nef_thread_pool/pub.hpp

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/*
 * SObjectizer-5
 */
 
/*!
 * \file
 * \brief Public interface of thread pool dispatcher that
 * provides noexcept guarantee for scheduling evt_finish demand.
 *
 * \since v.5.8.0
 */
 
#pragma once
 
#include <so_5/declspec.hpp>
 
#include <so_5/disp_binder.hpp>
 
#include <so_5/disp/mpmc_queue_traits/pub.hpp>
 
#include <so_5/disp/reuse/work_thread_activity_tracking.hpp>
#include <so_5/disp/reuse/work_thread_factory_params.hpp>
#include <so_5/disp/reuse/default_thread_pool_size.hpp>
 
#include <string_view>
#include <thread>
#include <utility>
 
namespace so_5
{
 
namespace disp
{
 
namespace nef_thread_pool
{
 
/*!
 * \brief Alias for namespace with traits of event queue.
 *
 * \since v.5.8.0
 */
namespace queue_traits = so_5::disp::mpmc_queue_traits;
 
//
// disp_params_t
//
/*!
 * \brief Parameters for %nef_thread_pool dispatcher.
 *
 * \since v.5.8.0
 */
class disp_params_t
  : public so_5::disp::reuse::work_thread_activity_tracking_flag_mixin_t< disp_params_t >
  , public so_5::disp::reuse::work_thread_factory_mixin_t< disp_params_t >
  {
    using activity_tracking_mixin_t = so_5::disp::reuse::
        work_thread_activity_tracking_flag_mixin_t< disp_params_t >;
    using thread_factory_mixin_t = so_5::disp::reuse::
        work_thread_factory_mixin_t< disp_params_t >;
 
  public :
    //! Default constructor.
    disp_params_t() = default;
 
    friend inline void
    swap(
      disp_params_t & a, disp_params_t & b ) noexcept
      {
        using std::swap;
 
        swap(
            static_cast< activity_tracking_mixin_t & >(a),
            static_cast< activity_tracking_mixin_t & >(b) );
 
        swap(
            static_cast< work_thread_factory_mixin_t & >(a),
            static_cast< work_thread_factory_mixin_t & >(b) );
 
        swap( a.m_thread_count, b.m_thread_count );
        swap( a.m_queue_params, b.m_queue_params );
      }
 
    //! Setter for thread count.
    disp_params_t &
    thread_count( std::size_t count )
      {
        m_thread_count = count;
        return *this;
      }
 
    //! Getter for thread count.
    std::size_t
    thread_count() const
      {
        return m_thread_count;
      }
 
    //! Setter for queue parameters.
    disp_params_t &
    set_queue_params( queue_traits::queue_params_t p )
      {
        m_queue_params = std::move(p);
        return *this;
      }
 
    //! Tuner for queue parameters.
    /*!
     * Accepts lambda-function or functional object which tunes
     * queue parameters.
      \code
      using namespace so_5::disp::nef_thread_pool;
      auto disp = make_dispatcher( env,
        "workers_disp",
        disp_params_t{}
          .thread_count( 10 )
          .tune_queue_params(
            []( queue_traits::queue_params_t & p ) {
              p.lock_factory( queue_traits::simple_lock_factory() );
            } ) );
      \endcode
     */
    template< typename L >
    disp_params_t &
    tune_queue_params( L tunner )
      {
        tunner( m_queue_params );
        return *this;
      }
 
    //! Getter for queue parameters.
    const queue_traits::queue_params_t &
    queue_params() const
      {
        return m_queue_params;
      }
 
  private :
    //! Count of working threads.
    /*!
     * Value 0 means that actual thread will be detected automatically.
     */
    std::size_t m_thread_count = { 0 };
    //! Queue parameters.
    queue_traits::queue_params_t m_queue_params;
  };
 
//
// bind_params_t
//
/*!
 * \brief Parameters for binding agents to %nef_thread_pool dispatcher.
 *
 * \since v.5.8.0
 */
class bind_params_t
  {
  public :
    //! Set maximum count of demands to be processed at once.
    bind_params_t &
    max_demands_at_once( std::size_t v )
      {
        m_max_demands_at_once = v;
        return *this;
      }
 
