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 //
 // basic_signal_set.hpp
 // ~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2023 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 BOOST_ASIO_BASIC_SIGNAL_SET_HPP
 #define BOOST_ASIO_BASIC_SIGNAL_SET_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
 
 #include <boost/asio/any_io_executor.hpp>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/io_object_impl.hpp>
 #include <boost/asio/detail/non_const_lvalue.hpp>
 #include <boost/asio/detail/signal_set_service.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/execution_context.hpp>
 #include <boost/asio/signal_set_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
 /// Provides signal functionality.
 /**
  * The basic_signal_set class provides the ability to perform an asynchronous
  * wait for one or more signals to occur.
  *
  * @par Thread Safety
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  *
  * @par Example
  * Performing an asynchronous wait:
  * @code
  * void handler(
  *     const boost::system::error_code& error,
  *     int signal_number)
  * {
  *   if (!error)
  *   {
  *     // A signal occurred.
  *   }
  * }
  *
  * ...
  *
  * // Construct a signal set registered for process termination.
  * boost::asio::signal_set signals(my_context, SIGINT, SIGTERM);
  *
  * // Start an asynchronous wait for one of the signals to occur.
  * signals.async_wait(handler);
  * @endcode
  *
  * @par Queueing of signal notifications
  *
  * If a signal is registered with a signal_set, and the signal occurs when
  * there are no waiting handlers, then the signal notification is queued. The
  * next async_wait operation on that signal_set will dequeue the notification.
  * If multiple notifications are queued, subsequent async_wait operations
  * dequeue them one at a time. Signal notifications are dequeued in order of
  * ascending signal number.
  *
  * If a signal number is removed from a signal_set (using the @c remove or @c
  * erase member functions) then any queued notifications for that signal are
  * discarded.
  *
  * @par Multiple registration of signals
  *
  * The same signal number may be registered with different signal_set objects.
  * When the signal occurs, one handler is called for each signal_set object.
  *
  * Note that multiple registration only works for signals that are registered
  * using Asio. The application must not also register a signal handler using
  * functions such as @c signal() or @c sigaction().
  *
  * @par Signal masking on POSIX platforms
  *
  * POSIX allows signals to be blocked using functions such as @c sigprocmask()
  * and @c pthread_sigmask(). For signals to be delivered, programs must ensure
  * that any signals registered using signal_set objects are unblocked in at
  * least one thread.
  */
 template <typename Executor = any_io_executor>
 class basic_signal_set : public signal_set_base
 {
 private:
   class initiate_async_wait;
 
 public:
   /// The type of the executor associated with the object.
   typedef Executor executor_type;
 
   /// Rebinds the signal set type to another executor.
   template <typename Executor1>
   struct rebind_executor
   {
     /// The signal set type when rebound to the specified executor.
     typedef basic_signal_set<Executor1> other;
   };
 
   /// Construct a signal set without adding any signals.
   /**
    * This constructor creates a signal set without registering for any signals.
    *
    * @param ex The I/O executor that the signal set will use, by default, to
    * dispatch handlers for any asynchronous operations performed on the
    * signal set.
    */
   explicit basic_signal_set(const executor_type& ex)
     : impl_(0, ex)
   {
   }
 
   /// Construct a signal set without adding any signals.
   /**
    * This constructor creates a signal set without registering for any signals.
    *
    * @param context An execution context which provides the I/O executor that
    * the signal set will use, by default, to dispatch handlers for any
    * asynchronous operations performed on the signal set.
    */
   template <typename ExecutionContext>
   explicit basic_signal_set(ExecutionContext& context,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(0, 0, context)
   {
   }
 
