Root/libs / corosio / src / corosio / src / detail / select / scheduler.cpp
Prev Index Next

libs/corosio/src/corosio/src/detail/select/scheduler.cpp

73.4% Lines (267/364) 87.5% Functions (28/32) 63.7% Branches (170/267)
libs/corosio/src/corosio/src/detail/select/scheduler.cpp
Line Branch Hits Source Code
1 //
2 // Copyright (c) 2026 Steve Gerbino
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 #include <boost/corosio/detail/platform.hpp>
11
12 #if BOOST_COROSIO_HAS_SELECT
13
14 #include "src/detail/select/scheduler.hpp"
15 #include "src/detail/select/op.hpp"
16 #include "src/detail/make_err.hpp"
17 #include "src/detail/posix/resolver_service.hpp"
18 #include "src/detail/posix/signals.hpp"
19
20 #include <boost/corosio/detail/except.hpp>
21 #include <boost/corosio/detail/thread_local_ptr.hpp>
22
23 #include <chrono>
24 #include <limits>
25
26 #include <errno.h>
27 #include <fcntl.h>
28 #include <sys/select.h>
29 #include <sys/socket.h>
30 #include <unistd.h>
31
32 /*
33 select Scheduler - Single Reactor Model
34 =======================================
35
36 This scheduler mirrors the epoll_scheduler design but uses select() instead
37 of epoll for I/O multiplexing. The thread coordination strategy is identical:
38 one thread becomes the "reactor" while others wait on a condition variable.
39
40 Thread Model
41 ------------
42 - ONE thread runs select() at a time (the reactor thread)
43 - OTHER threads wait on wakeup_event_ (condition variable) for handlers
44 - When work is posted, exactly one waiting thread wakes via notify_one()
45
46 Key Differences from epoll
47 --------------------------
48 - Uses self-pipe instead of eventfd for interruption (more portable)
49 - fd_set rebuilding each iteration (O(n) vs O(1) for epoll)
50 - FD_SETSIZE limit (~1024 fds on most systems)
51 - Level-triggered only (no edge-triggered mode)
52
53 Self-Pipe Pattern
54 -----------------
55 To interrupt a blocking select() call (e.g., when work is posted or a timer
56 expires), we write a byte to pipe_fds_[1]. The read end pipe_fds_[0] is
57 always in the read_fds set, so select() returns immediately. We drain the
58 pipe to clear the readable state.
59
60 fd-to-op Mapping
61 ----------------
62 We use an unordered_map<int, fd_state> to track which operations are
63 registered for each fd. This allows O(1) lookup when select() returns
64 ready fds. Each fd can have at most one read op and one write op registered.
65 */
66
67 namespace boost::corosio::detail {
68
69 namespace {
70
71 struct scheduler_context
72 {
73 select_scheduler const* key;
74 scheduler_context* next;
75 };
76
77 corosio::detail::thread_local_ptr<scheduler_context> context_stack;
78
79 struct thread_context_guard
80 {
81 scheduler_context frame_;
82
83 92 explicit thread_context_guard(
84 select_scheduler const* ctx) noexcept
85 92 : frame_{ctx, context_stack.get()}
86 {
87 92 context_stack.set(&frame_);
88 92 }
89
90 92 ~thread_context_guard() noexcept
91 {
92 92 context_stack.set(frame_.next);
93 92 }
94 };
95
96 } // namespace
97
98 120 select_scheduler::
99 select_scheduler(
100 capy::execution_context& ctx,
101 120 int)
102 120 : pipe_fds_{-1, -1}
103 120 , outstanding_work_(0)
104 120 , stopped_(false)
105 120 , shutdown_(false)
106 120 , max_fd_(-1)
107 120 , reactor_running_(false)
108 120 , reactor_interrupted_(false)
109 240 , idle_thread_count_(0)
110 {
111 // Create self-pipe for interrupting select()
112
1/2
✗ Branch 1 not taken.
✓ Branch 2 taken 120 times.
 120 if (::pipe(pipe_fds_) < 0)
113 ✗ detail::throw_system_error(make_err(errno), "pipe");
114
115 // Set both ends to non-blocking and close-on-exec
116
2/2
✓ Branch 0 taken 240 times.
✓ Branch 1 taken 120 times.
