. /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   594 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   594 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   594 : pipe_fds_{-1, -1} 143   594 : pipe_fds_{-1, -1}
HITCBC 144   594 , max_fd_(-1) 144   594 , max_fd_(-1)
145   { 145   {
HITCBC 146   594 if (::pipe(pipe_fds_) < 0) 146   594 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   1782 for (int i = 0; i < 2; ++i) 149   1782 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   1188 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   1188 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   1188 if (flags == -1) 152   1188 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   1188 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   1188 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   1188 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   1188 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   594 timer_svc_ = &get_timer_service(ctx, *this); 175   594 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   594 timer_svc_->set_on_earliest_changed( 176   594 timer_svc_->set_on_earliest_changed(
HITCBC 177   3991 timer_service::callback(this, [](void* p) { 177   4149 timer_service::callback(this, [](void* p) {
HITCBC 178   3397 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3555 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3397 })); 179   3555 }));
180   180  
HITCBC 181   594 get_resolver_service(ctx, *this); 181   594 get_resolver_service(ctx, *this);
HITCBC 182   594 get_signal_service(ctx, *this); 182   594 get_signal_service(ctx, *this);
HITCBC 183   594 get_stream_file_service(ctx, *this); 183   594 get_stream_file_service(ctx, *this);
HITCBC 184   594 get_random_access_file_service(ctx, *this); 184   594 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   594 completed_ops_.push(&task_op_); 186   594 completed_ops_.push(&task_op_);
HITCBC 187   594 } 187   594 }
188   188  
HITCBC 189   1188 inline select_scheduler::~select_scheduler() 189   1188 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   594 if (pipe_fds_[0] >= 0) 191   594 if (pipe_fds_[0] >= 0)
HITCBC 192   594 ::close(pipe_fds_[0]); 192   594 ::close(pipe_fds_[0]);
HITCBC 193   594 if (pipe_fds_[1] >= 0) 193   594 if (pipe_fds_[1] >= 0)
HITCBC 194   594 ::close(pipe_fds_[1]); 194   594 ::close(pipe_fds_[1]);
HITCBC 195   1188 } 195   1188 }
196   196  
197   inline void 197   inline void
HITCBC 198   594 select_scheduler::shutdown() 198   594 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   594 shutdown_drain(); 200   594 shutdown_drain();
201   201  
HITCBC 202   594 if (pipe_fds_[1] >= 0) 202   594 if (pipe_fds_[1] >= 0)
HITCBC 203   594 interrupt_reactor(); 203   594 interrupt_reactor();
HITCBC 204   594 } 204   594 }
205   205  
206   inline void 206   inline void
HITCBC 207   6701 select_scheduler::register_descriptor( 207   7032 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6701 if (fd < 0 || fd >= FD_SETSIZE) 210   7032 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   6701 desc->registered_events = reactor_event_read | reactor_event_write; 213   7032 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6701 desc->fd = fd; 214   7032 desc->fd = fd;
HITCBC 215   6701 desc->scheduler_ = this; 215   7032 desc->scheduler_ = this;
HITCBC 216   6701 desc->mutex.set_enabled(!single_threaded_); 216   7032 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6701 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7032 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6701 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7032 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6701 desc->impl_ref_.reset(); 221   7032 desc->impl_ref_.reset();
HITCBC 222   6701 desc->read_ready = false; 222   7032 desc->read_ready = false;
HITCBC 223   6701 desc->write_ready = false; 223   7032 desc->write_ready = false;
HITCBC 224   6701 } 224   7032 }
225   225  
226   { 226   {
HITCBC 227   6701 mutex_type::scoped_lock lock(mutex_); 227   7032 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6701 registered_descs_[fd] = desc; 228   7032 registered_descs_[fd] = desc;
HITCBC 229   6701 if (fd > max_fd_) 229   7032 if (fd > max_fd_)
HITCBC 230   6696 max_fd_ = fd; 230   7027 max_fd_ = fd;
HITCBC 231   6701 } 231   7032 }
232   232  
HITCBC 233   6701 interrupt_reactor(); 233   7032 interrupt_reactor();
HITCBC 234   6701 } 234   7032 }
235   235  
236   inline void 236   inline void