   /// Construct a signal set and add one signal.
   /**
    * This constructor creates a signal set and registers for one signal.
    *
    * @param ex The I/O executor that the signal set will use, by default, to
    * dispatch handlers for any asynchronous operations performed on the
    * signal set.
    *
    * @param signal_number_1 The signal number to be added.
    *
    * @note This constructor is equivalent to performing:
    * @code boost::asio::signal_set signals(ex);
    * signals.add(signal_number_1); @endcode
    */
   basic_signal_set(const executor_type& ex, int signal_number_1)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Construct a signal set and add one signal.
   /**
    * This constructor creates a signal set and registers for one signal.
    *
    * @param context An execution context which provides the I/O executor that
    * the signal set will use, by default, to dispatch handlers for any
    * asynchronous operations performed on the signal set.
    *
    * @param signal_number_1 The signal number to be added.
    *
    * @note This constructor is equivalent to performing:
    * @code boost::asio::signal_set signals(context);
    * signals.add(signal_number_1); @endcode
    */
   template <typename ExecutionContext>
   basic_signal_set(ExecutionContext& context, int signal_number_1,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Construct a signal set and add two signals.
   /**
    * This constructor creates a signal set and registers for two signals.
    *
    * @param ex The I/O executor that the signal set will use, by default, to
    * dispatch handlers for any asynchronous operations performed on the
    * signal set.
    *
    * @param signal_number_1 The first signal number to be added.
    *
    * @param signal_number_2 The second signal number to be added.
    *
    * @note This constructor is equivalent to performing:
    * @code boost::asio::signal_set signals(ex);
    * signals.add(signal_number_1);
    * signals.add(signal_number_2); @endcode
    */
   basic_signal_set(const executor_type& ex, int signal_number_1,
       int signal_number_2)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Construct a signal set and add two signals.
   /**
    * This constructor creates a signal set and registers for two signals.
    *
    * @param context An execution context which provides the I/O executor that
    * the signal set will use, by default, to dispatch handlers for any
    * asynchronous operations performed on the signal set.
    *
    * @param signal_number_1 The first signal number to be added.
    *
    * @param signal_number_2 The second signal number to be added.
    *
    * @note This constructor is equivalent to performing:
    * @code boost::asio::signal_set signals(context);
    * signals.add(signal_number_1);
    * signals.add(signal_number_2); @endcode
    */
   template <typename ExecutionContext>
   basic_signal_set(ExecutionContext& context, int signal_number_1,
       int signal_number_2,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Construct a signal set and add three signals.
   /**
    * This constructor creates a signal set and registers for three signals.
    *
    * @param ex The I/O executor that the signal set will use, by default, to
    * dispatch handlers for any asynchronous operations performed on the
    * signal set.
    *
    * @param signal_number_1 The first signal number to be added.
    *
    * @param signal_number_2 The second signal number to be added.
    *
    * @param signal_number_3 The third signal number to be added.
    *
    * @note This constructor is equivalent to performing:
    * @code boost::asio::signal_set signals(ex);
    * signals.add(signal_number_1);
    * signals.add(signal_number_2);
    * signals.add(signal_number_3); @endcode
    */
   basic_signal_set(const executor_type& ex, int signal_number_1,
       int signal_number_2, int signal_number_3)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
     boost::asio::detail::throw_error(ec, "add");
     impl_.get_service().add(impl_.get_implementation(), signal_number_3, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Construct a signal set and add three signals.
   /**
    * This constructor creates a signal set and registers for three signals.
    *
    * @param context An execution context which provides the I/O executor that
    * the signal set will use, by default, to dispatch handlers for any
    * asynchronous operations performed on the signal set.
    *
    * @param signal_number_1 The first signal number to be added.
    *
    * @param signal_number_2 The second signal number to be added.
    *
    * @param signal_number_3 The third signal number to be added.
    *
    * @note This constructor is equivalent to performing:
    * @code boost::asio::signal_set signals(context);
    * signals.add(signal_number_1);
    * signals.add(signal_number_2);
    * signals.add(signal_number_3); @endcode
    */
   template <typename ExecutionContext>
   basic_signal_set(ExecutionContext& context, int signal_number_1,
       int signal_number_2, int signal_number_3,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
     impl_.get_service().add(impl_.get_implementation(), signal_number_2, ec);
     boost::asio::detail::throw_error(ec, "add");
     impl_.get_service().add(impl_.get_implementation(), signal_number_3, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Destroys the signal set.
   /**
    * This function destroys the signal set, cancelling any outstanding
    * asynchronous wait operations associated with the signal set as if by
    * calling @c cancel.
    */
   ~basic_signal_set()
   {
   }
 
   /// Get the executor associated with the object.
   const executor_type& get_executor() noexcept
   {
     return impl_.get_executor();
   }
 
