60 lines
1.7 KiB
C++
60 lines
1.7 KiB
C++
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#pragma once
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#include <fc/interprocess/file_mapping.hpp>
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#include <memory>
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namespace fc
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{
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class path;
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namespace detail
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{
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/**
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* Base class used to hide common implementation details.
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*/
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class mmap_struct_base
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{
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public:
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size_t size()const { return _mapped_region->get_size(); }
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void flush() { _mapped_region->flush(); }
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protected:
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void open( const fc::path& file, size_t s, bool create );
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std::unique_ptr<fc::file_mapping> _file_mapping;
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std::unique_ptr<fc::mapped_region> _mapped_region;
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};
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};
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/**
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* @class mmap_struct
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* @brief A struct that has been mapped from a file.
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*
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* @note T must be POD
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*/
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template<typename T>
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class mmap_struct : public detail::mmap_struct_base
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{
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public:
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mmap_struct():_mapped_struct(nullptr){}
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/**
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* Create the file if it does not exist or is of the wrong size if create is true, then maps
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* the file to memory.
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*
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* @throw an exception if the file does not exist or is the wrong size and create is false
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*/
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void open( const fc::path& file, bool create = false )
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{
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detail::mmap_struct_base::open( file, sizeof(T), create );
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_mapped_struct = (T*)_mapped_region->get_address();
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}
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T* operator->() { return _mapped_struct; }
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const T* operator->()const { return _mapped_struct; }
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T& operator*() { return *_mapped_struct; }
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const T& operator*()const { return *_mapped_struct; }
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private:
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T* _mapped_struct;
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};
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}
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