[kepler-dev] change proposal for ptolemy.vergil.tree.EntityTreeModel class.

[Christopher Brooks]

Hi Jianwu,

Your change looks ok to me.  The diff between what you sent and what
is in the tree is below:

bash-3.2$ diff ~/Downloads/EntityTreeModelNew.java EntityTreeModel.java
30d29
< import java.lang.ref.WeakReference;
64c63
< public class EntityTreeModelNew implements TreeModel {
---
 > public class EntityTreeModel implements TreeModel {
70c69
<     public EntityTreeModelNew(NamedObj root) {
---
 >     public EntityTreeModel(NamedObj root) {
82c81
<         _listenerList.add(new WeakReference(listener));
---
 >         _listenerList.add(listener);
176c175
<         _listenerList.remove(new WeakReference(listener));
---
 >         _listenerList.remove(listener);
188c187
<             TreeModelListener listener = (TreeModelListener) ((WeakReference)listeners.next()).get();
---
 >             TreeModelListener listener = (TreeModelListener) listeners.next();
263c262
<     private List _listenerList = new LinkedList<WeakReference>();
---
 >     private List _listenerList = new LinkedList();


I folded in the change and added a comment:

   /** Add a listener to this model.
      *  @param listener The listener to add.
      *  @see #removeTreeModelListener(TreeModelListener)
      */
     public void addTreeModelListener(TreeModelListener listener) {
         // In http://bugzilla.ecoinformatics.org/show_bug.cgi?id=4801,
         // Jianwu Wang found that the _listenerList attribute in
         // ptolemy.vergil.tree.EntityTreeModel was leaking memory.
         // This attribute keeps holding some references, so that
         // instances of EntityTreeModel and its sub-classes can not be
         // GCed when a window is open and closed.
         //
         // When it and its sub-classes are used in Kepler,
         // addTreeModelListener() and removeTreeModelListener()
         // functions of EntityTreeModel class are called implicitly.
         // Jianwu did not find a good way to clean up after a window
         // is closed.  Changing the _listenerList attribute using
         // WeakReference fixe the leak.
         _listenerList.add(new WeakReference(listener));
     }

I updated the 8.0 release branch, thanks for the patch!

Derik, I think you would want this in the 2.1 release.  I'm still working on deterimining
if ptolemy-8.0.0 is what should be shipped with Kepler 2.1.

_Christopher


On 9/20/10 4:27 PM, Jianwu Wang wrote:
> As I mentioned at http://bugzilla.ecoinformatics.org/show_bug.cgi?id=4801, I found one class might need to be changed for memory leak.  It's the _listenerList attribute in
> ptolemy.vergil.tree.EntityTreeModel. One memory leak I'm tracing down is that this attribute keeps holding some references, so that instances of EntityTreeModel and its sub-classes can not be GCed
> when a window is open and closed.
>
>     When it and its sub-classes are used in Kepler,  addTreeModelListener() and removeTreeModelListener() functions of EntityTreeModel class are called implicitly.  I haven't find good ways to clean
> up after a window is closed.
>
>     If changing the  _listenerList attribute using WeakReference, it will be able to fix the leak.

-- 
Christopher Brooks, PMP                       University of California
CHESS Executive Director                      US Mail: 337 Cory Hall
Programmer/Analyst CHESS/Ptolemy/Trust        Berkeley, CA 94720-1774
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