include/boost/corosio/native/detail/uring/uring_file_service_base.hpp

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uring_file_service_base.hpp

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1		//
2		// Copyright (c) 2026 Michael Vandeberg
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_DETAIL_URING_URING_FILE_SERVICE_BASE_HPP
11		#define BOOST_COROSIO_NATIVE_DETAIL_URING_URING_FILE_SERVICE_BASE_HPP
12
13		#include <boost/corosio/detail/platform.hpp>
14
15		#if BOOST_COROSIO_HAS_URING
16
17		#include <boost/corosio/detail/object_pool.hpp>
18		#include <boost/corosio/detail/object_ref.hpp>
19		#include <boost/corosio/io/io_object.hpp>
20		#include <boost/corosio/native/detail/uring/uring_scheduler.hpp>
21
22		#include <vector>
23
24		/*
25		Shared lifecycle plumbing for io_uring file services.
26
27		uring_stream_file_service and uring_random_access_file_service were
28		byte-for-byte identical apart from the impl type and open_file's parameter
29		type: both pop-or-new the file impl from a per-service recycling pool
30		and close every file on shutdown. This base factors that out; the
31		concrete services add only open_file.
32
33		This is a separate base from uring_socket_service_base because file
34		services differ from socket services in two ways that match the reactor
35		socket service instead: they CLOSE files on shutdown (sockets: cancel
36		only), and the impl ctor takes just the scheduler (sockets: service +
37		scheduler). See tasks/proactor-dedup-decisions.md (#14).
38
39		Requirements on File: derive from intrusive_list<File>::node, a
40		`File(Derived&, uring_scheduler&)` constructor, a
41		`void close_file() noexcept` method (cancel in-flight ops + close fd),
42		a `void reuse() noexcept` method, and a `retire()` override that
43		recycles through the owning service's private `pool_` member
44		(reachable because `File` is a friend). uring_descriptor_service
45		reuses it too, as asio's file service reuses its descriptor service.
46
47		@tparam Derived The concrete service (CRTP; unused today but kept for
48		symmetry / future hooks).
49		@tparam ServiceBase The abstract service vtable base (file_service,
50		random_access_file_service).
51		@tparam File The concrete io_uring file impl type.
52		*/
53
54		namespace boost::corosio::detail {
55
56		template<class Derived, class ServiceBase, class File>
57		class uring_file_service_base : public ServiceBase
58		{
59		friend Derived;
60		friend File;
61
62		// Private CRTP ctor: only `Derived` (the concrete service, a friend)
63		// constructs the base — prevents inheriting with the wrong Derived
64		// (bugprone-crtp-constructor-accessibility).
65	233x	explicit uring_file_service_base(uring_scheduler& sched) noexcept
66	233x	: sched_(&sched)
67		{
68	233x	}
69
70		public:
71	233x	~uring_file_service_base() override = default;
72
73	364x	io_object::implementation* construct() override
74		{
75	364x	return pool_.acquire(static_cast<Derived&>(this), sched_);
76		}
77
78	364x	void destroy(io_object::implementation* p) override
79		{
80		// close_file() closes the fd only once its cancel reached the kernel.
81	364x	auto& impl = static_cast<File&>(*p);
82	364x	impl.close_file();
83	364x	release(&impl);
84	364x	}
85
86	652x	void close(io_object::handle& h) override
87		{
88	652x	if (h.get())
89	652x	static_cast<File&>(*h.get()).close_file();
90	652x	}
91
92	233x	void shutdown() override
93		{
94		// See uring_socket_service_base::shutdown(): snapshot under an
95		// acquired reference, close without the pool lock held;
96		// shutdown() sets shutting-down and takes the snapshot in one
97		// critical section, so a close that drops the last ref deletes
98		// rather than recycles.
99	233x	std::vector<File*> live;
100	233x	pool_.shutdown(
101	233x	[&](File* f)
102		{
103	12x	acquire(f);
104	12x	live.push_back(f);
105		});
106	245x	for (auto* f : live)
107		{
108	12x	f->close_file();
109	12x	release(f);
110		}
111	233x	}
112
113		/// Return the scheduler used by files created by this service.
114		uring_scheduler& scheduler() noexcept
115		{
116		return *sched_;
117		}
118
119		protected:
120		uring_scheduler* sched_;
121		object_pool<File> pool_;
122
123		private:
124		uring_file_service_base(uring_file_service_base const&) = delete;
125		uring_file_service_base& operator=(uring_file_service_base const&) = delete;
126		};
127
128		} // namespace boost::corosio::detail
129
130		#endif // BOOST_COROSIO_HAS_URING
131
132		#endif // BOOST_COROSIO_NATIVE_DETAIL_URING_URING_FILE_SERVICE_BASE_HPP
133