USharedMemoryObject.hpp

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// @formatter:off
//
// Balau core C++ library
//
// Copyright (C) 2017 Bora Software (contact@borasoftware.com)
//
// Licensed under the Boost Software License - Version 1.0 - August 17th, 2003.
// See the LICENSE file for the full license text.
//


#ifndef COM_BORA_SOFTWARE__BALAU_INTERPROCESS__UNMANAGED_SHARED_MEMORY_OBJECT2
#define COM_BORA_SOFTWARE__BALAU_INTERPROCESS__UNMANAGED_SHARED_MEMORY_OBJECT2

#include <Balau/Exception/ResourceExceptions.hpp>
#include <Balau/Interprocess/SharedMemoryUtils.hpp>
#include <Balau/Dev/Assert.hpp>
#include <Balau/Type/UUID.hpp>

#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/shared_memory_object.hpp>

namespace Balau::Interprocess {

template <typename T> class USharedMemoryObject {
    public: template <typename ... P> explicit USharedMemoryObject(const P & ... params)
        : USharedMemoryObject(CreateOnly, "SMO_" + UUID().asString(), params ...) {}

    public: template <typename ... P>
    USharedMemoryObject(boost::interprocess::create_only_t, std::string name_, const P & ... params)
        : name(std::move(name_)) {
        boost::interprocess::shared_memory_object::remove(name.c_str());

        sharedMemoryObject = boost::interprocess::shared_memory_object(
            CreateOnly, name.c_str(), boost::interprocess::read_write
        );

        sharedMemoryObject.truncate(sizeof(T));
        mappedRegion = boost::interprocess::mapped_region(sharedMemoryObject, boost::interprocess::read_write);
        object = new (mappedRegion.get_address()) T(params ...);
    }

    public: template <typename ... P>
    USharedMemoryObject(boost::interprocess::open_or_create_t, std::string name_, const P & ... params)
        : name(std::move(name_)) {
        boost::interprocess::shared_memory_object::remove(name.c_str());

        boost::interprocess::shared_memory_object shm_obj(
            boost::interprocess::open_or_create, name.c_str(), boost::interprocess::read_write
        );

        boost::interprocess::offset_t size;

        if (shm_obj.get_size(size)) {
            shm_obj.truncate(sizeof(T));
            boost::interprocess::mapped_region region(shm_obj, boost::interprocess::read_write);
            object = new (region.get_address()) T(params ...);
        } else {
            remap();
        }
    }

    public: USharedMemoryObject(boost::interprocess::open_only_t, std::string name_)
        : name(std::move(name_)) {
        boost::interprocess::shared_memory_object sharedMemoryObject(
            boost::interprocess::open_only, name.c_str(), boost::interprocess::read_write
        );

        remap();
    }

    public: USharedMemoryObject(boost::interprocess::open_read_only_t, std::string name_)
        : name(std::move(name_)) {
        boost::interprocess::shared_memory_object shm_obj(
            boost::interprocess::open_only, name.c_str(), boost::interprocess::read_only
        );

        remap();
    }

    public: USharedMemoryObject(USharedMemoryObject && rhs) noexcept
        : name(std::move(rhs.name))
        , sharedMemoryObject(std::move(rhs.sharedMemoryObject))
        , mappedRegion(std::move(rhs.mappedRegion))
        , object(rhs.object) {
        rhs.object = nullptr;
    }

    public: ~USharedMemoryObject() {
        boost::interprocess::shared_memory_object::remove(name.c_str());
    }

    public: USharedMemoryObject & operator = (USharedMemoryObject && rhs) noexcept {
        name = std::move(rhs.name);
        sharedMemoryObject = std::move(rhs.sharedMemoryObject);
        mappedRegion = std::move(rhs.mappedRegion);
        object = rhs.object;
        rhs.object = nullptr;
        return *this;
    }

    public: void remap() {
        mappedRegion = boost::interprocess::mapped_region(sharedMemoryObject, boost::interprocess::read_write);
        object = (T *) mappedRegion.get_address();
    }

    public: T * operator -> () {
        Assert::assertion(object != nullptr, "Attempt to dereference null object in shared memory object.");
        return object;
    }

    public: const T * operator -> () const {
        Assert::assertion(object != nullptr, "Attempt to dereference null object in shared memory object.");
        return object;
    }

    public: T & operator * () {
        Assert::assertion(object != nullptr, "Attempt to dereference null object in shared memory object.");
        return *object;
    }

    public: const T & operator * () const {
        Assert::assertion(object != nullptr, "Attempt to dereference null object in shared memory object.");
        return *object;
    }


    private: std::string name;
    private: boost::interprocess::shared_memory_object sharedMemoryObject;
    private: boost::interprocess::mapped_region mappedRegion;
    protected: T * object = nullptr;
};

} // namespace Balau::Interprocess

#endif // COM_BORA_SOFTWARE__BALAU_INTERPROCESS__UNMANAGED_SHARED_MEMORY_OBJECT2