. /include/boost/corosio /native /detail /select /select_scheduler.hpp
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1   // 1   //
2   // Copyright (c) 2026 Steve Gerbino 2   // Copyright (c) 2026 Steve Gerbino
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 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) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/corosio 7   // Official repository: https://github.com/cppalliance/corosio
8   // 8   //
9   9  
10   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 10   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
11   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 11   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
12   12  
13   #include <boost/corosio/detail/platform.hpp> 13   #include <boost/corosio/detail/platform.hpp>
14   14  
15   #if BOOST_COROSIO_HAS_SELECT 15   #if BOOST_COROSIO_HAS_SELECT
16   16  
17   #include <boost/corosio/detail/config.hpp> 17   #include <boost/corosio/detail/config.hpp>
18   #include <boost/capy/ex/execution_context.hpp> 18   #include <boost/capy/ex/execution_context.hpp>
19   19  
20   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp> 20   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
21   21  
22   #include <boost/corosio/native/detail/select/select_traits.hpp> 22   #include <boost/corosio/native/detail/select/select_traits.hpp>
23   #include <boost/corosio/detail/timer_service.hpp> 23   #include <boost/corosio/detail/timer_service.hpp>
24   #include <boost/corosio/native/detail/make_err.hpp> 24   #include <boost/corosio/native/detail/make_err.hpp>
25   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp> 25   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp>
26   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp> 26   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp>
27   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp> 27   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
28   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp> 28   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
29   29  
30   #include <boost/corosio/detail/except.hpp> 30   #include <boost/corosio/detail/except.hpp>
31   31  
32   #include <sys/select.h> 32   #include <sys/select.h>
33   #include <unistd.h> 33   #include <unistd.h>
34   #include <errno.h> 34   #include <errno.h>
35   #include <fcntl.h> 35   #include <fcntl.h>
36   36  
37   #include <atomic> 37   #include <atomic>
38   #include <chrono> 38   #include <chrono>
39   #include <cstdint> 39   #include <cstdint>
40   #include <limits> 40   #include <limits>
41   #include <mutex> 41   #include <mutex>
42   #include <unordered_map> 42   #include <unordered_map>
43   43  
44   namespace boost::corosio::detail { 44   namespace boost::corosio::detail {
45   45  
46   struct select_op; 46   struct select_op;
47   47  
48   /** POSIX scheduler using select() for I/O multiplexing. 48   /** POSIX scheduler using select() for I/O multiplexing.
49   49  
50   This scheduler implements the scheduler interface using the POSIX select() 50   This scheduler implements the scheduler interface using the POSIX select()
51   call for I/O event notification. It inherits the shared reactor threading 51   call for I/O event notification. It inherits the shared reactor threading
52   model from reactor_scheduler: signal state machine, inline completion 52   model from reactor_scheduler: signal state machine, inline completion
53   budget, work counting, and the do_one event loop. 53   budget, work counting, and the do_one event loop.
54   54  
55   The design mirrors epoll_scheduler for behavioral consistency: 55   The design mirrors epoll_scheduler for behavioral consistency:
56   - Same single-reactor thread coordination model 56   - Same single-reactor thread coordination model
57   - Same deferred I/O pattern (reactor marks ready; workers do I/O) 57   - Same deferred I/O pattern (reactor marks ready; workers do I/O)
58   - Same timer integration pattern 58   - Same timer integration pattern
59   59  
60   Known Limitations: 60   Known Limitations:
61   - FD_SETSIZE (~1024) limits maximum concurrent connections 61   - FD_SETSIZE (~1024) limits maximum concurrent connections
62   - O(n) scanning: rebuilds fd_sets each iteration 62   - O(n) scanning: rebuilds fd_sets each iteration
63   - Level-triggered only (no edge-triggered mode) 63   - Level-triggered only (no edge-triggered mode)
64   64  
65   @par Thread Safety 65   @par Thread Safety
66   All public member functions are thread-safe. 66   All public member functions are thread-safe.
67   */ 67   */
68   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler 68   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler
69   { 69   {
70   public: 70   public:
71   /** Construct the scheduler. 71   /** Construct the scheduler.
72   72  
73   Creates a self-pipe for reactor interruption. 73   Creates a self-pipe for reactor interruption.
74   74  
75   @param ctx Reference to the owning execution_context. 75   @param ctx Reference to the owning execution_context.
76   @param concurrency_hint Hint for expected thread count (unused). 76   @param concurrency_hint Hint for expected thread count (unused).