   /// Add a signal to a signal_set.
   /**
    * This function adds the specified signal to the set. It has no effect if the
    * signal is already in the set.
    *
    * @param signal_number The signal to be added to the set.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   void add(int signal_number)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Add a signal to a signal_set.
   /**
    * This function adds the specified signal to the set. It has no effect if the
    * signal is already in the set.
    *
    * @param signal_number The signal to be added to the set.
    *
    * @param ec Set to indicate what error occurred, if any.
    */
   BOOST_ASIO_SYNC_OP_VOID add(int signal_number,
       boost::system::error_code& ec)
   {
     impl_.get_service().add(impl_.get_implementation(), signal_number, ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Add a signal to a signal_set with the specified flags.
   /**
    * This function adds the specified signal to the set. It has no effect if the
    * signal is already in the set.
    *
    * Flags other than flags::dont_care require OS support for the @c sigaction
    * call, and this function will fail with @c error::operation_not_supported if
    * this is unavailable.
    *
    * The specified flags will conflict with a prior, active registration of the
    * same signal, if either specified a flags value other than flags::dont_care.
    * In this case, the @c add will fail with @c error::invalid_argument.
    *
    * @param signal_number The signal to be added to the set.
    *
    * @param f Flags to modify the behaviour of the specified signal.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   void add(int signal_number, flags_t f)
   {
     boost::system::error_code ec;
     impl_.get_service().add(impl_.get_implementation(), signal_number, f, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
   /// Add a signal to a signal_set with the specified flags.
   /**
    * This function adds the specified signal to the set. It has no effect if the
    * signal is already in the set.
    *
    * Flags other than flags::dont_care require OS support for the @c sigaction
    * call, and this function will fail with @c error::operation_not_supported if
    * this is unavailable.
    *
    * The specified flags will conflict with a prior, active registration of the
    * same signal, if either specified a flags value other than flags::dont_care.
    * In this case, the @c add will fail with @c error::invalid_argument.
    *
    * @param signal_number The signal to be added to the set.
    *
    * @param f Flags to modify the behaviour of the specified signal.
    *
    * @param ec Set to indicate what error occurred, if any.
    */
   BOOST_ASIO_SYNC_OP_VOID add(int signal_number, flags_t f,
       boost::system::error_code& ec)
   {
     impl_.get_service().add(impl_.get_implementation(), signal_number, f, ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Remove a signal from a signal_set.
   /**
    * This function removes the specified signal from the set. It has no effect
    * if the signal is not in the set.
    *
    * @param signal_number The signal to be removed from the set.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
    * @note Removes any notifications that have been queued for the specified
    * signal number.
    */
   void remove(int signal_number)
   {
     boost::system::error_code ec;
     impl_.get_service().remove(impl_.get_implementation(), signal_number, ec);
     boost::asio::detail::throw_error(ec, "remove");
   }
 
   /// Remove a signal from a signal_set.
   /**
    * This function removes the specified signal from the set. It has no effect
    * if the signal is not in the set.
    *
    * @param signal_number The signal to be removed from the set.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
    * @note Removes any notifications that have been queued for the specified
    * signal number.
    */
   BOOST_ASIO_SYNC_OP_VOID remove(int signal_number,
       boost::system::error_code& ec)
   {
     impl_.get_service().remove(impl_.get_implementation(), signal_number, ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Remove all signals from a signal_set.
   /**
    * This function removes all signals from the set. It has no effect if the set
    * is already empty.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
    * @note Removes all queued notifications.
    */
   void clear()
   {
     boost::system::error_code ec;
     impl_.get_service().clear(impl_.get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "clear");
   }
 
   /// Remove all signals from a signal_set.
   /**
    * This function removes all signals from the set. It has no effect if the set
    * is already empty.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
    * @note Removes all queued notifications.
    */
   BOOST_ASIO_SYNC_OP_VOID clear(boost::system::error_code& ec)
   {
     impl_.get_service().clear(impl_.get_implementation(), ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Cancel all operations associated with the signal set.
   /**
    * This function forces the completion of any pending asynchronous wait
    * operations against the signal set. The handler for each cancelled
    * operation will be invoked with the boost::asio::error::operation_aborted
    * error code.
    *
    * Cancellation does not alter the set of registered signals.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
    * @note If a registered signal occurred before cancel() is called, then the
    * handlers for asynchronous wait operations will:
    *
    * @li have already been invoked; or
    *
    * @li have been queued for invocation in the near future.
    *
    * These handlers can no longer be cancelled, and therefore are passed an
    * error code that indicates the successful completion of the wait operation.
    */
   void cancel()
   {
     boost::system::error_code ec;
     impl_.get_service().cancel(impl_.get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel");
   }
 
