber();
 
-    osg::Timer_t before = osg::Timer::instance()->tick();
+    osg::Timer_t before = osg::Timer::instance()->tick(), mid, last;
 
     RequestQueue::RequestList localFileLoadedList;
 
@@ -1445,7 +1481,7 @@ void DatabasePager::addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp)
         localFileLoadedList.swap(_dataToMergeList->_requestList);
     }
         
-    osg::Timer_t mid = osg::Timer::instance()->tick();
+    mid = osg::Timer::instance()->tick();
 
     // add the loaded data into the scene graph.
     for(RequestQueue::RequestList::iterator itr=localFileLoadedList.begin();
@@ -1457,13 +1493,12 @@ void DatabasePager::addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp)
         osg::RefNodePath refNodePath;
         if (databaseRequest->_observerNodePath.getRefNodePath(refNodePath))
         {
-            // OSG_NOTIFY(osg::NOTICE)<<"Merging "<<_frameNumber-(*itr)->_frameNumberLastRequest<<std::endl;
+            // OSG_NOTICE<<"Merging "<<_frameNumber-(*itr)->_frameNumberLastRequest<<std::endl;
             osg::Group* group = databaseRequest->_groupForAddingLoadedSubgraph;
 
             if (osgDB::Registry::instance()->getSharedStateManager())
                 osgDB::Registry::instance()->getSharedStateManager()->share(databaseRequest->_loadedModel.get());
 
-            registerPagedLODs(databaseRequest->_loadedModel.get(), frameStamp.getFrameNumber());
 
             osg::PagedLOD* plod = dynamic_cast<osg::PagedLOD*>(group);
             if (plod)
@@ -1483,7 +1518,9 @@ void DatabasePager::addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp)
 
             group->addChild(databaseRequest->_loadedModel.get());
 
-            // OSG_NOTIFY(osg::NOTICE)<<"merged subgraph"<<databaseRequest->_fileName<<" after "<<databaseRequest->_numOfRequests<<" requests and time="<<(timeStamp-databaseRequest->_timestampFirstRequest)*1000.0<<std::endl;
+            registerPagedLODs(group, frameStamp.getFrameNumber());
+
+            // OSG_NOTICE<<"merged subgraph"<<databaseRequest->_fileName<<" after "<<databaseRequest->_numOfRequests<<" requests and time="<<(timeStamp-databaseRequest->_timestampFirstRequest)*1000.0<<std::endl;
 
             double timeToMerge = timeStamp-databaseRequest->_timestampFirstRequest;
 
@@ -1501,10 +1538,10 @@ void DatabasePager::addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp)
         // reset the loadedModel pointer
         databaseRequest->_loadedModel = 0;
 
-        // OSG_NOTIFY(osg::NOTICE)<<"curr = "<<timeToMerge<<" min "<<getMinimumTimeToMergeTile()*1000.0<<" max = "<<getMaximumTimeToMergeTile()*1000.0<<" average = "<<getAverageTimToMergeTiles()*1000.0<<std::endl;
+        // OSG_NOTICE<<"curr = "<<timeToMerge<<" min "<<getMinimumTimeToMergeTile()*1000.0<<" max = "<<getMaximumTimeToMergeTile()*1000.0<<" average = "<<getAverageTimToMergeTiles()*1000.0<<std::endl;
     }
 
-    osg::Timer_t last = osg::Timer::instance()->tick();
+    last = osg::Timer::instance()->tick();
 
     if (!localFileLoadedList.empty())
     {
@@ -1512,49 +1549,31 @@ void DatabasePager::addLoadedDataToSceneGraph(const osg::FrameStamp &frameStamp)
             osg::Timer::instance()->delta_m(before,mid)<<"ms,\t"<<
             osg::Timer::instance()->delta_m(mid,last)<<"ms"<<
             "  objects"<<localFileLoadedList.size()<<std::endl<<std::endl;
-    } 
+    }
+
 }
 
-class DatabasePager::MarkPagedLODsVisitor : public osg::NodeVisitor
+class DatabasePager::CountPagedLODsVisitor : public osg::NodeVisitor
 {
 public:
-    MarkPagedLODsVisitor(const std::string& marker):
+    CountPagedLODsVisitor():
         osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ALL_CHILDREN),
-        _marker(marker),
-        _numPagedLODsMarked(0)
+        _numPagedLODs(0)
     {
     }
 