 360 for (int i = 0; i < 2; ++i)
117 {
118
1/1
✓ Branch 1 taken 240 times.
 240 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
119
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 240 times.
 240 if (flags == -1)
120 {
121 ✗ int errn = errno;
122 ✗ ::close(pipe_fds_[0]);
123 ✗ ::close(pipe_fds_[1]);
124 ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
125 }
126
2/3
✓ Branch 1 taken 240 times.
✗ Branch 3 not taken.
✓ Branch 4 taken 240 times.
 240 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
127 {
128 ✗ int errn = errno;
129 ✗ ::close(pipe_fds_[0]);
130 ✗ ::close(pipe_fds_[1]);
131 ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
132 }
133
2/3
✓ Branch 1 taken 240 times.
✗ Branch 3 not taken.
✓ Branch 4 taken 240 times.
 240 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
134 {
135 ✗ int errn = errno;
136 ✗ ::close(pipe_fds_[0]);
137 ✗ ::close(pipe_fds_[1]);
138 ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
139 }
140 }
141
142
1/1
✓ Branch 1 taken 120 times.
 120 timer_svc_ = &get_timer_service(ctx, *this);
143
1/1
✓ Branch 3 taken 120 times.
 120 timer_svc_->set_on_earliest_changed(
144 timer_service::callback(
145 this,
146 2307 [](void* p) { static_cast<select_scheduler*>(p)->interrupt_reactor(); }));
147
148 // Initialize resolver service
149
1/1
✓ Branch 1 taken 120 times.
 120 get_resolver_service(ctx, *this);
150
151 // Initialize signal service
152
1/1
✓ Branch 1 taken 120 times.
 120 get_signal_service(ctx, *this);
153
154 // Push task sentinel to interleave reactor runs with handler execution
155 120 completed_ops_.push(&task_op_);
156 120 }
157
158 240 select_scheduler::
159 120 ~select_scheduler()
160 {
161
1/2
✓ Branch 0 taken 120 times.
✗ Branch 1 not taken.
 120 if (pipe_fds_[0] >= 0)
162 120 ::close(pipe_fds_[0]);
163
1/2
✓ Branch 0 taken 120 times.
✗ Branch 1 not taken.
 120 if (pipe_fds_[1] >= 0)
164 120 ::close(pipe_fds_[1]);
165 240 }
166
167 void
168 120 select_scheduler::
169 shutdown()
170 {
171 {
172
1/1
✓ Branch 1 taken 120 times.
 120 std::unique_lock lock(mutex_);
173 120 shutdown_ = true;
174
175
2/2
✓ Branch 1 taken 120 times.
✓ Branch 2 taken 120 times.
 240 while (auto* h = completed_ops_.pop())
176 {
177
1/2
✓ Branch 0 taken 120 times.
✗ Branch 1 not taken.
 120 if (h == &task_op_)
178 120 continue;
179 ✗ lock.unlock();
180 ✗ h->destroy();
181 ✗ lock.lock();
182 120 }
183 120 }
184
185 120 outstanding_work_.store(0, std::memory_order_release);
186
187
1/2
✓ Branch 0 taken 120 times.
✗ Branch 1 not taken.
 120 if (pipe_fds_[1] >= 0)
188 120 interrupt_reactor();
189
190 120 wakeup_event_.notify_all();
191 120 }
192
193 void
194 168 select_scheduler::
195 post(capy::coro h) const
196 {
197 struct post_handler final
198 : scheduler_op
199 {
200 capy::coro h_;
201
202 explicit
203 168 post_handler(capy::coro h)
204 168 : h_(h)
205 {
206 168 }
207
208 ~post_handler() = default;
209
210 168 void operator()() override
211 {
212 168 auto h = h_;
213
1/2
✓ Branch 0 taken 168 times.
✗ Branch 1 not taken.
 168 delete this;
214
1/1
✓ Branch 1 taken 168 times.
 168 h.resume();
215 168 }
216
217 ✗ void destroy() override
218 {
219 ✗ delete this;
220 ✗ }
221 };
222
223
1/1
✓ Branch 1 taken 168 times.
 168 auto ph = std::make_unique<post_handler>(h);
224 168 outstanding_work_.fetch_add(1, std::memory_order_relaxed);
225
226
1/1
✓ Branch 1 taken 168 times.
