[RFC] Reference counting on Audio objects for /dev/dsp
Thu Jul 15 18:57:00 GMT 2004
On Thu, 15 Jul 2004, Christopher Faylor wrote:
> On Thu, Jul 15, 2004 at 09:44:34AM -0400, Igor Pechtchanski wrote:
> >I'd really like your comments on this patch. As I reported before, it
> >didn't quite work for me, but with the recent problems in testing another
> >(presumably working) patch, I suspect my test procedure isn't quite
> >correct anyway. The patch basically adds a (very problem-specific)
> >reference count to the Audio object(s), and doesn't delete the shared ones
> >until all pointers are gone. It doesn't seem to fix the bash redirection
> >problem, but does allow the "dsp_dup_close" testcase to run (again, I'd
> >like your opinion on whether it runs correctly).
> >The ChangeLog below is just for the record -- as I said, I don't expect
> >this to be checked in yet.
> > Igor
> >2004-07-06 Igor Pechtchanski <firstname.lastname@example.org>
> > * fhandler_dsp.cc (fhandler_dev_dsp::Audio::reference_count_):
> > New instance variable.
> > (fhandler_dev_dsp::Audio::inc): New function. Increment the
> > reference_count_.
> > (fhandler_dev_dsp::Audio::dec): New function. Decrement the
> > reference_count_ and delete if zero.
> > (fhandler_dev_dsp::close): Replace delete with a call to dec().
> > (fhandler_dev_dsp::dup): Copy audio_in_ and audio_out_ and call
> > inc() on each.
> Thanks for the patch. I have two problems, though.
> 1) Some minor problems with GNU formatting:
> fhc->audio_out_ = audio_out_; if (audio_out_) audio_out_->inc ()
> audio_out_ -> dec ();
Thanks for the review.
Yep. Once we determine whether this works (or if it doesn't, why), I'll
get the formatting in order before resubmitting. As I said before, I
don't expect this to be checked in for now.
> 2) The other problem is that I find it sort of odd to see the dec()
> method performing a deletion. Couldn't this be handled where, IMO,
> it should logically be handled, in the close function, e.g.,
> if (!audio_out_->dec ())
> delete audio_out_;
Umm, that's actually a rather standard construct in reference counting
(called "object suicide" -- you should get some references if you Google
for "object suicide reference counting").
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