-    META_NodeVisitor("osgDB","MarkPagedLODsVisitor")
+    META_NodeVisitor("osgDB","CountPagedLODsVisitor")
 
     virtual void apply(osg::PagedLOD& plod)
     {
-        if (plod.getName()!=_marker)
-        {
-            ++_numPagedLODsMarked;
-            plod.setName(_marker);
-    
-            traverse(plod);
-        }
+        ++_numPagedLODs;
+        traverse(plod);
     }
     
-    std::string _marker;
-    int _numPagedLODsMarked;
+    int _numPagedLODs;
 };
 
 void DatabasePager::removeExpiredSubgraphs(const osg::FrameStamp& frameStamp)
-{
-    if (_targetMaximumNumberOfPageLOD>0)
-    {
-        capped_removeExpiredSubgraphs(frameStamp);
-    }
-    else
-    {
-        expiry_removeExpiredSubgraphs(frameStamp);
-    }
-}
-
-void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameStamp)
 {
     static double s_total_iter_stage_a = 0.0;
     static double s_total_time_stage_a = 0.0;
@@ -1571,32 +1590,34 @@ void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameSt
     osg::Timer_t startTick = osg::Timer::instance()->tick();
 
 
-    unsigned int numPagedLODs = _activePagedLODList.size() + _inactivePagedLODList.size();
-    
-
     PagedLODList::iterator itr = _activePagedLODList.begin();
     for(PagedLODList::iterator itr = _activePagedLODList.begin();
         itr != _activePagedLODList.end();
         )
     {
         osg::PagedLOD* plod = itr->get();
-        
-        int delta = frameStamp.getFrameNumber() - plod->getFrameNumberOfLastTraversal();
-        if (delta>1)
+        if (plod)
         {
-            if (_releaseDelay!=DBL_MAX)
+            int delta = frameStamp.getFrameNumber() - plod->getFrameNumberOfLastTraversal();
+            if (delta>1)
             {
-                plod->releaseGLObjects();
-                OSG_NOTIFY(osg::INFO)<<"DatabasePager::removeExpiredSubgraphs(), releasing gl objects"<<std::endl;
-            }
+                if (_releaseDelay!=DBL_MAX)
+                {
+                    plod->releaseGLObjects();
+                }
 
-            _inactivePagedLODList.push_back(plod);
-            
-            itr = _activePagedLODList.erase(itr);
+                _inactivePagedLODList.push_back(plod);
+
+                itr = _activePagedLODList.erase(itr);
+            }
+            else
+            {
+                ++itr;
+            }
         }
         else
         {
-            ++itr;
+            itr = _activePagedLODList.erase(itr);
         }
     }
 
@@ -1605,21 +1626,28 @@ void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameSt
         )
     {
         osg::PagedLOD* plod = itr->get();
-        
-        int delta = frameStamp.getFrameNumber() - plod->getFrameNumberOfLastTraversal();
-        if (delta>1)
+        if (plod)
         {
-            ++itr;
+            int delta = frameStamp.getFrameNumber() - plod->getFrameNumberOfLastTraversal();
+            if (delta>1)
+            {
+                ++itr;
+            }
+            else
+            {
+                _activePagedLODList.push_back(plod);
+
+                itr = _inactivePagedLODList.erase(itr);
+            }
         }
         else
         {
-            _activePagedLODList.push_back(plod);
-            
             itr = _inactivePagedLODList.erase(itr);
         }
     }
 
     int inactivePLOD = _inactivePagedLODList.size();
+    unsigned int numPagedLODs = _activePagedLODList.size() + _inactivePagedLODList.size();
 
     
     osg::Timer_t end_a_Tick = osg::Timer::instance()->tick();
@@ -1648,47 +1676,51 @@ void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameSt
     double expiryTime = frameStamp.getReferenceTime() - 0.1;
     int expiryFrame = frameStamp.getFrameNumber() - 1;
 
