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

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uring_socket_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_SOCKET_SERVICE_BASE_HPP
11		#define BOOST_COROSIO_NATIVE_DETAIL_URING_URING_SOCKET_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		#include <boost/capy/ex/execution_context.hpp>
22
23		#include <vector>
24
25		/*
26		Shared lifecycle plumbing for io_uring socket/datagram services.
27
28		construct / destroy / shutdown / close / scheduler() are identical across
29		uring_tcp_service, uring_udp_service, uring_local_stream_service,
30		and uring_local_datagram_service — they all pop-or-new the impl from a
31		per-service recycling pool, cancel on shutdown, and close eagerly. This
32		base factors that out; the concrete services add only the protocol-
33		specific open/bind/adopt.
34
35		This is io_uring's own service base rather than a reuse of
36		reactor_socket_service: io_uring cancels (not closes) on shutdown and
37		constructs impls with a (service&, scheduler&) ctor, vs. the reactor's
38		close-on-shutdown and Impl(Derived&) ctor. Reusing the reactor template
39		would force a teardown behavior change for marginal extra sharing. See
40		tasks/proactor-dedup-decisions.md (#13).
41
42		Requirements on Socket: a `(Derived& service, uring_scheduler& sched)`
43		constructor, a `void close_socket() noexcept` method (cancel in-flight
44		ops + close fd + reset cached endpoints), a `void reuse() noexcept`
45		method, and derivation from `intrusive_list<Socket>::node` (the pool's
46		live/free linkage).
47
48		@tparam Derived The concrete service (CRTP, passed to the Socket ctor).
49		@tparam ServiceBase The abstract service vtable base (tcp_service, ...).
50		@tparam Socket The concrete io_uring socket impl type.
51		*/
52
53		namespace boost::corosio::detail {
54
55		template<class Derived, class ServiceBase, class Socket>
56		class uring_socket_service_base : public ServiceBase
57		{
58		friend Derived;
59		friend Socket;
60
61		// Private CRTP ctor: only `Derived` (the concrete service, a friend)
62		// constructs the base — prevents inheriting with the wrong Derived
63		// (bugprone-crtp-constructor-accessibility).
64	745x	explicit uring_socket_service_base(capy::execution_context& ctx)
65	745x	: sched_(&ctx.template use_service<uring_scheduler>())
66		{
67	745x	}
68
69		public:
70	745x	~uring_socket_service_base() override = default;
71
72	745x	void shutdown() override
73		{
74		// Snapshot live impls under an acquired reference, then cancel
75		// without the pool lock held to avoid inversion if cancel() ever
76		// re-enters the service. shutdown() sets shutting-down and
77		// takes the snapshot under one critical section, so each
78		// cancel's own release (if it drops the last ref) deletes
79		// rather than recycles. In-flight ops hold their own
80		// references, so every impl stays alive while its cancel CQEs
81		// are processed.
82	745x	std::vector<Socket*> live;
83	745x	pool_.shutdown(
84	745x	[&](Socket* s)
85		{
86	842x	acquire(s);
87	842x	live.push_back(s);
88		});
89	1587x	for (auto* s : live)
90		{
91	842x	s->cancel();
92	842x	release(s);
93		}
94	745x	}
95
96	7755x	io_object::implementation* construct() override
97		{
98	7755x	return acquire_impl();
99		}
100
101	11348x	void destroy(io_object::implementation* p) override
102		{
103	11348x	if (!p)
104	✗	return;
105	11348x	release(static_cast<Socket*>(p));
106		}
107
108		// Close the fd eagerly when the public close() is called, before
109		// destroy() drops the service's reference and recycling runs.
110	18670x	void close(io_object::handle& h) override
111		{
112	18670x	if (auto* sock = static_cast<Socket*>(h.get()))
113	18670x	sock->close_socket();
114	18670x	}
115
116		/// Return the scheduler used by sockets created by this service.
117		uring_scheduler& scheduler() noexcept
118		{
119		return *sched_;
120		}
121
122		protected:
123		/** Pop a recycled impl or news one, with the service reference held.
124
125		Used by both `construct()` and the `adopt_fd` accepted-connection
126		path (which additionally calls `assign_fd()` on the result).
127		*/
128	11348x	Socket* acquire_impl()
129		{
130	11348x	return pool_.acquire(static_cast<Derived&>(this), sched_);
131		}
132
133		uring_scheduler* sched_;
134		object_pool<Socket> pool_;
135
136		private:
137		uring_socket_service_base(uring_socket_service_base const&) = delete;
138		uring_socket_service_base&
139		operator=(uring_socket_service_base const&) = delete;
140		};
141
142		} // namespace boost::corosio::detail
143
144		#endif // BOOST_COROSIO_HAS_URING
145
146		#endif // BOOST_COROSIO_NATIVE_DETAIL_URING_URING_SOCKET_SERVICE_BASE_HPP
147