ceph/src/boost/boost/asio/basic_signal_set.hpp

   1 //
   2 // basic_signal_set.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2022 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_BASIC_SIGNAL_SET_HPP
  12 #define BOOST_ASIO_BASIC_SIGNAL_SET_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
  20 #include <boost/asio/any_io_executor.hpp>
  21 #include <boost/asio/async_result.hpp>
  22 #include <boost/asio/detail/handler_type_requirements.hpp>
  23 #include <boost/asio/detail/io_object_impl.hpp>
  24 #include <boost/asio/detail/non_const_lvalue.hpp>
  25 #include <boost/asio/detail/signal_set_service.hpp>
  26 #include <boost/asio/detail/throw_error.hpp>
  27 #include <boost/asio/detail/type_traits.hpp>
  28 #include <boost/asio/error.hpp>
  29 #include <boost/asio/execution_context.hpp>
  30
  31 #include <boost/asio/detail/push_options.hpp>
  32
  33 namespace boost {
  34 namespace asio {
  35
  36 /// Provides signal functionality.
  37 /**
  38  * The basic_signal_set class provides the ability to perform an asynchronous
  39  * wait for one or more signals to occur.
  40  *
  41  * @par Thread Safety
  42  * @e Distinct @e objects: Safe.@n
  43  * @e Shared @e objects: Unsafe.
  44  *
  45  * @par Example
  46  * Performing an asynchronous wait:
  47  * @code
  48  * void handler(
  49  *     const boost::system::error_code& error,
  50  *     int signal_number)
  51  * {
  52  *   if (!error)
  53  *   {
  54  *     // A signal occurred.
  55  *   }
  56  * }
  57  *
  58  * ...
  59  *
  60  * // Construct a signal set registered for process termination.
  61  * boost::asio::signal_set signals(my_context, SIGINT, SIGTERM);
  62  *
  63  * // Start an asynchronous wait for one of the signals to occur.
  64  * signals.async_wait(handler);
  65  * @endcode
  66  *
  67  * @par Queueing of signal notifications
  68  *
  69  * If a signal is registered with a signal_set, and the signal occurs when
  70  * there are no waiting handlers, then the signal notification is queued. The
  71  * next async_wait operation on that signal_set will dequeue the notification.
  72  * If multiple notifications are queued, subsequent async_wait operations
  73  * dequeue them one at a time. Signal notifications are dequeued in order of
  74  * ascending signal number.
  75  *
  76  * If a signal number is removed from a signal_set (using the @c remove or @c
  77  * erase member functions) then any queued notifications for that signal are
  78  * discarded.
  79  *
  80  * @par Multiple registration of signals
  81  *
  82  * The same signal number may be registered with different signal_set objects.
  83  * When the signal occurs, one handler is called for each signal_set object.
  84  *
  85  * Note that multiple registration only works for signals that are registered
  86  * using Asio. The application must not also register a signal handler using
  87  * functions such as @c signal() or @c sigaction().
  88  *
  89  * @par Signal masking on POSIX platforms
  90  *
  91  * POSIX allows signals to be blocked using functions such as @c sigprocmask()
  92  * and @c pthread_sigmask(). For signals to be delivered, programs must ensure
  93  * that any signals registered using signal_set objects are unblocked in at
  94  * least one thread.
  95  */
  96 template <typename Executor = any_io_executor>
  97 class basic_signal_set
  98 {
  99 public:
 100   /// The type of the executor associated with the object.
 101   typedef Executor executor_type;
 102
 103   /// Rebinds the signal set type to another executor.
 104   template <typename Executor1>
 105   struct rebind_executor
 106   {
 107     /// The signal set type when rebound to the specified executor.
 108     typedef basic_signal_set<Executor1> other;
 109   };
 110
 111   /// Construct a signal set without adding any signals.
 112   /**
 113    * This constructor creates a signal set without registering for any signals.
 114    *
 115    * @param ex The I/O executor that the signal set will use, by default, to
 116    * dispatch handlers for any asynchronous operations performed on the
 117    * signal set.
 118    */
 119   explicit basic_signal_set(const executor_type& ex)
 120     : impl_(0, ex)
 121   {
 122   }
 123
 124   /// Construct a signal set without adding any signals.
 125   /**
 126    * This constructor creates a signal set without registering for any signals.
