Index/src / corosio / src / io_context.cpp

src/corosio/src/io_context.cpp

100.0% Lines (81/81) 100.0% List of functions (15/15) 73.1% Branches (19/26)
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io_context.cpp
f(x) Functions (15)
Function Calls Lines Branches Blocks
boost::corosio::select_t::construct(boost::capy::execution_context&, unsigned int) :53 1171x 100.0% – 100.0% boost::corosio::kqueue_t::construct(boost::capy::execution_context&, unsigned int) :63 1806x 100.0% – 100.0% boost::corosio::(anonymous namespace)::check_options(boost::corosio::io_context_options const&) :95 47x 100.0% 75.0% 66.0% boost::corosio::(anonymous namespace)::create_thread_pool(boost::capy::execution_context&, boost::corosio::io_context_options const&) :116 2967x 100.0% – 100.0% boost::corosio::(anonymous namespace)::make_threading_config(boost::corosio::io_context_options const&) :132 2967x 100.0% – 100.0% boost::corosio::(anonymous namespace)::apply_scheduler_options(boost::corosio::detail::scheduler&, boost::corosio::io_context_options const&, unsigned int) :146 45x 100.0% 83.3% 91.0% boost::corosio::(anonymous namespace)::finish_construction(boost::corosio::detail::scheduler&) :198 2963x 100.0% – 100.0% boost::corosio::(anonymous namespace)::construct_default(boost::capy::execution_context&, unsigned int) :207 634x 100.0% – 100.0% boost::corosio::io_context::io_context() :222 617x 100.0% – 100.0% boost::corosio::io_context::io_context(unsigned int) :227 1250x 100.0% 50.0% 100.0% boost::corosio::io_context::io_context(boost::corosio::io_context_options const&, unsigned int) :236 22x 100.0% 66.7% 100.0% boost::corosio::io_context::apply_options_pre_(boost::corosio::io_context_options const&) :251 47x 100.0% – 100.0% boost::corosio::io_context::apply_options_post_(boost::corosio::io_context_options const&, unsigned int) :257 45x 100.0% – 100.0% boost::corosio::io_context::apply_threading_(boost::corosio::io_context_options const&) :266 2922x 100.0% – 100.0% boost::corosio::io_context::~io_context() :273 5728x 100.0% – 100.0%
Line Branch TLA Hits Source Code
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 #include <boost/corosio/io_context.hpp>
12 #include <boost/corosio/backend.hpp>
13 #include <boost/corosio/detail/thread_pool.hpp>
14
15 #include <algorithm>
16 #include <stdexcept>
17 #include <thread>
18
19 #if BOOST_COROSIO_HAS_EPOLL
20 #include <boost/corosio/native/detail/epoll/epoll_scheduler.hpp>
21 #endif
22
23 #if BOOST_COROSIO_HAS_SELECT
24 #include <boost/corosio/native/detail/select/select_scheduler.hpp>
25 #endif
26
27 #if BOOST_COROSIO_HAS_KQUEUE
28 #include <boost/corosio/native/detail/kqueue/kqueue_scheduler.hpp>
29 #endif
30
31 #if BOOST_COROSIO_HAS_URING
32 #include <boost/corosio/native/detail/uring/uring_scheduler.hpp>
33 #endif
34
35 #if BOOST_COROSIO_HAS_IOCP
36 #include <boost/corosio/native/detail/iocp/win_scheduler.hpp>
37 #endif
38
39 namespace boost::corosio {
40
41 #if BOOST_COROSIO_HAS_EPOLL
42 detail::scheduler&
43 epoll_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
44 {
45 auto& sched = ctx.make_service<detail::epoll_scheduler>(
46 static_cast<int>(concurrency_hint));
47 return sched;
48 }
49 #endif
50
51 #if BOOST_COROSIO_HAS_SELECT
52 detail::scheduler&
53 1171x select_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
54 {
55 2342x auto& sched = ctx.make_service<detail::select_scheduler>(
56 1171x static_cast<int>(concurrency_hint));
57 1171x return sched;
58 }
59 #endif
60
61 #if BOOST_COROSIO_HAS_KQUEUE
62 detail::scheduler&
63 1806x kqueue_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
64 {
65 3612x auto& sched = ctx.make_service<detail::kqueue_scheduler>(
66 1806x static_cast<int>(concurrency_hint));
67 1806x return sched;
68 }
69 #endif
70
71 #if BOOST_COROSIO_HAS_IOCP
72 detail::scheduler&
73 iocp_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
74 {
75 auto& sched = ctx.make_service<detail::win_scheduler>(
76 static_cast<int>(concurrency_hint));
77 return sched;
78 }
79 #endif
80
81 #if BOOST_COROSIO_HAS_URING
82 detail::scheduler&
83 uring_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
84 {
85 auto& sched = ctx.make_service<detail::uring_scheduler>(
86 static_cast<int>(concurrency_hint));
87 return sched;
88 }
89 #endif
90
91 namespace {
92
93 // Reject options that construct() would otherwise act on.