-    MarkPagedLODsVisitor markerVistor("NeedToRemove");
+    CountPagedLODsVisitor countPagedLODsVisitor;
 
     for(PagedLODList::iterator itr = _inactivePagedLODList.begin();
-        itr!=_inactivePagedLODList.end() && markerVistor._numPagedLODsMarked<numToPrune;
+        itr!=_inactivePagedLODList.end() && countPagedLODsVisitor._numPagedLODs<numToPrune;
         ++itr)
     {
         osg::PagedLOD* plod = itr->get();
-
-        osg::NodeList localChildrenRemoved;
-        plod->removeExpiredChildren(expiryTime, expiryFrame, localChildrenRemoved);
-        if (!localChildrenRemoved.empty())
+        if (plod)
         {
-            for(osg::NodeList::iterator critr = localChildrenRemoved.begin();
-                critr!=localChildrenRemoved.end();
-                ++critr)
+            osg::NodeList localChildrenRemoved;
+            plod->removeExpiredChildren(expiryTime, expiryFrame, localChildrenRemoved);
+            if (!localChildrenRemoved.empty())
             {
-                (*critr)->accept(markerVistor);
+                for(osg::NodeList::iterator critr = localChildrenRemoved.begin();
+                    critr!=localChildrenRemoved.end();
+                    ++critr)
+                {
+                    (*critr)->accept(countPagedLODsVisitor);
+                }
+
+                std::copy(localChildrenRemoved.begin(),localChildrenRemoved.end(),std::back_inserter(childrenRemoved));
             }
-            
-            std::copy(localChildrenRemoved.begin(),localChildrenRemoved.end(),std::back_inserter(childrenRemoved));
         }
     }
     
     for(PagedLODList::iterator itr = _activePagedLODList.begin();
-        itr!=_activePagedLODList.end() && markerVistor._numPagedLODsMarked<numToPrune;
+        itr!=_activePagedLODList.end() && countPagedLODsVisitor._numPagedLODs<numToPrune;
         ++itr)
     {
         osg::PagedLOD* plod = itr->get();
-
-        osg::NodeList localChildrenRemoved;
-        plod->removeExpiredChildren(expiryTime, expiryFrame, localChildrenRemoved);
-        if (!localChildrenRemoved.empty())
+        if (plod)
         {
-            for(osg::NodeList::iterator critr = localChildrenRemoved.begin();
-                critr!=localChildrenRemoved.end();
-                ++critr)
+            osg::NodeList localChildrenRemoved;
+            plod->removeExpiredChildren(expiryTime, expiryFrame, localChildrenRemoved);
+            if (!localChildrenRemoved.empty())
             {
-                (*critr)->accept(markerVistor);
+                for(osg::NodeList::iterator critr = localChildrenRemoved.begin();
+                    critr!=localChildrenRemoved.end();
+                    ++critr)
+                {
+                    (*critr)->accept(countPagedLODsVisitor);
+                }
+
+                std::copy(localChildrenRemoved.begin(),localChildrenRemoved.end(),std::back_inserter(childrenRemoved));
             }
-            
-            std::copy(localChildrenRemoved.begin(),localChildrenRemoved.end(),std::back_inserter(childrenRemoved));
         }
     }
     
@@ -1701,7 +1733,7 @@ void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameSt
 
 
 
-    //OSG_NOTIFY(osg::NOTICE)<<"numToPrune "<<numToPrune<< " markerVistor._numPagedLODsMarked="<<markerVistor._numPagedLODsMarked<< " childrenRemoved.size()="<<childrenRemoved.size()<<std::endl;
+    //OSG_NOTICE<<"numToPrune "<<numToPrune<< " countPagedLODsVisitor._numPagedLODsMarked="<<countPagedLODsVisitor._numPagedLODsMarked<< " childrenRemoved.size()="<<childrenRemoved.size()<<std::endl;
 
     if (!childrenRemoved.empty())
     { 
@@ -1717,48 +1749,12 @@ void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameSt
             {
                 _fileRequestQueue->_childrenToDeleteList.push_back(critr->get());
             }
-            
+
             updateBlock = true;
-
         }
 
-        int numRemoved = 0;
-        int numToRemove = markerVistor._numPagedLODsMarked;
-        
-        
-        //OSG_NOTIFY(osg::NOTICE)<<"Children to remove "<<childrenRemoved.size()<<" numToRemove="<<numToRemove<<std::endl;
-
-        // OSG_NOTIFY(osg::NOTICE)<<"   time 2 "<<osg::Timer::instance()->delta_m(before,osg::Timer::instance()->tick())<<" ms "<<std::endl;
-        int numSkipped = 0;
-        for(PagedLODList::iterator itr = _inactivePagedLODList.begin();
-            itr!=_inactivePagedLODList.end() && numRemoved<numToRemove;
-            )
-        {
-            osg::PagedLOD* plod = itr->get();
-            if (plod && plod->getName() != markerVistor._marker)
-            {
-                ++itr;
-                
-                ++numSkipped;
-                
-                // OSG_NOTIFY(osg::NOTICE)<<"skipping"<<std::endl;
-            }
-            else
-            {
-                // OSG_NOTIFY(osg::NOTICE)<<"removing"<<std::endl;
-
-                ++numRemoved;
-
-                itr = _inactivePagedLODList.erase(itr);
-            }
-        }
-
-        OSG_NOTIFY(osg::INFO)<<"Number of PagedLODs skipped="<<numSkipped<<" removed "<<numRemoved<<std::endl;
-
-
         childrenRemoved.clear();
 
