Re: [Boost-users] [Boost.Uuid] Passing UUIDs with MPI

Subject: Re: [Boost-users] [Boost.Uuid] Passing UUIDs with MPI
From: Andy Tompkins (atompkins_at_[hidden])
Date: 2010-07-05 21:08:24

Hi Didier,

On Thu, 10 Jun 2010 22:53 +0200, "Didier Devaurs"
<ddevaurs_at_[hidden]> wrote:
> Hello,
> 
> I'm having troubles trying to pass a uuid with MPI routines.
> Since a uuid is serialized as a primitive type, I was expecting it could
> be declared as an MPI datatype using:
> BOOST_IS_MPI_DATATYPE(boost::uuids::uuid)
> and sent via MPI routines.

This makes sense to me from reading the docs:
http://www.boost.org/doc/libs/1_43_0/doc/html/mpi/tutorial.html#mpi.user_data_types

> I've written a short program to illustrate the problem. It compiles but
> produces a "segmentation fault" error when I'm trying to run it:

In the same section, I also read that if one uses this optimization 
(BOOST_IS_MPI_DATATYPE) but shouldn't be, a result could be a
segmentation fault.

> #include <iostream>
> #include <boost/mpi.hpp>
> #include <boost/uuid/uuid.hpp>
> #include <boost/uuid/uuid_io.hpp>
> #include <boost/uuid/uuid_generators.hpp>
> #include <boost/uuid/uuid_serialize.hpp>
> 
> BOOST_IS_MPI_DATATYPE(boost::uuids::uuid)
> 
> int main()
> {
>   boost::mpi::environment env;
>   boost::mpi::communicator world;
> 
>   if (world.rank() == 0) {
>     boost::uuids::uuid u;
>     u = boost::uuids::random_generator()();
>     std::cout << "u = " << u << std::endl;
>     world.send(1, 0, u);
>   }
>   else {
>     boost::uuids::uuid v;
>     world.recv(0, 0, v);
>     std::cout << "v = " << v << std::endl;
>   }
>   return 0;
> }
> 
> Does anybody have an idea whether passing uuids would be possible, and if
> yes what is wrong in my code?
> 
> Thank you,
> Didier Devaurs

I do not know much about Boost.MPI.  I will continue learning about it
to try 
to solve the problem.

Regards,
Andy.