ceph/src/boost/boost/asio/strand.hpp

   1 //
   2 // strand.hpp
   3 // ~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2018 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_STRAND_HPP
  12 #define BOOST_ASIO_STRAND_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/detail/strand_executor_service.hpp>
  20 #include <boost/asio/detail/type_traits.hpp>
  21
  22 #include <boost/asio/detail/push_options.hpp>
  23
  24 namespace boost {
  25 namespace asio {
  26
  27 /// Provides serialised function invocation for any executor type.
  28 template <typename Executor>
  29 class strand
  30 {
  31 public:
  32   /// The type of the underlying executor.
  33   typedef Executor inner_executor_type;
  34
  35   /// Default constructor.
  36   /**
  37    * This constructor is only valid if the underlying executor type is default
  38    * constructible.
  39    */
  40   strand()
  41     : executor_(),
  42       impl_(use_service<detail::strand_executor_service>(
  43             executor_.context()).create_implementation())
  44   {
  45   }
  46
  47   /// Construct a strand for the specified executor.
  48   explicit strand(const Executor& e)
  49     : executor_(e),
  50       impl_(use_service<detail::strand_executor_service>(
  51             executor_.context()).create_implementation())
  52   {
  53   }
  54
  55   /// Copy constructor.
  56   strand(const strand& other) BOOST_ASIO_NOEXCEPT
  57     : executor_(other.executor_),
  58       impl_(other.impl_)
  59   {
  60   }
  61
  62   /// Converting constructor.
  63   /**
  64    * This constructor is only valid if the @c OtherExecutor type is convertible
  65    * to @c Executor.
  66    */
  67   template <class OtherExecutor>
  68   strand(
  69       const strand<OtherExecutor>& other) BOOST_ASIO_NOEXCEPT
  70     : executor_(other.executor_),
  71       impl_(other.impl_)
  72   {
  73   }
  74
  75   /// Assignment operator.
  76   strand& operator=(const strand& other) BOOST_ASIO_NOEXCEPT
  77   {
  78     executor_ = other.executor_;
  79     impl_ = other.impl_;
  80     return *this;
  81   }
  82
  83   /// Converting assignment operator.
  84   /**
  85    * This assignment operator is only valid if the @c OtherExecutor type is
  86    * convertible to @c Executor.
  87    */
  88   template <class OtherExecutor>
  89   strand& operator=(
  90       const strand<OtherExecutor>& other) BOOST_ASIO_NOEXCEPT
  91   {
  92     executor_ = other.executor_;
  93     impl_ = other.impl_;
  94     return *this;
  95   }
  96
  97 #if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
  98   /// Move constructor.
  99   strand(strand&& other) BOOST_ASIO_NOEXCEPT
 100     : executor_(BOOST_ASIO_MOVE_CAST(Executor)(other.executor_)),
 101       impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_))
 102   {
 103   }
 104
 105   /// Converting move constructor.
 106   /**
 107    * This constructor is only valid if the @c OtherExecutor type is convertible
 108    * to @c Executor.
 109    */
 110   template <class OtherExecutor>
 111   strand(strand<OtherExecutor>&& other) BOOST_ASIO_NOEXCEPT
 112     : executor_(BOOST_ASIO_MOVE_CAST(OtherExecutor)(other)),
 113       impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_))
 114   {
 115   }
 116
 117   /// Move assignment operator.
 118   strand& operator=(strand&& other) BOOST_ASIO_NOEXCEPT
 119   {
 120     executor_ = BOOST_ASIO_MOVE_CAST(Executor)(other);
 121     impl_ = BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_);
 122     return *this;
 123   }
 124
 125   /// Converting move assignment operator.
 126   /**
 127    * This assignment operator is only valid if the @c OtherExecutor type is
 128    * convertible to @c Executor.
 129    */
 130   template <class OtherExecutor>
 131   strand& operator=(
 132       const strand<OtherExecutor>&& other) BOOST_ASIO_NOEXCEPT
 133   {
 134     executor_ = BOOST_ASIO_MOVE_CAST(OtherExecutor)(other);
 135     impl_ = BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_);
 136     return *this;
 137   }
 138 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 139
 140   /// Destructor.
 141   ~strand()
 142   {
 143   }
 144
 145   /// Obtain the underlying executor.
 146   inner_executor_type get_inner_executor() const BOOST_ASIO_NOEXCEPT
 147   {
 148     return executor_;
 149   }
 150
 151   /// Obtain the underlying execution context.
 152   execution_context& context() const BOOST_ASIO_NOEXCEPT
 153   {
 154     return executor_.context();
 155   }
 156
 157   /// Inform the strand that it has some outstanding work to do.
