Index/src / corosio / src / io_context.cpp

src/corosio/src/io_context.cpp

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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) :55 1925x 100.0% – 100.0% boost::corosio::kqueue_t::construct(boost::capy::execution_context&, unsigned int) :65 2714x 100.0% – 100.0% boost::corosio::(anonymous namespace)::check_options(boost::corosio::io_context_options const&) :97 61x 100.0% 75.0% 68.0% boost::corosio::(anonymous namespace)::create_thread_pool(boost::capy::execution_context&, boost::corosio::io_context_options const&) :140 4629x 100.0% – 100.0% boost::corosio::(anonymous namespace)::make_threading_config(boost::corosio::io_context_options const&) :156 4629x 100.0% – 100.0% boost::corosio::(anonymous namespace)::apply_scheduler_options(boost::corosio::detail::scheduler&, boost::corosio::io_context_options const&, unsigned int) :170 49x 100.0% 83.3% 91.0% boost::corosio::(anonymous namespace)::finish_construction(boost::corosio::detail::scheduler&) :222 4628x 100.0% – 100.0% boost::corosio::(anonymous namespace)::construct_default(boost::capy::execution_context&, unsigned int) :231 792x 100.0% – 100.0% boost::corosio::io_context::io_context() :246 775x 100.0% – 100.0% boost::corosio::io_context::io_context(unsigned int) :251 1566x 100.0% 50.0% 100.0% boost::corosio::io_context::io_context(boost::corosio::io_context_options const&, unsigned int) :260 22x 100.0% 66.7% 100.0% boost::corosio::io_context::apply_options_pre_(boost::corosio::io_context_options const&) :275 61x 100.0% – 100.0% boost::corosio::io_context::apply_options_post_(boost::corosio::io_context_options const&, unsigned int) :281 49x 100.0% – 100.0% boost::corosio::io_context::apply_threading_(boost::corosio::io_context_options const&) :290 4580x 100.0% – 100.0% boost::corosio::io_context::~io_context() :297 9026x 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 <limits>
17 #include <stdexcept>
18 #include <thread>
19
20 #if BOOST_COROSIO_HAS_EPOLL
21 #include <boost/corosio/native/detail/epoll/epoll_scheduler.hpp>
22 #include <sys/epoll.h>
23 #endif
24
25 #if BOOST_COROSIO_HAS_SELECT
26 #include <boost/corosio/native/detail/select/select_scheduler.hpp>
27 #endif
28
29 #if BOOST_COROSIO_HAS_KQUEUE
30 #include <boost/corosio/native/detail/kqueue/kqueue_scheduler.hpp>
31 #endif
32
33 #if BOOST_COROSIO_HAS_URING
34 #include <boost/corosio/native/detail/uring/uring_scheduler.hpp>
35 #endif
36
37 #if BOOST_COROSIO_HAS_IOCP
38 #include <boost/corosio/native/detail/iocp/win_scheduler.hpp>
39 #endif
40
41 namespace boost::corosio {
42
43 #if BOOST_COROSIO_HAS_EPOLL
44 detail::scheduler&
45 epoll_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
46 {
47 auto& sched = ctx.make_service<detail::epoll_scheduler>(
48 static_cast<int>(concurrency_hint));
49 return sched;
50 }
51 #endif
52
53 #if BOOST_COROSIO_HAS_SELECT
54 detail::scheduler&
55 1925x select_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
56 {
57 3850x auto& sched = ctx.make_service<detail::select_scheduler>(
58 1925x static_cast<int>(concurrency_hint));
59 1925x return sched;
60 }
61 #endif
62
63 #if BOOST_COROSIO_HAS_KQUEUE
64 detail::scheduler&
65 2714x kqueue_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
66 {
67 5428x auto& sched = ctx.make_service<detail::kqueue_scheduler>(
68 2714x static_cast<int>(concurrency_hint));
69 2714x return sched;
70 }
71 #endif
72
73 #if BOOST_COROSIO_HAS_IOCP
74 detail::scheduler&
75 iocp_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
76 {
77 auto& sched = ctx.make_service<detail::win_scheduler>(
78 static_cast<int>(concurrency_hint));
79 return sched;
80 }
81 #endif
82
83 #if BOOST_COROSIO_HAS_URING
84 detail::scheduler&
85 uring_t::construct(capy::execution_context& ctx, unsigned concurrency_hint)
86 {
87 auto& sched = ctx.make_service<detail::uring_scheduler>(
88 static_cast<int>(concurrency_hint));
89 return sched;
90 }
91 #endif
92
93 namespace {
94
95 // Reject options that construct() would otherwise act on.
