Re: Partial serialization of a program

From: Markus Lavin (markus.lavin_at_[hidden])
Date: 2022-11-04 09:40:08

Thanks for the comments!

I believe that the split member approach as used in your example would be a workable solution to my problem.

Ideally though it would be nice if, by some C++ magic, one could tell Boost serialization that pointers to this particular class require special handling (i.e. using the map to get the unique id) and then serialize them as normal in the serialize template. That way not all users of the framework of my program would need to know deeper details of the serialization strategy.


-----Original Message-----
From: kila suelika via Boost-users <boost-users_at_[hidden]<mailto:kila%20suelika%20via%20Boost-users%20%3cboost-users_at_[hidden]%3e>>
Reply-To: boost-users_at_[hidden]<mailto:boost-users_at_[hidden]>
To: boost-users_at_[hidden]<mailto:boost-users_at_[hidden]>
Cc: kila suelika <semeegozy_at_[hidden]<mailto:kila%20suelika%20%3csemeegozy_at_[hidden]%3e>>
Subject: Re: [Boost-users] Partial serialization of a program
Date: Fri, 04 Nov 2022 10:47:19 +0800

I write an example where one can manually set pointer in load:

#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <sstream>

#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <iostream>
#include <map>
#include <string>

#include <boost/serialization/split_member.hpp>

std::map<std::string, int> m{ {"x",5} };
struct A
{
friend class boost::serialization::access;
int* x;

template <class Archive>
void save(Archive& ar, const unsigned int version) const {

}
template <class Archive>
void load(Archive& ar, const unsigned int version) {
x = &(::m["x"]);//Access outside data.
}
BOOST_SERIALIZATION_SPLIT_MEMBER()
};

int main()
{
A a;

std::stringstream s;
boost::archive::binary_oarchive oa(s);
oa << a;

boost::archive::binary_iarchive ia(s);
A a0;
ia >> a0;

std::cout << *(a0.x) << std::endl;
}

On Fri, Nov 4, 2022 at 7:20 AM Gavin Lambert via Boost-users <boost-users_at_[hidden]<mailto:boost-users_at_[hidden]>> wrote:
On 3/11/2022 20:40, Markus Lavin wrote:
> If a serialized object in the dynamic part contains a pointer to a
> non-seralized object in the static part then how do I deal with that.
> Clearly the address cannot be serialized since it may change between
> builds and even between runs (ASLR). The program does contain a
> 'registry' though where all relevant static objects are registered with
> a unique identifier.
>
> So question is would it somehow be possible to have Boost serialization
> use this registry to serialize the unique identifier instead of trying
> to serialize the entire object when one of those pointers are serialized?

Each class can choose exactly what data it serializes and deserializes,
and what it does with it.

For this case it sounds like you probably want
https://www.boost.org/doc/libs/1_80_0/libs/serialization/doc/tutorial.html#splitting
bs%2F1_80_0%2Flibs%2Fserialization%2Fdoc%2Ftutorial.html%23splitting>
such that you can save an internal id and then reload that id and look
up the corresponding pointer, rather than serializing the other object
directly.  You can still cascade into the other object as a reference to
save/load its dynamic state after that.

You will likely also want to read about
https://www.boost.org/doc/libs/1_80_0/libs/serialization/doc/special.html#objecttracking
%2Flibs%2F1_80_0%2Flibs%2Fserialization%2Fdoc%2Fspecial.html%23objecttracking>

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