 168 std::unique_lock lock(mutex_);
227 168 completed_ops_.push(ph.release());
228
1/1
✓ Branch 1 taken 168 times.
 168 wake_one_thread_and_unlock(lock);
229 168 }
230
231 void
232 161022 select_scheduler::
233 post(scheduler_op* h) const
234 {
235 161022 outstanding_work_.fetch_add(1, std::memory_order_relaxed);
236
237
1/1
✓ Branch 1 taken 161022 times.
 161022 std::unique_lock lock(mutex_);
238 161022 completed_ops_.push(h);
239
1/1
✓ Branch 1 taken 161022 times.
 161022 wake_one_thread_and_unlock(lock);
240 161022 }
241
242 void
243 2304 select_scheduler::
244 on_work_started() noexcept
245 {
246 2304 outstanding_work_.fetch_add(1, std::memory_order_relaxed);
247 2304 }
248
249 void
250 2298 select_scheduler::
251 on_work_finished() noexcept
252 {
253
2/2
✓ Branch 0 taken 18 times.
✓ Branch 1 taken 2280 times.
 4596 if (outstanding_work_.fetch_sub(1, std::memory_order_acq_rel) == 1)
254 18 stop();
255 2298 }
256
257 bool
258 167894 select_scheduler::
259 running_in_this_thread() const noexcept
260 {
261
2/2
✓ Branch 1 taken 167739 times.
✓ Branch 2 taken 155 times.
 167894 for (auto* c = context_stack.get(); c != nullptr; c = c->next)
262
1/2
✓ Branch 0 taken 167739 times.
✗ Branch 1 not taken.
 167739 if (c->key == this)
263 167739 return true;
264 155 return false;
265 }
266
267 void
268 18 select_scheduler::
269 stop()
270 {
271 18 bool expected = false;
272
1/2
✓ Branch 1 taken 18 times.
✗ Branch 2 not taken.
 18 if (stopped_.compare_exchange_strong(expected, true,
273 std::memory_order_release, std::memory_order_relaxed))
274 {
275 // Wake all threads so they notice stopped_ and exit
276 {
277
1/1
✓ Branch 1 taken 18 times.
 18 std::lock_guard lock(mutex_);
278 18 wakeup_event_.notify_all();
279 18 }
280
1/1
✓ Branch 1 taken 18 times.
 18 interrupt_reactor();
281 }
282 18 }
283
284 bool
285 1 select_scheduler::
286 stopped() const noexcept
287 {
288 1 return stopped_.load(std::memory_order_acquire);
289 }
290
291 void
292 34 select_scheduler::
293 restart()
294 {
295 34 stopped_.store(false, std::memory_order_release);
296 34 }
297
298 std::size_t
299 89 select_scheduler::
300 run()
301 {
302
1/2
✗ Branch 1 not taken.
✓ Branch 2 taken 89 times.
 89 if (stopped_.load(std::memory_order_acquire))
303 ✗ return 0;
304
305
1/2
✗ Branch 1 not taken.
✓ Branch 2 taken 89 times.
 178 if (outstanding_work_.load(std::memory_order_acquire) == 0)
306 {
307 ✗ stop();
308 ✗ return 0;
309 }
310
311 89 thread_context_guard ctx(this);
312
313 89 std::size_t n = 0;
314
3/3
✓ Branch 1 taken 165473 times.
✓ Branch 3 taken 165384 times.
✓ Branch 4 taken 89 times.
 165473 while (do_one(-1))
315
1/2
✓ Branch 1 taken 165384 times.
✗ Branch 2 not taken.
 165384 if (n != (std::numeric_limits<std::size_t>::max)())
316 165384 ++n;
317 89 return n;
318 89 }
319
320 std::size_t
321 ✗ select_scheduler::
322 run_one()
323 {
324 ✗ if (stopped_.load(std::memory_order_acquire))
325 ✗ return 0;
326
327 ✗ if (outstanding_work_.load(std::memory_order_acquire) == 0)
328 {
329 ✗ stop();
330 ✗ return 0;
331 }
332
333 ✗ thread_context_guard ctx(this);
334 ✗ return do_one(-1);
335 ✗ }
336
337 std::size_t
338 3 select_scheduler::
339 wait_one(long usec)
340 {
341
1/2
✗ Branch 1 not taken.
