Re: Memory ownership from pango_context_load_font(..)

[Behdad Esfahbod <behdad behdad org>]

Hi Martin,

I'm not sure I understand what you are doing here.  Did you originally obtain 
a reference to the fontmap?  The *_get_* functions do not return a reference.
That's all I can say right now.

Regards,
behdad

On 06/02/2009 03:16 AM, Martin Sevior wrote:
> Sorry for the long delay, it was difficult to explain the problem and
> when I finally understood it the solution was straight forward.
>
> The symptom as I said earlier was that abiword would *sometimes* crash
> on exit due to a segfault with pango-cairo.
>
> The backtrace should it orginating in Cairo Graphics class destructor.
>
> The original code was this:
>
> 	_destroyFonts();
> 	delete m_pPFontGUI;
>          if(m_pLayoutFontMap)
>                  g_object_unref(m_pLayoutFontMap);
> 	if(m_pLayoutContext)
> 		g_object_unref(m_pLayoutContext);
>
>
> The fix was to do the following. The comments explain why it is (I
> think) OK and won't cause a memory leak.
>
>
> 	_destroyFonts();
> 	delete m_pPFontGUI;
> 	if(m_pLayoutContext)
> 		g_object_unref(m_pLayoutContext);
>
> 	// MES After much reading and playing I discovered that the
> 	// FontMap gets unreferenced after every font that uses it is
> 	// removed provided the Context is also unrefed. Leaving the unref of
> 	// the FontMap causes an intermitent crash on exit, particularly on
> 	// documents with lots of Math. This fixes those crashes and checks with
> 	// valgrind show no measureable increase in leacked memory.
> 	//
> 	m_pLayoutFontMap = NULL;
> -----------------------------------------------------------------------------------------------
>
> Do you think this is valid? Will the final
> g_object_unref(m_pLayoutContext) also do the an unref on the FontMap
> and so delete it?
>
> Cheers!
>
> Martin
>
> }
> On Tue, May 12, 2009 at 1:19 AM, Behdad Esfahbod<behdad behdad org>  wrote:
> > On 05/11/2009 11:08 AM, Martin Sevior wrote:
> > > Is the only way to free a PangoFont * pF to do
> > >
> > > g_object_unref(pF)
> > > ?
> > Yes.
> >
> > > Is there pango_font_free(pF) or similar?
> > No.
> >
> > What's the problem you are facing?  The caching stuff in pangofc is quite
> > complex.  I may be able to help if you describe what anomaly you are seeing.
> >
> > behdad
> >
> > > Thanks again!
> > >
> > > Martin