include/boost/corosio/native/native_stream_file.hpp

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native_stream_file.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_NATIVE_NATIVE_STREAM_FILE_HPP
12		#define BOOST_COROSIO_NATIVE_NATIVE_STREAM_FILE_HPP
13
14		#include <boost/corosio/stream_file.hpp>
15		#include <boost/corosio/backend.hpp>
16
17		#ifndef BOOST_COROSIO_MRDOCS
18		#if BOOST_COROSIO_HAS_EPOLL \|\| BOOST_COROSIO_HAS_SELECT \|\| \
19		BOOST_COROSIO_HAS_KQUEUE
20		#include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
21		#endif
22
23		#if BOOST_COROSIO_HAS_IO_URING
24		#include <boost/corosio/native/detail/io_uring/io_uring_stream_file.hpp>
25		#endif
26
27		#if BOOST_COROSIO_HAS_IOCP
28		#include <boost/corosio/native/detail/iocp/win_file_service.hpp>
29		#endif
30		#endif // !BOOST_COROSIO_MRDOCS
31
32		namespace boost::corosio {
33
34		/** A sequential file with devirtualized async I/O operations.
35
36		This class template inherits from @ref stream_file and shadows
37		`read_some` / `write_some` with versions that call the backend
38		implementation directly, allowing the compiler to inline through
39		the entire call chain.
40
41		Non-async operations (`open`, `close`, `size`, `resize`, `seek`,
42		`sync_data`, `sync_all`) remain unchanged and dispatch through
43		the compiled library.
44
45		A `native_stream_file` IS-A `stream_file` and can be passed to
46		any function expecting `stream_file&` or `io_stream&`, in which
47		case virtual dispatch is used transparently.
48
49		@note On POSIX platforms, file I/O is dispatched to a thread
50		pool regardless of the chosen reactor backend, so all three
51		reactor tags (`epoll`, `select`, `kqueue`) resolve to the same
52		underlying implementation. The `Backend` template parameter
53		exists for API symmetry with @ref native_tcp_socket and friends.
54		The vtable savings are smaller relative to the thread-pool /
55		overlapped-I/O cost than they are for socket operations.
56
57		@tparam Backend A backend tag value (e.g., `epoll`, `iocp`).
58
59		@par Thread Safety
60		Same as @ref stream_file.
61
62		@par Example
63		@par !example native_stream_file
64
65		@see stream_file, epoll_t, iocp_t
66		*/
67		template<auto Backend>
68		class native_stream_file : public stream_file
69		{
70		using backend_type = decltype(Backend);
71		using impl_type = typename backend_type::stream_file_type;
72		using service_type = typename backend_type::stream_file_service_type;
73
74	12x	impl_type& get_impl() noexcept
75		{
76	12x	return static_cast<impl_type>(h_.get());
77		}
78
79		template<class MutableBufferSequence>
80		struct native_read_awaitable
81		{
82		native_stream_file& self_;
83		MutableBufferSequence buffers_;
84		std::stop_token token_;
85		mutable std::error_code ec_;
86		mutable std::size_t bytes_transferred_ = 0;
87
88	6x	native_read_awaitable(
89		native_stream_file& self,
90		MutableBufferSequence buffers) noexcept
91	6x	: self_(self)
92	6x	, buffers_(std::move(buffers))
93		{
94	6x	}
95
96	6x	bool await_ready() const noexcept
97		{
98		// A pre-set ec_ means the initiator failed before
99		// dispatch (e.g. a closed object).
100	6x	return static_cast<bool>(ec_) \|\| token_.stop_requested();
101		}
102
103	6x	[[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept
104		{
105	6x	if (token_.stop_requested())
106	2x	return {make_error_code(std::errc::operation_canceled), 0};
107	4x	return {ec_, bytes_transferred_};
108		}
109
110	6x	auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
111		-> std::coroutine_handle<>
112		{
113	6x	token_ = env->stop_token;
114	18x	return self_.get_impl().read_some(
115	18x	h, env->executor, buffers_, token_, &ec_, &bytes_transferred_);
116		}
117		};
118
119		template<class ConstBufferSequence>
120		struct native_write_awaitable
121		{
122		native_stream_file& self_;
123		ConstBufferSequence buffers_;
124		std::stop_token token_;
125		mutable std::error_code ec_;
126		mutable std::size_t bytes_transferred_ = 0;
127
128	6x	native_write_awaitable(
129		native_stream_file& self,
130		ConstBufferSequence buffers) noexcept
131	6x	: self_(self)
132	6x	, buffers_(std::move(buffers))
133		{
134	6x	}
135
136	6x	bool await_ready() const noexcept
137		{
138		// A pre-set ec_ means the initiator failed before
139		// dispatch (e.g. a closed object).
140	6x	return static_cast<bool>(ec_) \|\| token_.stop_requested();
141		}
142
143	6x	[[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept
144		{
145	6x	if (token_.stop_requested())
146	2x	return {make_error_code(std::errc::operation_canceled), 0};
147	4x	return {ec_, bytes_transferred_};
148		}
149
150	6x	auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
151		-> std::coroutine_handle<>
152		{
153	6x	token_ = env->stop_token;
154	18x	return self_.get_impl().write_some(
155	18x	h, env->executor, buffers_, token_, &ec_, &bytes_transferred_);
156		}
157		};
158
159		public:
160		/** Construct a native stream file from an execution context.
161
162		@param ctx The execution context that will own this file.
163		*/
164	16x	explicit native_stream_file(capy::execution_context& ctx)
165	16x	: io_object(create_handle<service_type>(ctx))
166		{
167	16x	}
168
169		/** Construct a native stream file from an executor.
170
171		@param ex The executor whose context will own this file.
172		*/
173		template<class Ex>
174		requires(!std::same_as<std::remove_cvref_t<Ex>, native_stream_file>) &&
175		capy::Executor<Ex>
176		explicit native_stream_file(Ex const& ex) : native_stream_file(ex.context())
177		{
178		}
179
180		/// Move construct.
181		native_stream_file(native_stream_file&&) noexcept = default;
182
183		/// Move assign.
184		native_stream_file& operator=(native_stream_file&&) noexcept = default;
185
186		native_stream_file(native_stream_file const&) = delete;
187		native_stream_file& operator=(native_stream_file const&) = delete;
188
189		/** Asynchronously read data from the file.
190
191		Calls the backend implementation directly, bypassing virtual
192		dispatch. Otherwise identical to @ref io_stream::read_some.
193		*/
194		template<capy::MutableBufferSequence MB>
195	6x	[[nodiscard]] auto read_some(MB const& buffers)
196		{
197	6x	return native_read_awaitable<MB>(*this, buffers);
198		}
199
200		/** Asynchronously write data to the file.
201
202		Calls the backend implementation directly, bypassing virtual
203		dispatch. Otherwise identical to @ref io_stream::write_some.
204		*/
205		template<capy::ConstBufferSequence CB>
206	6x	[[nodiscard]] auto write_some(CB const& buffers)
207		{
208	6x	return native_write_awaitable<CB>(*this, buffers);
209		}
210		};
211
212		} // namespace boost::corosio
213
214		#endif // BOOST_COROSIO_NATIVE_NATIVE_STREAM_FILE_HPP
215