http://stackoverflow.com/questions/17240875/using-boost-flyweight-with-shared-memory

gistfile1.cpp

#include <boost/interprocess/managed_mapped_file.hpp>
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/string.hpp>
#include <boost/flyweight.hpp>
#include <boost/flyweight/no_tracking.hpp>
#include <boost/flyweight/hashed_factory.hpp>

using namespace boost::flyweights;
using namespace boost::container;
using namespace boost::interprocess;


typedef boost::interprocess::allocator<boost::mpl::_1, boost::interprocess::managed_mapped_file::segment_manager> ShmFactoryEntryAllocator;

typedef boost::interprocess::allocator<char, boost::interprocess::managed_mapped_file::segment_manager> ShmAllocatorChar;

typedef boost::interprocess::basic_string<char, std::char_traits<char>, ShmAllocatorChar> ShmString;


class MyShmAllocator : public ShmFactoryEntryAllocator {
public:
  static boost::interprocess::managed_mapped_file::segment_manager *segmentManager;

  MyShmAllocator()
    : ShmFactoryEntryAllocator(segmentManager) {
  }

};

boost::interprocess::managed_mapped_file::segment_manager *MyShmAllocator::segmentManager = NULL;


// TODO: using ShmFactoryEntryAllocator does not work
typedef boost::flyweights::hashed_factory<boost::hash<ShmString>, std::equal_to<ShmString>, MyShmAllocator> ShmStringHashedFactory;
//typedef boost::flyweights::hashed_factory<boost::hash<ShmString>, std::equal_to<ShmString>, ShmFactoryEntryAllocator> ShmStringHashedFactory;
//typedef boost::flyweights::hashed_factory<boost::hash<ShmString>, std::equal_to<ShmString>, std::allocator<boost::mpl::_1> > ShmStringHashedFactory;

// TODO: need to be able to use a hashed_factory with our custom allocator.
typedef boost::flyweights::flyweight<ShmString, ShmStringHashedFactory> ShmFlyweightString;
//typedef boost::flyweights::flyweight<ShmString> ShmFlyweightString;




int main(int argc, char** argv)
{
  managed_mapped_file *segment = new managed_mapped_file(create_only, "memory.dat", 409600);
  ShmFactoryEntryAllocator factoryEntryAllocator(segment->get_segment_manager());
  MyShmAllocator::segmentManager = segment->get_segment_manager();

  // create a normal string in shared-memory.
  ShmString *ps1 = segment->construct<ShmString>("s1")("some shm normal string", factoryEntryAllocator);

  // create a flyweight string in shared memory.
  ShmFlyweightString *ps2 = segment->construct<ShmFlyweightString>(anonymous_instance)("some shm flyweight string", factoryEntryAllocator);

  return 0;
}