 127    *
 128    * @param context An execution context which provides the I/O executor that
 129    * the signal set will use, by default, to dispatch handlers for any
 130    * asynchronous operations performed on the signal set.
 131    */
 132   template <typename ExecutionContext>
 133   explicit basic_signal_set(ExecutionContext& context,
 134       typename constraint<
 135         is_convertible<ExecutionContext&, execution_context&>::value,
 136         defaulted_constraint
 137       >::type = defaulted_constraint())
 138     : impl_(0, 0, context)
 139   {
 140   }
 141
 142   /// Construct a signal set and add one signal.
 143   /**
 144    * This constructor creates a signal set and registers for one signal.
 145    *
 146    * @param ex The I/O executor that the signal set will use, by default, to
 147    * dispatch handlers for any asynchronous operations performed on the
 148    * signal set.
 149    *
 150    * @param signal_number_1 The signal number to be added.
 151    *
 152    * @note This constructor is equivalent to performing:
 153    * @code boost::asio::signal_set signals(ex);
 154    * signals.add(signal_number_1); @endcode
 155    */
 156   basic_signal_set(const executor_type& ex, int signal_number_1)
 157     : impl_(0, ex)
 158   {
 159     boost::system::error_code ec;
 160     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
 161     boost::asio::detail::throw_error(ec, "add");
 162   }
 163
 164   /// Construct a signal set and add one signal.
 165   /**
 166    * This constructor creates a signal set and registers for one signal.
 167    *
 168    * @param context An execution context which provides the I/O executor that
 169    * the signal set will use, by default, to dispatch handlers for any
 170    * asynchronous operations performed on the signal set.
 171    *
 172    * @param signal_number_1 The signal number to be added.
 173    *
 174    * @note This constructor is equivalent to performing:
 175    * @code boost::asio::signal_set signals(context);
 176    * signals.add(signal_number_1); @endcode
 177    */
 178   template <typename ExecutionContext>
 179   basic_signal_set(ExecutionContext& context, int signal_number_1,
 180       typename constraint<
 181         is_convertible<ExecutionContext&, execution_context&>::value,
 182         defaulted_constraint
 183       >::type = defaulted_constraint())
 184     : impl_(0, 0, context)
 185   {
 186     boost::system::error_code ec;
 187     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
 188     boost::asio::detail::throw_error(ec, "add");
 189   }
 190
 191   /// Construct a signal set and add two signals.
 192   /**
 193    * This constructor creates a signal set and registers for two signals.
 194    *
 195    * @param ex The I/O executor that the signal set will use, by default, to
 196    * dispatch handlers for any asynchronous operations performed on the
 197    * signal set.
 198    *
 199    * @param signal_number_1 The first signal number to be added.
 200    *
 201    * @param signal_number_2 The second signal number to be added.
 202    *
 203    * @note This constructor is equivalent to performing:
 204    * @code boost::asio::signal_set signals(ex);
 205    * signals.add(signal_number_1);
 206    * signals.add(signal_number_2); @endcode
 207    */
 208   basic_signal_set(const executor_type& ex, int signal_number_1,
 209       int signal_number_2)
 210     : impl_(0, ex)
 211   {
 212     boost::system::error_code ec;
 213     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
 214     boost::asio::detail::throw_error(ec, "add");
 215     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
 216     boost::asio::detail::throw_error(ec, "add");
 217   }
 218
 219   /// Construct a signal set and add two signals.
 220   /**
 221    * This constructor creates a signal set and registers for two signals.
 222    *
 223    * @param context An execution context which provides the I/O executor that
 224    * the signal set will use, by default, to dispatch handlers for any
 225    * asynchronous operations performed on the signal set.
 226    *
 227    * @param signal_number_1 The first signal number to be added.
 228    *
 229    * @param signal_number_2 The second signal number to be added.
 230    *
 231    * @note This constructor is equivalent to performing:
 232    * @code boost::asio::signal_set signals(context);
 233    * signals.add(signal_number_1);
 234    * signals.add(signal_number_2); @endcode
 235    */
 236   template <typename ExecutionContext>
 237   basic_signal_set(ExecutionContext& context, int signal_number_1,
 238       int signal_number_2,
 239       typename constraint<
 240         is_convertible<ExecutionContext&, execution_context&>::value,
 241         defaulted_constraint
 242       >::type = defaulted_constraint())
 243     : impl_(0, 0, context)
 244   {
 245     boost::system::error_code ec;
 246     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
 247     boost::asio::detail::throw_error(ec, "add");
 248     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
 249     boost::asio::detail::throw_error(ec, "add");
 250   }
 251
 252   /// Construct a signal set and add three signals.
