io_context_strand.hpp

//
// io_context_strand.hpp
// ~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2020 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 ASIO_IO_CONTEXT_STRAND_HPP
#define ASIO_IO_CONTEXT_STRAND_HPP

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

#include "asio/detail/config.hpp"

#if !defined(ASIO_NO_EXTENSIONS) \
  && !defined(ASIO_NO_TS_EXECUTORS)

#include "asio/async_result.hpp"
#include "asio/detail/handler_type_requirements.hpp"
#include "asio/detail/strand_service.hpp"
#include "asio/detail/wrapped_handler.hpp"
#include "asio/io_context.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {


class io_context::strand
{
public:

  explicit strand(asio::io_context& io_context)
    : service_(asio::use_service<
        asio::detail::strand_service>(io_context))
  {
    service_.construct(impl_);
  }


  ~strand()
  {
  }

  asio::io_context& context() const ASIO_NOEXCEPT
  {
    return service_.get_io_context();
  }


  void on_work_started() const ASIO_NOEXCEPT
  {
    context().get_executor().on_work_started();
  }


  void on_work_finished() const ASIO_NOEXCEPT
  {
    context().get_executor().on_work_finished();
  }


  template <typename Function, typename Allocator>
  void dispatch(ASIO_MOVE_ARG(Function) f, const Allocator& a) const
  {
    typename decay<Function>::type tmp(ASIO_MOVE_CAST(Function)(f));
    service_.dispatch(impl_, tmp);
    (void)a;
  }

#if !defined(ASIO_NO_DEPRECATED)

  template <typename LegacyCompletionHandler>
  ASIO_INITFN_AUTO_RESULT_TYPE(LegacyCompletionHandler, void ())
  dispatch(ASIO_MOVE_ARG(LegacyCompletionHandler) handler)
  {
    return async_initiate<LegacyCompletionHandler, void ()>(
        initiate_dispatch(), handler, this);
  }
#endif // !defined(ASIO_NO_DEPRECATED)


  template <typename Function, typename Allocator>
  void post(ASIO_MOVE_ARG(Function) f, const Allocator& a) const
  {
    typename decay<Function>::type tmp(ASIO_MOVE_CAST(Function)(f));
    service_.post(impl_, tmp);
    (void)a;
  }

#if !defined(ASIO_NO_DEPRECATED)

  template <typename LegacyCompletionHandler>
  ASIO_INITFN_AUTO_RESULT_TYPE(LegacyCompletionHandler, void ())
  post(ASIO_MOVE_ARG(LegacyCompletionHandler) handler)
  {
    return async_initiate<LegacyCompletionHandler, void ()>(
        initiate_post(), handler, this);
  }
#endif // !defined(ASIO_NO_DEPRECATED)


  template <typename Function, typename Allocator>
  void defer(ASIO_MOVE_ARG(Function) f, const Allocator& a) const
  {
    typename decay<Function>::type tmp(ASIO_MOVE_CAST(Function)(f));
    service_.post(impl_, tmp);
    (void)a;
  }

#if !defined(ASIO_NO_DEPRECATED)

  template <typename Handler>
#if defined(GENERATING_DOCUMENTATION)
  unspecified
#else
  detail::wrapped_handler<strand, Handler, detail::is_continuation_if_running>
#endif
  wrap(Handler handler)
  {
    return detail::wrapped_handler<io_context::strand, Handler,
        detail::is_continuation_if_running>(*this, handler);
  }
#endif // !defined(ASIO_NO_DEPRECATED)


  bool running_in_this_thread() const ASIO_NOEXCEPT
  {
    return service_.running_in_this_thread(impl_);
  }


  friend bool operator==(const strand& a, const strand& b) ASIO_NOEXCEPT
  {
    return a.impl_ == b.impl_;
  }


  friend bool operator!=(const strand& a, const strand& b) ASIO_NOEXCEPT
  {
    return a.impl_ != b.impl_;
  }

private:
#if !defined(ASIO_NO_DEPRECATED)
  struct initiate_dispatch
  {
    template <typename LegacyCompletionHandler>
    void operator()(ASIO_MOVE_ARG(LegacyCompletionHandler) handler,
        strand* self) const
    {
      // If you get an error on the following line it means that your
      // handler does not meet the documented type requirements for a
      // LegacyCompletionHandler.
      ASIO_LEGACY_COMPLETION_HANDLER_CHECK(
          LegacyCompletionHandler, handler) type_check;

      detail::non_const_lvalue<LegacyCompletionHandler> handler2(handler);
      self->service_.dispatch(self->impl_, handler2.value);
    }
  };

  struct initiate_post
  {
    template <typename LegacyCompletionHandler>
    void operator()(ASIO_MOVE_ARG(LegacyCompletionHandler) handler,
        strand* self) const
    {
      // If you get an error on the following line it means that your
      // handler does not meet the documented type requirements for a
      // LegacyCompletionHandler.
      ASIO_LEGACY_COMPLETION_HANDLER_CHECK(
          LegacyCompletionHandler, handler) type_check;

      detail::non_const_lvalue<LegacyCompletionHandler> handler2(handler);
      self->service_.post(self->impl_, handler2.value);
    }
  };
#endif // !defined(ASIO_NO_DEPRECATED)

  asio::detail::strand_service& service_;
  mutable asio::detail::strand_service::implementation_type impl_;
};

} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // !defined(ASIO_NO_EXTENSIONS)
       //   && !defined(ASIO_NO_TS_EXECUTORS)

#endif // ASIO_IO_CONTEXT_STRAND_HPP