[osg-users] DeleteHandler::_numFramesToRetainObjects
Anders Backman
andersb at cs.umu.se
Thu Aug 2 06:30:14 PDT 2007
Was that a typo or a new feature ;-)
There is nothing such as instance() in DeleteHandler.
There is also nothing that prevents the
osg::Referenced::getDeleteHandler() to return 0, so one should also
check for that, which makes the code,... well a little to much, dont
you think?
if (osg::Referenced::getDeleteHandler()) {
osg::Referenced::getDeleteHandler()->setNumFramesToRetainObjects(0);
osg::Referenced::getDeleteHandler()->flushAll();
}
On 8/2/07, Robert Osfield <robert.osfield at gmail.com> wrote:
> Hi Anders,
>
> If you need to ensure that DeleteHandler is no longer cashing data,
> then you could either let the Viewer destruct then reset the
> DeleteHandler or stop the viewer threading then reset the
> DeleteHandler. Setting SingleThreaded will stop all the threads and
> do away with the need for the caching. i.e.
>
> viewer.stopThreading();
> osg::DeleteHander::instance()->setNumFramesToRetainObjects(0);
> osg::DeleteHander::instance()->flushAll();
>
> The Viewer could have the DeleteHandler flush into the destructor, but
> this would break apps that have multiple Viewers run at one time so we
> have to rely on the above.
>
> Robert
>
> On 8/2/07, Anders Backman <andersb at cs.umu.se> wrote:
> > That depends when the osgViewer library is unloaded?
> > If that is done during the destructor of a Singleton, then no, there
> > is no way of controlling the order in which static singletons are
> > deleted, right?
> >
> > If it is done during the deletion of the osg::Viewer object, then one
> > have to keep the scope of the Viewer so that it goes out of scope
> > before the shutdown of my singleton...
> >
> > The reason for all this is that OpenAL does not like to be shutdown
> > outside the scope of main() for some reason.
> > So I have to do all the deallocation of osgAL inside the scope of
> > main() or I will get a crasch inside OpenAL.
> >
> > /Anders
> >
> >
> > On 8/2/07, Robert Osfield <robert.osfield at gmail.com> wrote:
> > > Hi Anders,
> > >
> > > The DeleteHandler now retains objects for two frames when either
> > > DrawThreadPerContext or CullThreadPerCameraDrawThreadPerContext is
> > > used to ensure that objects used but not referenced in the draw thread
> > > aren't deleted by the main or cull threadeds.
> > >
> > > When one closes the Viewer one can manually switch off the caching of
> > > deleted objects and then flush the DeletaHandler. In the SVN version
> > > of the OSG this is now automatically done when the osgViewer library
> > > is unloaded, so perhaps this is enough for your purposes.
> > >
> > > Robert.
> > >
> > > On 8/2/07, Anders Backman <andersb at cs.umu.se> wrote:
> > > > Hi (again)...
> > > >
> > > > I just stumbled across another issue with osg2.0 regarding a (new)
> > > > policy for reference handling:
> > > >
> > > > It seems that There is something named _numFramesToRetainObjects in
> > > > the default DeleteHandler, which in my case seems to default to 2.
> > > > So When a Referenced object is unref():ed and # of ref_ptr:s pointing
> > > > to the object, it will still live for another two frames.
> > > >
> > > > This caused problems in my case, where I wanted to be sure that all
> > > > objects are gone before end of main() {} scope.
> > > >
> > > > What happens now is that during shutdown, some objects are pushed to a
> > > > list for later deletion, the scope of main() {} ends, and a atExit()
> > > > function is called, executing the actual deletion of the objects.
> > > >
> > > > Example:
> > > >
> > > > void main() {
> > > > 1. SingletonManager::init();
> > > >
> > > > create objects and register with the SingletonManager()
> > > >
> > > > SingletonManager::shutdown(); // delete all registrated objects
> > > > within the SingletonManager().
> > > >
> > > >
> > > > }
> > > >
> > > > // end of main() atExit called which will do the actual deletion of
> > > > objects (that should have been deleted by the SingletonManager()
> > > >
> > > > Which causes problems!
> > > >
> > > > Now, how to fix this?
> > > > One way would be to change the _numFramesToRetainObjects=0, before
> > > > calling SingletonManager::shutdown(), but that seems a little bit to
> > > > introvert, I don´t really know what happens after the
> > > > SingletonManager::shutdown() call, there is a reason for
> > > > _numFramesToRetainObjects==2 I guess?
> > > >
> > > >
> > > > The following code WORKS just fine:
> > > >
> > > > osg::Referenced::getDeleteHandler()->setNumFramesToRetainObjects(0);
> > > > SingletonManager::shutdown();
> > > >
> > > >
> > > > The DeleteHandler is common to ALL objects using Referenced, right?
> > > >
> > > > There must be a better way of handling this for me?
> > > > I would prefer not to put this code into SingletonManager::shutdown()
> > > > as it implies that this MUST be the last thing you do, because it
> > > > changes the state of the rest of the application...
> > > >
> > > > Cheers,
> > > > Anders
> > > >
> > > >
> > > >
> > > > --
> > > >
> > > >
> > > > ________________________________________________________________
> > > > Anders Backman Email: andersb at cs.umu.se
> > > > HPC2N/VRlab Phone: +46 (0)90-786 9936
> > > > Umea university Cellular: +46 (0)70-392 64 67
> > > > S-901 87 UMEA SWEDEN Fax: +46 90-786 6126
> > > > http://www.cs.umu.se/~andersb
> > > > _______________________________________________
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> > > >
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> > >
> >
> >
> > --
> >
> >
> > ________________________________________________________________
> > Anders Backman Email: andersb at cs.umu.se
> > HPC2N/VRlab Phone: +46 (0)90-786 9936
> > Umea university Cellular: +46 (0)70-392 64 67
> > S-901 87 UMEA SWEDEN Fax: +46 90-786 6126
> > http://www.cs.umu.se/~andersb
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> >
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--
________________________________________________________________
Anders Backman Email: andersb at cs.umu.se
HPC2N/VRlab Phone: +46 (0)90-786 9936
Umea university Cellular: +46 (0)70-392 64 67
S-901 87 UMEA SWEDEN Fax: +46 90-786 6126
http://www.cs.umu.se/~andersb
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