Re: [Boost-users] [boost][serialization] void_upcast is very slow

Subject: Re: [Boost-users] [boost][serialization] void_upcast is very slow
From: Robert Ramey (ramey_at_[hidden])
Date: 2008-12-03 15:16:46

My preference would be to detect mulitple inheritance at compile time
if that's possible.

Make a TRAK ticket for this item.

Robert Ramey

Jacob wrote:
> The original "inline void_upcast" method checks if the pointer to the
> object is of the right type, by traversing its parents. This is
> necessary when using multiple inheritance, since in such a case the
> adress of the pointer to the object can vary depending on which base
> class it is cast to.
>
> While profiling one of my projects I noticed that most of the time was
> spent in the void_upcast method. I modified the method to return the
> pointer directly(see below), resulting in a high performance increase.
> This "solution" is possible if you avoid multiple inheritance all
> together, which I did. In my particular project I experienced a 75%
> speed increase implementing this, going from about 10 seconds to 2.5
> seconds.
>
> Would it be possible to implement some functionality to turn on and
> off the upcasting for given classes, kind of like the tracking of
> objects is currently administrated?
>
> Modified "inline void_upcast":
>
> /inline void *
> void_upcast(
>  extended_type_info const & derived,
>  extended_type_info const & base,
>  void * const t
> ){
>  return const_cast<void*>(t);
> }/
>
> Yours sincerely,
>
> Jacob Holm