Re: [g-a-devel]Deleting accessible objects

[Bill Haneman <bill haneman sun com>]

On Thu, 2002-08-29 at 14:03, Padraig O'Briain wrote:
> Bill, Michael,
> 
> When a window is deleted at-poke reports the state of the frame as DEFUNCT so 
> the state change is being made.

cool, that sounds right to me.
 
> <digression>
> I have logged bug 91957 about at-poke still showing a DEFUNCT frame for the 
> deleted window and will commit the proposed patch tomorrow.
> </digresssion>
> 
> I do not understand the relation between the Accessible in the client and the 
> AtkObject in the application. Should calling Accessible_ref and 
> Accessible_unref() in the client have an impact on the reference count of the 
> AtkObject?

Only in this sense: when an Accessible (bonobo 'at-spi' object) has a
positive refcount one would keep the atkobject around, decrementing the
refcount of the Accessible to zero should decrement the atkobject
refcount.  I think however that the atkobject refcount should remain
positive while the backing widget is alive, thus I think that an
atkobject in the 'normal' case with a live Accessible should have a
refcount of two, and the acts of destroying the backing widget and of
unreffing the Accessible to zero should decrement the refcount.  I would
expect that this means that the sequence of events

widget is destroyed->atkobject state changes->client unrefs Accessible

would result in two atkobject unrefs.

WHat have I forgotten? :-)

-Bill
 
> Padraig
> 
> > Subject: Re: [g-a-devel]Deleting accessible objects
> > To: Michael Meeks <michael ximian com>
> > Cc: "Padraig O'Briain" <Padraig Obriain sun com>, accessibility mailing list 
> <gnome-accessibility-devel gnome org>
> > Content-Transfer-Encoding: 7bit
> > Mime-Version: 1.0
> > 
> > On Thu, 2002-08-29 at 13:07, Michael Meeks wrote:
> > > Hi Padraig,
> > > 
> > > On Wed, 2002-08-28 at 16:52, Padraig O'Briain wrote:
> > > > I have been running gtk-demo with at-poke. I cause a window to be created 
> in 
> > > > gtk-demo, and examine its contents to ensure that accessible obecjts are 
> created 
> > > > and then delete the window. I would expect to see GAIL obejcts being 
> deleted in 
> > > > gtk-demo but I have not seen any evidence of GAIL objects being deleted 
> when the 
> > > > corresponding widgets are deleted.
> > > > 
> > > > Should these GAIL obejcts be deleted?
> > > 
> > > 	Well; there are 2 points here.
> > > 
> > > 	It seems to me that there is 0 point in keeping around a heavy
> > > CORBA/Bonobo proxy for an otherwise dead AtkObject - so I think
> > > (personally) that coupling the lifecycle of the BonoboObject primarily
> > > to the AtkObject, and secondarily to the reference count would make more
> > > sense than the current setup.
> > 
> > Hmm, well at the moment we use state information for determining when an
> > at-spi accessible object is 'defunct'.  At the moment a client
> > application receives (or should receive) notification when this happens,
> > via a state change on the object (to state DEFUNCT).  It's the client's
> > responsibility to unref the object in this case.
> > 
> > Personally I don't think this is so bad; though I can see the attraction
> > of just destroying the proxy and relying on CORBA exceptions to inform
> > the client of object death, the current model gives the client better
> > information on why the object died - at least if it's working as I think
> > we intended.
> > 
> > It's possible that we handle the case of a destroyed widget correctly,
> > but somehow are accidentally holding a reference to the GtkWidget in
> > case where we should not, and thus might be preventing the finalize code
> > from triggering the state change to DEFUNCT.  
> > 
> > I'd suggest we check to see whether state-changed event for the unmapped
> > window is getting fired, and make sure the window gets destroyed by the
> > app if we haven't loaded accessibility, etc.
> > 
> > -Bill
> > 
> > > 	Secondly - there are 3 places there may be a bug:
> > > 
> > > 	a) libspi/ g_object reference counting - perhaps we leak a 
> > > 	   reference here, and the BonoboObject peer doesn't release it.
> > > 
> > > 	b) cspi/ perhaps we don't release the remote reference correctly
> > > 	   when we quit.
> > > 
> > > 	c) most likely - at-poke has an Accessible_ref / unref leak 
> > > 	   somewhere. I believe if you exit the app it should auto-cleanup
> > > 
> > > 
> > > -- 
> > >  mmeeks gnu org  <><, Pseudo Engineer, itinerant idiot
> > > 
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> > > Gnome-accessibility-devel gnome org
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> > 
> > 
>