DrawPrimitiveStore causes memory leak issues because of _doStore

(Copied from forums at Rob Bateman's request)

So I continued doing work on why flash objects weren't freed when they 
had no refs in my code.  The next culprit I found was the 
DrawPrimitiveStore.  When a createDrawDisplayObject is called 
it will either create a new one, or pop one out of _doStore if 
possible to save the create step.  When reset() is called on the 
DrawPrimitiveStore the entire _doArray is stuffed into the _doStore 
for reuse. 

The problem is that it doesn't clear the references in each of these 
DrawDisplayObjects to source, session, or displayobject before it 
stuff it into the store.  This means that every cached 
DrawDisplayObject in _doStore is holding onto refs it shouldn't, and 
keeping flash objects from being garbage collected.  In our case, 
large movieclips on MovieClipSprites were hanging around because of 
refs in here. 

Now if a DrawDisplayObject is pulled out and reused, the 
source,session, and displayobject fields get set to new values and 
this frees the old refs, but if the number of objects goes down, 
you're left with objects in the cache that don't get reused and memory 
that doesn't get freed.  I believe the right thing to do is to clear 
the refs in the _doArray before stuffing it into the _doStore, like 
this: 

        for (_object in _doDictionary) { 
                _session = _object as AbstractRenderSession; 
                if (_session.updated) { 
                        _doArray = _doDictionary[_session] as Array; 
                        var i:int; 
                        for  (i = 0; i < _doArray.length; i++) 
                        {       // Clear any references so we can gc these 
if needed 
                                var dobj:DrawDisplayObject = _doArray[i] 
as DrawDisplayObject; 
                                        dobj.source = null; 
                                dobj.session = null; 
                                dobj.displayobject = null; 
                        } 
                        _doStore = _doStore.concat(_doArray); 
                        _doArray.length = 0; 
                } 
        } 

I made these changes in my prviate build, and it seems to gc correctly 
now.  I'm not sure if there are any sideeffects I'm causing here that 
I don't understand, so I'm chucking it for comment.  Does this look 
right?
Original issue reported on code.google.com by RickSa...@gmail.com on 29 Sep 2009 at 10:35
kottore / away3d

DrawPrimitiveStore causes memory leak issues because of _doStore #67
