include/boost/corosio/native/native_timer.hpp

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native_timer.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_NATIVE_NATIVE_TIMER_HPP
11		#define BOOST_COROSIO_NATIVE_NATIVE_TIMER_HPP
12
13		#include <boost/corosio/timer.hpp>
14		#include <boost/corosio/backend.hpp>
15		#include <boost/corosio/detail/timer_service.hpp>
16
17		namespace boost::corosio {
18
19		/** An asynchronous timer with devirtualized wait operations.
20
21		This class template inherits from @ref timer and shadows the
22		`wait` operation with a version that calls the backend
23		implementation directly, allowing the compiler to inline
24		through the entire call chain.
25
26		Non-async operations (`cancel`, `expires_at`, `expires_after`)
27		remain unchanged and dispatch through the compiled library.
28
29		A `native_timer` IS-A `timer` and can be passed to any function
30		expecting `timer&`.
31
32		@tparam Backend A backend tag value (e.g., `epoll`).
33		The timer implementation is backend-independent; the
34		tag selects the concrete impl type for devirtualization.
35
36		@par Thread Safety
37		Same as @ref timer.
38
39		@see timer, epoll_t, iocp_t
40		*/
41		template<auto Backend>
42		class native_timer : public timer
43		{
44		using impl_type = detail::timer_service::implementation;
45
46	10x	impl_type& get_impl() noexcept
47		{
48	10x	return static_cast<impl_type>(h_.get());
49		}
50
51		struct native_wait_awaitable
52		{
53		native_timer& self_;
54		std::stop_token token_;
55		mutable std::error_code ec_;
56		detail::continuation_op cont_op_;
57
58	10x	explicit native_wait_awaitable(native_timer& self) noexcept
59	10x	: self_(self)
60		{
61	10x	}
62
63	10x	bool await_ready() const noexcept
64		{
65	10x	return token_.stop_requested();
66		}
67
68	10x	capy::io_result<> await_resume() const noexcept
69		{
70	10x	if (token_.stop_requested())
71	✗	return {capy::error::canceled};
72	10x	return {ec_};
73		}
74
75	10x	auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
76		-> std::coroutine_handle<>
77		{
78	10x	token_ = env->stop_token;
79	10x	cont_op_.cont.h = h;
80	10x	auto& impl = self_.get_impl();
81		// Fast path: already expired and not in the heap
82	20x	if (impl.heap_index_ == timer::implementation::npos &&
83	20x	(impl.expiry_ == (time_point::min)() \|\|
84	20x	impl.expiry_ <= clock_type::now()))
85		{
86	2x	ec_ = {};
87	2x	auto d = env->executor;
88	2x	d.post(cont_op_.cont);
89	2x	return std::noop_coroutine();
90		}
91	8x	return impl.wait(h, env->executor, std::move(token_), &ec_, &cont_op_.cont);
92		}
93		};
94
95		public:
96		/** Construct a native timer from an execution context.
97
98		@param ctx The execution context that will own this timer.
99		*/
100	14x	explicit native_timer(capy::execution_context& ctx) : timer(ctx) {}
101
102		/** Construct a native timer with an initial absolute expiry.
103
104		@param ctx The execution context that will own this timer.
105		@param t The initial expiry time point.
106		*/
107		native_timer(capy::execution_context& ctx, time_point t) : timer(ctx, t) {}
108
109		/** Construct a native timer with an initial relative expiry.
110
111		@param ctx The execution context that will own this timer.
112		@param d The initial expiry duration relative to now.
113		*/
114		template<class Rep, class Period>
115	2x	native_timer(
116		capy::execution_context& ctx, std::chrono::duration<Rep, Period> d)
117	2x	: timer(ctx, d)
118		{
119	2x	}
120
121		/** Move construct.
122
123		@param other The timer to move from.
124
125		@pre No awaitables returned by @p other's methods exist.
126		@pre The execution context associated with @p other must
127		outlive this timer.
128		*/
129	✗	native_timer(native_timer&&) noexcept = default;
130
131		/** Move assign.
132
133		@param other The timer to move from.
134
135		@pre No awaitables returned by either `*this` or @p other's
136		methods exist.
137		@pre The execution context associated with @p other must
138		outlive this timer.
139		*/
140		native_timer& operator=(native_timer&&) noexcept = default;
141
142		native_timer(native_timer const&) = delete;
143		native_timer& operator=(native_timer const&) = delete;
144
145		/** Wait for the timer to expire.
146
147		Calls the backend implementation directly, bypassing virtual
148		dispatch. Otherwise identical to @ref timer::wait.
149
150		@return An awaitable yielding `io_result<>`.
151
152		This timer must outlive the returned awaitable.
153		*/
154	10x	auto wait()
155		{
156	10x	return native_wait_awaitable(*this);
157		}
158		};
159
160		} // namespace boost::corosio
161
162		#endif
163