text: //
  // detail/dev_poll_reactor.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2012 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_DEV_POLL_REACTOR_HPP
  #define BOOST_ASIO_DETAIL_DEV_POLL_REACTOR_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_HAS_DEV_POLL)
  
  #include <boost/limits.hpp>
  #include <cstddef>
  #include <vector>
  #include <sys/devpoll.h>
  #include <boost/asio/detail/dev_poll_reactor_fwd.hpp>
  #include <boost/asio/detail/hash_map.hpp>
  #include <boost/asio/detail/mutex.hpp>
  #include <boost/asio/detail/op_queue.hpp>
  #include <boost/asio/detail/reactor_op.hpp>
  #include <boost/asio/detail/reactor_op_queue.hpp>
  #include <boost/asio/detail/select_interrupter.hpp>
  #include <boost/asio/detail/socket_types.hpp>
  #include <boost/asio/detail/timer_queue_base.hpp>
  #include <boost/asio/detail/timer_queue_fwd.hpp>
  #include <boost/asio/detail/timer_queue_set.hpp>
  #include <boost/asio/detail/wait_op.hpp>
  #include <boost/asio/io_service.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  class dev_poll_reactor
    : public boost::asio::detail::service_base<dev_poll_reactor>
  {
  public:
    enum op_types { read_op = 0, write_op = 1,
      connect_op = 1, except_op = 2, max_ops = 3 };
  
    // Per-descriptor data.
    struct per_descriptor_data
    {
    };
  
    // Constructor.
    BOOST_ASIO_DECL dev_poll_reactor(boost::asio::io_service& io_service);
  
    // Destructor.
    BOOST_ASIO_DECL ~dev_poll_reactor();
  
    // Destroy all user-defined handler objects owned by the service.
    BOOST_ASIO_DECL void shutdown_service();
  
    // Recreate internal descriptors following a fork.
    BOOST_ASIO_DECL void fork_service(
        boost::asio::io_service::fork_event fork_ev);
  
    // Initialise the task.
    BOOST_ASIO_DECL void init_task();
  
    // Register a socket with the reactor. Returns 0 on success, system error
    // code on failure.
    BOOST_ASIO_DECL int register_descriptor(socket_type, per_descriptor_data&);
  
    // Register a descriptor with an associated single operation. Returns 0 on
    // success, system error code on failure.
    BOOST_ASIO_DECL int register_internal_descriptor(
        int op_type, socket_type descriptor,
        per_descriptor_data& descriptor_data, reactor_op* op);
  
    // Move descriptor registration from one descriptor_data object to another.
    BOOST_ASIO_DECL void move_descriptor(socket_type descriptor,
        per_descriptor_data& target_descriptor_data,
        per_descriptor_data& source_descriptor_data);
  
    // Post a reactor operation for immediate completion.
    void post_immediate_completion(reactor_op* op)
    {
      io_service_.post_immediate_completion(op);
    }
  
    // Start a new operation. The reactor operation will be performed when the
    // given descriptor is flagged as ready, or an error has occurred.
    BOOST_ASIO_DECL void start_op(int op_type, socket_type descriptor,
        per_descriptor_data&, reactor_op* op, bool allow_speculative);
  
    // Cancel all operations associated with the given descriptor. The
    // handlers associated with the descriptor will be invoked with the
    // operation_aborted error.
    BOOST_ASIO_DECL void cancel_ops(socket_type descriptor, per_descriptor_data&);
  
    // Cancel any operations that are running against the descriptor and remove
    // its registration from the reactor.
    BOOST_ASIO_DECL void deregister_descriptor(socket_type descriptor,
        per_descriptor_data&, bool closing);
  
    // Cancel any operations that are running against the descriptor and remove
    // its registration from the reactor.
    BOOST_ASIO_DECL void deregister_internal_descriptor(
        socket_type descriptor, per_descriptor_data&);
  
    // 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)());
  
    // Run /dev/poll once until interrupted or events are ready to be dispatched.
    BOOST_ASIO_DECL void run(bool block, op_queue<operation>& ops);
  
    // Interrupt the select loop.
    BOOST_ASIO_DECL void interrupt();
  
  private:
    // Create the /dev/poll file descriptor. Throws an exception if the descriptor
    // cannot be created.
    BOOST_ASIO_DECL static int do_dev_poll_create();
  
    // 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);
  
    // Get the timeout value for the /dev/poll DP_POLL operation. The timeout
    // value is returned as a number of milliseconds. A return value of -1
    // indicates that the poll should block indefinitely.
    BOOST_ASIO_DECL int get_timeout();
  
    // Cancel all operations associated with the given descriptor. The do_cancel
    // function of the handler objects will be invoked. This function does not
    // acquire the dev_poll_reactor's mutex.
    BOOST_ASIO_DECL void cancel_ops_unlocked(socket_type descriptor,
        const boost::system::error_code& ec);
  
    // Helper class used to reregister descriptors after a fork.
    class fork_helper;
    friend class fork_helper;
  
    // Add a pending event entry for the given descriptor.
    BOOST_ASIO_DECL ::pollfd& add_pending_event_change(int descriptor);
  
    // The io_service implementation used to post completions.
    io_service_impl& io_service_;
  
    // Mutex to protect access to internal data.
    boost::asio::detail::mutex mutex_;
  
    // The /dev/poll file descriptor.
    int dev_poll_fd_;
  
    // Vector of /dev/poll events waiting to be written to the descriptor.
    std::vector< ::pollfd> pending_event_changes_;
  
    // Hash map to associate a descriptor with a pending event change index.
    hash_map<int, std::size_t> pending_event_change_index_;
  
    // The interrupter is used to break a blocking DP_POLL operation.
    select_interrupter interrupter_;
  
    // The queues of read, write and except operations.
    reactor_op_queue<socket_type> op_queue_[max_ops];
  
    // The timer queues.
    timer_queue_set timer_queues_;
  
    // 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/dev_poll_reactor.hpp>
  #if defined(BOOST_ASIO_HEADER_ONLY)
  # include <boost/asio/detail/impl/dev_poll_reactor.ipp>
  #endif // defined(BOOST_ASIO_HEADER_ONLY)
  
  #endif // defined(BOOST_ASIO_HAS_DEV_POLL)
  
  #endif // BOOST_ASIO_DETAIL_DEV_POLL_REACTOR_HPP
  