Re: Custom memory manager and calling unref for Cairo::RefPtr<Cairo::Context>

[Jonathon Jongsma <jonathon quotidian org>]

Roman Yazmin wrote:
> Hi everyone.
>
> I'm using custom memory manager and operators like new and delete are 
> overloaded.
>
> Sample code:
>
>     bool MyDraw::on_expose_event(GdkEventExpose* event)
>     {
>         Glib::RefPtr<Gdk::Window> window = get_window();
>         if(window)
>         {
>            Cairo::RefPtr<Cairo::Context> cr =
>     window->create_cairo_context();
>         }
>     }
>
>
>
> When unref  for Cairo::RefPtr<Cairo::Context> is called (cr goes out 
> of scope)
> I have a crash.
>
> Crashing here: cairomm/refptr.h
>
>     template <class T_CppObject> inline
>     void RefPtr<T_CppObject>::unref()
>     {
>       if(pCppRefcount_)
>       {
>         --(*pCppRefcount_);
>
>         if(*pCppRefcount_ == 0)
>         {
>           if(pCppObject_)
>           {
>             delete pCppObject_;
>             pCppObject_ = 0;
>           }
>
>           delete pCppRefcount_; //<<<<<<-------------------------
>     crash here, (in my overloaded delete operator, he can't found some
>     internal information and assertion happens )
>           pCppRefcount_ = 0;
>         }
>       }
>     }
>
>
> As I understand, pCppRefcount is allocated not with my overloaded new 
> operator.
> It seems like it is allocated somewhere by create_cairo_context() method.
> I am using Windows platform, and allocating memory in DLL and free it
> in host application is not good idea, especially with different 
> allocation methods.
>  
> Is any idea how to resolve this issue?
> I'm still want to use my own memory manager for new/delete.
>
> Thanks.

Sorry it took so long to reply.

the pCppRefcount_ member is not allocated in cairo, it is allocated 
using 'new' (see line 228: 
http://cgit.freedesktop.org/cairomm/tree/cairomm/refptr.h#228).  Since 
it's defined in a header, it should be using your custom new operator.  
I just did a very crude test and i was able to override new and delete 
and both the creation and deletion of the pCppRefcount_ member used my 
custom allocation functions.  Is it possible that your custom allocator 
has a bug?


Jonner