✓ Branch 2 taken 3 times.
 3 if (stopped_.load(std::memory_order_acquire))
342 ✗ return 0;
343
344
1/2
✗ Branch 1 not taken.
✓ Branch 2 taken 3 times.
 6 if (outstanding_work_.load(std::memory_order_acquire) == 0)
345 {
346 ✗ stop();
347 ✗ return 0;
348 }
349
350 3 thread_context_guard ctx(this);
351
1/1
✓ Branch 1 taken 3 times.
 3 return do_one(usec);
352 3 }
353
354 std::size_t
355 ✗ select_scheduler::
356 poll()
357 {
358 ✗ if (stopped_.load(std::memory_order_acquire))
359 ✗ return 0;
360
361 ✗ if (outstanding_work_.load(std::memory_order_acquire) == 0)
362 {
363 ✗ stop();
364 ✗ return 0;
365 }
366
367 ✗ thread_context_guard ctx(this);
368
369 ✗ std::size_t n = 0;
370 ✗ while (do_one(0))
371 ✗ if (n != (std::numeric_limits<std::size_t>::max)())
372 ✗ ++n;
373 ✗ return n;
374 ✗ }
375
376 std::size_t
377 ✗ select_scheduler::
378 poll_one()
379 {
380 ✗ if (stopped_.load(std::memory_order_acquire))
381 ✗ return 0;
382
383 ✗ if (outstanding_work_.load(std::memory_order_acquire) == 0)
384 {
385 ✗ stop();
386 ✗ return 0;
387 }
388
389 ✗ thread_context_guard ctx(this);
390 ✗ return do_one(0);
391 ✗ }
392
393 void
394 4309 select_scheduler::
395 register_fd(int fd, select_op* op, int events) const
396 {
397 // Validate fd is within select() limits
398
2/4
✓ Branch 0 taken 4309 times.
✗ Branch 1 not taken.
✗ Branch 2 not taken.
✓ Branch 3 taken 4309 times.
 4309 if (fd < 0 || fd >= FD_SETSIZE)
399 ✗ detail::throw_system_error(make_err(EINVAL), "select: fd out of range");
400
401 {
402
1/1
✓ Branch 1 taken 4309 times.
 4309 std::lock_guard lock(mutex_);
403
404
1/1
✓ Branch 1 taken 4309 times.
 4309 auto& state = registered_fds_[fd];
405
2/2
✓ Branch 0 taken 2233 times.
✓ Branch 1 taken 2076 times.
 4309 if (events & event_read)
406 2233 state.read_op = op;
407
2/2
✓ Branch 0 taken 2076 times.
✓ Branch 1 taken 2233 times.
 4309 if (events & event_write)
408 2076 state.write_op = op;
409
410
2/2
✓ Branch 0 taken 178 times.
✓ Branch 1 taken 4131 times.
 4309 if (fd > max_fd_)
411 178 max_fd_ = fd;
412 4309 }
413
414 // Wake the reactor so a thread blocked in select() rebuilds its fd_sets
415 // with the newly registered fd.
416 4309 interrupt_reactor();
417 4309 }
418
419 void
420 4316 select_scheduler::
421 deregister_fd(int fd, int events) const
422 {
423
1/1
✓ Branch 1 taken 4316 times.
 4316 std::lock_guard lock(mutex_);
424
425
1/1
✓ Branch 1 taken 4316 times.
 4316 auto it = registered_fds_.find(fd);
426
2/2
✓ Branch 2 taken 4203 times.
✓ Branch 3 taken 113 times.
 4316 if (it == registered_fds_.end())
427 4203 return;
428
429
1/2
✓ Branch 0 taken 113 times.
✗ Branch 1 not taken.
 113 if (events & event_read)
430 113 it->second.read_op = nullptr;
431
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 113 times.
 113 if (events & event_write)
432 ✗ it->second.write_op = nullptr;
433
434 // Remove entry if both are null
435
3/6
✓ Branch 1 taken 113 times.
✗ Branch 2 not taken.
✓ Branch 4 taken 113 times.
✗ Branch 5 not taken.
✓ Branch 6 taken 113 times.
✗ Branch 7 not taken.
