Re: [boost] [Serialization] Improving performance

Subject: Re: [boost] [Serialization] Improving performance
From: David Abrahams (dave_at_[hidden])
Date: 2009-01-20 14:16:39

on Tue Jan 20 2009, "Hartmut Kaiser" <hartmut.kaiser-AT-gmail.com> wrote:

> Hi all,
>
> in one of my projects I have a lot of types (>1000) to be serialized using a
> pointer to a single base class. At some point we found the
> serialization/deserialzation time to be O(N*M), where N is the number of
> types and M the number of classes in the derivation hierarchy. 
>
> Wondering why this is so significant I started digging and measuring. I
> found the type information registry used for the void_upcast() to be the
> culprit. It's a plain std::vector<const void_caster *>
> ($BOOST_ROOT_1_37/libs/serialization/src/void_cast.cpp:37) which is searched
> sequentially a lot (once for each derived/base pair for each serialization
> call). Moreover, this vector isn't even kept sorted.
>
>     it = std::find_if(
>         s.begin(), 
>         s.end(),
>         void_cast_detail::match(& ca)
>     );
>
> ($BOOST_ROOT_1_37/libs/serialization/src/void_cast.cpp:180). Changing this
> to be a std::set improves the picture significantly! 
>
> What's the reasoning behind using a std::vector<> instead of a std::set<> or
> a similar indexed structure?

I have a highly optimized component in Boost.Python that I *believe* is
doing the same job.  Perhaps we should factor it out and share?

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com