94 void
95 47x check_options([[maybe_unused]] io_context_options const& opts)
96 {
97 #if BOOST_COROSIO_POSIX
98
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 47x if (opts.thread_pool_size < 1)
99
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 2x throw std::invalid_argument("thread_pool_size must be at least 1");
100 #endif
101 45x }
102
103 // Create the shared pool that runs blocking file and DNS work. Runs
104 // after construct() so the pool is newer than the scheduler its work
105 // items post completions to: services shut down newest first, and the
106 // pool must join its workers while that scheduler can still drain what
107 // the last of them posted. Only the service is built here; its workers
108 // wait for a first post, so a context that hands off no blocking work
109 // carries no thread for the pool it holds.
110 //
111 // Every io_context constructor has to reach here, and reach it before
112 // anything can call thread_pool_ref::get(): that is what keeps the
113 // binding from ever constructing a pool on an initiator's thread, and
114 // make_service throws on a duplicate if get() got there first.
115 void
116 2967x create_thread_pool(
117 capy::execution_context& ctx,
118 [[maybe_unused]] io_context_options const& opts)
119 {
120 #if BOOST_COROSIO_POSIX
121 2967x ctx.make_service<detail::thread_pool>(opts.thread_pool_size);
122 #else
123 // thread_pool_size is a POSIX file-service option; the IOCP
124 // backend uses the pool for DNS alone.
125 ctx.make_service<detail::thread_pool>();
126 #endif
127 2967x }
128
129 // Map the locking tier to the scheduler's threading facilities. one_thread is
130 // set only for the lockless tiers, where a single run thread is guaranteed.
131 detail::scheduler::threading_config
132 2967x make_threading_config(io_context_options const& opts)
133 {
134 2967x detail::scheduler::threading_config cfg;
135 2967x cfg.scheduler_locking = opts.locking != locking_mode::unsafe;
136 2967x cfg.reactor_io_locking = opts.locking == locking_mode::safe;
137 2967x cfg.one_thread = opts.locking != locking_mode::safe;
138 2967x return cfg;
139 }
140
141 // Apply runtime tuning after construction. `concurrency_hint` is the effective
142 // hint (normalized to 1 for lockless tiers). Budget heuristic: with default
143 // budgets and hint > 1, disable the inline-completion fast path so multi-thread
144 // runs post everything for cross-thread work-stealing.
145 void
146 45x apply_scheduler_options(
147 [[maybe_unused]] detail::scheduler& sched,
148 [[maybe_unused]] io_context_options const& opts,
149 [[maybe_unused]] unsigned concurrency_hint)
150 {
151 45x sched.configure_threading(make_threading_config(opts));
152
153 #if BOOST_COROSIO_HAS_EPOLL || BOOST_COROSIO_HAS_KQUEUE || \
154 BOOST_COROSIO_HAS_SELECT
155 // dynamic_cast — when io_uring is also linked, the runtime probe may
156 // have selected uring_scheduler instead of a reactor_scheduler.
157
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 45x if (auto* reactor = dynamic_cast<detail::reactor_scheduler*>(&sched))
158 {
159 // Detect "user kept the defaults" by comparing all three to the
160 // io_context-options-defined struct defaults.