77   */ 77   */
78   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1); 78   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
79   79  
80   /// Destroy the scheduler. 80   /// Destroy the scheduler.
81   ~select_scheduler() override; 81   ~select_scheduler() override;
82   82  
83   select_scheduler(select_scheduler const&) = delete; 83   select_scheduler(select_scheduler const&) = delete;
84   select_scheduler& operator=(select_scheduler const&) = delete; 84   select_scheduler& operator=(select_scheduler const&) = delete;
85   85  
86   /// Shut down the scheduler, draining pending operations. 86   /// Shut down the scheduler, draining pending operations.
87   void shutdown() override; 87   void shutdown() override;
88   88  
89   /** Return the maximum file descriptor value supported. 89   /** Return the maximum file descriptor value supported.
90   90  
91   Returns FD_SETSIZE - 1, the maximum fd value that can be 91   Returns FD_SETSIZE - 1, the maximum fd value that can be
92   monitored by select(). Operations with fd >= FD_SETSIZE 92   monitored by select(). Operations with fd >= FD_SETSIZE
93   will fail with EINVAL. 93   will fail with EINVAL.
94   94  
95   @return The maximum supported file descriptor value. 95   @return The maximum supported file descriptor value.
96   */ 96   */
97   static constexpr int max_fd() noexcept 97   static constexpr int max_fd() noexcept
98   { 98   {
99   return FD_SETSIZE - 1; 99   return FD_SETSIZE - 1;
100   } 100   }
101   101  
102   /** Register a descriptor for persistent monitoring. 102   /** Register a descriptor for persistent monitoring.
103   103  
104   The fd is added to the registered_descs_ map and will be 104   The fd is added to the registered_descs_ map and will be
105   included in subsequent select() calls. The reactor is 105   included in subsequent select() calls. The reactor is
106   interrupted so a blocked select() rebuilds its fd_sets. 106   interrupted so a blocked select() rebuilds its fd_sets.
107   107  
108   @param fd The file descriptor to register. 108   @param fd The file descriptor to register.
109   @param desc Pointer to descriptor state for this fd. 109   @param desc Pointer to descriptor state for this fd.
110   */ 110   */
111   void register_descriptor(int fd, reactor_descriptor_state* desc) const; 111   void register_descriptor(int fd, reactor_descriptor_state* desc) const;
112   112  
113   /** Deregister a persistently registered descriptor. 113   /** Deregister a persistently registered descriptor.
114   114  
115   @param fd The file descriptor to deregister. 115   @param fd The file descriptor to deregister.
116   */ 116   */
117   void deregister_descriptor(int fd) const; 117   void deregister_descriptor(int fd) const;
118   118  
119   /** Interrupt the reactor so it rebuilds its fd_sets. 119   /** Interrupt the reactor so it rebuilds its fd_sets.
120   120  
121   Called when a write or connect op is registered after 121   Called when a write or connect op is registered after
122   the reactor's snapshot was taken. Without this, select() 122   the reactor's snapshot was taken. Without this, select()
123   may block not watching for writability on the fd. 123   may block not watching for writability on the fd.