-
         if (updateBlock)
         {
             _fileRequestQueue->updateBlock();
@@ -1772,108 +1768,12 @@ void DatabasePager::capped_removeExpiredSubgraphs(const osg::FrameStamp& frameSt
     s_total_time_stage_c += time_c;
     if (s_total_max_stage_c<time_c) s_total_max_stage_c = time_c;
 
-
-
-    OSG_NOTIFY(osg::INFO)<<"active="<<_activePagedLODList.size()<<" inactive="<<_inactivePagedLODList.size()<<" overall = "<<osg::Timer::instance()->delta_m(startTick,end_c_Tick)<<
+    OSG_INFO<<"active="<<_activePagedLODList.size()<<" inactive="<<_inactivePagedLODList.size()<<" overall = "<<osg::Timer::instance()->delta_m(startTick,end_c_Tick)<<
                               " A="<<time_a<<" avg="<<s_total_time_stage_a/s_total_iter_stage_a<<" max = "<<s_total_max_stage_a<<
                               " B="<<time_b<<" avg="<<s_total_time_stage_b/s_total_iter_stage_b<<" max = "<<s_total_max_stage_b<<
                               " C="<<time_c<<" avg="<<s_total_time_stage_c/s_total_iter_stage_c<<" max = "<<s_total_max_stage_c<<std::endl;
 }
 
-void DatabasePager::expiry_removeExpiredSubgraphs(const osg::FrameStamp& frameStamp)
-{
-//    OSG_NOTIFY(osg::NOTICE)<<"DatabasePager::new_removeExpiredSubgraphs()"<<std::endl;
-
-    static double s_total_iter = 0.0;
-    static double s_total_time = 0.0;
-    static double s_total_max = 0.0;
-    
-    osg::Timer_t startTick = osg::Timer::instance()->tick();
-
-    double expiryTime = frameStamp.getReferenceTime() - _expiryDelay;
-    int expiryFrame = frameStamp.getFrameNumber() - _expiryFrames;
-
-    double releaseTime = frameStamp.getReferenceTime() - _releaseDelay;
-    int releaseFrame = frameStamp.getFrameNumber() - _releaseFrames;
-
-    osg::NodeList childrenRemoved;
-    
-    for(PagedLODList::iterator itr = _activePagedLODList.begin();
-        itr!=_activePagedLODList.end();
-        ++itr)
-    {
-        osg::PagedLOD* plod = itr->get();
-        
-        
-        if (_releaseDelay!=DBL_MAX && plod->releaseGLObjectsOnExpiredChildren(releaseTime, releaseFrame))
-        {
-            OSG_NOTIFY(osg::INFO)<<"DatabasePager::removeExpiredSubgraphs(), releasing gl objects"<<std::endl;
-        }
-        
-        plod->removeExpiredChildren(expiryTime, expiryFrame, childrenRemoved);
-    }
-    
-    if (!childrenRemoved.empty())
-    { 
-        MarkPagedLODsVisitor markerVistor("NeedToRemove");
-        for(osg::NodeList::iterator critr = childrenRemoved.begin();
-            critr!=childrenRemoved.end();
-            ++critr)
-        {
-            (*critr)->accept(markerVistor);
-        }    
-    
-        // OSG_NOTIFY(osg::NOTICE)<<"Children to remove "<<childrenRemoved.size()<<std::endl;
-    
-        // pass the objects across to the database pager delete list
-        if (_deleteRemovedSubgraphsInDatabaseThread)
-        {
-            OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_fileRequestQueue->_childrenToDeleteListMutex);
-            for (osg::NodeList::iterator critr = childrenRemoved.begin();
-                 critr!=childrenRemoved.end();
-                 ++critr)
-            {
-                _fileRequestQueue->_childrenToDeleteList.push_back(critr->get());
-            }
-
-            _fileRequestQueue->updateBlock();
-        }
-
-        // OSG_NOTIFY(osg::NOTICE)<<"   time 2 "<<osg::Timer::instance()->delta_m(before,osg::Timer::instance()->tick())<<" ms "<<std::endl;
-        for(PagedLODList::iterator itr = _activePagedLODList.begin();
-            itr!=_activePagedLODList.end();
-            )
-        {
-            osg::PagedLOD* plod = itr->get();
-            if (plod && plod->getName() != markerVistor._marker)
-            {
-                ++itr;
-            }
-            else
-            {
-                PagedLODList::iterator itr_to_erase = itr;
-                ++itr;
-
-                _activePagedLODList.erase(itr_to_erase);            
-            }
-        }
-
-        childrenRemoved.clear();
-
-
-    }
-
-    osg::Timer_t endTick = osg::Timer::instance()->tick();
-    double time = osg::Timer::instance()->delta_m(startTick,endTick);
-
-    s_total_iter += 1.0;
-    s_total_time += time;
-    if (s_total_max<time) s_total_max = time;
-
-    OSG_NOTIFY(osg::INFO)<<"_activePagedLODList.size()="<<_activePagedLODList.size()<<" overall = "<<time<<
-                              " avg="<<s_total_time/s_total_iter<<" max = "<<s_total_max<<std::endl;
-}
-
 class DatabasePager::FindPagedLODsVisitor : public osg::NodeVisitor
 {
 public:
@@ -1884,30 +1784,49 @@ public:
         _frameNumber(frameNumber)
     {
     }
-    
+
     META_NodeVisitor("osgDB","FindPagedLODsVisitor")
 
