Yeah, I've noticed it's wrong only after I stripped it down. I was using raw pointers, because I tried to hide OSG behind my application API (so that OSG headers are not required at build time). I didn't know of d-pointer approach at that time, but now I'm rewriting it with the approach.
Thanks for the feedback. 2013/5/28 Robert Osfield <robert.osfi...@gmail.com> > Hi Micheal, > > On 27 May 2013 17:39, michael kapelko <korn...@gmail.com> wrote: > > I've stripped down my OSG app to the attached archive. Upon exit there's > > some threading error, not real crash. But when I make my mCamera > > reference-count-controlled by osg::ref_ptr my app crashes. So may be I'm > > having my threading exit hanging due to not using osg::ref_ptr. > > I've just looked at your example and it really is convoluted and wrong > in a number of ways, we aren't talking OSG bugs, we are talking bugs > in your code. > > 1) You have an event handler that "has a" Viewer, and you attach this > event handler to the Viewer, which takes a reference, via ref_ptr<>, > to that event handler creating a > circular reference. > > 2) You take a C pointer to the a Camera that you assign to the viewer, > which takes a referecence, via ref_ptr<>, so the Viewer takes > ownership and will destruct it > it automatically once the Viewer gets destructed, but... you > manually call unref() and the event handler to force destruction of > the viewer's Camera. This will either > cause a dangling pointer in the Viewer or a dangling pointer in > the event handler, both of which will attempt to unref() it. > > The code is crazy. We have lots of OSG example that show as sensible > way to use the OSG, none of them have an event handler owning the > viewer. Also you'll almost next see examples of code explicitly > calling unref(), it's only in very rare cases where you might want to > not use ref_ptr<> and directly call ref() and unref(), and where you > do you have to be very careful about management of the pointers > involved. I almost never write code that explicitly calls ref() and > unref(), instead ref_ptr<> is my tool, it's robust and easy to use. > > I'm guessing you've resorted to using the unref() because you created > a circular reference without realizing it and tried to hack your way > out of this design/implementation error. > > In you own I strongly recommend that you make the viewer the topmost > object in the chain, *always* leave the event handler as a child of > the viewer, and *never* use ref()/unref() - use ref_ptr<> instead. > > Robert. > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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