Re: [Boost-users] [Boost.MPI] question about serializingcustomobject

26 Aug 2010

      Cristobal Navarro wrote:
...
i made some progress while we were mailing between us.
first of all, im trying to see if my object can be serialized /
deserialized in the common way without going into MPI yet.
good idea - one thing at a time.
...
objects are Lattices, they have Nodes and Edges. nothing more.
...
it compiles and links ok, and when i test serialization /
deserialization with the following code..:
printf("serializing to binlat.x...\n");
                //!file mode
                /*
                std::ofstream ofs("binlat.x", ios::binary);
                boost::archive::binary_oarchive oa(ofs);
                */
                oa << *(this->lat);
                ofs.close();
                lat->print(); //check what lattice im serializing
                //!Deserialization - read file  binlat.x and
reconstruct 
                printf("reconstructing serialized binlat.x...\n");
                Lattice nl;
                std::ifstream ifs("binlat.x", ios::binary);
                boost::archive::binary_iarchive ia(ifs);
                //!deserialize object
                ia >> nl;
                ifs.close();
                nl.print();
Hmmm- what surrounds this?
...
oa << *(this->lat);
doesn't look right to me.  coincidentally, this same construct is used on another thread

anyay

try

{
   const class Lattice lat ...
    ...
    ar << lat
}

that might work better.

Robert Ramey
...
i get bad errors when deserializing, complaining about a bool and
char. 
serializing to binlat.x...
Lattice::print().....START
Nodes=2   Edges= 1
Node[0] sp=1 ext=1
Linked to edge 2 (Node 3 or 0 )
Node[3] sp=1 ext=2
Linked to edge 2 (Node 3 or 0 )
Lattice::print().....END
[enter]
reconstructing swerialized binlat.x...
[enter]
plattice:
/usr/local/include/boost/archive/basic_binary_iprimitive.hpp:98: void
boost::archive::basic_binary_iprimitive::load(bool&) [with Archive = boost::archive::binary_iarchive,
Elem = char, Tr = std::char_traits<char>]: Assertion `0 == i || 1 ==
i' failed.     
[lenovo00:29384] *** Process received signal ***
[lenovo00:29384] Signal: Aborted (6)
[lenovo00:29384] Signal code:  (-6)
[lenovo00:29384] [ 0] [0xfea410]
[lenovo00:29384] [ 1] /lib/tls/i686/cmov/libc.so.6(abort+0x182)
[0xd41a82] 
[lenovo00:29384] [ 2]
/lib/tls/i686/cmov/libc.so.6(__assert_fail+0xf8) [0xd37718] 
[lenovo00:29384] [ 3]
..
..
*** End of error message ***
i started debugging, and realized that the problem is completely gone
when i remove "edges" from the serialization members of "Lattice"
object.  
its weird, because "edge" is a map of  and much simplier
than "nodes" which does work. obviously i cannot continue without
edges, so i need to fix it somehow, but i dont understand the error
related to edges, maybe is something im not seeing.
dont get distracted by the messy code, i had to edit it a little to
focus on the case. 
regards
Cristobal
On Thu, Aug 26, 2010 at 4:35 PM, Robert Ramey  wrote:
...
Change the "would" into "is": it is possible to mix Boost.MPI with
Boost.Serialization. Any objext that can be serialized can be sent by
Boost.MPI. This was actually the basic idea behind Boost.MPI, to use
Boost.Serialization to pack and unpack MPI buffers, or to create
custom MPI datatypes.
On thing that I never understood is why you need MPI data types at
all. 
If one is serializing (packing) to a binary array, and sending that,
what 
hae MPI data types have to do with it.
If one were using heterogenious machines, I could understand the
usage of MPI types. But as I understand it, the MPI serialization
presumes 
that the machines are binary compatible.  So I'm just not seeing this.
Robert Ramey
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