 113 if (!it->second.read_op && !it->second.write_op)
436 {
437
1/1
✓ Branch 1 taken 113 times.
 113 registered_fds_.erase(it);
438
439 // Recalculate max_fd_ if needed
440
2/2
✓ Branch 0 taken 112 times.
✓ Branch 1 taken 1 time.
 113 if (fd == max_fd_)
441 {
442 112 max_fd_ = pipe_fds_[0]; // At minimum, the pipe read end
443
1/2
✗ Branch 7 not taken.
✓ Branch 8 taken 112 times.
 112 for (auto& [registered_fd, state] : registered_fds_)
444 {
445 ✗ if (registered_fd > max_fd_)
446 ✗ max_fd_ = registered_fd;
447 }
448 }
449 }
450 4316 }
451
452 void
453 4309 select_scheduler::
454 work_started() const noexcept
455 {
456 4309 outstanding_work_.fetch_add(1, std::memory_order_relaxed);
457 4309 }
458
459 void
460 165505 select_scheduler::
461 work_finished() const noexcept
462 {
463
2/2
✓ Branch 0 taken 72 times.
✓ Branch 1 taken 165433 times.
 331010 if (outstanding_work_.fetch_sub(1, std::memory_order_acq_rel) == 1)
464 {
465 // Last work item completed - wake all threads so they can exit.
466 72 std::unique_lock lock(mutex_);
467 72 wakeup_event_.notify_all();
468
1/4
✗ Branch 0 not taken.
✓ Branch 1 taken 72 times.
✗ Branch 2 not taken.
✗ Branch 3 not taken.
 72 if (reactor_running_ && !reactor_interrupted_)
469 {
470 ✗ reactor_interrupted_ = true;
471 ✗ lock.unlock();
472 ✗ interrupt_reactor();
473 }
474 72 }
475 165505 }
476
477 void
478 6953 select_scheduler::
479 interrupt_reactor() const
480 {
481 6953 char byte = 1;
482
1/1
✓ Branch 1 taken 6953 times.
 6953 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
483 6953 }
484
485 void
486 161190 select_scheduler::
487 wake_one_thread_and_unlock(std::unique_lock<std::mutex>& lock) const
488 {
489
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 161190 times.
 161190 if (idle_thread_count_ > 0)
490 {
491 // Idle worker exists - wake it via condvar
492 ✗ wakeup_event_.notify_one();
493 ✗ lock.unlock();
494 }
495
4/4
✓ Branch 0 taken 245 times.
✓ Branch 1 taken 160945 times.
✓ Branch 2 taken 199 times.
✓ Branch 3 taken 46 times.
 161190 else if (reactor_running_ && !reactor_interrupted_)
496 {
497 // No idle workers but reactor is running - interrupt it
498 199 reactor_interrupted_ = true;
499 199 lock.unlock();
500 199 interrupt_reactor();
501 }
502 else
503 {
504 // No one to wake
505 160991 lock.unlock();
506 }
507 161190 }
508
509 struct work_guard
510 {
511 select_scheduler const* self;
512 271710 ~work_guard() { self->work_finished(); }
513 };
514
515 long
516 6489 select_scheduler::
517 calculate_timeout(long requested_timeout_us) const
518 {
519
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 6489 times.
 6489 if (requested_timeout_us == 0)
520 ✗ return 0;
521
522 6489 auto nearest = timer_svc_->nearest_expiry();
523
3/3
✓ Branch 2 taken 6489 times.
✓ Branch 4 taken 36 times.
✓ Branch 5 taken 6453 times.
 6489 if (nearest == timer_service::time_point::max())
524 36 return requested_timeout_us;
525
526 6453 auto now = std::chrono::steady_clock::now();
527
3/3
✓ Branch 1 taken 6453 times.
✓ Branch 4 taken 37 times.
✓ Branch 5 taken 6416 times.
 6453 if (nearest <= now)
528 37 return 0;
529
530
1/1
✓ Branch 1 taken 6416 times.
 6416 auto timer_timeout_us = std::chrono::duration_cast<std::chrono::microseconds>(
531
1/1
✓ Branch 1 taken 6416 times.
 12832 nearest - now).count();
532
533
1/2
✓ Branch 0 taken 6416 times.
✗ Branch 1 not taken.
