Added DatabasePager::setUseFrameBlock(bool) method

include/osgDB/DatabasePager

@@ -84,6 +84,16 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
         /** run does the database paging.*/        
         virtual void run();
         
+        /** Set the use of the frame block which, if enabled, blocks the DatabasePager 
+          * from executing which the current frame is being drawn.  
+          * When a single processor machine is being used it can be useful to block on
+          * frame to help prevent the database paging thread from slowing the cull and draw
+          * traversals which in turn can cause frame drops.*/
+        void setUseFrameBlock(bool useFrameBlock) { _useFrameBlock = useFrameBlock; }
+        
+        /** Get the whether UseFrameBlock is on or off.*/
+        bool getUseFrameBlock() const { return _useFrameBlock; }
+        
         
         /** Signal the database thread that the update, cull and draw has begun for a new frame.
           * Note, this is called by the application so that the database pager can go to sleep while the CPU is busy on the main rendering threads. */
@@ -196,6 +206,7 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
 
         virtual ~DatabasePager();
 
+        bool                            _useFrameBlock;
         osg::ref_ptr<Block>             _frameBlock;
         int                             _frameNumber;