[7u12] Request for approval for 7177111 - Jcomponent.AccessibleJComponent.AddPropertyListeners adds exponential listeners

[Edvard Wendelin]

Approved. Just make sure you open a backport targeted to 8 so that you 
don't forget about the forward-port.

Cheers,
Edvard

On 12/12/2012 10:55 PM, Pete Brunet wrote:
> This is a request to push the following to 7u12:
>
> 7177111 - Jcomponent.AccessibleJComponent.AddPropertyListeners adds
> exponential listeners.
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7177111
>
> Problem
> When an AT (Assistive Technology, such as a screen reader) accesses a
> Java application with several nested frames, too many property change
> listeners are added resulting in a severe performance impact for an AT user.
>   
> The issue is due to the fact that there is an accessibleContainerHandler
> field in both javax.swing.JComponent.AccessibleJComponent and its
> superclass, java.awt.Container.AccessibleAWTContainer.  When an AT calls
> JComponent.AccessibleJComponent.addPropertyChangeListener a handler is
> new'd and assigned to its accessibleContainerHandler field and then the
> same method in the superclass is called and it also new's and assigns a
> handler to its accessibleContainerHandler field.  Since there are two
> handlers, when a child component is later added there are two callbacks
> and for each one the AT will call addPropertyChangeListener, each of
> which will add two handlers.  For deeply nested trees the explosion of
> events has a negative impact on performance, i.e. there are 2 handlers
> added for the first level, 4 for the second level, 8 for the third
> level, etc.
>   
> Solution
> Remove protected field
> javax.swing.JComponent.AccessibleJComponent.accessibleContainerHandler.
> Instead, the protected field of the same name in
> java.awt.Container.AWTAccessibleContainer will be used.
>
> Notes:
> - The same fix is also one of a set of fixes for 7179482 which will go
> into 8.
> - Both 7177111 and 7179482 have been reviewed and approved by Artem
> Ananiev, Anthony Petrov, and Alexandr Scherbatiy.
> - See the reviews at:
>    -
> http://mail.openjdk.java.net/pipermail/swing-dev/2012-November/002332.html
>    - http://mail.openjdk.java.net/pipermail/awt-dev/2012-November/003829.html
> - See the code change at:
> http://cr.openjdk.java.net/~ptbrunet/7177111/webrev.03/
> - It has been determined that this fix will not cause a binary
> incompatibility.
>
> Thank you,
> Pete
>
>
>