124   */ 124   */
125   void notify_reactor() const; 125   void notify_reactor() const;
126   126  
127   private: 127   private:
128   void 128   void
129   run_task(lock_type& lock, context_type* ctx, 129   run_task(lock_type& lock, context_type* ctx,
130   long timeout_us) override; 130   long timeout_us) override;
131   void interrupt_reactor() const override; 131   void interrupt_reactor() const override;
132   long calculate_timeout(long requested_timeout_us) const; 132   long calculate_timeout(long requested_timeout_us) const;
133   133  
134   // Self-pipe for interrupting select() 134   // Self-pipe for interrupting select()
135   int pipe_fds_[2]; // [0]=read, [1]=write 135   int pipe_fds_[2]; // [0]=read, [1]=write
136   136  
137   // Per-fd tracking for fd_set building 137   // Per-fd tracking for fd_set building
138   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_; 138   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_;
139   mutable int max_fd_ = -1; 139   mutable int max_fd_ = -1;
140   }; 140   };
141   141  
HITCBC 142   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   428 : pipe_fds_{-1, -1} 143   428 : pipe_fds_{-1, -1}
HITCBC 144   428 , max_fd_(-1) 144   428 , max_fd_(-1)
145   { 145   {
HITCBC 146   428 if (::pipe(pipe_fds_) < 0) 146   428 if (::pipe(pipe_fds_) < 0)
MISUBC 147   ✗ detail::throw_system_error(make_err(errno), "pipe"); 147   ✗ detail::throw_system_error(make_err(errno), "pipe");
148   148  
HITCBC 149   1284 for (int i = 0; i < 2; ++i) 149   1284 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   856 if (flags == -1) 152   856 if (flags == -1)
153   { 153   {
MISUBC 154   ✗ int errn = errno; 154   ✗ int errn = errno;
MISUBC 155   ✗ ::close(pipe_fds_[0]); 155   ✗ ::close(pipe_fds_[0]);
MISUBC 156   ✗ ::close(pipe_fds_[1]); 156   ✗ ::close(pipe_fds_[1]);
MISUBC 157   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL"); 157   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
158   } 158   }
HITCBC 159   856 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   856 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
160   { 160   {
MISUBC 161   ✗ int errn = errno; 161   ✗ int errn = errno;
MISUBC 162   ✗ ::close(pipe_fds_[0]); 162   ✗ ::close(pipe_fds_[0]);
MISUBC 163   ✗ ::close(pipe_fds_[1]); 163   ✗ ::close(pipe_fds_[1]);
MISUBC 164   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL"); 164   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
165   } 165   }
HITCBC 166   856 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   856 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
167   { 167   {
MISUBC 168   ✗ int errn = errno; 168   ✗ int errn = errno;
MISUBC 169   ✗ ::close(pipe_fds_[0]); 169   ✗ ::close(pipe_fds_[0]);
MISUBC 170   ✗ ::close(pipe_fds_[1]); 170   ✗ ::close(pipe_fds_[1]);
MISUBC 171   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD"); 171   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
172   } 172   }
173   } 173   }
174   174  
HITCBC 175   428 timer_svc_ = &get_timer_service(ctx, *this); 175   428 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   428 timer_svc_->set_on_earliest_changed( 176   428 timer_svc_->set_on_earliest_changed(
HITCBC 177   2735 timer_service::callback(this, [](void* p) { 177   1807 timer_service::callback(this, [](void* p) {
HITCBC 178   2307 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   1379 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   2307 })); 179   1379 }));
180   180  
HITCBC 181   428 get_resolver_service(ctx, *this); 181   428 get_resolver_service(ctx, *this);
HITCBC 182   428 get_signal_service(ctx, *this); 182   428 get_signal_service(ctx, *this);
HITCBC 183   428 get_stream_file_service(ctx, *this); 183   428 get_stream_file_service(ctx, *this);
HITCBC 184   428 get_random_access_file_service(ctx, *this); 184   428 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   428 completed_ops_.push(&task_op_); 186   428 completed_ops_.push(&task_op_);
HITCBC 187   428 } 187   428 }
188   188  
HITCBC 189   856 inline select_scheduler::~select_scheduler() 189   856 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   428 if (pipe_fds_[0] >= 0) 191   428 if (pipe_fds_[0] >= 0)
HITCBC 192   428 ::close(pipe_fds_[0]); 192   428 ::close(pipe_fds_[0]);
HITCBC 193   428 if (pipe_fds_[1] >= 0) 193   428 if (pipe_fds_[1] >= 0)
HITCBC 194   428 ::close(pipe_fds_[1]); 194   428 ::close(pipe_fds_[1]);
HITCBC 195   856 } 195   856 }
196   196  
197   inline void 197   inline void
HITCBC 198   428 select_scheduler::shutdown() 198   428 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   428 shutdown_drain(); 200   428 shutdown_drain();
201   201  
HITCBC 202   428 if (pipe_fds_[1] >= 0) 202   428 if (pipe_fds_[1] >= 0)
HITCBC 203   428 interrupt_reactor(); 203   428 interrupt_reactor();
HITCBC 204   428 } 204   428 }
205   205  
206   inline void 206   inline void
HITCBC 207   4466 select_scheduler::register_descriptor( 207   2610 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   4466 if (fd < 0 || fd >= FD_SETSIZE) 210   2610 if (fd < 0 || fd >= FD_SETSIZE)
MISUBC 211   ✗ detail::throw_system_error(make_err(EINVAL), "select: fd out of range"); 211   ✗ detail::throw_system_error(make_err(EINVAL), "select: fd out of range");
212   212  
HITCBC 213   4466 desc->registered_events = reactor_event_read | reactor_event_write; 213   2610 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   4466 desc->fd = fd; 214   2610 desc->fd = fd;
HITCBC 215   4466 desc->scheduler_ = this; 215   2610 desc->scheduler_ = this;
