//
// win_iocp_operation.hpp
// ~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2006 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_OPERATION_HPP
#define BOOST_ASIO_DETAIL_WIN_IOCP_OPERATION_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include <boost/asio/detail/push_options.hpp>

#include <boost/asio/detail/win_iocp_io_service_fwd.hpp>

#if defined(BOOST_ASIO_HAS_IOCP)

#include <boost/asio/detail/socket_types.hpp>

namespace boost {
namespace asio {
namespace detail {

// Base class for all IOCP operations. A function pointer is used instead of
// virtual functions to avoid the associated overhead.
//
// This class inherits from OVERLAPPED so that we can downcast to get back to
// the win_iocp_operation pointer from the LPOVERLAPPED out parameter of
// GetQueuedCompletionStatus.
struct win_iocp_operation
  : public OVERLAPPED
{
  typedef void (*invoke_func_type)(win_iocp_operation*, DWORD, size_t);
  typedef void (*destroy_func_type)(win_iocp_operation*);

  win_iocp_operation(invoke_func_type invoke_func,
      destroy_func_type destroy_func)
    : invoke_func_(invoke_func),
      destroy_func_(destroy_func)
  {
    Internal = 0;
    InternalHigh = 0;
    Offset = 0;
    OffsetHigh = 0;
    hEvent = 0;
  }

  void do_completion(DWORD last_error, size_t bytes_transferred)
  {
    invoke_func_(this, last_error, bytes_transferred);
  }

  void destroy()
  {
    destroy_func_(this);
  }

protected:
  // Prevent deletion through this type.
  ~win_iocp_operation()
  {
  }

private:
  invoke_func_type invoke_func_;
  destroy_func_type destroy_func_;
};

} // namespace detail
} // namespace asio
} // namespace boost

#endif // defined(BOOST_ASIO_HAS_IOCP)

#include <boost/asio/detail/pop_options.hpp>

#endif // BOOST_ASIO_DETAIL_WIN_IOCP_OPERATION_HPP