ceph/src/boost/boost/asio/experimental/impl/promise.hpp

   1 //
   2 // experimental/impl/promise.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2021-2022 Klemens D. Morgenstern
   6 //                         (klemens dot morgenstern at gmx dot net)
   7 //
   8 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   9 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  10 //
  11 #ifndef BOOST_ASIO_EXPERIMENTAL_IMPL_PROMISE_HPP
  12 #define BOOST_ASIO_EXPERIMENTAL_IMPL_PROMISE_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/cancellation_signal.hpp>
  19 #include <boost/asio/experimental/detail/completion_handler_erasure.hpp>
  20 #include <tuple>
  21 #include <optional>
  22
  23 #include <boost/asio/detail/push_options.hpp>
  24
  25 namespace boost {
  26 namespace asio {
  27 namespace experimental {
  28
  29 template<typename Signature = void(), typename Executor = any_io_executor>
  30 struct promise;
  31
  32 namespace detail {
  33
  34 template<typename Signature, typename Executor>
  35 struct promise_impl;
  36
  37 template<typename ... Ts, typename Executor>
  38 struct promise_impl<void(Ts...), Executor>
  39 {
  40   using result_type = std::tuple<Ts...>;
  41
  42   promise_impl(Executor executor = {})
  43     : executor(std::move(executor))
  44   {
  45   }
  46
  47   std::optional<result_type> result;
  48   bool done{false};
  49   detail::completion_handler_erasure<void(Ts...), Executor> completion;
  50   cancellation_signal cancel;
  51   Executor executor;
  52 };
  53
  54 template<typename Signature = void(), typename Executor = any_io_executor>
  55 struct promise_handler;
  56
  57 template<typename Signature, typename Executor>
  58 struct promise_handler;
  59
  60 template<typename ... Ts, typename Executor>
  61 struct promise_handler<void(Ts...), Executor>
  62 {
  63   using promise_type = promise<void(Ts...), Executor>;
  64
  65   promise_handler(Executor executor) // get_associated_allocator(exec)
  66     : impl_{
  67         std::allocate_shared<promise_impl<void(Ts...), Executor>>(
  68           get_associated_allocator(executor))}
  69   {
  70     impl_->executor = std::move(executor);
  71   }
  72
  73   std::shared_ptr<promise_impl<void(Ts...), Executor>> impl_;
  74
  75   using cancellation_slot_type = cancellation_slot;
  76
  77   cancellation_slot_type get_cancellation_slot() const noexcept
  78   {
  79     return impl_->cancel.slot();
  80   }
  81
  82   auto make_promise() -> promise<void(Ts...), Executor>
  83   {
  84     return {impl_};
  85   }
  86
  87   void operator()(std::remove_reference_t<Ts>... ts)
  88   {
  89     assert(impl_);
  90     impl_->result.emplace(std::move(ts)...);
  91     impl_->done = true;
  92     if (auto f = std::exchange(impl_->completion, nullptr); f != nullptr)
  93       std::apply(std::move(f), std::move(*impl_->result));
  94   }
  95 };
  96
  97 } // namespace detail
  98 } // namespace experimental
  99 } // namespace asio
 100 } // namespace boost
 101
 102 #include <boost/asio/detail/pop_options.hpp>
 103
 104 #endif // BOOST_ASIO_EXPERIMENTAL_IMPL_PROMISE_HPP