HITCBC 237   6701 select_scheduler::deregister_descriptor(int fd) const 237   7032 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6701 mutex_type::scoped_lock lock(mutex_); 239   7032 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6701 auto it = registered_descs_.find(fd); 241   7032 auto it = registered_descs_.find(fd);
HITCBC 242   6701 if (it == registered_descs_.end()) 242   7032 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6701 registered_descs_.erase(it); 245   7032 registered_descs_.erase(it);
246   246  
HITCBC 247   6701 if (fd == max_fd_) 247   7032 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6588 max_fd_ = pipe_fds_[0]; 249   6918 max_fd_ = pipe_fds_[0];
HITCBC 250   12928 for (auto& [registered_fd, state] : registered_descs_) 250   13588 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6340 if (registered_fd > max_fd_) 252   6670 if (registered_fd > max_fd_)
HITCBC 253   6293 max_fd_ = registered_fd; 253   6623 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6701 } 256   7032 }
257   257  
258   inline void 258   inline void
HITCBC 259   3255 select_scheduler::notify_reactor() const 259   3421 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3255 interrupt_reactor(); 261   3421 interrupt_reactor();
HITCBC 262   3255 } 262   3421 }
263   263  
264   inline void 264   inline void
HITCBC 265   14378 select_scheduler::interrupt_reactor() const 265   15034 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14378 char byte = 1; 267   15034 char byte = 1;
HITCBC 268   14378 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15034 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14378 } 269   15034 }
270   270  
271   inline long 271   inline long
HITCBC 272   202629 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   210770 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   202629 if (requested_timeout_us == 0) 274   210770 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   202629 auto nearest = timer_svc_->nearest_expiry(); 277   210770 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   202629 if (nearest == timer_service::time_point::max()) 278   210770 if (nearest == timer_service::time_point::max())
HITCBC 279   402 return requested_timeout_us; 279   402 return requested_timeout_us;
280   280  
HITCBC 281   202227 auto now = std::chrono::steady_clock::now(); 281   210368 auto now = std::chrono::steady_clock::now();
HITCBC 282   202227 if (nearest <= now) 282   210368 if (nearest <= now)
HITCBC 283   717 return 0; 283   720 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   201510 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   209648 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   201510 .count(); 287   209648 .count();
288   288  
HITCBC 289   201510 constexpr auto long_max = 289   209648 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   201510 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   209648 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   201510 static_cast<long long>(0)), 293   209648 static_cast<long long>(0)),
HITCBC 294   201510 long_max); 294   209648 long_max);
295   295  
HITCBC 296   201510 if (requested_timeout_us < 0) 296   209648 if (requested_timeout_us < 0)
HITCBC 297   201510 return static_cast<long>(capped_timer_us); 297   209648 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   228391 select_scheduler::run_task( 305   234244 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   228391 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   234244 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   228391 int snapshot_count = 0; 323   234244 int snapshot_count = 0;
324   324  
HITCBC 325   611562 for (auto& [fd, desc] : registered_descs_) 325   608400 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   383171 if (snapshot_count < FD_SETSIZE) 327   374156 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   383171 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   374156 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   383171 snapshot[snapshot_count].fd = fd; 330   374156 snapshot[snapshot_count].fd = fd;
HITCBC 331   383171 snapshot[snapshot_count].desc = desc; 331   374156 snapshot[snapshot_count].desc = desc;
HITCBC 332   383171 snapshot[snapshot_count].needs_write = 332   374156 snapshot[snapshot_count].needs_write =
HITCBC 333   383171 (desc->write_op || desc->connect_op); 333   374156 (desc->write_op || desc->connect_op);
HITCBC 334   383171 ++snapshot_count; 334   374156 ++snapshot_count;