 158   /**
 159    * The strand delegates this call to its underlying executor.
 160    */
 161   void on_work_started() const BOOST_ASIO_NOEXCEPT
 162   {
 163     executor_.on_work_started();
 164   }
 165
 166   /// Inform the strand that some work is no longer outstanding.
 167   /**
 168    * The strand delegates this call to its underlying executor.
 169    */
 170   void on_work_finished() const BOOST_ASIO_NOEXCEPT
 171   {
 172     executor_.on_work_finished();
 173   }
 174
 175   /// Request the strand to invoke the given function object.
 176   /**
 177    * This function is used to ask the strand to execute the given function
 178    * object on its underlying executor. The function object will be executed
 179    * inside this function if the strand is not otherwise busy and if the
 180    * underlying executor's @c dispatch() function is also able to execute the
 181    * function before returning.
 182    *
 183    * @param f The function object to be called. The executor will make
 184    * a copy of the handler object as required. The function signature of the
 185    * function object must be: @code void function(); @endcode
 186    *
 187    * @param a An allocator that may be used by the executor to allocate the
 188    * internal storage needed for function invocation.
 189    */
 190   template <typename Function, typename Allocator>
 191   void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
 192   {
 193     detail::strand_executor_service::dispatch(impl_,
 194         executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
 195   }
 196
 197   /// Request the strand to invoke the given function object.
 198   /**
 199    * This function is used to ask the executor to execute the given function
 200    * object. The function object will never be executed inside this function.
 201    * Instead, it will be scheduled by the underlying executor's defer function.
 202    *
 203    * @param f The function object to be called. The executor will make
 204    * a copy of the handler object as required. The function signature of the
 205    * function object must be: @code void function(); @endcode
 206    *
 207    * @param a An allocator that may be used by the executor to allocate the
 208    * internal storage needed for function invocation.
 209    */
 210   template <typename Function, typename Allocator>
 211   void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
 212   {
 213     detail::strand_executor_service::post(impl_,
 214         executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
 215   }
 216
 217   /// Request the strand to invoke the given function object.
 218   /**
 219    * This function is used to ask the executor to execute the given function
 220    * object. The function object will never be executed inside this function.
 221    * Instead, it will be scheduled by the underlying executor's defer function.
 222    *
 223    * @param f The function object to be called. The executor will make
 224    * a copy of the handler object as required. The function signature of the
 225    * function object must be: @code void function(); @endcode
 226    *
 227    * @param a An allocator that may be used by the executor to allocate the
 228    * internal storage needed for function invocation.
 229    */
 230   template <typename Function, typename Allocator>
 231   void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
 232   {
 233     detail::strand_executor_service::defer(impl_,
 234         executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
 235   }
 236
 237   /// Determine whether the strand is running in the current thread.
 238   /**
 239    * @return @c true if the current thread is executing a function that was
 240    * submitted to the strand using post(), dispatch() or defer(). Otherwise
 241    * returns @c false.
 242    */
 243   bool running_in_this_thread() const BOOST_ASIO_NOEXCEPT
 244   {
 245     return detail::strand_executor_service::running_in_this_thread(impl_);
 246   }
 247
 248   /// Compare two strands for equality.
 249   /**
 250    * Two strands are equal if they refer to the same ordered, non-concurrent
 251    * state.
 252    */
 253   friend bool operator==(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
 254   {
 255     return a.impl_ == b.impl_;
 256   }
 257
 258   /// Compare two strands for inequality.
 259   /**
 260    * Two strands are equal if they refer to the same ordered, non-concurrent
 261    * state.
 262    */
 263   friend bool operator!=(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
 264   {
 265     return a.impl_ != b.impl_;
 266   }
 267
 268 private:
 269   Executor executor_;
 270   typedef detail::strand_executor_service::implementation_type
 271     implementation_type;
 272   implementation_type impl_;
 273 };
 274
 275 } // namespace asio
 276 } // namespace boost
 277
 278 #include <boost/asio/detail/pop_options.hpp>
 279
 280 // If both io_context.hpp and strand.hpp have been included, automatically
 281 // include the header file needed for the io_context::strand class.
 282 #if !defined(BOOST_ASIO_NO_EXTENSIONS)
 283 # if defined(BOOST_ASIO_IO_CONTEXT_HPP)
 284 #  include <boost/asio/io_context_strand.hpp>
 285 # endif // defined(BOOST_ASIO_IO_CONTEXT_HPP)
 286 #endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 287
 288 #endif // BOOST_ASIO_STRAND_HPP