 253   /**
 254    * This constructor creates a signal set and registers for three signals.
 255    *
 256    * @param ex The I/O executor that the signal set will use, by default, to
 257    * dispatch handlers for any asynchronous operations performed on the
 258    * signal set.
 259    *
 260    * @param signal_number_1 The first signal number to be added.
 261    *
 262    * @param signal_number_2 The second signal number to be added.
 263    *
 264    * @param signal_number_3 The third signal number to be added.
 265    *
 266    * @note This constructor is equivalent to performing:
 267    * @code boost::asio::signal_set signals(ex);
 268    * signals.add(signal_number_1);
 269    * signals.add(signal_number_2);
 270    * signals.add(signal_number_3); @endcode
 271    */
 272   basic_signal_set(const executor_type& ex, int signal_number_1,
 273       int signal_number_2, int signal_number_3)
 274     : impl_(0, ex)
 275   {
 276     boost::system::error_code ec;
 277     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
 278     boost::asio::detail::throw_error(ec, "add");
 279     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
 280     boost::asio::detail::throw_error(ec, "add");
 281     impl_.get_service().add(impl_.get_implementation(), signal_number_3, ec);
 282     boost::asio::detail::throw_error(ec, "add");
 283   }
 284
 285   /// Construct a signal set and add three signals.
 286   /**
 287    * This constructor creates a signal set and registers for three signals.
 288    *
 289    * @param context An execution context which provides the I/O executor that
 290    * the signal set will use, by default, to dispatch handlers for any
 291    * asynchronous operations performed on the signal set.
 292    *
 293    * @param signal_number_1 The first signal number to be added.
 294    *
 295    * @param signal_number_2 The second signal number to be added.
 296    *
 297    * @param signal_number_3 The third signal number to be added.
 298    *
 299    * @note This constructor is equivalent to performing:
 300    * @code boost::asio::signal_set signals(context);
 301    * signals.add(signal_number_1);
 302    * signals.add(signal_number_2);
 303    * signals.add(signal_number_3); @endcode
 304    */
 305   template <typename ExecutionContext>
 306   basic_signal_set(ExecutionContext& context, int signal_number_1,
 307       int signal_number_2, int signal_number_3,
 308       typename constraint<
 309         is_convertible<ExecutionContext&, execution_context&>::value,
 310         defaulted_constraint
 311       >::type = defaulted_constraint())
 312     : impl_(0, 0, context)
 313   {
 314     boost::system::error_code ec;
 315     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
 316     boost::asio::detail::throw_error(ec, "add");
 317     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
 318     boost::asio::detail::throw_error(ec, "add");
 319     impl_.get_service().add(impl_.get_implementation(), signal_number_3, ec);
 320     boost::asio::detail::throw_error(ec, "add");
 321   }
 322
 323   /// Destroys the signal set.
 324   /**
 325    * This function destroys the signal set, cancelling any outstanding
 326    * asynchronous wait operations associated with the signal set as if by
 327    * calling @c cancel.
 328    */
 329   ~basic_signal_set()
 330   {
 331   }
 332
 333   /// Get the executor associated with the object.
 334   executor_type get_executor() BOOST_ASIO_NOEXCEPT
 335   {
 336     return impl_.get_executor();
 337   }
 338
 339   /// Add a signal to a signal_set.
 340   /**
 341    * This function adds the specified signal to the set. It has no effect if the
 342    * signal is already in the set.
 343    *
 344    * @param signal_number The signal to be added to the set.
 345    *
 346    * @throws boost::system::system_error Thrown on failure.
 347    */
 348   void add(int signal_number)
 349   {
 350     boost::system::error_code ec;
 351     impl_.get_service().add(impl_.get_implementation(), signal_number, ec);
 352     boost::asio::detail::throw_error(ec, "add");
 353   }
 354
 355   /// Add a signal to a signal_set.
 356   /**
 357    * This function adds the specified signal to the set. It has no effect if the
 358    * signal is already in the set.
