Context.hpp

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/* Copyright 2021 Jan Stephan
 *
 * Licensed under the EUPL, Version 1.2 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the “Licence”).
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 *
 *     http://ec.europa.eu/idabc/eupl.html
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the Licence is distributed on an “AS IS” basis, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 *  Licence permissions and limitations under the Licence.
 */
 
#pragma once
 
#include <bactria/core/Activation.hpp>
#include <bactria/core/Plugin.hpp>
#include <bactria/metrics/Plugin.hpp>
#include <bactria/ranges/Plugin.hpp>
#include <bactria/reports/Plugin.hpp>
 
#include <utility>
 
namespace bactria
{
    class Context final
    {
    public:
        // The plugin handles are reference counted. Copying them around doesn't hurt.
 
        Context() = default;
 
        Context(Context const& other) noexcept = default;
 
        auto operator=(Context const& rhs) noexcept -> Context& = default;
 
        Context(Context&& other) noexcept
            : m_metricsHandle{std::exchange(other.m_metricsHandle, plugin_handle_t{})}
            , m_rangesHandle{std::exchange(other.m_rangesHandle, plugin_handle_t{})}
            , m_reportsHandle{std::exchange(other.m_reportsHandle, plugin_handle_t{})}
        {
        }
 
        auto operator=(Context&& rhs) noexcept -> Context&
        {
            m_metricsHandle = std::exchange(rhs.m_metricsHandle, plugin_handle_t{});
            m_rangesHandle = std::exchange(rhs.m_rangesHandle, plugin_handle_t{});
            m_reportsHandle = std::exchange(rhs.m_reportsHandle, plugin_handle_t{});
            return *this;
        }
 
        ~Context()
        {
            /* At first glance, this seems wrong. However, on all supported platforms the plugin handle is reference
             * counted (per process), so having multiple contexts loading / unloading the library is not a problem. */
            if(reports::plugin::activated())
                unload_plugin(m_reportsHandle);
 
            if(ranges::plugin::activated())
                unload_plugin(m_rangesHandle);
 
            if(metrics::plugin::activated())
                unload_plugin(m_metricsHandle);
        }
 
    private:
        plugin_handle_t m_metricsHandle{metrics::plugin::activated() ? metrics::plugin::load() : plugin_handle_t{}};
        plugin_handle_t m_rangesHandle{ranges::plugin::activated() ? ranges::plugin::load() : plugin_handle_t{}};
        plugin_handle_t m_reportsHandle{reports::plugin::activated() ? reports::plugin::load() : plugin_handle_t{}};
    };
 
} // namespace bactria