161 45x io_context_options defaults;
162 45x bool budget_at_defaults =
163
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 45x opts.inline_budget_initial == defaults.inline_budget_initial &&
164
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 35x opts.inline_budget_max == defaults.inline_budget_max &&
165 16x opts.unassisted_budget == defaults.unassisted_budget;
166
167 45x unsigned init = opts.inline_budget_initial;
168 45x unsigned max = opts.inline_budget_max;
169 45x unsigned ua = opts.unassisted_budget;
170
171
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 45x if (budget_at_defaults && concurrency_hint > 1)
172 {
173 // Multi-thread default: disable budget (post-everything).
174 4x init = 0;
175 4x max = 0;
176 4x ua = 0;
177 4x }
178
179 45x reactor->configure_reactor(opts.max_events_per_poll, init, max, ua);
180 45x }
181 #endif
182
183 #if BOOST_COROSIO_HAS_URING
184 if (auto* uring_sched = dynamic_cast<detail::uring_scheduler*>(&sched))
185 {
186 if (opts.enable_sqpoll)
187 uring_sched->configure_sqpoll(
188 true, opts.sq_thread_idle_ms, opts.sq_thread_cpu);
189 }
190 #endif
191 45x }
192
193 // Bring up backend infrastructure whose setup depends on the options
194 // applied above. Runs last in every constructor: an io_context that
195 // constructs is usable, so a kernel that refuses the infrastructure is
196 // reported from the constructor and not from the first operation.
197 void
198 2963x finish_construction([[maybe_unused]] detail::scheduler& sched)
199 {
200 #if BOOST_COROSIO_HAS_URING
201 if (auto* uring_sched = dynamic_cast<detail::uring_scheduler*>(&sched))
202 uring_sched->init_ring();
203 #endif
204 2963x }
205
206 detail::scheduler&
207 634x construct_default(capy::execution_context& ctx, unsigned concurrency_hint)
208 {
209 #if BOOST_COROSIO_HAS_IOCP
210 return iocp_t::construct(ctx, concurrency_hint);
211 #elif BOOST_COROSIO_HAS_EPOLL
212 return epoll_t::construct(ctx, concurrency_hint);
213 #elif BOOST_COROSIO_HAS_KQUEUE
214 634x return kqueue_t::construct(ctx, concurrency_hint);
215 #elif BOOST_COROSIO_HAS_SELECT
216 return select_t::construct(ctx, concurrency_hint);
217 #endif
218 }
219
220 } // anonymous namespace
221
222 617x io_context::io_context()
223 617x : io_context(std::max(1u, std::thread::hardware_concurrency()))
224 {
225 617x }
226
227 1250x io_context::io_context(unsigned concurrency_hint)
228 625x : capy::execution_context(this)
229
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 625x , sched_(&construct_default(*this, concurrency_hint))
230 625x {
231 // Threading config only; the plain path leaves the reactor budget at its
232 // defaults (no options-ctor budget heuristic).
233
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 625x apply_threading_(io_context_options{});
234 1250x }
235
236 22x io_context::io_context(
237 io_context_options const& opts_in, unsigned concurrency_hint)
238 11x : capy::execution_context(this)
239 11x , sched_(nullptr)
240 11x {
241
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 11x apply_options_pre_(opts_in);
242 // Computed before construct_default so IOCP's completion port is created
243 // with the effective concurrency.
244 9x unsigned const eff =
245 9x detail::effective_concurrency_hint(opts_in, concurrency_hint);
246
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 9x sched_ = &construct_default(*this, eff);
247
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 9x apply_options_post_(opts_in, eff);
248 22x }
249
250 void
251 47x io_context::apply_options_pre_(io_context_options const& opts)
252 {
253 47x check_options(opts);
254 47x }
255
256 void
257 45x io_context::apply_options_post_(
258 io_context_options const& opts_in, unsigned concurrency_hint)
259 {
260 45x create_thread_pool(*this, opts_in);
261 45x apply_scheduler_options(*sched_, opts_in, concurrency_hint);
262 45x finish_construction(*sched_);
263 45x }
264
265 void
266 2922x io_context::apply_threading_(io_context_options const& opts_in)
267 {
268 2922x create_thread_pool(*this, opts_in);
269 2922x sched_->configure_threading(make_threading_config(opts_in));
270 2922x finish_construction(*sched_);
271 2922x }
272
273 5728x io_context::~io_context()
274 2765x {
275 2963x shutdown();
276 2963x destroy();
277 5728x }
278
279 } // namespace boost::corosio
280