    //! Get maximum count of demands to do processed at once.
    [[nodiscard]]
    std::size_t
    query_max_demands_at_once() const
      {
        return m_max_demands_at_once;
      }
 
  private :
    //! Maximum count of demands to be processed at once.
    std::size_t m_max_demands_at_once = { 1 };
  };
 
//
// default_thread_pool_size
//
using so_5::disp::reuse::default_thread_pool_size;
 
namespace impl {
 
class actual_dispatcher_iface_t;
 
//
// basic_dispatcher_iface_t
//
/*!
 * \brief The very basic interface of %thread_pool dispatcher.
 *
 * This class contains a minimum that is necessary for implementation
 * of dispatcher_handle class.
 *
 * \since v.5.8.0
 */
class basic_dispatcher_iface_t
  : public std::enable_shared_from_this<actual_dispatcher_iface_t>
  {
  public :
    virtual ~basic_dispatcher_iface_t() noexcept = default;
 
    [[nodiscard]]
    virtual disp_binder_shptr_t
    binder( bind_params_t params ) = 0;
  };
 
using basic_dispatcher_iface_shptr_t =
    std::shared_ptr< basic_dispatcher_iface_t >;
 
class dispatcher_handle_maker_t;
 
} /* namespace impl */
 
//
// dispatcher_handle_t
//
 
/*!
 * \brief A handle for %nef_thread_pool dispatcher.
 *
 * \since v.5.8.0
 */
class [[nodiscard]] dispatcher_handle_t
  {
    friend class impl::dispatcher_handle_maker_t;
 
    //! A reference to actual implementation of a dispatcher.
    impl::basic_dispatcher_iface_shptr_t m_dispatcher;
 
    dispatcher_handle_t(
      impl::basic_dispatcher_iface_shptr_t dispatcher ) noexcept
      : m_dispatcher{ std::move(dispatcher) }
      {}
 
    //! Is this handle empty?
    bool
    empty() const noexcept { return !m_dispatcher; }
 
  public :
    dispatcher_handle_t() noexcept = default;
 
    //! Get a binder for that dispatcher.
    /*!
     * Usage example:
     * \code
     * using namespace so_5::disp::nef_thread_pool;
     *
     * so_5::environment_t & env = ...;
     * auto disp = make_dispatcher( env );
     * bind_params_t params;
     * params.max_demands_at_once( 10u );
     *
     * env.introduce_coop( [&]( so_5::coop_t & coop ) {
     *  coop.make_agent_with_binder< some_agent_type >(
     *    disp.binder( params ),
     *    ... );
     *
     *  coop.make_agent_with_binder< another_agent_type >(
     *    disp.binder( params ),
     *    ... );
     *
     *  ...
     * } );
     * \endcode
     *
     * \attention
     * An attempt to call this method on empty handle is UB.
     */
    [[nodiscard]]
    disp_binder_shptr_t
    binder(
      bind_params_t params ) const
      {
        return m_dispatcher->binder( params );
      }
 
    //! Create a binder for that dispatcher.
    /*!
     * This method allows parameters tuning via lambda-function
     * or other functional objects.
     *
     * Usage example:
     * \code
     * using namespace so_5::disp::nef_thread_pool;
     *
     * so_5::environment_t & env = ...;
     * env.introduce_coop( [&]( so_5::coop_t & coop ) {
     *  coop.make_agent_with_binder< some_agent_type >(
     *    // Create dispatcher instance.
     *    make_dispatcher( env )
     *      // Make and tune binder for that dispatcher.
     *      .binder( []( auto & params ) {
     *        params.max_demands_at_once( 10u );
     *      } ),
     *    ... );
     * \endcode
     *
     * \attention
     * An attempt to call this method on empty handle is UB.
     */
    template< typename Setter >
    [[nodiscard]]
    std::enable_if_t<
        std::is_invocable_v< Setter, bind_params_t& >,
        disp_binder_shptr_t >
    binder(
      //! Function for the parameters tuning.
      Setter && params_setter ) const
      {
        bind_params_t p;
        params_setter( p );
 
        return this->binder( p );
      }
 
    //! Get a binder for that dispatcher with default binding params.
    /*!
     * \attention
     * An attempt to call this method on empty handle is UB.
     */
    [[nodiscard]]
    disp_binder_shptr_t
    binder() const
      {
        return this->binder( bind_params_t{} );
      }
 
