text: //
  // detail/win_iocp_socket_service_base.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2010 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_WIN_IOCP_SOCKET_SERVICE_BASE_HPP
  #define BOOST_ASIO_DETAIL_WIN_IOCP_SOCKET_SERVICE_BASE_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_IOCP)
  
  #include <boost/type_traits/is_same.hpp>
  #include <boost/utility/addressof.hpp>
  #include <boost/asio/error.hpp>
  #include <boost/asio/io_service.hpp>
  #include <boost/asio/socket_base.hpp>
  #include <boost/asio/detail/bind_handler.hpp>
  #include <boost/asio/detail/buffer_sequence_adapter.hpp>
  #include <boost/asio/detail/fenced_block.hpp>
  #include <boost/asio/detail/handler_alloc_helpers.hpp>
  #include <boost/asio/detail/handler_invoke_helpers.hpp>
  #include <boost/asio/detail/mutex.hpp>
  #include <boost/asio/detail/operation.hpp>
  #include <boost/asio/detail/reactor.hpp>
  #include <boost/asio/detail/reactor_op.hpp>
  #include <boost/asio/detail/socket_holder.hpp>
  #include <boost/asio/detail/socket_ops.hpp>
  #include <boost/asio/detail/socket_types.hpp>
  #include <boost/asio/detail/win_iocp_io_service.hpp>
  #include <boost/asio/detail/win_iocp_null_buffers_op.hpp>
  #include <boost/asio/detail/win_iocp_socket_send_op.hpp>
  #include <boost/asio/detail/win_iocp_socket_recv_op.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  class win_iocp_socket_service_base
  {
  public:
    // The implementation type of the socket.
    struct base_implementation_type
    {
      // The native socket representation.
      socket_type socket_;
  
      // The current state of the socket.
      socket_ops::state_type state_;
  
      // We use a shared pointer as a cancellation token here to work around the
      // broken Windows support for cancellation. MSDN says that when you call
      // closesocket any outstanding WSARecv or WSASend operations will complete
      // with the error ERROR_OPERATION_ABORTED. In practice they complete with
      // ERROR_NETNAME_DELETED, which means you can't tell the difference between
      // a local cancellation and the socket being hard-closed by the peer.
      socket_ops::shared_cancel_token_type cancel_token_;
  
      // Per-descriptor data used by the reactor.
      reactor::per_descriptor_data reactor_data_;
  
  #if defined(BOOST_ASIO_ENABLE_CANCELIO)
      // The ID of the thread from which it is safe to cancel asynchronous
      // operations. 0 means no asynchronous operations have been started yet.
      // ~0 means asynchronous operations have been started from more than one
      // thread, and cancellation is not supported for the socket.
      DWORD safe_cancellation_thread_id_;
  #endif // defined(BOOST_ASIO_ENABLE_CANCELIO)
  
      // Pointers to adjacent socket implementations in linked list.
      base_implementation_type* next_;
      base_implementation_type* prev_;
    };
  
    // Constructor.
    BOOST_ASIO_DECL win_iocp_socket_service_base(
        boost::asio::io_service& io_service);
  
    // Destroy all user-defined handler objects owned by the service.
    BOOST_ASIO_DECL void shutdown_service();
  
    // Construct a new socket implementation.
    BOOST_ASIO_DECL void construct(base_implementation_type& impl);
  
    // Destroy a socket implementation.
    BOOST_ASIO_DECL void destroy(base_implementation_type& impl);
  
    // Determine whether the socket is open.
    bool is_open(const base_implementation_type& impl) const
    {
      return impl.socket_ != invalid_socket;
    }
  
    // Destroy a socket implementation.
    BOOST_ASIO_DECL boost::system::error_code close(
        base_implementation_type& impl, boost::system::error_code& ec);
  
    // Cancel all operations associated with the socket.
    BOOST_ASIO_DECL boost::system::error_code cancel(
        base_implementation_type& impl, boost::system::error_code& ec);
  
    // Determine whether the socket is at the out-of-band data mark.
    bool at_mark(const base_implementation_type& impl,
        boost::system::error_code& ec) const
    {
      return socket_ops::sockatmark(impl.socket_, ec);
    }
  
    // Determine the number of bytes available for reading.
    std::size_t available(const base_implementation_type& impl,
        boost::system::error_code& ec) const
    {
      return socket_ops::available(impl.socket_, ec);
    }
  
    // Place the socket into the state where it will listen for new connections.
    boost::system::error_code listen(base_implementation_type& impl,
        int backlog, boost::system::error_code& ec)
    {
      socket_ops::listen(impl.socket_, backlog, ec);
      return ec;
    }
  
    // Perform an IO control command on the socket.
    template <typename IO_Control_Command>
    boost::system::error_code io_control(base_implementation_type& impl,
        IO_Control_Command& command, boost::system::error_code& ec)
    {
      socket_ops::ioctl(impl.socket_, impl.state_, command.name(),
          static_cast<ioctl_arg_type*>(command.data()), ec);
      return ec;
    }
  
