Re: [Boost-users] boost::serialization - serializing boost::smart_ptrs won't work

From: Sascha Friedmann (sascha.friedmann_at_[hidden])
Date: 2006-08-09 19:16:17

I have now another problem, too. When I am loading a map that contains a 
  shared_ptr I have memory leaks, because the use_count is wrong. In my 
real project I have a use_count of 5, but I can get it down to 2, when I 
am using new to create the object, that has the map.

I've written a small example, that is basically the same as my real 
project, but it has also a use_count of 2 after loading the map in:

> #include <boost/archive/text_oarchive.hpp>
> #include <boost/archive/text_iarchive.hpp>
> 
> #include <boost/serialization/serialization.hpp>
> #include <boost/serialization/map.hpp>
> #include <boost/serialization/shared_ptr.hpp>
> 
> #include <boost/serialization/export.hpp>
> 
> #include <fstream>
> 
> struct ATest
> {
> 	int i;
> 	ATest()
> 	 : i( 1 )
> 	{
> 	}
> 	virtual ~ATest(){}
> 
> 	template< class Archive >
> 	void serialize( Archive& ar, const unsigned )
> 	{
> 		ar & i;
> 	}
> };
> BOOST_CLASS_EXPORT( ATest )
> 
> struct BTest : ATest
> {
> 	int c;
> 	BTest()
> 	 : c( 2 )
> 	{
> 	}
> 
> 	template< class Archive >
> 	void serialize( Archive& ar, const unsigned )
> 	{
> 		ar & boost::serialization::base_object< ATest >( *this );
> 		ar & c;
> 	}
> 	
> };
> BOOST_CLASS_EXPORT( BTest )
> 
> 
> typedef std::map< int, boost::shared_ptr< ATest > > MyMap;
> 
> 
> BOOST_CLASS_TRACKING( MyMap, boost::serialization::track_never)
> 
> int main()
> {
> 	MyMap myMap;
> 	myMap[ 0 ] = boost::shared_ptr< ATest >( new BTest );
> 	myMap[ 1 ] = boost::shared_ptr< ATest >( new BTest );
> 
> 	std::ofstream ofs( "map.txt" );
> 	boost::archive::text_oarchive oar( ofs );
> 
> 	oar << myMap;
> 
> 	ofs.close();
> 
> 	std::ifstream ifs( "map.txt" );
> 	boost::archive::text_iarchive iar( ifs );
> 
> 	MyMap myMap1;
> 
> 	iar >> myMap1;
> }

Maybe you can tell me what I am doing wrong :-)

Sascha Friedmann