96 void
97 61x check_options([[maybe_unused]] io_context_options const& opts)
98 {
99 #if BOOST_COROSIO_POSIX
100
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 61x if (opts.thread_pool_size < 1)
101
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 2x throw std::invalid_argument("thread_pool_size must be at least 1");
102 #endif
103 #if BOOST_COROSIO_HAS_EPOLL || BOOST_COROSIO_HAS_KQUEUE || \
104 BOOST_COROSIO_HAS_SELECT
105 // The reactor narrows these to int.
106 59x constexpr auto int_max =
107 static_cast<unsigned>((std::numeric_limits<int>::max)());
108 #if BOOST_COROSIO_HAS_EPOLL
109 // Larger than epoll_wait accepts, which would fail every wait.
110 constexpr auto max_events =
111 static_cast<unsigned>(int_max / sizeof(epoll_event));
112 if (opts.max_events_per_poll < 1 || opts.max_events_per_poll > max_events)
113 throw std::invalid_argument(
114 "max_events_per_poll must be in "
115 "[1, INT_MAX / sizeof(epoll_event)]");
116 #else
117
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 59x if (opts.max_events_per_poll < 1 || opts.max_events_per_poll > int_max)
118
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 6x throw std::invalid_argument(
119 "max_events_per_poll must be in [1, INT_MAX]");
120 #endif
121
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 53x if (opts.inline_budget_max > int_max)
122
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 4x throw std::invalid_argument(
123 "inline_budget_max must be in [0, INT_MAX]");
124 #endif
125 49x }
126
127 // Create the shared pool that runs blocking file and DNS work. Runs
128 // after construct() so the pool is newer than the scheduler its work
129 // items post completions to: services shut down newest first, and the
130 // pool must join its workers while that scheduler can still drain what
131 // the last of them posted. Only the service is built here; its workers
132 // wait for a first post, so a context that hands off no blocking work
133 // carries no thread for the pool it holds.
134 //
135 // Every io_context constructor has to reach here, and reach it before
136 // anything can call thread_pool_ref::get(): that is what keeps the
137 // binding from ever constructing a pool on an initiator's thread, and
138 // make_service throws on a duplicate if get() got there first.
139 void
140 4629x create_thread_pool(
141 capy::execution_context& ctx,
142 [[maybe_unused]] io_context_options const& opts)
143 {
144 #if BOOST_COROSIO_POSIX
145 4629x ctx.make_service<detail::thread_pool>(opts.thread_pool_size);
146 #else
147 // thread_pool_size is a POSIX file-service option; the IOCP
148 // backend uses the pool for DNS alone.
149 ctx.make_service<detail::thread_pool>();
150 #endif
151 4629x }
152
153 // Map the locking tier to the scheduler's threading facilities. one_thread is
154 // set only for the lockless tiers, where a single run thread is guaranteed.
155 detail::scheduler::threading_config
156 4629x make_threading_config(io_context_options const& opts)
157 {
158 4629x detail::scheduler::threading_config cfg;
159 4629x cfg.scheduler_locking = opts.locking != locking_mode::unsafe;
160 4629x cfg.reactor_io_locking = opts.locking == locking_mode::safe;
161 4629x cfg.one_thread = opts.locking != locking_mode::safe;
162 4629x return cfg;
163 }
164
165 // Apply runtime tuning after construction. `concurrency_hint` is the effective
166 // hint (normalized to 1 for lockless tiers). Budget heuristic: with default
167 // budgets and hint > 1, disable the inline-completion fast path so multi-thread
168 // runs post everything for cross-thread work-stealing.
169 void
170 49x apply_scheduler_options(
171 [[maybe_unused]] detail::scheduler& sched,
172 [[maybe_unused]] io_context_options const& opts,
173 [[maybe_unused]] unsigned concurrency_hint)
174 {
175 49x sched.configure_threading(make_threading_config(opts));
176
177 #if BOOST_COROSIO_HAS_EPOLL || BOOST_COROSIO_HAS_KQUEUE || \
178 BOOST_COROSIO_HAS_SELECT
179 // dynamic_cast — when io_uring is also linked, the runtime probe may
180 // have selected uring_scheduler instead of a reactor_scheduler.
181
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 49x if (auto* reactor = dynamic_cast<detail::reactor_scheduler*>(&sched))
182 {
183 // Detect "user kept the defaults" by comparing all three to the
184 // io_context-options-defined struct defaults.