    //! Is this handle empty?
    operator bool() const noexcept { return empty(); }
 
    //! Does this handle contain a reference to dispatcher?
    bool
    operator!() const noexcept { return !empty(); }
 
    //! Drop the content of handle.
    void
    reset() noexcept { m_dispatcher.reset(); }
  };
 
//
// make_dispatcher
//
/*!
 * \brief Create an instance %nef_thread_pool dispatcher.
 *
 * \par Usage sample
\code
using namespace so_5::disp::nef_thread_pool;
auto disp = make_dispatcher(
  env,
  "db_workers_pool",
  disp_params_t{}
    .thread_count( 16 )
    .tune_queue_params( []( queue_traits::queue_params_t & params ) {
        params.lock_factory( queue_traits::simple_lock_factory() );
      } ) );
auto coop = env.make_coop(
  // The main dispatcher for that coop will be
  // this instance of nef_thread_pool dispatcher.
  disp.binder() );
\endcode
 *
 * \since v.5.8.0
 */
[[nodiscard]]
SO_5_FUNC dispatcher_handle_t
make_dispatcher(
  //! SObjectizer Environment to work in.
  environment_t & env,
  //! Value for creating names of data sources for
  //! run-time monitoring.
  const std::string_view data_sources_name_base,
  //! Parameters for the dispatcher.
  disp_params_t disp_params );
 
//
// make_dispatcher
//
/*!
 * \brief Create an instance of %nef_thread_pool dispatcher.
 *
 * \par Usage sample
\code
auto disp = so_5::disp::nef_thread_pool::make_dispatcher(
  env,
  "db_workers_pool",
  16 );
auto coop = env.make_coop(
  // The main dispatcher for that coop will be
  // this instance of nef_thread_pool dispatcher.
  disp.binder() );
\endcode
 *
 * \since v.5.8.0
 */
[[nodiscard]]
inline dispatcher_handle_t
make_dispatcher(
  //! SObjectizer Environment to work in.
  environment_t & env,
  //! Value for creating names of data sources for
  //! run-time monitoring.
  const std::string_view data_sources_name_base,
  //! Count of working threads.
  std::size_t thread_count )
  {
    return make_dispatcher(
        env,
        data_sources_name_base,
        disp_params_t{}.thread_count( thread_count ) );
  }
 
/*!
 * \brief Create an instance of %nef_thread_pool dispatcher.
 *
 * \par Usage sample
\code
auto disp = so_5::disp::nef_thread_pool::make_dispatcher( env, 16 );
 
auto coop = env.make_coop(
  // The main dispatcher for that coop will be
  // this instance of nef_thread_pool dispatcher.
  disp.binder() );
\endcode
 *
 * \since v.5.8.0
 */
[[nodiscard]]
inline dispatcher_handle_t
make_dispatcher(
  //! SObjectizer Environment to work in.
  environment_t & env,
  //! Count of working threads.
  std::size_t thread_count )
  {
    return make_dispatcher( env, std::string_view{}, thread_count );
  }
 
//
// make_dispatcher
//
/*!
 * \brief Create an instance of %nef_thread_pool dispatcher with the default
 * count of working threads.
 *
 * Count of work threads will be detected by default_thread_pool_size()
 * function.
 *
 * \par Usage sample
\code
auto disp = so_5::disp::nef_thread_pool::make_instance( env );
 
auto coop = env.make_coop(
  // The main dispatcher for that coop will be
  // this instance of nef_thread_pool dispatcher.
  disp.binder() );
\endcode
 *
 * \since v.5.8.0
 */
[[nodiscard]]
inline dispatcher_handle_t
make_dispatcher(
  //! SObjectizer Environment to work in.
  environment_t & env )
  {
    return make_dispatcher(
        env,
        std::string_view{},
        default_thread_pool_size() );
  }
 
} /* namespace nef_thread_pool */
 
} /* namespace disp */
 
} /* namespace so_5 */