completion_handler.hpp 2.4 KB

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  1. //
  2. // detail/completion_handler.hpp
  3. // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  4. //
  5. // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  6. //
  7. // Distributed under the Boost Software License, Version 1.0. (See accompanying
  8. // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  9. //
  10. #ifndef ASIO_DETAIL_COMPLETION_HANDLER_HPP
  11. #define ASIO_DETAIL_COMPLETION_HANDLER_HPP
  12. #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  13. # pragma once
  14. #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  15. #include "asio/detail/addressof.hpp"
  16. #include "asio/detail/config.hpp"
  17. #include "asio/detail/fenced_block.hpp"
  18. #include "asio/detail/handler_alloc_helpers.hpp"
  19. #include "asio/detail/handler_invoke_helpers.hpp"
  20. #include "asio/detail/operation.hpp"
  21. #include "asio/detail/push_options.hpp"
  22. namespace asio {
  23. namespace detail {
  24. template <typename Handler>
  25. class completion_handler : public operation
  26. {
  27. public:
  28. ASIO_DEFINE_HANDLER_PTR(completion_handler);
  29. completion_handler(Handler& h)
  30. : operation(&completion_handler::do_complete),
  31. handler_(ASIO_MOVE_CAST(Handler)(h))
  32. {
  33. }
  34. static void do_complete(io_service_impl* owner, operation* base,
  35. const asio::error_code& /*ec*/,
  36. std::size_t /*bytes_transferred*/)
  37. {
  38. // Take ownership of the handler object.
  39. completion_handler* h(static_cast<completion_handler*>(base));
  40. ptr p = { asio::detail::addressof(h->handler_), h, h };
  41. ASIO_HANDLER_COMPLETION((h));
  42. // Make a copy of the handler so that the memory can be deallocated before
  43. // the upcall is made. Even if we're not about to make an upcall, a
  44. // sub-object of the handler may be the true owner of the memory associated
  45. // with the handler. Consequently, a local copy of the handler is required
  46. // to ensure that any owning sub-object remains valid until after we have
  47. // deallocated the memory here.
  48. Handler handler(ASIO_MOVE_CAST(Handler)(h->handler_));
  49. p.h = asio::detail::addressof(handler);
  50. p.reset();
  51. // Make the upcall if required.
  52. if (owner)
  53. {
  54. fenced_block b(fenced_block::half);
  55. ASIO_HANDLER_INVOCATION_BEGIN(());
  56. asio_handler_invoke_helpers::invoke(handler, handler);
  57. ASIO_HANDLER_INVOCATION_END;
  58. }
  59. }
  60. private:
  61. Handler handler_;
  62. };
  63. } // namespace detail
  64. } // namespace asio
  65. #include "asio/detail/pop_options.hpp"
  66. #endif // ASIO_DETAIL_COMPLETION_HANDLER_HPP