ceph/src/boost/boost/asio/defer.hpp

   1 //
   2 // defer.hpp
   3 // ~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2020 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
  11 #ifndef BOOST_ASIO_DEFER_HPP
  12 #define BOOST_ASIO_DEFER_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/detail/config.hpp>
  19 #include <boost/asio/async_result.hpp>
  20 #include <boost/asio/detail/type_traits.hpp>
  21 #include <boost/asio/execution_context.hpp>
  22 #include <boost/asio/execution/executor.hpp>
  23 #include <boost/asio/is_executor.hpp>
  24
  25 #include <boost/asio/detail/push_options.hpp>
  26
  27 namespace boost {
  28 namespace asio {
  29
  30 /// Submits a completion token or function object for execution.
  31 /**
  32  * This function submits an object for execution using the object's associated
  33  * executor. The function object is queued for execution, and is never called
  34  * from the current thread prior to returning from <tt>defer()</tt>.
  35  *
  36  * The use of @c defer(), rather than @ref post(), indicates the caller's
  37  * preference that the executor defer the queueing of the function object. This
  38  * may allow the executor to optimise queueing for cases when the function
  39  * object represents a continuation of the current call context.
  40  *
  41  * This function has the following effects:
  42  *
  43  * @li Constructs a function object handler of type @c Handler, initialized
  44  * with <tt>handler(forward<CompletionToken>(token))</tt>.
  45  *
  46  * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
  47  * initializing the object as <tt>result(handler)</tt>.
  48  *
  49  * @li Obtains the handler's associated executor object @c ex by performing
  50  * <tt>get_associated_executor(handler)</tt>.
  51  *
  52  * @li Obtains the handler's associated allocator object @c alloc by performing
  53  * <tt>get_associated_allocator(handler)</tt>.
  54  *
  55  * @li Performs <tt>ex.defer(std::move(handler), alloc)</tt>.
  56  *
  57  * @li Returns <tt>result.get()</tt>.
  58  */
  59 template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) CompletionToken>
  60 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, void()) defer(
  61     BOOST_ASIO_MOVE_ARG(CompletionToken) token);
  62
  63 /// Submits a completion token or function object for execution.
  64 /**
  65  * This function submits an object for execution using the specified executor.
  66  * The function object is queued for execution, and is never called from the
  67  * current thread prior to returning from <tt>defer()</tt>.
  68  *
  69  * The use of @c defer(), rather than @ref post(), indicates the caller's
  70  * preference that the executor defer the queueing of the function object. This
  71  * may allow the executor to optimise queueing for cases when the function
  72  * object represents a continuation of the current call context.
  73  *
  74  * This function has the following effects:
  75  *
  76  * @li Constructs a function object handler of type @c Handler, initialized
  77  * with <tt>handler(forward<CompletionToken>(token))</tt>.
  78  *
  79  * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
  80  * initializing the object as <tt>result(handler)</tt>.
  81  *
  82  * @li Obtains the handler's associated executor object @c ex1 by performing
  83  * <tt>get_associated_executor(handler)</tt>.
  84  *
  85  * @li Creates a work object @c w by performing <tt>make_work(ex1)</tt>.
  86  *
  87  * @li Obtains the handler's associated allocator object @c alloc by performing
  88  * <tt>get_associated_allocator(handler)</tt>.
  89  *
  90  * @li Constructs a function object @c f with a function call operator that
  91  * performs <tt>ex1.dispatch(std::move(handler), alloc)</tt> followed by
  92  * <tt>w.reset()</tt>.
  93  *
  94  * @li Performs <tt>Executor(ex).defer(std::move(f), alloc)</tt>.
  95  *
  96  * @li Returns <tt>result.get()</tt>.
  97  */
  98 template <typename Executor,
  99     BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) CompletionToken
 100       BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(Executor)>
 101 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, void()) defer(
 102     const Executor& ex,
 103     BOOST_ASIO_MOVE_ARG(CompletionToken) token
 104       BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(Executor),
 105     typename enable_if<
 106       execution::is_executor<Executor>::value || is_executor<Executor>::value
 107     >::type* = 0);
 108
 109 /// Submits a completion token or function object for execution.
 110 /**
 111  * @returns <tt>defer(ctx.get_executor(), forward<CompletionToken>(token))</tt>.
 112  */
 113 template <typename ExecutionContext,
 114     BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) CompletionToken
 115       BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
 116         typename ExecutionContext::executor_type)>
 117 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, void()) defer(
 118     ExecutionContext& ctx,
 119     BOOST_ASIO_MOVE_ARG(CompletionToken) token
 120       BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
 121         typename ExecutionContext::executor_type),
 122     typename enable_if<is_convertible<
 123       ExecutionContext&, execution_context&>::value>::type* = 0);
 124
 125 } // namespace asio
 126 } // namespace boost
 127
 128 #include <boost/asio/detail/pop_options.hpp>
 129
 130 #include <boost/asio/impl/defer.hpp>
 131
 132 #endif // BOOST_ASIO_DEFER_HPP