   /// Cancel all operations associated with the signal set.
   /**
    * This function forces the completion of any pending asynchronous wait
    * operations against the signal set. The handler for each cancelled
    * operation will be invoked with the boost::asio::error::operation_aborted
    * error code.
    *
    * Cancellation does not alter the set of registered signals.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
    * @note If a registered signal occurred before cancel() is called, then the
    * handlers for asynchronous wait operations will:
    *
    * @li have already been invoked; or
    *
    * @li have been queued for invocation in the near future.
    *
    * These handlers can no longer be cancelled, and therefore are passed an
    * error code that indicates the successful completion of the wait operation.
    */
   BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
     impl_.get_service().cancel(impl_.get_implementation(), ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous operation to wait for a signal to be delivered.
   /**
    * This function may be used to initiate an asynchronous wait against the
    * signal set. It is an initiating function for an @ref
    * asynchronous_operation, and always returns immediately.
    *
    * For each call to async_wait(), the completion handler will be called
    * exactly once. The completion handler will be called when:
    *
    * @li One of the registered signals in the signal set occurs; or
    *
    * @li The signal set was cancelled, in which case the handler is passed the
    * error code boost::asio::error::operation_aborted.
    *
    * @param token The @ref completion_token that will be used to produce a
    * completion handler, which will be called when the wait completes.
    * Potential completion tokens include @ref use_future, @ref use_awaitable,
    * @ref yield_context, or a function object with the correct completion
    * signature. The function signature of the completion handler must be:
    * @code void handler(
    *   const boost::system::error_code& error, // Result of operation.
    *   int signal_number // Indicates which signal occurred.
    * ); @endcode
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the completion handler will not be invoked from within this function.
    * On immediate completion, invocation of the handler will be performed in a
    * manner equivalent to using boost::asio::post().
    *
    * @par Completion Signature
    * @code void(boost::system::error_code, int) @endcode
    *
    * @par Per-Operation Cancellation
    * This asynchronous operation supports cancellation for the following
    * boost::asio::cancellation_type values:
    *
    * @li @c cancellation_type::terminal
    *
    * @li @c cancellation_type::partial
    *
    * @li @c cancellation_type::total
    */
   template <
     BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, int))
       SignalToken = default_completion_token_t<executor_type>>
   auto async_wait(
       SignalToken&& token = default_completion_token_t<executor_type>())
     -> decltype(
       async_initiate<SignalToken, void (boost::system::error_code, int)>(
         declval<initiate_async_wait>(), token))
   {
     return async_initiate<SignalToken, void (boost::system::error_code, int)>(
         initiate_async_wait(this), token);
   }
 
 private:
   // Disallow copying and assignment.
   basic_signal_set(const basic_signal_set&) = delete;
   basic_signal_set& operator=(const basic_signal_set&) = delete;
 
   class initiate_async_wait
   {
   public:
     typedef Executor executor_type;
 
     explicit initiate_async_wait(basic_signal_set* self)
       : self_(self)
     {
     }
 
     const executor_type& get_executor() const noexcept
     {
       return self_->get_executor();
     }
 
     template <typename SignalHandler>
     void operator()(SignalHandler&& handler) const
     {
       // If you get an error on the following line it means that your handler
       // does not meet the documented type requirements for a SignalHandler.
       BOOST_ASIO_SIGNAL_HANDLER_CHECK(SignalHandler, handler) type_check;
 
       detail::non_const_lvalue<SignalHandler> handler2(handler);
       self_->impl_.get_service().async_wait(
           self_->impl_.get_implementation(),
           handler2.value, self_->impl_.get_executor());
     }
 
   private:
     basic_signal_set* self_;
   };
 
   detail::io_object_impl<detail::signal_set_service, Executor> impl_;
 };
 
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
 #endif // BOOST_ASIO_BASIC_SIGNAL_SET_HPP

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