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		#include <boost/corosio/detail/op_base.hpp>
17
18		#ifndef BOOST_COROSIO_MRDOCS
19		#if BOOST_COROSIO_HAS_EPOLL \|\| BOOST_COROSIO_HAS_SELECT \|\| \
20		BOOST_COROSIO_HAS_KQUEUE
21		#include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
22		#endif
23
24		#if BOOST_COROSIO_HAS_URING
25		#include <boost/corosio/native/detail/uring/uring_stream_file.hpp>
26		#endif
27
28		#if BOOST_COROSIO_HAS_IOCP
29		#include <boost/corosio/native/detail/iocp/win_file_service.hpp>
30		#endif
31		#endif // !BOOST_COROSIO_MRDOCS
32
33		namespace boost::corosio {
34
35		/** A sequential file with devirtualized async I/O operations.
36
37		This class template inherits from @ref stream_file and shadows
38		`read_some` / `write_some` with versions that call the backend
39		implementation directly, allowing the compiler to inline through
40		the entire call chain.
41
42		Non-async operations (`open`, `close`, `size`, `resize`, `seek`,
43		`sync_data`, `sync_all`) remain unchanged and dispatch through
44		the compiled library.
45
46		A `native_stream_file` IS-A `stream_file` and can be passed to
47		any function expecting `stream_file&` or `io_stream&`, in which
48		case virtual dispatch is used transparently.
49
50		@note On POSIX platforms, file I/O is dispatched to a thread
51		pool regardless of the chosen reactor backend, so all three
52		reactor tags (`epoll`, `select`, `kqueue`) resolve to the same
53		underlying implementation. The `Backend` template parameter
54		exists for API symmetry with @ref native_tcp_socket and friends.
55		The vtable savings are smaller relative to the thread-pool /
56		overlapped-I/O cost than they are for socket operations.
57
58		@tparam Backend A backend tag value (e.g., `epoll`, `iocp`).
59
60		@par Thread Safety
61		Same as @ref stream_file.
62
63		@par Example
64		@par !example native_stream_file
65
66		@see stream_file, epoll_t, iocp_t
67		*/
68		template<auto Backend>
69		class native_stream_file : public stream_file
70		{
71		using backend_type = decltype(Backend);
72		using impl_type = typename backend_type::stream_file_type;
73		using service_type = typename backend_type::stream_file_service_type;
74
75	8x	impl_type& get_impl() noexcept
76		{
77	8x	return static_cast<impl_type>(h_.get());
78		}
79
80		template<class MutableBufferSequence>
81		struct native_read_awaitable
82		: detail::bytes_op_base<native_read_awaitable<MutableBufferSequence>>
83		{
84		native_stream_file& self_;
85		MutableBufferSequence buffers_;
86
87	6x	native_read_awaitable(
88		native_stream_file& self, MutableBufferSequence buffers) noexcept
89	6x	: self_(self)
90	6x	, buffers_(std::move(buffers))
91		{
92	6x	}
93
94		std::coroutine_handle<>
95	4x	dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
96		{
97	12x	return self_.get_impl().read_some(
98	12x	h, ex, buffers_, this->token_, &this->ec_, &this->bytes_);
99		}
100		};
101
102		template<class ConstBufferSequence>
103		struct native_write_awaitable
104		: detail::bytes_op_base<native_write_awaitable<ConstBufferSequence>>
105		{
106		native_stream_file& self_;
107		ConstBufferSequence buffers_;
108
109	6x	native_write_awaitable(
110		native_stream_file& self, ConstBufferSequence buffers) noexcept
111	6x	: self_(self)
112	6x	, buffers_(std::move(buffers))
113		{
114	6x	}
115
116		std::coroutine_handle<>
117	4x	dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
118		{
119	12x	return self_.get_impl().write_some(
120	12x	h, ex, buffers_, this->token_, &this->ec_, &this->bytes_);
121		}
122		};
123
124		public:
125		/** Construct a native stream file from an execution context.
126
127		@param ctx The execution context that will own this file.
128		*/
129	16x	explicit native_stream_file(capy::execution_context& ctx)
130	16x	: io_object(create_handle<service_type>(ctx))
131		{
132	16x	}
133
134		/** Construct a native stream file from an executor.
135
136		@param ex The executor whose context will own this file.
137		*/
138		template<class Ex>
139		requires(!std::same_as<std::remove_cvref_t<Ex>, native_stream_file>) &&
140		capy::Executor<Ex>
141		explicit native_stream_file(Ex const& ex) : native_stream_file(ex.context())
142		{
143		}
144
145		/// Move construct.
146		native_stream_file(native_stream_file&&) noexcept = default;
147
148		/// Move assign.
149		native_stream_file& operator=(native_stream_file&&) noexcept = default;
150
151		native_stream_file(native_stream_file const&) = delete;
152		native_stream_file& operator=(native_stream_file const&) = delete;
153
154		/** Asynchronously read data from the file.
155
156		Calls the backend implementation directly, bypassing virtual
157		dispatch. Otherwise identical to @ref io_stream::read_some.
158		*/
159		template<capy::MutableBufferSequence MB>
160	6x	[[nodiscard]] auto read_some(MB const& buffers)
161		{
162	6x	return native_read_awaitable<MB>(*this, buffers);
163		}
164
165		/** Asynchronously write data to the file.
166
167		Calls the backend implementation directly, bypassing virtual
168		dispatch. Otherwise identical to @ref io_stream::write_some.
169		*/
170		template<capy::ConstBufferSequence CB>
171	6x	[[nodiscard]] auto write_some(CB const& buffers)
172		{
173	6x	return native_write_awaitable<CB>(*this, buffers);
174		}
175		};
176
177		} // namespace boost::corosio
178
179		#endif // BOOST_COROSIO_NATIVE_NATIVE_STREAM_FILE_HPP
180