HITCBC 216   4466 desc->mutex.set_enabled(!single_threaded_); 216   2610 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   4466 desc->ready_events_.store(0, std::memory_order_relaxed); 217   2610 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   4466 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   2610 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   4466 desc->impl_ref_.reset(); 221   2610 desc->impl_ref_.reset();
HITCBC 222   4466 desc->read_ready = false; 222   2610 desc->read_ready = false;
HITCBC 223   4466 desc->write_ready = false; 223   2610 desc->write_ready = false;
HITCBC 224   4466 } 224   2610 }
225   225  
226   { 226   {
HITCBC 227   4466 mutex_type::scoped_lock lock(mutex_); 227   2610 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   4466 registered_descs_[fd] = desc; 228   2610 registered_descs_[fd] = desc;
HITCBC 229   4466 if (fd > max_fd_) 229   2610 if (fd > max_fd_)
HITCBC 230   4462 max_fd_ = fd; 230   2606 max_fd_ = fd;
HITCBC 231   4466 } 231   2610 }
232   232  
HITCBC 233   4466 interrupt_reactor(); 233   2610 interrupt_reactor();
HITCBC 234   4466 } 234   2610 }
235   235  
236   inline void 236   inline void
HITCBC 237   4466 select_scheduler::deregister_descriptor(int fd) const 237   2610 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   4466 mutex_type::scoped_lock lock(mutex_); 239   2610 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   4466 auto it = registered_descs_.find(fd); 241   2610 auto it = registered_descs_.find(fd);
HITCBC 242   4466 if (it == registered_descs_.end()) 242   2610 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   4466 registered_descs_.erase(it); 245   2610 registered_descs_.erase(it);
246   246  
HITCBC 247   4466 if (fd == max_fd_) 247   2610 if (fd == max_fd_)
248   { 248   {
HITCBC 249   4362 max_fd_ = pipe_fds_[0]; 249   2506 max_fd_ = pipe_fds_[0];
HITCBC 250   8513 for (auto& [registered_fd, state] : registered_descs_) 250   4801 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   4151 if (registered_fd > max_fd_) 252   2295 if (registered_fd > max_fd_)
HITCBC 253   4126 max_fd_ = registered_fd; 253   2270 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   4466 } 256   2610 }
257   257  
258   inline void 258   inline void
HITCBC 259   2092 select_scheduler::notify_reactor() const 259   1164 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   2092 interrupt_reactor(); 261   1164 interrupt_reactor();
HITCBC 262   2092 } 262   1164 }
263   263  
264   inline void 264   inline void
HITCBC 265   9579 select_scheduler::interrupt_reactor() const 265   5867 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   9579 char byte = 1; 267   5867 char byte = 1;
HITCBC 268   9579 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   5867 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   9579 } 269   5867 }
270   270  
271   inline long 271   inline long
HITCBC 272   163967 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   169855 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   163967 if (requested_timeout_us == 0) 274   169855 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   163967 auto nearest = timer_svc_->nearest_expiry(); 277   169855 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   163967 if (nearest == timer_service::time_point::max()) 278   169855 if (nearest == timer_service::time_point::max())
HITCBC 279   175 return requested_timeout_us; 279   175 return requested_timeout_us;
280   280  
HITCBC 281   163792 auto now = std::chrono::steady_clock::now(); 281   169680 auto now = std::chrono::steady_clock::now();
HITCBC 282   163792 if (nearest <= now) 282   169680 if (nearest <= now)
HITCBC 283   770 return 0; 283   548 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   163022 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   169132 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   163022 .count(); 287   169132 .count();
288   288  
HITCBC 289   163022 constexpr auto long_max = 289   169132 constexpr auto long_max =
290   static_cast<long long>((std::numeric_limits<long>::max)()); 290   static_cast<long long>((std::numeric_limits<long>::max)());
291   auto capped_timer_us = 291   auto capped_timer_us =
HITCBC 292   163022 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   169132 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   163022 static_cast<long long>(0)), 293   169132 static_cast<long long>(0)),
HITCBC 294   163022 long_max); 294   169132 long_max);
295   295  
HITCBC 296   163022 if (requested_timeout_us < 0) 296   169132 if (requested_timeout_us < 0)
HITCBC 297   163022 return static_cast<long>(capped_timer_us); 297   169132 return static_cast<long>(capped_timer_us);
298   298  
299   return static_cast<long>( 299   return static_cast<long>(
MISUBC 300   ✗ (std::min)(static_cast<long long>(requested_timeout_us), 300   ✗ (std::min)(static_cast<long long>(requested_timeout_us),
MISUBC 301   ✗ capped_timer_us)); 301   ✗ capped_timer_us));
302   } 302   }
303   303  
304   inline void 304   inline void
HITCBC 305   190156 select_scheduler::run_task( 305   191494 select_scheduler::run_task(
306   lock_type& lock, context_type* ctx, long timeout_us) 306   lock_type& lock, context_type* ctx, long timeout_us)
307   { 307   {
308   long effective_timeout_us = 308   long effective_timeout_us =
HITCBC 309   190156 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   191494 task_interrupted_ ? 0 : calculate_timeout(timeout_us);
310   310  
311   // Snapshot registered descriptors while holding lock. 311   // Snapshot registered descriptors while holding lock.
