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		//
4		// Distributed under the Boost Software License, Version 1.0. (See accompanying
5		// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6		//
7		// Official repository: https://github.com/cppalliance/corosio
8		//
9
10		#ifndef BOOST_COROSIO_IO_IO_SIGNAL_SET_HPP
11		#define BOOST_COROSIO_IO_IO_SIGNAL_SET_HPP
12
13		#include <boost/corosio/detail/config.hpp>
14		#include <boost/corosio/detail/op_base.hpp>
15		#include <boost/corosio/io/io_object.hpp>
16		#include <boost/capy/io_result.hpp>
17		#include <boost/capy/error.hpp>
18		#include <boost/capy/ex/executor_ref.hpp>
19		#include <boost/capy/ex/io_env.hpp>
20
21		#include <coroutine>
22		#include <stop_token>
23		#include <system_error>
24
25		namespace boost::corosio {
26
27		/** Abstract base for asynchronous signal sets.
28
29		Provides the common signal set interface: `wait` and `cancel`.
30		Concrete classes like @ref signal_set add signal registration
31		(add, remove, clear) and platform-specific flags.
32
33		@par Thread Safety
34		Distinct objects: Safe.
35		Shared objects: Unsafe.
36
37		@see signal_set, io_object
38		*/
39		class BOOST_COROSIO_DECL io_signal_set : public io_object
40		{
41		struct wait_awaitable : detail::value_op_base<wait_awaitable, int>
42		{
43		io_signal_set& s_;
44
45	1143x	explicit wait_awaitable(io_signal_set& s) noexcept : s_(s) {}
46
47		std::coroutine_handle<>
48	1113x	dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
49		{
50	1113x	return s_.get().wait(h, ex, token_, &ec_, &value_);
51		}
52		};
53
54		public:
55		/** Define backend hooks for signal set wait and cancel.
56
57		Platform backends derive from this to implement
58		signal delivery notification.
59		*/
60		struct implementation : io_object::implementation
61		{
62		/** Initiate an asynchronous wait for a signal.
63
64		@param h Coroutine handle to resume on completion.
65		@param ex Executor for dispatching the completion.
66		@param token Stop token for cancellation.
67		@param ec Output error code.
68		@param signo Output signal number.
69
70		@return Coroutine handle to resume immediately.
71		*/
72		virtual std::coroutine_handle<> wait(
73		std::coroutine_handle<> h,
74		capy::executor_ref ex,
75		std::stop_token token,
76		std::error_code* ec,
77		int* signo) = 0;
78
79		/** Cancel all pending wait operations.
80
81		Cancelled waiters complete with an error that
82		compares equal to `capy::cond::canceled`.
83		*/
84		virtual void cancel() noexcept = 0;
85		};
86
87		/** Cancel all operations associated with the signal set.
88
89		Forces the completion of any pending asynchronous wait
90		operations. Each cancelled operation completes with an error
91		code that compares equal to `capy::cond::canceled`.
92
93		Cancellation does not alter the set of registered signals.
94		*/
95	17x	void cancel() noexcept
96		{
97	17x	do_cancel();
98	17x	}
99
100		/** Wait for a signal to be delivered.
101
102		The operation supports cancellation via `std::stop_token` through
103		the affine awaitable protocol. If the associated stop token is
104		triggered, the operation completes immediately with an error
105		that compares equal to `capy::cond::canceled`.
106
107		This signal set must outlive the returned awaitable.
108
109		@note On Windows a stop request resumes the awaiting coroutine
110		inline, on the thread that called `request_stop()`. On POSIX
111		it always resumes on a thread running the execution context.
112
113		@return An awaitable that completes with `io_result<int>`.
114		Returns the signal number when a signal is delivered,
115		or an error code on failure.
116		*/
117	1143x	[[nodiscard]] auto wait()
118		{
119	1143x	return wait_awaitable(*this);
120		}
121
122		protected:
123		/** Dispatch cancel to the concrete implementation. */
124		virtual void do_cancel() noexcept = 0;
125
126	190x	explicit io_signal_set(handle h) noexcept : io_object(std::move(h)) {}
127
128		/// Move construct.
129	2x	io_signal_set(io_signal_set&& other) noexcept : io_object(std::move(other))
130		{
131	2x	}
132
133		/// Move assign.
134		io_signal_set& operator=(io_signal_set&& other) noexcept
135		{
136		if (this != &other)
137		h_ = std::move(other.h_);
138		return *this;
139		}
140
141		io_signal_set(io_signal_set const&) = delete;
142		io_signal_set& operator=(io_signal_set const&) = delete;
143
144		private:
145	1113x	implementation& get() const noexcept
146		{
147	1113x	return static_cast<implementation>(h_.get());
148		}
149		};
150
151		} // namespace boost::corosio
152
153		#endif
154