stable_interprocess_container.hpp

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/*
Copyright (c) 2025 acrion innovations GmbH
Authors: Stefan Zipproth, s.zipproth@acrion.ch
 
This file is part of Cbeam, see https://github.com/acrion/cbeam and https://cbeam.org
 
Cbeam is offered under a commercial and under the AGPL license.
For commercial licensing, contact us at https://acrion.ch/sales. For AGPL licensing, see below.
 
AGPL licensing:
 
Cbeam is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
 
Cbeam is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
 
You should have received a copy of the GNU Affero General Public License
along with Cbeam. If not, see <https://www.gnu.org/licenses/>.
*/
 
#pragma once
 
#include <cbeam/container/buffer.hpp>                  // for cbeam::container::buffer
#include <cbeam/error/runtime_error.hpp>               // for cbeam::error:runtime_error
#include <cbeam/logging/log_manager.hpp>               // for CBEAM_LOG
#include <cbeam/memory/interprocess_shared_memory.hpp> // for cbeam::memory::interprocess_shared_memory
#include <cbeam/serialization/traits.hpp>              // for cbeam::serialization::traits, cbeam::serialization::serialized_object
 
#include <cstring>   // for memcpy, size_t, std::memcpy, std::size_t
#include <string>    // for std::allocator, std::operator+, std::string_literals::operator""s, std::char_traits, std::to_string, std::string, std::string_literals
 
namespace cbeam::container
{
    template <typename T>
    class stable_interprocess_container : public memory::interprocess_shared_memory
    {
    public:
        stable_interprocess_container(const std::string& unique_identifier, std::size_t size)
            : interprocess_shared_memory(unique_identifier, size)
        {
        }
 
        stable_interprocess_container(const stable_interprocess_container&)            = delete;
        stable_interprocess_container& operator=(const stable_interprocess_container&) = delete;
        stable_interprocess_container(stable_interprocess_container&&)                 = delete;
        stable_interprocess_container& operator=(stable_interprocess_container&&)      = delete;

        virtual void clear()
        {
            auto lock = get_lock_guard(); // Locks the mutex to ensure exclusive access
            serialize(T{});               // Resets the container by serializing an empty instance of T
        }

        virtual bool empty() const
        {
            auto lock = get_lock_guard(); // Locks the mutex for safe access
            return deserialize().empty(); // Deserializes the container and checks if it's empty
        }

        virtual size_t size() const
        {
            auto lock = get_lock_guard();
            return deserialize().size();
        }

        template <typename Func>
        void foreach (Func func)
        {
            T local_instance;
            {
                auto lock      = get_lock_guard();
                local_instance = deserialize();
            }
 
            for (const auto& item : local_instance)
            {
                if (!func(item))
                {
                    break;
                }
            }
        }
 
    protected:
        T deserialize() const
        {
            cbeam::serialization::serialized_object it = data();
 
            if (it)
            {
                T result;
                cbeam::serialization::traits<T>::deserialize(it, result);
                return result;
            }
            else
            {
                return {};
            }
        }

        void serialize(const T& container)
        {
            using namespace std::string_literals;
 
            container::buffer buffer;
            cbeam::serialization::traits<const T>::serialize(container, buffer);
 
            if (buffer.size() > capacity())
            {
                std::string errorMessage = "cbeam::stable_interprocess_container::serialize: size of serialized container ("s + std::to_string(buffer.size())
                                         + " bytes) exceeds shared memory size ("s + std::to_string(capacity()) + " bytes)."s;
                CBEAM_LOG(errorMessage);
                throw cbeam::error::runtime_error(errorMessage);
            }
            std::memcpy(data(), buffer.get(), buffer.size());
        }
    };
}