 359    *
 360    * @param signal_number The signal to be added to the set.
 361    *
 362    * @param ec Set to indicate what error occurred, if any.
 363    */
 364   BOOST_ASIO_SYNC_OP_VOID add(int signal_number,
 365       boost::system::error_code& ec)
 366   {
 367     impl_.get_service().add(impl_.get_implementation(), signal_number, ec);
 368     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 369   }
 370
 371   /// Remove a signal from a signal_set.
 372   /**
 373    * This function removes the specified signal from the set. It has no effect
 374    * if the signal is not in the set.
 375    *
 376    * @param signal_number The signal to be removed from the set.
 377    *
 378    * @throws boost::system::system_error Thrown on failure.
 379    *
 380    * @note Removes any notifications that have been queued for the specified
 381    * signal number.
 382    */
 383   void remove(int signal_number)
 384   {
 385     boost::system::error_code ec;
 386     impl_.get_service().remove(impl_.get_implementation(), signal_number, ec);
 387     boost::asio::detail::throw_error(ec, "remove");
 388   }
 389
 390   /// Remove a signal from a signal_set.
 391   /**
 392    * This function removes the specified signal from the set. It has no effect
 393    * if the signal is not in the set.
 394    *
 395    * @param signal_number The signal to be removed from the set.
 396    *
 397    * @param ec Set to indicate what error occurred, if any.
 398    *
 399    * @note Removes any notifications that have been queued for the specified
 400    * signal number.
 401    */
 402   BOOST_ASIO_SYNC_OP_VOID remove(int signal_number,
 403       boost::system::error_code& ec)
 404   {
 405     impl_.get_service().remove(impl_.get_implementation(), signal_number, ec);
 406     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 407   }
 408
 409   /// Remove all signals from a signal_set.
 410   /**
 411    * This function removes all signals from the set. It has no effect if the set
 412    * is already empty.
 413    *
 414    * @throws boost::system::system_error Thrown on failure.
 415    *
 416    * @note Removes all queued notifications.
 417    */
 418   void clear()
 419   {
 420     boost::system::error_code ec;
 421     impl_.get_service().clear(impl_.get_implementation(), ec);
 422     boost::asio::detail::throw_error(ec, "clear");
 423   }
 424
 425   /// Remove all signals from a signal_set.
 426   /**
 427    * This function removes all signals from the set. It has no effect if the set
 428    * is already empty.
 429    *
 430    * @param ec Set to indicate what error occurred, if any.
 431    *
 432    * @note Removes all queued notifications.
 433    */
 434   BOOST_ASIO_SYNC_OP_VOID clear(boost::system::error_code& ec)
 435   {
 436     impl_.get_service().clear(impl_.get_implementation(), ec);
 437     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 438   }
 439
 440   /// Cancel all operations associated with the signal set.
 441   /**
 442    * This function forces the completion of any pending asynchronous wait
 443    * operations against the signal set. The handler for each cancelled
 444    * operation will be invoked with the boost::asio::error::operation_aborted
 445    * error code.
 446    *
 447    * Cancellation does not alter the set of registered signals.
 448    *
 449    * @throws boost::system::system_error Thrown on failure.
 450    *
 451    * @note If a registered signal occurred before cancel() is called, then the
 452    * handlers for asynchronous wait operations will:
 453    *
 454    * @li have already been invoked; or
 455    *
 456    * @li have been queued for invocation in the near future.
 457    *
 458    * These handlers can no longer be cancelled, and therefore are passed an
 459    * error code that indicates the successful completion of the wait operation.
 460    */
 461   void cancel()
 462   {
 463     boost::system::error_code ec;
 464     impl_.get_service().cancel(impl_.get_implementation(), ec);
 465     boost::asio::detail::throw_error(ec, "cancel");
 466   }
 467
 468   /// Cancel all operations associated with the signal set.
 469   /**
 470    * This function forces the completion of any pending asynchronous wait
 471    * operations against the signal set. The handler for each cancelled
 472    * operation will be invoked with the boost::asio::error::operation_aborted
 473    * error code.
 474    *
 475    * Cancellation does not alter the set of registered signals.
 476    *
 477    * @param ec Set to indicate what error occurred, if any.