 6416 if (requested_timeout_us < 0)
534 6416 return static_cast<long>(timer_timeout_us);
535
536 ✗ return static_cast<long>((std::min)(
537 ✗ static_cast<long long>(requested_timeout_us),
538 ✗ static_cast<long long>(timer_timeout_us)));
539 }
540
541 void
542 80014 select_scheduler::
543 run_reactor(std::unique_lock<std::mutex>& lock)
544 {
545 // Calculate timeout considering timers, use 0 if interrupted
546
3/3
✓ Branch 0 taken 73525 times.
✓ Branch 1 taken 6489 times.
✓ Branch 3 taken 6489 times.
 80014 long effective_timeout_us = reactor_interrupted_ ? 0 : calculate_timeout(-1);
547
548 // Build fd_sets from registered_fds_
549 fd_set read_fds, write_fds, except_fds;
550
2/2
✓ Branch 0 taken 1280224 times.
✓ Branch 1 taken 80014 times.
 1360238 FD_ZERO(&read_fds);
551
2/2
✓ Branch 0 taken 1280224 times.
✓ Branch 1 taken 80014 times.
 1360238 FD_ZERO(&write_fds);
552
2/2
✓ Branch 0 taken 1280224 times.
✓ Branch 1 taken 80014 times.
 1360238 FD_ZERO(&except_fds);
553
554 // Always include the interrupt pipe
555 80014 FD_SET(pipe_fds_[0], &read_fds);
556 80014 int nfds = pipe_fds_[0];
557
558 // Add registered fds
559
2/2
✓ Branch 7 taken 8301 times.
✓ Branch 8 taken 80014 times.
 88315 for (auto& [fd, state] : registered_fds_)
560 {
561
2/2
✓ Branch 0 taken 6225 times.
✓ Branch 1 taken 2076 times.
 8301 if (state.read_op)
562 6225 FD_SET(fd, &read_fds);
563
2/2
✓ Branch 0 taken 2076 times.
✓ Branch 1 taken 6225 times.
 8301 if (state.write_op)
564 {
565 2076 FD_SET(fd, &write_fds);
566 // Also monitor for errors on connect operations
567 2076 FD_SET(fd, &except_fds);
568 }
569
2/2
✓ Branch 0 taken 6229 times.
✓ Branch 1 taken 2072 times.
 8301 if (fd > nfds)
570 6229 nfds = fd;
571 }
572
573 // Convert timeout to timeval
574 struct timeval tv;
575 80014 struct timeval* tv_ptr = nullptr;
576
2/2
✓ Branch 0 taken 79978 times.
✓ Branch 1 taken 36 times.
 80014 if (effective_timeout_us >= 0)
577 {
578 79978 tv.tv_sec = effective_timeout_us / 1000000;
579 79978 tv.tv_usec = effective_timeout_us % 1000000;
580 79978 tv_ptr = &tv;
581 }
582
583
1/1
✓ Branch 1 taken 80014 times.
 80014 lock.unlock();
584
585
1/1
✓ Branch 1 taken 80014 times.
 80014 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr);
586 80014 int saved_errno = errno;
587
588 // Process timers outside the lock
589
1/1
✓ Branch 1 taken 80014 times.
 80014 timer_svc_->process_expired();
590
591
1/4
✗ Branch 0 not taken.
✓ Branch 1 taken 80014 times.
✗ Branch 2 not taken.
✗ Branch 3 not taken.
 80014 if (ready < 0 && saved_errno != EINTR)
592 ✗ detail::throw_system_error(make_err(saved_errno), "select");
593
594 // Re-acquire lock before modifying completed_ops_
595
1/1
✓ Branch 1 taken 80014 times.
 80014 lock.lock();
596
597 // Drain the interrupt pipe if readable
598
4/4
✓ Branch 0 taken 4348 times.
✓ Branch 1 taken 75666 times.
✓ Branch 2 taken 4340 times.
✓ Branch 3 taken 8 times.
 80014 if (ready > 0 && FD_ISSET(pipe_fds_[0], &read_fds))
599 {
600 char buf[256];
601
3/3
✓ Branch 1 taken 8680 times.
✓ Branch 3 taken 4340 times.
✓ Branch 4 taken 4340 times.
