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			/** Delivers a registered signal to the waiting coroutine.
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			private:
44			friend io_signal_set;
45			friend detail::value_op_base<wait_awaitable, int>;
46
47			io_signal_set& s_;
48
49		572x	explicit wait_awaitable(io_signal_set& s) noexcept : s_(s) {}
50
51			std::coroutine_handle<>
52		525x	dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
53			{
54	1/1 ✓ Branch 4 → 5 taken 525 times.	525x	return s_.get().wait(h, ex, token_, &ec_, &value_);
55			}
56			};
57
58			public:
59			/** Define backend hooks for signal set wait and cancel.
60
61			Platform backends derive from this to implement
62			signal delivery notification.
63			*/
64			struct implementation : io_object::implementation
65			{
66			/** Initiate an asynchronous wait for a signal.
67
68			@param h Coroutine handle to resume on completion.
69			@param ex Executor for dispatching the completion.
70			@param token Stop token for cancellation.
71			@param ec Output error code.
72			@param signo Output signal number.
73
74			@return Coroutine handle to resume immediately.
75			*/
76			virtual std::coroutine_handle<> wait(
77			std::coroutine_handle<> h,
78			capy::executor_ref ex,
79			std::stop_token token,
80			std::error_code* ec,
81			int* signo) = 0;
82
83			/** Cancel all pending wait operations.
84
85			Cancelled waiters complete with an error that
86			compares equal to `capy::cond::canceled`.
87			*/
88			virtual void cancel() noexcept = 0;
89			};
90
91			/** Cancel all operations associated with the signal set.
92
93			Forces the completion of any pending asynchronous wait
94			operations. Each cancelled operation completes with an error
95			code that compares equal to `capy::cond::canceled`.
96
97			Cancellation does not alter the set of registered signals.
98			*/
99		9x	void cancel() noexcept
100			{
101		9x	do_cancel();
102		9x	}
103
104			/** Wait for a signal to be delivered.
105
106			The operation supports cancellation via `std::stop_token` through
107			the affine awaitable protocol. If the associated stop token is
108			triggered, the operation completes immediately with an error
109			that compares equal to `capy::cond::canceled`.
110
111			This signal set must outlive the returned awaitable.
112
113			@note On Windows a stop request resumes the awaiting coroutine
114			inline, on the thread that called `request_stop()`. On POSIX
115			it always resumes on a thread running the execution context.
116
117			@return An awaitable that completes with `io_result<int>`.
118			Returns the signal number when a signal is delivered,
119			or an error code on failure.
120			*/
121		572x	[[nodiscard]] auto wait()
122			{
123		572x	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		81x	explicit io_signal_set(handle h) noexcept : io_object(std::move(h)) {}
135
136			/// Move construct.
137		1x	io_signal_set(io_signal_set&& other) noexcept : io_object(std::move(other))
138			{
139		1x	}
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		525x	implementation& get() const noexcept
156			{
157		525x	return static_cast<implementation>(h_.get());
158			}
159			};
160
161			} // namespace boost::corosio
162
163			#endif
164