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

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