     virtual void apply(osg::PagedLOD& plod)
     {
         plod.setFrameNumberOfLastTraversal(_frameNumber);
-        
-        _activePagedLODList.push_back(&plod);
-    
+
+        bool needsToBeInserted = true;
+
+        osg::ObserverSet* observerSet = plod.getObserverSet();
+        if (observerSet)
+        {
+            const osg::ObserverSet::Observers& observers = observerSet->getObservers();
+            for(osg::ObserverSet::Observers::const_iterator itr = observers.begin();
+                itr != observers.end() && needsToBeInserted;
+                ++itr)
+            {
+                if (dynamic_cast<PagedLODObserver*>(*itr))
+                {
+                    needsToBeInserted = false;
+                }
+            }
+        }
+
+        if (needsToBeInserted)
+        {
+            _activePagedLODList.push_back(&plod);
+        }
+
         traverse(plod);
     }
-    
+
     DatabasePager::PagedLODList& _activePagedLODList;
     int _frameNumber;
-        
+
 protected:
-    
+
     FindPagedLODsVisitor& operator = (const FindPagedLODsVisitor&) { return *this; }
 };
 
 void DatabasePager::registerPagedLODs(osg::Node* subgraph, int frameNumber)
 {
     if (!subgraph) return;
-    
     FindPagedLODsVisitor fplv(_activePagedLODList, frameNumber);
     subgraph->accept(fplv);
 }
@@ -1944,7 +1863,7 @@ DatabasePager::CompileOperation::CompileOperation(osgDB::DatabasePager* database
 
 void DatabasePager::CompileOperation::operator () (osg::GraphicsContext* context)
 {
-    // OSG_NOTIFY(osg::NOTICE)<<"Background thread compiling"<<std::endl;
+    // OSG_NOTICE<<"Background thread compiling"<<std::endl;
 
     if (_databasePager.valid()) _databasePager->compileAllGLObjects(*(context->getState()));
     
@@ -1965,7 +1884,7 @@ void DatabasePager::compileAllGLObjects(osg::State& state)
 
 void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
 {
-    // OSG_NOTIFY(osg::NOTICE)<<"DatabasePager::compileGLObjects "<<_frameNumber<<std::endl;
+    // OSG_NOTICE<<"DatabasePager::compileGLObjects "<<_frameNumber<<std::endl;
 
     bool compileAll = (availableTime==DBL_MAX);
 