 8680 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) {}
602 }
603
604 // Process I/O completions
605 80014 int completions_queued = 0;
606
2/2
✓ Branch 0 taken 4348 times.
✓ Branch 1 taken 75666 times.
 80014 if (ready > 0)
607 {
608 // Iterate over registered fds (copy keys to avoid iterator invalidation)
609 4348 std::vector<int> fds_to_check;
610
1/1
✓ Branch 2 taken 4348 times.
 4348 fds_to_check.reserve(registered_fds_.size());
611
2/2
✓ Branch 7 taken 6246 times.
✓ Branch 8 taken 4348 times.
 10594 for (auto& [fd, state] : registered_fds_)
612
1/1
✓ Branch 1 taken 6246 times.
 6246 fds_to_check.push_back(fd);
613
614
2/2
✓ Branch 5 taken 6246 times.
✓ Branch 6 taken 4348 times.
 10594 for (int fd : fds_to_check)
615 {
616
1/1
✓ Branch 1 taken 6246 times.
 6246 auto it = registered_fds_.find(fd);
617
1/2
✗ Branch 2 not taken.
✓ Branch 3 taken 6246 times.
 6246 if (it == registered_fds_.end())
618 ✗ continue;
619
620 6246 auto& state = it->second;
621
622 // Check for errors (especially for connect operations)
623 6246 bool has_error = FD_ISSET(fd, &except_fds);
624
625 // Process read readiness
626
5/6
✓ Branch 0 taken 4162 times.
✓ Branch 1 taken 2084 times.
✓ Branch 2 taken 2042 times.
✓ Branch 3 taken 2120 times.
✗ Branch 4 not taken.
✓ Branch 5 taken 2042 times.
 6246 if (state.read_op && (FD_ISSET(fd, &read_fds) || has_error))
627 {
628 2120 auto* op = state.read_op;
629 // Claim the op by exchanging to unregistered. Both registering and
630 // registered states mean the op is ours to complete.
631 2120 auto prev = op->registered.exchange(
632 select_registration_state::unregistered, std::memory_order_acq_rel);
633
1/2
✓ Branch 0 taken 2120 times.
✗ Branch 1 not taken.
 2120 if (prev != select_registration_state::unregistered)
634 {
635 2120 state.read_op = nullptr;
636
637
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 2120 times.
 2120 if (has_error)
638 {
639 ✗ int errn = 0;
640 ✗ socklen_t len = sizeof(errn);
641 ✗ if (::getsockopt(fd, SOL_SOCKET, SO_ERROR, &errn, &len) < 0)
642 ✗ errn = errno;
643 ✗ if (errn == 0)
644 ✗ errn = EIO;
645 ✗ op->complete(errn, 0);
646 }
647 else
648 {
649 2120 op->perform_io();
650 }
651
652 2120 completed_ops_.push(op);
653 2120 ++completions_queued;
654 }
655 }
656
657 // Process write readiness
658
5/6
✓ Branch 0 taken 2084 times.
✓ Branch 1 taken 4162 times.
✓ Branch 2 taken 8 times.
✓ Branch 3 taken 2076 times.
✗ Branch 4 not taken.
✓ Branch 5 taken 8 times.
 6246 if (state.write_op && (FD_ISSET(fd, &write_fds) || has_error))
659 {
660 2076 auto* op = state.write_op;
661 // Claim the op by exchanging to unregistered. Both registering and
662 // registered states mean the op is ours to complete.
663 2076 auto prev = op->registered.exchange(
664 select_registration_state::unregistered, std::memory_order_acq_rel);
665
1/2
✓ Branch 0 taken 2076 times.
✗ Branch 1 not taken.
 2076 if (prev != select_registration_state::unregistered)
666 {
667 2076 state.write_op = nullptr;
668
669
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 2076 times.
 2076 if (has_error)
670 {
671 ✗ int errn = 0;
672 ✗ socklen_t len = sizeof(errn);
673 ✗ if (::getsockopt(fd, SOL_SOCKET, SO_ERROR, &errn, &len) < 0)
674 ✗ errn = errno;
675 ✗ if (errn == 0)
676 ✗ errn = EIO;
677 ✗ op->complete(errn, 0);
678 }
679 else
680 {
681 2076 op->perform_io();
682 }
683
684 2076 completed_ops_.push(op);
685 2076 ++completions_queued;
686 }
687 }
688
689 // Clean up empty entries
690
4/4
✓ Branch 0 taken 4204 times.