312   // Record which fds need write monitoring to avoid a hot loop: 312   // Record which fds need write monitoring to avoid a hot loop:
313   // select is level-triggered so writable sockets (nearly always 313   // select is level-triggered so writable sockets (nearly always
314   // writable) would cause select() to return immediately every 314   // writable) would cause select() to return immediately every
315   // iteration if unconditionally added to write_fds. 315   // iteration if unconditionally added to write_fds.
316   struct fd_entry 316   struct fd_entry
317   { 317   {
318   int fd; 318   int fd;
319   reactor_descriptor_state* desc; 319   reactor_descriptor_state* desc;
320   bool needs_write; 320   bool needs_write;
321   }; 321   };
322   fd_entry snapshot[FD_SETSIZE]; 322   fd_entry snapshot[FD_SETSIZE];
HITCBC 323   190156 int snapshot_count = 0; 323   191494 int snapshot_count = 0;
324   324  
HITCBC 325   524436 for (auto& [fd, desc] : registered_descs_) 325   512333 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   334280 if (snapshot_count < FD_SETSIZE) 327   320839 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   334280 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   320839 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   334280 snapshot[snapshot_count].fd = fd; 330   320839 snapshot[snapshot_count].fd = fd;
HITCBC 331   334280 snapshot[snapshot_count].desc = desc; 331   320839 snapshot[snapshot_count].desc = desc;
HITCBC 332   334280 snapshot[snapshot_count].needs_write = 332   320839 snapshot[snapshot_count].needs_write =
HITCBC 333   334280 (desc->write_op || desc->connect_op); 333   320839 (desc->write_op || desc->connect_op);
HITCBC 334   334280 ++snapshot_count; 334   320839 ++snapshot_count;
HITCBC 335   334280 } 335   320839 }
336   } 336   }
337   337  
HITCBC 338   190156 if (lock.owns_lock()) 338   191494 if (lock.owns_lock())
HITCBC 339   163967 lock.unlock(); 339   169855 lock.unlock();
340   340  
HITCBC 341   190156 task_cleanup on_exit{this, &lock, ctx}; 341   191494 task_cleanup on_exit{this, &lock, ctx};
342   342  
343   fd_set read_fds, write_fds, except_fds; 343   fd_set read_fds, write_fds, except_fds;
HITCBC 344   3232652 FD_ZERO(&read_fds); 344   3255398 FD_ZERO(&read_fds);
HITCBC 345   3232652 FD_ZERO(&write_fds); 345   3255398 FD_ZERO(&write_fds);
HITCBC 346   3232652 FD_ZERO(&except_fds); 346   3255398 FD_ZERO(&except_fds);
347   347  
HITCBC 348   190156 FD_SET(pipe_fds_[0], &read_fds); 348   191494 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   190156 int nfds = pipe_fds_[0]; 349   191494 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   524436 for (int i = 0; i < snapshot_count; ++i) 351   512333 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   334280 int fd = snapshot[i].fd; 353   320839 int fd = snapshot[i].fd;
HITCBC 354   334280 FD_SET(fd, &read_fds); 354   320839 FD_SET(fd, &read_fds);
HITCBC 355   334280 if (snapshot[i].needs_write) 355   320839 if (snapshot[i].needs_write)
HITCBC 356   2179 FD_SET(fd, &write_fds); 356   1251 FD_SET(fd, &write_fds);
HITCBC 357   334280 FD_SET(fd, &except_fds); 357   320839 FD_SET(fd, &except_fds);
HITCBC 358   334280 if (fd > nfds) 358   320839 if (fd > nfds)
HITCBC 359   189803 nfds = fd; 359   191143 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   190156 struct timeval* tv_ptr = nullptr; 363   191494 struct timeval* tv_ptr = nullptr;
HITCBC 364   190156 if (effective_timeout_us >= 0) 364   191494 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   189982 tv.tv_sec = effective_timeout_us / 1000000; 366   191320 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   189982 tv.tv_usec = effective_timeout_us % 1000000; 367   191320 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   189982 tv_ptr = &tv; 368   191320 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   190156 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   191494 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr);
372   372  
373   // EINTR: signal interrupted select(), just retry. 373   // EINTR: signal interrupted select(), just retry.