@@ -2010,14 +1929,14 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
 
                 // we have StateSet's to compile
                 StateSetList& sslist = dtc.first;
-                //OSG_NOTIFY(osg::INFO)<<"Compiling statesets"<<std::endl;
+                //OSG_INFO<<"Compiling statesets"<<std::endl;
                 StateSetList::iterator itr=sslist.begin();
                 unsigned int objTemp = numObjectsCompiled;
                 for(;
                     itr!=sslist.end() && (compileAll || ((elapsedTime+estimatedTextureDuration)<availableTime && numObjectsCompiled<_maximumNumOfObjectsToCompilePerFrame));
                     ++itr)
                 {
-                    //OSG_NOTIFY(osg::INFO)<<"    Compiling stateset "<<(*itr).get()<<std::endl;
+                    //OSG_INFO<<"    Compiling stateset "<<(*itr).get()<<std::endl;
                     if (isCompiled(itr->get(), state.getContextID())
                         || (sharedManager && sharedManager->isShared(itr->get())))
                     {
@@ -2052,7 +1971,7 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
             if (!dtc.second.empty() && (compileAll || ((elapsedTime+estimatedDrawableDuration)<availableTime && numObjectsCompiled<_maximumNumOfObjectsToCompilePerFrame)))
             {
                 // we have Drawable's to compile
-                //OSG_NOTIFY(osg::INFO)<<"Compiling drawables"<<std::endl;
+                //OSG_INFO<<"Compiling drawables"<<std::endl;
                 DrawableList& dwlist = dtc.second;
                 DrawableList::iterator itr=dwlist.begin();
                 unsigned int objTemp = numObjectsCompiled;
@@ -2060,7 +1979,7 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
                     itr!=dwlist.end() && (compileAll || ((elapsedTime+estimatedDrawableDuration)<availableTime && numObjectsCompiled<_maximumNumOfObjectsToCompilePerFrame));
                     ++itr)
                 {
-                    //OSG_NOTIFY(osg::INFO)<<"    Compiling drawable "<<(*itr).get()<<std::endl;
+                    //OSG_INFO<<"    Compiling drawable "<<(*itr).get()<<std::endl;
                     if (isCompiled(itr->get(), state.getContextID()))
                     {
                         elapsedTime = timer.delta_s(start_tick,timer.tick());
@@ -2085,7 +2004,7 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
                 dwlist.erase(dwlist.begin(),itr);
             }
 
-            //OSG_NOTIFY(osg::INFO)<<"Checking if compiled"<<std::endl;
+            //OSG_INFO<<"Checking if compiled"<<std::endl;
 
             // now check the to compile entries for all active graphics contexts
             // to make sure that all have been compiled. They won't be
@@ -2101,13 +2020,13 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
             }
 
             //if (numObjectsCompiled > 0)
-            //OSG_NOTIFY(osg::NOTICE)<< _frameNumber << "compiled " << numObjectsCompiled << " objects" << std::endl;
+            //OSG_NOTICE<< _frameNumber << "compiled " << numObjectsCompiled << " objects" << std::endl;
             
             if (allCompiled)
             {
                 // we've compiled all of the current databaseRequest so we can now pop it off the
                 // to compile list and place it on the merge list.
-                // OSG_NOTIFY(osg::NOTICE)<<"All compiled"<<std::endl;
+                // OSG_NOTICE<<"All compiled"<<std::endl;
 
 
                 OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_dataToCompileList->_requestMutex);
@@ -2140,7 +2059,7 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
             }
             else 
             {
-                // OSG_NOTIFY(osg::NOTICE)<<"Not all compiled"<<std::endl;
+                // OSG_NOTICE<<"Not all compiled"<<std::endl;
                 databaseRequest = 0;
             }
 
@@ -2149,9 +2068,9 @@ void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
 
         availableTime -= elapsedTime;
 
-        //OSG_NOTIFY(osg::NOTICE)<<"elapsedTime="<<elapsedTime<<"\ttime remaining ="<<availableTime<<"\tnumObjectsCompiled = "<<numObjectsCompiled<<std::endl;
-        //OSG_NOTIFY(osg::NOTICE)<<"estimatedTextureDuration="<<estimatedTextureDuration;
-        //OSG_NOTIFY(osg::NOTICE)<<"\testimatedDrawableDuration="<<estimatedDrawableDuration<<std::endl;
+        //OSG_NOTICE<<"elapsedTime="<<elapsedTime<<"\ttime remaining ="<<availableTime<<"\tnumObjectsCompiled = "<<numObjectsCompiled<<std::endl;
+        //OSG_NOTICE<<"estimatedTextureDuration="<<estimatedTextureDuration;
+        //OSG_NOTICE<<"\testimatedDrawableDuration="<<estimatedDrawableDuration<<std::endl;
     }
     else
     {