    /// Disable sends or receives on the socket.
    boost::system::error_code shutdown(base_implementation_type& impl,
        socket_base::shutdown_type what, boost::system::error_code& ec)
    {
      socket_ops::shutdown(impl.socket_, what, ec);
      return ec;
    }
  
    // Send the given data to the peer. Returns the number of bytes sent.
    template <typename ConstBufferSequence>
    size_t send(base_implementation_type& impl,
        const ConstBufferSequence& buffers,
        socket_base::message_flags flags, boost::system::error_code& ec)
    {
      buffer_sequence_adapter<boost::asio::const_buffer,
          ConstBufferSequence> bufs(buffers);
  
      return socket_ops::sync_send(impl.socket_, impl.state_,
          bufs.buffers(), bufs.count(), flags, bufs.all_empty(), ec);
    }
  
    // Wait until data can be sent without blocking.
    size_t send(base_implementation_type& impl, const null_buffers&,
        socket_base::message_flags, boost::system::error_code& ec)
    {
      // Wait for socket to become ready.
      socket_ops::poll_write(impl.socket_, ec);
  
      return 0;
    }
  
    // Start an asynchronous send. The data being sent must be valid for the
    // lifetime of the asynchronous operation.
    template <typename ConstBufferSequence, typename Handler>
    void async_send(base_implementation_type& impl,
        const ConstBufferSequence& buffers,
        socket_base::message_flags flags, Handler handler)
    {
      // Allocate and construct an operation to wrap the handler.
      typedef win_iocp_socket_send_op<ConstBufferSequence, Handler> op;
      typename op::ptr p = { boost::addressof(handler),
        boost_asio_handler_alloc_helpers::allocate(
          sizeof(op), handler), 0 };
      p.p = new (p.v) op(impl.cancel_token_, buffers, handler);
  
      buffer_sequence_adapter<boost::asio::const_buffer,
          ConstBufferSequence> bufs(buffers);
  
      start_send_op(impl, bufs.buffers(), bufs.count(), flags,
          (impl.state_ & socket_ops::stream_oriented) != 0 && bufs.all_empty(),
          p.p);
      p.v = p.p = 0;
    }
  
    // Start an asynchronous wait until data can be sent without blocking.
    template <typename Handler>
    void async_send(base_implementation_type& impl, const null_buffers&,
        socket_base::message_flags, Handler handler)
    {
      // Allocate and construct an operation to wrap the handler.
      typedef win_iocp_null_buffers_op<Handler> op;
      typename op::ptr p = { boost::addressof(handler),
        boost_asio_handler_alloc_helpers::allocate(
          sizeof(op), handler), 0 };
      p.p = new (p.v) op(impl.cancel_token_, handler);
  
      start_reactor_op(impl, reactor::write_op, p.p);
      p.v = p.p = 0;
    }
  
    // Receive some data from the peer. Returns the number of bytes received.
    template <typename MutableBufferSequence>
    size_t receive(base_implementation_type& impl,
        const MutableBufferSequence& buffers,
        socket_base::message_flags flags, boost::system::error_code& ec)
    {
      buffer_sequence_adapter<boost::asio::mutable_buffer,
          MutableBufferSequence> bufs(buffers);
  
      return socket_ops::sync_recv(impl.socket_, impl.state_,
          bufs.buffers(), bufs.count(), flags, bufs.all_empty(), ec);
    }
  
    // Wait until data can be received without blocking.
    size_t receive(base_implementation_type& impl, const null_buffers&,
        socket_base::message_flags, boost::system::error_code& ec)
    {
      // Wait for socket to become ready.
      socket_ops::poll_read(impl.socket_, ec);
  
      return 0;
    }
  
    // Start an asynchronous receive. The buffer for the data being received
    // must be valid for the lifetime of the asynchronous operation.
    template <typename MutableBufferSequence, typename Handler>
    void async_receive(base_implementation_type& impl,
        const MutableBufferSequence& buffers,
        socket_base::message_flags flags, Handler handler)
    {
      // Allocate and construct an operation to wrap the handler.
      typedef win_iocp_socket_recv_op<MutableBufferSequence, Handler> op;
      typename op::ptr p = { boost::addressof(handler),
        boost_asio_handler_alloc_helpers::allocate(
          sizeof(op), handler), 0 };
      p.p = new (p.v) op(impl.state_, impl.cancel_token_, buffers, handler);
  
      buffer_sequence_adapter<boost::asio::mutable_buffer,
          MutableBufferSequence> bufs(buffers);
  
      start_receive_op(impl, bufs.buffers(), bufs.count(), flags,
          (impl.state_ & socket_ops::stream_oriented) != 0 && bufs.all_empty(),
          p.p);
      p.v = p.p = 0;
    }
  