HITCBC 335   383171 } 335   374156 }
336   } 336   }
337   337  
HITCBC 338   228391 if (lock.owns_lock()) 338   234244 if (lock.owns_lock())
HITCBC 339   202629 lock.unlock(); 339   210770 lock.unlock();
340   340  
HITCBC 341   228391 task_cleanup on_exit{this, &lock, ctx}; 341   234244 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   3882647 FD_ZERO(&read_fds); 344   3982148 FD_ZERO(&read_fds);
HITCBC 345   3882647 FD_ZERO(&write_fds); 345   3982148 FD_ZERO(&write_fds);
HITCBC 346   3882647 FD_ZERO(&except_fds); 346   3982148 FD_ZERO(&except_fds);
347   347  
HITCBC 348   228391 FD_SET(pipe_fds_[0], &read_fds); 348   234244 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   228391 int nfds = pipe_fds_[0]; 349   234244 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   611562 for (int i = 0; i < snapshot_count; ++i) 351   608400 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   383171 int fd = snapshot[i].fd; 353   374156 int fd = snapshot[i].fd;
HITCBC 354   383171 FD_SET(fd, &read_fds); 354   374156 FD_SET(fd, &read_fds);
HITCBC 355   383171 if (snapshot[i].needs_write) 355   374156 if (snapshot[i].needs_write)
HITCBC 356   14746 FD_SET(fd, &write_fds); 356   12431 FD_SET(fd, &write_fds);
HITCBC 357   383171 FD_SET(fd, &except_fds); 357   374156 FD_SET(fd, &except_fds);
HITCBC 358   383171 if (fd > nfds) 358   374156 if (fd > nfds)
HITCBC 359   227945 nfds = fd; 359   233795 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   228391 struct timeval* tv_ptr = nullptr; 363   234244 struct timeval* tv_ptr = nullptr;
HITCBC 364   228391 if (effective_timeout_us >= 0) 364   234244 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   227993 tv.tv_sec = effective_timeout_us / 1000000; 366   233846 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   227993 tv.tv_usec = effective_timeout_us % 1000000; 367   233846 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   227993 tv_ptr = &tv; 368   233846 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   228391 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   234244 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   228391 if (ready < 0) 376   234244 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   228391 timer_svc_->process_expired(); 384   234244 timer_svc_->process_expired();
385   385  
HITCBC 386   228391 op_queue local_ops; 386   234244 op_queue local_ops;
387   387  
HITCBC 388   228391 if (ready > 0) 388   234244 if (ready > 0)
389   { 389   {
HITCBC 390   209764 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   216486 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   13884 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14534 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   543916 for (int i = 0; i < snapshot_count; ++i) 398   542882 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   334152 int fd = snapshot[i].fd; 400   326396 int fd = snapshot[i].fd;
HITCBC 401   334152 reactor_descriptor_state* desc = snapshot[i].desc; 401   326396 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   334152 std::uint32_t flags = 0; 403   326396 std::uint32_t flags = 0;
HITCBC 404   334152 if (FD_ISSET(fd, &read_fds)) 404   326396 if (FD_ISSET(fd, &read_fds))
HITCBC 405   206219 flags |= reactor_event_read; 405   212774 flags |= reactor_event_read;
HITCBC 406   334152 if (FD_ISSET(fd, &write_fds)) 406   326396 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3252 flags |= reactor_event_write; 407   3418 flags |= reactor_event_write;
HITCBC 408   334152 if (FD_ISSET(fd, &except_fds)) 408   326396 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   334152 if (flags == 0) 411   326396 if (flags == 0)
HITCBC 412   124690 continue; 412   110214 continue;
413   413  
HITCBC 414   209462 desc->add_ready_events(flags); 414   216182 desc->add_ready_events(flags);
415   415  
HITCBC 416   209462 bool expected = false; 416   216182 bool expected = false;
HITCBC 417   209462 if (desc->is_enqueued_.compare_exchange_strong( 417   216182 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   209462 local_ops.push(desc); 421   216182 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   228391 lock.lock(); 426   234244 lock.lock();
427   427  
HITCBC 428   228391 if (!local_ops.empty()) 428   234244 if (!local_ops.empty())
HITCBC 429   206301 completed_ops_.splice(local_ops); 429   212856 completed_ops_.splice(local_ops);
HITCBC 430   228391 } 430   234244 }
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