fixed_size.hpp

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/*!
 * \file
 * \brief Implementation of fixed-size mchain.
 *
 * \since
 * v.1.4.0
 */

#pragma once

#include <so_5/impl/mchain_details.hpp>
#include <so_5/impl/make_mchain.hpp>
#include <so_5/impl/internal_env_iface.hpp>

#include <array>

namespace so_5
{

namespace extra
{

namespace mchains
{

namespace fixed_size
{

namespace details
{

//
// demand_queue_t
//
/*!
 * \brief Implementation of demands queue for fixed-size message chain with
 * "static" storage.
 *
 * \since
 * v.1.4.0
 */
template< std::size_t Size >
class demand_queue_t
    {
    public :
        // NOTE: constructor of this format is necessary
        // because the standard implementation of mchain from SO-5
        // requires it.
        demand_queue_t( so_5::mchain_props::capacity_t /*capacity*/ ) {}

        //! Is queue full?
        [[nodiscard]] bool
        is_full() const { return Size == m_size; }

        //! Is queue empty?
        [[nodiscard]] bool
        is_empty() const { return 0u == m_size; }

        //! Access to front item of the queue.
        [[nodiscard]] so_5::mchain_props::demand_t &
        front()
            {
                so_5::mchain_props::details::ensure_queue_not_empty( *this );
                return m_storage[ m_head ];
            }

        //! Remove the front item from queue.
        void
        pop_front()
            {
                so_5::mchain_props::details::ensure_queue_not_empty( *this );
                m_storage[ m_head ] = so_5::mchain_props::demand_t{};
                m_head = (m_head + 1u) % Size;
                --m_size;
            }

        //! Add a new item to the end of the queue.
        void
        push_back( so_5::mchain_props::demand_t && demand )
            {
                so_5::mchain_props::details::ensure_queue_not_full( *this );
                auto index = (m_head + m_size) % Size;
                m_storage[ index ] = std::move(demand);
                ++m_size;
            }

        //! Size of the queue.
        std::size_t
        size() const { return m_size; }

    private :
        //! Queue's storage.
        std::array< so_5::mchain_props::demand_t, Size > m_storage;

        //! Index of the queue head.
        std::size_t m_head{ 0u };
        //! The current size of the queue.
        std::size_t m_size{ 0u };
    };

} /* namespace details */

//
// create_mchain
//
/*!
 * \brief Helper function for creation of fixed-size mchain.
 *
 * Creates a mchain without waiting on attempt to push a new message
 * into full mchain.
 *
 * Usage example:
 * \code
    so_5::wrapped_env_t sobj;

    auto reply_ch = so_5::extra::mchains::fixed_size::create_mchain<1>(
            sobj.environment(),
            so_5::mchain_props::overflow_reaction_t::drop_newest);
 * \endcode
 *
 * \brief
 * v.1.4.0
 */
template< std::size_t Size >
[[nodiscard]] mchain_t
create_mchain(
    environment_t & env,
    so_5::mchain_props::overflow_reaction_t overflow_reaction )
    {
        so_5::impl::internal_env_iface_t env_iface{ env };

        return so_5::impl::make_mchain< details::demand_queue_t<Size> >(
                outliving_mutable( env_iface.msg_tracing_stuff_nonchecked() ),
                make_limited_without_waiting_mchain_params(
                        // NOTE: this value won't be used.
                        Size,
                        // NOTE: this value won't be used.
                        so_5::mchain_props::memory_usage_t::preallocated,
                        overflow_reaction ),
                env,
                env_iface.allocate_mbox_id() );
    }

//
// create_mchain
//
/*!
 * \brief Helper function for creation of fixed-size mchain.
 *
 * Creates a mchain with waiting on attempt to push a new message
 * into full mchain.
 *
 * Usage example:
 * \code
    so_5::wrapped_env_t sobj;

    auto reply_ch = so_5::extra::mchains::fixed_size::create_mchain<5>(
            sobj.environment(),
            std::chrono::milliseconds{250},
            so_5::mchain_props::overflow_reaction_t::remove_oldest);
 * \endcode
 *
 * \brief
 * v.1.4.0
 */
template< std::size_t Size >
[[nodiscard]] mchain_t
create_mchain(
    environment_t & env,
    so_5::mchain_props::duration_t wait_timeout,
    so_5::mchain_props::overflow_reaction_t overflow_reaction )
    {
        so_5::impl::internal_env_iface_t env_iface{ env };

        return so_5::impl::make_mchain< details::demand_queue_t<Size> >(
                outliving_mutable( env_iface.msg_tracing_stuff_nonchecked() ),
                make_limited_with_waiting_mchain_params(
                        // NOTE: this value won't be used.
                        Size,
                        // NOTE: this value won't be used.
                        so_5::mchain_props::memory_usage_t::preallocated,
                        overflow_reaction,
                        wait_timeout ),
                env,
                env_iface.allocate_mbox_id() );
    }

//
// create_mchain
//
/*!
 * \brief Helper function for creation of fixed-size mchain.
 *
 * Usage example:
 * \code
    so_5::wrapped_env_t sobj;

    auto params = so_5::make_limited_with_waiting_mchain_params(
            1, // Will be ignored.
            so_5::mchain_props::memory_usage_t::preallocated, // Will be ignored.
            so_5::mchain_props::overflow_reaction_t::throw_exception,
            std::chrono::seconds{3});
    params.disable_msg_tracing();
    params.not_empty_notificator([]{...});
            
    auto reply_ch = so_5::extra::mchains::fixed_size::create_mchain<20>(
            sobj.environment(),
            params);
 * \endcode
 *
 * \attention
 * Value of params.capacity() will be ignored.
 *
 * \brief
 * v.1.4.0
 */
template< std::size_t Size >
[[nodiscard]] mchain_t
create_mchain(
    environment_t & env,
    const so_5::mchain_params_t & params )
    {
        so_5::impl::internal_env_iface_t env_iface{ env };

        return so_5::impl::make_mchain< details::demand_queue_t<Size> >(
                outliving_mutable( env_iface.msg_tracing_stuff_nonchecked() ),
                // NOTE: some of params's value won't be used.
                params,
                env,
                env_iface.allocate_mbox_id() );
    }

} /* namespace fixed_size */

} /* namespace mchains */

} /* namespace extra */

} /* namespace so_5 */