✓ Branch 1 taken 2042 times.
✓ Branch 2 taken 4196 times.
✓ Branch 3 taken 8 times.
 6246 if (!state.read_op && !state.write_op)
691
1/1
✓ Branch 1 taken 4196 times.
 4196 registered_fds_.erase(it);
692 }
693 4348 }
694
695
2/2
✓ Branch 0 taken 2124 times.
✓ Branch 1 taken 77890 times.
 80014 if (completions_queued > 0)
696 {
697
2/2
✓ Branch 0 taken 52 times.
✓ Branch 1 taken 2072 times.
 2124 if (completions_queued == 1)
698 52 wakeup_event_.notify_one();
699 else
700 2072 wakeup_event_.notify_all();
701 }
702 80014 }
703
704 std::size_t
705 165476 select_scheduler::
706 do_one(long timeout_us)
707 {
708
1/1
✓ Branch 1 taken 165476 times.
 165476 std::unique_lock lock(mutex_);
709
710 for (;;)
711 {
712
2/2
✓ Branch 1 taken 18 times.
✓ Branch 2 taken 245472 times.
 245490 if (stopped_.load(std::memory_order_acquire))
713 18 return 0;
714
715 245472 scheduler_op* op = completed_ops_.pop();
716
717
2/2
✓ Branch 0 taken 80086 times.
✓ Branch 1 taken 165386 times.
 245472 if (op == &task_op_)
718 {
719 80086 bool more_handlers = !completed_ops_.empty();
720
721
2/2
✓ Branch 0 taken 6561 times.
✓ Branch 1 taken 73525 times.
 80086 if (!more_handlers)
722 {
723
2/2
✓ Branch 1 taken 72 times.
✓ Branch 2 taken 6489 times.
 13122 if (outstanding_work_.load(std::memory_order_acquire) == 0)
724 {
725 72 completed_ops_.push(&task_op_);
726 72 return 0;
727 }
728
1/2
✗ Branch 0 not taken.
✓ Branch 1 taken 6489 times.
 6489 if (timeout_us == 0)
729 {
730 ✗ completed_ops_.push(&task_op_);
731 ✗ return 0;
732 }
733 }
734
735
3/4
✓ Branch 0 taken 6489 times.
✓ Branch 1 taken 73525 times.
✗ Branch 2 not taken.
✓ Branch 3 taken 6489 times.
 80014 reactor_interrupted_ = more_handlers || timeout_us == 0;
736 80014 reactor_running_ = true;
737
738
3/4
✓ Branch 0 taken 73525 times.
✓ Branch 1 taken 6489 times.
✗ Branch 2 not taken.
✓ Branch 3 taken 73525 times.
 80014 if (more_handlers && idle_thread_count_ > 0)
739 ✗ wakeup_event_.notify_one();
740
741
1/1
✓ Branch 1 taken 80014 times.
 80014 run_reactor(lock);
742
743 80014 reactor_running_ = false;
744 80014 completed_ops_.push(&task_op_);
745 80014 continue;
746 80014 }
747
748
1/2
✓ Branch 0 taken 165386 times.
✗ Branch 1 not taken.
 165386 if (op != nullptr)
749 {
750
1/1
✓ Branch 1 taken 165386 times.
 165386 lock.unlock();
751 165386 work_guard g{this};
752
1/1
✓ Branch 1 taken 165386 times.
 165386 (*op)();
753 165386 return 1;
754 165386 }
755
756 ✗ if (outstanding_work_.load(std::memory_order_acquire) == 0)
757 ✗ return 0;
758
759 ✗ if (timeout_us == 0)
760 ✗ return 0;
761
762 ✗ ++idle_thread_count_;
763 ✗ if (timeout_us < 0)
764 ✗ wakeup_event_.wait(lock);
765 else
766 ✗ wakeup_event_.wait_for(lock, std::chrono::microseconds(timeout_us));
767 ✗ --idle_thread_count_;
768 80014 }
769 165476 }
770
771 } // namespace boost::corosio::detail
772
773 #endif // BOOST_COROSIO_HAS_SELECT
774