co_spawn.hpp 3.8 KB

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  1. //
  2. // impl/co_spawn.hpp
  3. // ~~~~~~~~~~~~~~~~~
  4. //
  5. // Copyright (c) 2003-2019 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 BOOST_ASIO_IMPL_CO_SPAWN_HPP
  11. #define BOOST_ASIO_IMPL_CO_SPAWN_HPP
  12. #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  13. # pragma once
  14. #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  15. #include <boost/asio/detail/config.hpp>
  16. #include <boost/asio/awaitable.hpp>
  17. #include <boost/asio/dispatch.hpp>
  18. #include <boost/asio/post.hpp>
  19. #include <boost/asio/use_awaitable.hpp>
  20. #include <boost/asio/detail/push_options.hpp>
  21. namespace boost {
  22. namespace asio {
  23. namespace detail {
  24. template <typename T, typename Executor, typename F, typename Handler>
  25. awaitable<void, Executor> co_spawn_entry_point(
  26. awaitable<T, Executor>*, Executor ex, F f, Handler handler)
  27. {
  28. auto spawn_work = make_work_guard(ex);
  29. auto handler_work = make_work_guard(handler, ex);
  30. (void) co_await (post)(spawn_work.get_executor(),
  31. use_awaitable_t<Executor>{});
  32. bool done = false;
  33. try
  34. {
  35. T t = co_await f();
  36. done = true;
  37. (dispatch)(handler_work.get_executor(),
  38. [handler = std::move(handler), t = std::move(t)]() mutable
  39. {
  40. handler(std::exception_ptr(), std::move(t));
  41. });
  42. }
  43. catch (...)
  44. {
  45. if (done)
  46. throw;
  47. (dispatch)(handler_work.get_executor(),
  48. [handler = std::move(handler), e = std::current_exception()]() mutable
  49. {
  50. handler(e, T());
  51. });
  52. }
  53. }
  54. template <typename Executor, typename F, typename Handler>
  55. awaitable<void, Executor> co_spawn_entry_point(
  56. awaitable<void, Executor>*, Executor ex, F f, Handler handler)
  57. {
  58. auto spawn_work = make_work_guard(ex);
  59. auto handler_work = make_work_guard(handler, ex);
  60. (void) co_await (post)(spawn_work.get_executor(),
  61. use_awaitable_t<Executor>{});
  62. std::exception_ptr e = nullptr;
  63. try
  64. {
  65. co_await f();
  66. }
  67. catch (...)
  68. {
  69. e = std::current_exception();
  70. }
  71. (dispatch)(handler_work.get_executor(),
  72. [handler = std::move(handler), e]() mutable
  73. {
  74. handler(e);
  75. });
  76. }
  77. struct initiate_co_spawn
  78. {
  79. template <typename Handler, typename Executor, typename F>
  80. void operator()(Handler&& handler, const Executor& ex, F&& f) const
  81. {
  82. typedef typename result_of<F()>::type awaitable_type;
  83. typedef typename awaitable_type::executor_type executor_type;
  84. executor_type ex2(ex);
  85. auto a = (co_spawn_entry_point)(static_cast<awaitable_type*>(nullptr),
  86. ex2, std::forward<F>(f), std::forward<Handler>(handler));
  87. awaitable_handler<executor_type, void>(std::move(a), ex2).launch();
  88. }
  89. };
  90. } // namespace detail
  91. template <typename Executor, typename F, typename CompletionToken>
  92. inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
  93. typename detail::awaitable_signature<typename result_of<F()>::type>::type)
  94. co_spawn(const Executor& ex, F&& f, CompletionToken&& token,
  95. typename enable_if<
  96. is_executor<Executor>::value
  97. >::type*)
  98. {
  99. return async_initiate<CompletionToken,
  100. typename detail::awaitable_signature<typename result_of<F()>::type>>(
  101. detail::initiate_co_spawn(), token, ex, std::forward<F>(f));
  102. }
  103. template <typename ExecutionContext, typename F, typename CompletionToken>
  104. inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
  105. typename detail::awaitable_signature<typename result_of<F()>::type>::type)
  106. co_spawn(ExecutionContext& ctx, F&& f, CompletionToken&& token,
  107. typename enable_if<
  108. is_convertible<ExecutionContext&, execution_context&>::value
  109. >::type*)
  110. {
  111. return (co_spawn)(ctx.get_executor(), std::forward<F>(f),
  112. std::forward<CompletionToken>(token));
  113. }
  114. } // namespace asio
  115. } // namespace boost
  116. #include <boost/asio/detail/pop_options.hpp>
  117. #endif // BOOST_ASIO_IMPL_CO_SPAWN_HPP