Simplified the API for using the DatabasePager, by providing a single

DatabasePager::updateSceneGraph(..) method, and added a ref_ptr<> into
osDB::Registry for managing a single DatabasePager in a centralised way.

src/osgDB/DatabasePager.cpp

@@ -30,6 +30,7 @@ DatabasePager::DatabasePager()
 
 DatabasePager::~DatabasePager()
 {
+    //std::cout<<"DatabasePager::~DatabasePager()"<<std::endl;
     if( isRunning() )
     {
         // cancel the thread..
@@ -44,6 +45,7 @@ DatabasePager::~DatabasePager()
         }
         
     }
+    std::cout<<"DatabasePager::~DatabasePager() stopped running"<<std::endl;
         
 }
 
@@ -175,10 +177,10 @@ void DatabasePager::signalEndFrame()
     _frameBlock->release();
 }
 
-class FindCompileableRenderingObjectsVisitor : public osg::NodeVisitor
+class FindCompileableGLObjectsVisitor : public osg::NodeVisitor
 {
 public:
-    FindCompileableRenderingObjectsVisitor(DatabasePager::DataToCompile& dataToCompile):
+    FindCompileableGLObjectsVisitor(DatabasePager::DataToCompile& dataToCompile):
         osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ALL_CHILDREN),
         _dataToCompile(dataToCompile)
     {
@@ -331,7 +333,7 @@ void DatabasePager::run()
                     ++itr;                
 
                     // find all the compileable rendering objects
-                    FindCompileableRenderingObjectsVisitor frov(dtc);
+                    FindCompileableGLObjectsVisitor frov(dtc);
                     databaseRequest->_loadedModel->accept(frov);
 
                     if (!dtc.first.empty() || !dtc.second.empty())
@@ -569,7 +571,7 @@ void DatabasePager::registerPagedLODs(osg::Node* subgraph)
     if (subgraph) subgraph->accept(fplv);
 }
 
-void DatabasePager::setCompileRenderingObjectsForContexID(unsigned int contextID, bool on)
+void DatabasePager::setCompileGLObjectsForContexID(unsigned int contextID, bool on)
 {
     if (on)
     {
@@ -581,13 +583,13 @@ void DatabasePager::setCompileRenderingObjectsForContexID(unsigned int contextID
     }
 }
 
-bool DatabasePager::getCompileRenderingObjectsForContexID(unsigned int contextID)
+bool DatabasePager::getCompileGLObjectsForContexID(unsigned int contextID)
 {
     return _activeGraphicsContexts.count(contextID)!=0;
 }
 
 
-void DatabasePager::compileRenderingObjects(osg::State& state, double& availableTime)
+void DatabasePager::compileGLObjects(osg::State& state, double& availableTime)
 {
 
     const osg::Timer& timer = *osg::Timer::instance();

src/osgDB/Registry.cpp

@@ -197,6 +197,11 @@ Registry::Registry()
 
 Registry::~Registry()
 {
+    // switch off the pager and its associated thread before we clean up 
+    // rest of the Registry.
+    _databasePager = 0;
+
+    // unload all the plugin before we finally destruct.
     closeAllLibraries();
 }
 
@@ -1835,3 +1840,10 @@ void Registry::clearObjectCache()
 {
     _objectCache.clear();
 }
+
+DatabasePager* Registry::getOrCreateDatabasePager()
+{
+    if (!_databasePager) _databasePager = new DatabasePager;
+    
+    return _databasePager.get();
+}