mmap_struct.hpp

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#pragma once
#include <fc/interprocess/file_mapping.hpp>
#include <memory>
 
namespace fc
{
   class path;
   namespace detail
   {
       class mmap_struct_base
       {
          public:
            size_t size()const;
            void flush();
 
          protected:
            void open( const fc::path& file, size_t s, bool create );
            std::unique_ptr<fc::file_mapping>  _file_mapping;
            std::unique_ptr<fc::mapped_region> _mapped_region;
       };
   };
 
   template<typename T>
   class mmap_struct : public detail::mmap_struct_base
   {
      public:
        mmap_struct():_mapped_struct(nullptr){}
        void open( const fc::path& file, bool create = false )
        {
            detail::mmap_struct_base::open( file, sizeof(T), create ); 
            _mapped_struct = (T*)_mapped_region->get_address();
        }
 
        T*       operator->()      { return _mapped_struct; }
        const T* operator->()const { return _mapped_struct; }
 
        T&       operator*()       { return *_mapped_struct; }
        const T& operator*()const  { return *_mapped_struct; }
 
      private:
        T*                                 _mapped_struct;
   };
 
}