185 49x io_context_options defaults;
186 49x bool budget_at_defaults =
187
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 49x opts.inline_budget_initial == defaults.inline_budget_initial &&
188
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 39x opts.inline_budget_max == defaults.inline_budget_max &&
189 20x opts.unassisted_budget == defaults.unassisted_budget;
190
191 49x unsigned init = opts.inline_budget_initial;
192 49x unsigned max = opts.inline_budget_max;
193 49x unsigned ua = opts.unassisted_budget;
194
195
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 49x if (budget_at_defaults && concurrency_hint > 1)
196 {
197 // Multi-thread default: disable budget (post-everything).
198 2x init = 0;
199 2x max = 0;
200 2x ua = 0;
201 2x }
202
203 49x reactor->configure_reactor(opts.max_events_per_poll, init, max, ua);
204 49x }
205 #endif
206
207 #if BOOST_COROSIO_HAS_URING
208 if (auto* uring_sched = dynamic_cast<detail::uring_scheduler*>(&sched))
209 {
210 if (opts.enable_sqpoll)
211 uring_sched->configure_sqpoll(
212 true, opts.sq_thread_idle_ms, opts.sq_thread_cpu);
213 }
214 #endif
215 49x }
216
217 // Bring up backend infrastructure whose setup depends on the options
218 // applied above. Runs last in every constructor: an io_context that
219 // constructs is usable, so a kernel that refuses the infrastructure is
220 // reported from the constructor and not from the first operation.
221 void
222 4628x finish_construction([[maybe_unused]] detail::scheduler& sched)
223 {
224 #if BOOST_COROSIO_HAS_URING
225 if (auto* uring_sched = dynamic_cast<detail::uring_scheduler*>(&sched))
226 uring_sched->init_ring();
227 #endif
228 4628x }
229
230 detail::scheduler&
231 792x construct_default(capy::execution_context& ctx, unsigned concurrency_hint)
232 {
233 #if BOOST_COROSIO_HAS_IOCP
234 return iocp_t::construct(ctx, concurrency_hint);
235 #elif BOOST_COROSIO_HAS_EPOLL
236 return epoll_t::construct(ctx, concurrency_hint);
237 #elif BOOST_COROSIO_HAS_KQUEUE
238 792x return kqueue_t::construct(ctx, concurrency_hint);
239 #elif BOOST_COROSIO_HAS_SELECT
240 return select_t::construct(ctx, concurrency_hint);
241 #endif
242 }
243
244 } // anonymous namespace
245
246 775x io_context::io_context()
247 775x : io_context(std::max(1u, std::thread::hardware_concurrency()))
248 {
249 775x }
250
251 1566x io_context::io_context(unsigned concurrency_hint)
252 783x : capy::execution_context(this)
253
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 783x , sched_(&construct_default(*this, concurrency_hint))
254 783x {
255 // Threading config only; the plain path leaves the reactor budget at its
256 // defaults (no options-ctor budget heuristic).
257
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 783x apply_threading_(io_context_options{});
258 1566x }
259
260 22x io_context::io_context(
261 io_context_options const& opts_in, unsigned concurrency_hint)
262 11x : capy::execution_context(this)
263 11x , sched_(nullptr)
264 11x {
265
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 11x apply_options_pre_(opts_in);
266 // Computed before construct_default so IOCP's completion port is created
267 // with the effective concurrency.
268 9x unsigned const eff =
269 9x detail::effective_concurrency_hint(opts_in, concurrency_hint);
270
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 9x sched_ = &construct_default(*this, eff);
271
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 9x apply_options_post_(opts_in, eff);
272 22x }
273
274 void
275 61x io_context::apply_options_pre_(io_context_options const& opts)
276 {
277 61x check_options(opts);
278 61x }
279
280 void
281 49x io_context::apply_options_post_(
282 io_context_options const& opts_in, unsigned concurrency_hint)
283 {
284 49x create_thread_pool(*this, opts_in);
285 49x apply_scheduler_options(*sched_, opts_in, concurrency_hint);
286 49x finish_construction(*sched_);
287 49x }
288
289 void
290 4580x io_context::apply_threading_(io_context_options const& opts_in)
291 {
292 4580x create_thread_pool(*this, opts_in);
293 4580x sched_->configure_threading(make_threading_config(opts_in));
294 4580x finish_construction(*sched_);
295 4580x }
296
297 9026x io_context::~io_context()
298 4397x {
299 4629x shutdown();
300 4629x destroy();
301 9026x }
302
303 } // namespace boost::corosio
304