    // Wait until data can be received without blocking.
    template <typename Handler>
    void async_receive(base_implementation_type& impl, const null_buffers&,
        socket_base::message_flags flags, Handler handler)
    {
      // Allocate and construct an operation to wrap the handler.
      typedef win_iocp_null_buffers_op<Handler> op;
      typename op::ptr p = { boost::addressof(handler),
        boost_asio_handler_alloc_helpers::allocate(
          sizeof(op), handler), 0 };
      p.p = new (p.v) op(impl.cancel_token_, handler);
  
      start_null_buffers_receive_op(impl, flags, p.p);
      p.v = p.p = 0;
    }
  
    // Helper function to restart an asynchronous accept operation.
    BOOST_ASIO_DECL void restart_accept_op(socket_type s,
        socket_holder& new_socket, int family, int type, int protocol,
        void* output_buffer, DWORD address_length, operation* op);
  
  protected:
    // Open a new socket implementation.
    BOOST_ASIO_DECL boost::system::error_code do_open(
        base_implementation_type& impl, int family, int type,
        int protocol, boost::system::error_code& ec);
  
    // Assign a native socket to a socket implementation.
    BOOST_ASIO_DECL boost::system::error_code do_assign(
        base_implementation_type& impl, int type,
        socket_type native_socket, boost::system::error_code& ec);
  
    // Helper function to start an asynchronous send operation.
    BOOST_ASIO_DECL void start_send_op(base_implementation_type& impl,
        WSABUF* buffers, std::size_t buffer_count,
        socket_base::message_flags flags, bool noop, operation* op);
  
    // Helper function to start an asynchronous send_to operation.
    BOOST_ASIO_DECL void start_send_to_op(base_implementation_type& impl,
        WSABUF* buffers, std::size_t buffer_count,
        const socket_addr_type* addr, int addrlen,
        socket_base::message_flags flags, operation* op);
  
    // Helper function to start an asynchronous receive operation.
    BOOST_ASIO_DECL void start_receive_op(base_implementation_type& impl,
        WSABUF* buffers, std::size_t buffer_count,
        socket_base::message_flags flags, bool noop, operation* op);
  
    // Helper function to start an asynchronous null_buffers receive operation.
    BOOST_ASIO_DECL void start_null_buffers_receive_op(
        base_implementation_type& impl,
        socket_base::message_flags flags, reactor_op* op);
  
    // Helper function to start an asynchronous receive_from operation.
    BOOST_ASIO_DECL void start_receive_from_op(base_implementation_type& impl,
        WSABUF* buffers, std::size_t buffer_count, socket_addr_type* addr,
        socket_base::message_flags flags, int* addrlen, operation* op);
  
    // Helper function to start an asynchronous accept operation.
    BOOST_ASIO_DECL void start_accept_op(base_implementation_type& impl,
        bool peer_is_open, socket_holder& new_socket, int family, int type,
        int protocol, void* output_buffer, DWORD address_length, operation* op);
  
    // Start an asynchronous read or write operation using the the reactor.
    BOOST_ASIO_DECL void start_reactor_op(base_implementation_type& impl,
        int op_type, reactor_op* op);
  
    // Start the asynchronous connect operation using the reactor.
    BOOST_ASIO_DECL void start_connect_op(base_implementation_type& impl,
        reactor_op* op, const socket_addr_type* addr, std::size_t addrlen);
  
    // Helper function to close a socket when the associated object is being
    // destroyed.
    BOOST_ASIO_DECL void close_for_destruction(base_implementation_type& impl);
  
    // Update the ID of the thread from which cancellation is safe.
    BOOST_ASIO_DECL void update_cancellation_thread_id(
        base_implementation_type& impl);
  
    // Helper function to get the reactor. If no reactor has been created yet, a
    // new one is obtained from the io_service and a pointer to it is cached in
    // this service.
    BOOST_ASIO_DECL reactor& get_reactor();
  
    // Helper function to emulate InterlockedCompareExchangePointer functionality
    // for:
    // - very old Platform SDKs; and
    // - platform SDKs where MSVC's /Wp64 option causes spurious warnings.
    BOOST_ASIO_DECL void* interlocked_compare_exchange_pointer(
        void** dest, void* exch, void* cmp);
  
    // Helper function to emulate InterlockedExchangePointer functionality for:
    // - very old Platform SDKs; and
    // - platform SDKs where MSVC's /Wp64 option causes spurious warnings.
    BOOST_ASIO_DECL void* interlocked_exchange_pointer(void** dest, void* val);
  
    // The io_service used to obtain the reactor, if required.
    boost::asio::io_service& io_service_;
  
    // The IOCP service used for running asynchronous operations and dispatching
    // handlers.
    win_iocp_io_service& iocp_service_;
  
    // The reactor used for performing connect operations. This object is created
    // only if needed.
    reactor* reactor_;
  
    // Mutex to protect access to the linked list of implementations. 
    boost::asio::detail::mutex mutex_;
  
    // The head of a linked list of all implementations.
    base_implementation_type* impl_list_;
  };
  
  } // namespace detail
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #if defined(BOOST_ASIO_HEADER_ONLY)
  # include <boost/asio/detail/impl/win_iocp_socket_service_base.ipp>
  #endif // defined(BOOST_ASIO_HEADER_ONLY)
  
  #endif // defined(BOOST_ASIO_HAS_IOCP)
  
  #endif // BOOST_ASIO_DETAIL_WIN_IOCP_SOCKET_SERVICE_BASE_HPP
  