Re: [boost] [serialization] fast array serialization (10x speedup)

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-11-24 12:58:26

David Abrahams wrote:

>>> Yes, it does, in theory. Reality isn't that bad. For every M, the
>>> archive author has already added the necessary overloads for every
>>> "fundamental" type that supports optimized array operations.
>
> In most cases this shouldn't require a separate overload for every
> fundamental type, since the actual array serialization procedure is
> often the same for _every_ type that can use the optimization.  But
> again, that's a question of how much work the archive author is
> required to do, so Robert may not consider it a valid argument.

I prefer enumerating the overloads explicitly, but you can use a single 
SFINAE'd overload.

> However, our approach is designed to make it very easy and more
> foolproof to provide the necessary information for such a type: in
> Matthias' original design, a trait specialization; in the more recent
> design, an overload of optimize_array that returns mpl::true_.  In
> your proposal you need a separate overload of save_sequence.

Providing a save_sequence overload is approximately the same amount of work 
as adding a partial specialization or an optimize_array overload.

> Then you likely either have to duplicate the normal fast serialization
> procedure in your overload...

... which is not a problem for archives supporting your .load_array or 
.save_array protocol.

> or you have to dispatch to something written by the archive author that
> may be named differently for every archive.

Quite right. save_sequence for char[] can cover "bitwise serializability", 
though.