 478    *
 479    * @note If a registered signal occurred before cancel() is called, then the
 480    * handlers for asynchronous wait operations will:
 481    *
 482    * @li have already been invoked; or
 483    *
 484    * @li have been queued for invocation in the near future.
 485    *
 486    * These handlers can no longer be cancelled, and therefore are passed an
 487    * error code that indicates the successful completion of the wait operation.
 488    */
 489   BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
 490   {
 491     impl_.get_service().cancel(impl_.get_implementation(), ec);
 492     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 493   }
 494
 495   /// Start an asynchronous operation to wait for a signal to be delivered.
 496   /**
 497    * This function may be used to initiate an asynchronous wait against the
 498    * signal set. It is an initiating function for an @ref
 499    * asynchronous_operation, and always returns immediately.
 500    *
 501    * For each call to async_wait(), the completion handler will be called
 502    * exactly once. The completion handler will be called when:
 503    *
 504    * @li One of the registered signals in the signal set occurs; or
 505    *
 506    * @li The signal set was cancelled, in which case the handler is passed the
 507    * error code boost::asio::error::operation_aborted.
 508    *
 509    * @param token The @ref completion_token that will be used to produce a
 510    * completion handler, which will be called when the wait completes.
 511    * Potential completion tokens include @ref use_future, @ref use_awaitable,
 512    * @ref yield_context, or a function object with the correct completion
 513    * signature. The function signature of the completion handler must be:
 514    * @code void handler(
 515    *   const boost::system::error_code& error, // Result of operation.
 516    *   int signal_number // Indicates which signal occurred.
 517    * ); @endcode
 518    * Regardless of whether the asynchronous operation completes immediately or
 519    * not, the completion handler will not be invoked from within this function.
 520    * On immediate completion, invocation of the handler will be performed in a
 521    * manner equivalent to using boost::asio::post().
 522    *
 523    * @par Completion Signature
 524    * @code void(boost::system::error_code, int) @endcode
 525    *
 526    * @par Per-Operation Cancellation
 527    * This asynchronous operation supports cancellation for the following
 528    * boost::asio::cancellation_type values:
 529    *
 530    * @li @c cancellation_type::terminal
 531    *
 532    * @li @c cancellation_type::partial
 533    *
 534    * @li @c cancellation_type::total
 535    */
 536   template <
 537     BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, int))
 538       SignalToken BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)>
 539   BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(SignalToken,
 540       void (boost::system::error_code, int))
 541   async_wait(
 542       BOOST_ASIO_MOVE_ARG(SignalToken) token
 543         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(executor_type))
 544   {
 545     return async_initiate<SignalToken, void (boost::system::error_code, int)>(
 546         initiate_async_wait(this), token);
 547   }
 548
 549 private:
 550   // Disallow copying and assignment.
 551   basic_signal_set(const basic_signal_set&) BOOST_ASIO_DELETED;
 552   basic_signal_set& operator=(const basic_signal_set&) BOOST_ASIO_DELETED;
 553
 554   class initiate_async_wait
 555   {
 556   public:
 557     typedef Executor executor_type;
 558
 559     explicit initiate_async_wait(basic_signal_set* self)
 560       : self_(self)
 561     {
 562     }
 563
 564     executor_type get_executor() const BOOST_ASIO_NOEXCEPT
 565     {
 566       return self_->get_executor();
 567     }
 568
 569     template <typename SignalHandler>
 570     void operator()(BOOST_ASIO_MOVE_ARG(SignalHandler) handler) const
 571     {
 572       // If you get an error on the following line it means that your handler
 573       // does not meet the documented type requirements for a SignalHandler.
 574       BOOST_ASIO_SIGNAL_HANDLER_CHECK(SignalHandler, handler) type_check;
 575
 576       detail::non_const_lvalue<SignalHandler> handler2(handler);
 577       self_->impl_.get_service().async_wait(
 578           self_->impl_.get_implementation(),
 579           handler2.value, self_->impl_.get_executor());
 580     }
 581
 582   private:
 583     basic_signal_set* self_;
 584   };
 585
 586   detail::io_object_impl<detail::signal_set_service, Executor> impl_;
 587 };
 588
 589 } // namespace asio
 590 } // namespace boost
 591
 592 #include <boost/asio/detail/pop_options.hpp>
 593
 594 #endif // BOOST_ASIO_BASIC_SIGNAL_SET_HPP