text: //
  // detail/winrt_timer_scheduler.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #ifndef BOOST_ASIO_DETAIL_WINRT_TIMER_SCHEDULER_HPP
  #define BOOST_ASIO_DETAIL_WINRT_TIMER_SCHEDULER_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include <boost/asio/detail/config.hpp>
  
  #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
  
  #include <cstddef>
  #include <boost/asio/detail/event.hpp>
  #include <boost/asio/detail/limits.hpp>
  #include <boost/asio/detail/mutex.hpp>
  #include <boost/asio/detail/op_queue.hpp>
  #include <boost/asio/detail/thread.hpp>
  #include <boost/asio/detail/timer_queue_base.hpp>
  #include <boost/asio/detail/timer_queue_set.hpp>
  #include <boost/asio/detail/wait_op.hpp>
  #include <boost/asio/execution_context.hpp>
  
  #if defined(BOOST_ASIO_HAS_IOCP)
  # include <boost/asio/detail/win_iocp_io_context.hpp>
  #else // defined(BOOST_ASIO_HAS_IOCP)
  # include <boost/asio/detail/scheduler.hpp>
  #endif // defined(BOOST_ASIO_HAS_IOCP)
  
  #if defined(BOOST_ASIO_HAS_IOCP)
  # include <boost/asio/detail/thread.hpp>
  #endif // defined(BOOST_ASIO_HAS_IOCP)
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  class winrt_timer_scheduler
    : public execution_context_service_base<winrt_timer_scheduler>
  {
  public:
    // Constructor.
    BOOST_ASIO_DECL winrt_timer_scheduler(execution_context& context);
  
    // Destructor.
    BOOST_ASIO_DECL ~winrt_timer_scheduler();
  
    // Destroy all user-defined handler objects owned by the service.
    BOOST_ASIO_DECL void shutdown();
  
    // Recreate internal descriptors following a fork.
    BOOST_ASIO_DECL void notify_fork(execution_context::fork_event fork_ev);
  
    // Initialise the task. No effect as this class uses its own thread.
    BOOST_ASIO_DECL void init_task();
  
    // Add a new timer queue to the reactor.
    template <typename Time_Traits>
    void add_timer_queue(timer_queue<Time_Traits>& queue);
  
    // Remove a timer queue from the reactor.
    template <typename Time_Traits>
    void remove_timer_queue(timer_queue<Time_Traits>& queue);
  
    // Schedule a new operation in the given timer queue to expire at the
    // specified absolute time.
    template <typename Time_Traits>
    void schedule_timer(timer_queue<Time_Traits>& queue,
        const typename Time_Traits::time_type& time,
        typename timer_queue<Time_Traits>::per_timer_data& timer, wait_op* op);
  
    // Cancel the timer operations associated with the given token. Returns the
    // number of operations that have been posted or dispatched.
    template <typename Time_Traits>
    std::size_t cancel_timer(timer_queue<Time_Traits>& queue,
        typename timer_queue<Time_Traits>::per_timer_data& timer,
        std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
  
    // Move the timer operations associated with the given timer.
    template <typename Time_Traits>
    void move_timer(timer_queue<Time_Traits>& queue,
        typename timer_queue<Time_Traits>::per_timer_data& to,
        typename timer_queue<Time_Traits>::per_timer_data& from);
  
  private:
    // Run the select loop in the thread.
    BOOST_ASIO_DECL void run_thread();
  
    // Entry point for the select loop thread.
    BOOST_ASIO_DECL static void call_run_thread(winrt_timer_scheduler* reactor);
  
    // Helper function to add a new timer queue.
    BOOST_ASIO_DECL void do_add_timer_queue(timer_queue_base& queue);
  
    // Helper function to remove a timer queue.
    BOOST_ASIO_DECL void do_remove_timer_queue(timer_queue_base& queue);
  
    // The scheduler implementation used to post completions.
  #if defined(BOOST_ASIO_HAS_IOCP)
    typedef class win_iocp_io_context scheduler_impl;
  #else
    typedef class scheduler scheduler_impl;
  #endif
    scheduler_impl& scheduler_;
  
    // Mutex used to protect internal variables.
    boost::asio::detail::mutex mutex_;
  
    // Event used to wake up background thread.
    boost::asio::detail::event event_;
  
    // The timer queues.
    timer_queue_set timer_queues_;
  
    // The background thread that is waiting for timers to expire.
    boost::asio::detail::thread* thread_;
  
    // Does the background thread need to stop.
    bool stop_thread_;
  
    // Whether the service has been shut down.
    bool shutdown_;
  };
  
  } // namespace detail
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #include <boost/asio/detail/impl/winrt_timer_scheduler.hpp>
  #if defined(BOOST_ASIO_HEADER_ONLY)
  # include <boost/asio/detail/impl/winrt_timer_scheduler.ipp>
  #endif // defined(BOOST_ASIO_HEADER_ONLY)
  
  #endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
  
  #endif // BOOST_ASIO_DETAIL_WINRT_TIMER_SCHEDULER_HPP
  