include/boost/corosio/io/io_signal_set.hpp

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io_signal_set.hpp

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1		//
2		// Copyright (c) 2026 Steve Gerbino
3		// Copyright (c) 2026 Michael Vandeberg
4		//
5		// Distributed under the Boost Software License, Version 1.0. (See accompanying
6		// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7		//
8		// Official repository: https://github.com/cppalliance/corosio
9		//
10
11		#ifndef BOOST_COROSIO_IO_IO_SIGNAL_SET_HPP
12		#define BOOST_COROSIO_IO_IO_SIGNAL_SET_HPP
13
14		#include <boost/corosio/detail/config.hpp>
15		#include <boost/corosio/detail/op_base.hpp>
16		#include <boost/corosio/io/io_object.hpp>
17		#include <boost/capy/results.hpp>
18		#include <boost/capy/error.hpp>
19		#include <boost/capy/ex/executor_ref.hpp>
20		#include <boost/capy/ex/await_context.hpp>
21
22		#include <boost/capy/continuation.hpp>
23
24		#include <coroutine>
25		#include <stop_token>
26		#include <system_error>
27
28		namespace boost::corosio {
29
30		/** Delivers a registered signal to the waiting coroutine.
31
32		Provides the common signal set interface: `wait` and `cancel`.
33		Concrete classes like @ref signal_set add signal registration
34		(add, remove, clear) and platform-specific flags.
35
36		@par Thread Safety
37		Distinct objects: Safe.
38		Shared objects: Unsafe.
39
40		@see @ref signal_set, @ref io_object
41		*/
42		class BOOST_COROSIO_DECL io_signal_set : public io_object
43		{
44		struct wait_awaitable : detail::value_op_base<wait_awaitable, int>
45		{
46		private:
47		friend io_signal_set;
48		friend detail::value_op_base<wait_awaitable, int>;
49
50		io_signal_set& s_;
51
52	205775x	explicit wait_awaitable(io_signal_set& s) noexcept : s_(s) {}
53
54		std::coroutine_handle<>
55	205738x	dispatch(capy::continuation& cont, capy::executor_ref ex) const
56		{
57	205738x	return s_.get().wait(cont, ex, token_, &ec_, &value_);
58		}
59		};
60
61		public:
62		/** Define backend hooks for signal set wait and cancel.
63
64		Platform backends derive from this to implement
65		signal delivery notification.
66		*/
67		struct implementation : io_object::implementation
68		{
69		/** Initiate an asynchronous wait for a signal.
70
71		@param cont Continuation to resume on completion; it lives in
72		the awaiting frame until then.
73		@param ex Executor for dispatching the completion.
74		@param token Stop token for cancellation.
75		@param ec Output error code.
76		@param signo Output signal number.
77
78		@return Coroutine handle to resume immediately.
79		*/
80		virtual std::coroutine_handle<> wait(
81		capy::continuation& cont,
82		capy::executor_ref ex,
83		std::stop_token token,
84		std::error_code* ec,
85		int* signo) = 0;
86
87		/** Cancel all pending wait operations.
88
89		Cancelled waiters complete with an error that
90		compares equal to `capy::cond::canceled`.
91		*/
92		virtual void cancel() noexcept = 0;
93		};
94
95		/** Cancel all operations associated with the signal set.
96
97		Forces the completion of any pending asynchronous wait
98		operations. Each cancelled operation completes with an error
99		code that compares equal to `capy::cond::canceled`.
100
101		Cancellation does not alter the set of registered signals.
102		*/
103	200021x	void cancel() noexcept
104		{
105	200021x	do_cancel();
106	200021x	}
107
108		/** Wait for a signal to be delivered.
109
110		The operation supports cancellation via `std::stop_token` through
111		the affine awaitable protocol. If the associated stop token is
112		triggered, the operation completes immediately with an error
113		that compares equal to `capy::cond::canceled`.
114
115		This signal set must outlive the returned awaitable.
116
117		@return An awaitable that completes with `results<int>`.
118		Returns the signal number when a signal is delivered,
119		or an error code on failure.
120		*/
121	205775x	[[nodiscard]] auto wait()
122		{
123	205775x	return wait_awaitable(*this);
124		}
125
126		protected:
127		/** Dispatch cancel to the concrete implementation. */
128		virtual void do_cancel() noexcept = 0;
129
130		/** Adopt an existing handle.
131
132		@param h The handle the signal set takes ownership of.
133		*/
134	3478x	explicit io_signal_set(handle h) noexcept : io_object(std::move(h)) {}
135
136		/// Move construct.
137	4x	io_signal_set(io_signal_set&& other) noexcept : io_object(std::move(other))
138		{
139	4x	}
140
141		/// Move assign.
142		io_signal_set& operator=(io_signal_set&& other) noexcept
143		{
144		if (this != &other)
145		h_ = std::move(other.h_);
146		return *this;
147		}
148
149		/// Copy construction is disabled; the handle is uniquely owned.
150		io_signal_set(io_signal_set const&) = delete;
151		/// Copy assignment is disabled; the handle is uniquely owned.
152		io_signal_set& operator=(io_signal_set const&) = delete;
153
154		private:
155	205738x	implementation& get() const noexcept
156		{
157	205738x	return static_cast<implementation>(h_.get());
158		}
159		};
160
161		} // namespace boost::corosio
162
163		#endif
164