Re: [boost] Serialization Library Review

[Matthias Troyer]

On Sunday, November 17, 2002, at 07:08 PM, Robert Ramey wrote:

Date: Sun, 17 Nov 2002 10:19:23 +0100
From: Matthias Troyer <[EMAIL PROTECTED]>
It is mentioned in several places in the code, docs and in this list
that the native binary archive derivations have absolutly no
pretentensions to portabability.  ABSOLUTELY NONE.  Knowing that
many users will ignore this admonishment, I included code
do double check that at least this size and endian ness of
the data types match between the loading and saving machine
so that the most obvious blunders will be detected and an exception be
thrown. I don't know what else I can do. The current
library has NO instance of a portable binary archive.  Many have
written to tell me how easy it is but I'm still waiting for someone
to submit one.

I believe we all agree that portable binary archive formats are essential in addition to the text based one.
This discussion started because I asked you, why you don't consider using int8_t, int16_t, int32_t in addition to int64_t as the primitive types? That would make implementing a portable binary archive MUCH easier.

Will someone please write and submit a derivative that stores the data
using XDR?

Ill do that immediately, once the code compiles with g++ v3.x . It should not take longer than an hour then. I don't want to submit code though that I cannot test because the library does not compile.

2.) The second problem is speed when serializing large containers of
basic data types, e.g. a vector<double> or ublas vectors and matrices.
In my applications these can easily by hundreds of megabyte in size.
In
the current implementation, serializing a
std::vector<double>(10000000)
requires ten million virtual function calls. In order to prevent this,
I propose to add extra virtual functions (like the operator<< above),
which serialize C-arrays of basic data tyes, i.e. functions like

Serialization version 6 which was submitted for review includes
serialization of C-arrays. It is documented in the reference
under the title "Serialization Implementations included in the Library"
and a test case was added to test.cpp.

Yes, but it does so by calling the virtual operator << for each
element, which is very slow if you
call it millions of times.

In conjunction with this, the serialization for std::vector and for
ublas vectors, etc. has to be adapted to make use of these optimized
serialization functions for basic data types.

The library permits override of the included implementations.
Of course,  this has to be up to the person who finds the
the included implementation inconvenient in some way as he is
the only one who knows what he wants changed.

That will not work since overriding is a compile-time decision while I
decide the archive format at runtime and thus need to have these
optimized functions available as virtual functions.

have you considered trying to provide your own specialization for the
following operator ( and << as well)

template<class T>
inline boost::basic_iarchive & operator>>(boost::basic_iarchive &ar, T &t){

I am confused by that answer. Could you please elaborate?

Thanks in advance,

Matthias

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