374   // EBADF: an fd was closed between snapshot and select(); retry 374   // EBADF: an fd was closed between snapshot and select(); retry
375   // with a fresh snapshot from registered_descs_. 375   // with a fresh snapshot from registered_descs_.
HITCBC 376   190156 if (ready < 0) 376   191494 if (ready < 0)
377   { 377   {
MISUBC 378   ✗ if (errno == EINTR || errno == EBADF) 378   ✗ if (errno == EINTR || errno == EBADF)
MISUBC 379   ✗ return; 379   ✗ return;
MISUBC 380   ✗ detail::throw_system_error(make_err(errno), "select"); 380   ✗ detail::throw_system_error(make_err(errno), "select");
381   } 381   }
382   382  
383   // Process timers outside the lock 383   // Process timers outside the lock
HITCBC 384   190156 timer_svc_->process_expired(); 384   191494 timer_svc_->process_expired();
385   385  
HITCBC 386   190156 op_queue local_ops; 386   191494 op_queue local_ops;
387   387  
HITCBC 388   190156 if (ready > 0) 388   191494 if (ready > 0)
389   { 389   {
HITCBC 390   172503 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   177458 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   9186 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   5478 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   452964 for (int i = 0; i < snapshot_count; ++i) 398   449153 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   280461 int fd = snapshot[i].fd; 400   271695 int fd = snapshot[i].fd;
HITCBC 401   280461 reactor_descriptor_state* desc = snapshot[i].desc; 401   271695 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   280461 std::uint32_t flags = 0; 403   271695 std::uint32_t flags = 0;
HITCBC 404   280461 if (FD_ISSET(fd, &read_fds)) 404   271695 if (FD_ISSET(fd, &read_fds))
HITCBC 405   170203 flags |= reactor_event_read; 405   176084 flags |= reactor_event_read;
HITCBC 406   280461 if (FD_ISSET(fd, &write_fds)) 406   271695 if (FD_ISSET(fd, &write_fds))
HITCBC 407   2091 flags |= reactor_event_write; 407   1163 flags |= reactor_event_write;
HITCBC 408   280461 if (FD_ISSET(fd, &except_fds)) 408   271695 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   280461 if (flags == 0) 411   271695 if (flags == 0)
HITCBC 412   108176 continue; 412   94457 continue;
413   413  
HITCBC 414   172285 desc->add_ready_events(flags); 414   177238 desc->add_ready_events(flags);
415   415  
HITCBC 416   172285 bool expected = false; 416   177238 bool expected = false;
HITCBC 417   172285 if (desc->is_enqueued_.compare_exchange_strong( 417   177238 if (desc->is_enqueued_.compare_exchange_strong(
418   expected, true, std::memory_order_release, 418   expected, true, std::memory_order_release,
419   std::memory_order_relaxed)) 419   std::memory_order_relaxed))
420   { 420   {
HITCBC 421   172285 local_ops.push(desc); 421   177238 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   190156 lock.lock(); 426   191494 lock.lock();
427   427  
HITCBC 428   190156 if (!local_ops.empty()) 428   191494 if (!local_ops.empty())
HITCBC 429   170199 completed_ops_.splice(local_ops); 429   176080 completed_ops_.splice(local_ops);
HITCBC 430   190156 } 430   191494 }
431   431  
432   } // namespace boost::corosio::detail 432   } // namespace boost::corosio::detail
433   433  
434   #endif // BOOST_COROSIO_HAS_SELECT 434   #endif // BOOST_COROSIO_HAS_SELECT
435   435  
436   #endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 436   #endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP