. /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   239 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   239 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   239 : pipe_fds_{-1, -1} 143   239 : pipe_fds_{-1, -1}
HITCBC 144   239 , max_fd_(-1) 144   239 , max_fd_(-1)
145   { 145   {
HITCBC 146   239 if (::pipe(pipe_fds_) < 0) 146   239 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   717 for (int i = 0; i < 2; ++i) 149   717 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   478 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   478 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   478 if (flags == -1) 152   478 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   478 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   478 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   478 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   478 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   239 timer_svc_ = &get_timer_service(ctx, *this); 175   239 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   239 timer_svc_->set_on_earliest_changed( 176   239 timer_svc_->set_on_earliest_changed(
HITCBC 177   3817 timer_service::callback(this, [](void* p) { 177   3900 timer_service::callback(this, [](void* p) {
HITCBC 178   3578 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3661 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3578 })); 179   3661 }));
180   180  
HITCBC 181   239 get_resolver_service(ctx, *this); 181   239 get_resolver_service(ctx, *this);
HITCBC 182   239 get_signal_service(ctx, *this); 182   239 get_signal_service(ctx, *this);
HITCBC 183   239 get_stream_file_service(ctx, *this); 183   239 get_stream_file_service(ctx, *this);
HITCBC 184   239 get_random_access_file_service(ctx, *this); 184   239 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   239 completed_ops_.push(&task_op_); 186   239 completed_ops_.push(&task_op_);
HITCBC 187   239 } 187   239 }
188   188  
HITCBC 189   478 inline select_scheduler::~select_scheduler() 189   478 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   239 if (pipe_fds_[0] >= 0) 191   239 if (pipe_fds_[0] >= 0)
HITCBC 192   239 ::close(pipe_fds_[0]); 192   239 ::close(pipe_fds_[0]);
HITCBC 193   239 if (pipe_fds_[1] >= 0) 193   239 if (pipe_fds_[1] >= 0)
HITCBC 194   239 ::close(pipe_fds_[1]); 194   239 ::close(pipe_fds_[1]);
HITCBC 195   478 } 195   478 }
196   196  
197   inline void 197   inline void
HITCBC 198   239 select_scheduler::shutdown() 198   239 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   239 shutdown_drain(); 200   239 shutdown_drain();
201   201  
HITCBC 202   239 if (pipe_fds_[1] >= 0) 202   239 if (pipe_fds_[1] >= 0)
HITCBC 203   239 interrupt_reactor(); 203   239 interrupt_reactor();
HITCBC 204   239 } 204   239 }
205   205  
206   inline void 206   inline void
HITCBC 207   6875 select_scheduler::register_descriptor( 207   7042 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6875 if (fd < 0 || fd >= FD_SETSIZE) 210   7042 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   6875 desc->registered_events = reactor_event_read | reactor_event_write; 213   7042 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6875 desc->fd = fd; 214   7042 desc->fd = fd;
HITCBC 215   6875 desc->scheduler_ = this; 215   7042 desc->scheduler_ = this;
HITCBC 216   6875 desc->mutex.set_enabled(!single_threaded_); 216   7042 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6875 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7042 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6875 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7042 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6875 desc->impl_ref_.reset(); 221   7042 desc->impl_ref_.reset();
HITCBC 222   6875 desc->read_ready = false; 222   7042 desc->read_ready = false;
HITCBC 223   6875 desc->write_ready = false; 223   7042 desc->write_ready = false;
HITCBC 224   6875 } 224   7042 }
225   225  
226   { 226   {
HITCBC 227   6875 mutex_type::scoped_lock lock(mutex_); 227   7042 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6875 registered_descs_[fd] = desc; 228   7042 registered_descs_[fd] = desc;
HITCBC 229   6875 if (fd > max_fd_) 229   7042 if (fd > max_fd_)
HITCBC 230   6871 max_fd_ = fd; 230   7038 max_fd_ = fd;
HITCBC 231   6875 } 231   7042 }
232   232  
HITCBC 233   6875 interrupt_reactor(); 233   7042 interrupt_reactor();
HITCBC 234   6875 } 234   7042 }
235   235  
236   inline void 236   inline void
HITCBC 237   6875 select_scheduler::deregister_descriptor(int fd) const 237   7042 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6875 mutex_type::scoped_lock lock(mutex_); 239   7042 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6875 auto it = registered_descs_.find(fd); 241   7042 auto it = registered_descs_.find(fd);
HITCBC 242   6875 if (it == registered_descs_.end()) 242   7042 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6875 registered_descs_.erase(it); 245   7042 registered_descs_.erase(it);
246   246  
HITCBC 247   6875 if (fd == max_fd_) 247   7042 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6812 max_fd_ = pipe_fds_[0]; 249   6980 max_fd_ = pipe_fds_[0];
HITCBC 250   13510 for (auto& [registered_fd, state] : registered_descs_) 250   13846 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6698 if (registered_fd > max_fd_) 252   6866 if (registered_fd > max_fd_)
HITCBC 253   6683 max_fd_ = registered_fd; 253   6851 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6875 } 256   7042 }
257   257  
258   inline void 258   inline void
HITCBC 259   3364 select_scheduler::notify_reactor() const 259   3447 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3364 interrupt_reactor(); 261   3447 interrupt_reactor();
HITCBC 262   3364 } 262   3447 }
263   263  
264   inline void 264   inline void
HITCBC 265   14221 select_scheduler::interrupt_reactor() const 265   14554 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14221 char byte = 1; 267   14554 char byte = 1;
HITCBC 268   14221 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   14554 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14221 } 269   14554 }
270   270  
271   inline long 271   inline long
HITCBC 272   114437 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   117408 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   114437 if (requested_timeout_us == 0) 274   117408 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   114437 auto nearest = timer_svc_->nearest_expiry(); 277   117408 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   114437 if (nearest == timer_service::time_point::max()) 278   117408 if (nearest == timer_service::time_point::max())
HITCBC 279   56 return requested_timeout_us; 279   56 return requested_timeout_us;
280   280  
HITCBC 281   114381 auto now = std::chrono::steady_clock::now(); 281   117352 auto now = std::chrono::steady_clock::now();
HITCBC 282   114381 if (nearest <= now) 282   117352 if (nearest <= now)
HITCBC 283   359 return 0; 283   367 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   114022 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   116985 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   114022 .count(); 287   116985 .count();
288   288  
HITCBC 289   114022 constexpr auto long_max = 289   116985 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   114022 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   116985 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   114022 static_cast<long long>(0)), 293   116985 static_cast<long long>(0)),
HITCBC 294   114022 long_max); 294   116985 long_max);
295   295  
HITCBC 296   114022 if (requested_timeout_us < 0) 296   116985 if (requested_timeout_us < 0)
HITCBC 297   114016 return static_cast<long>(capped_timer_us); 297   116979 return static_cast<long>(capped_timer_us);
298   298  
299   return static_cast<long>( 299   return static_cast<long>(
HITCBC 300   6 (std::min)(static_cast<long long>(requested_timeout_us), 300   6 (std::min)(static_cast<long long>(requested_timeout_us),
HITCBC 301   6 capped_timer_us)); 301   6 capped_timer_us));
302   } 302   }
303   303  
304   inline void 304   inline void
HITCBC 305   135651 select_scheduler::run_task( 305   141672 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   135651 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   141672 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   135651 int snapshot_count = 0; 323   141672 int snapshot_count = 0;
324   324  
HITCBC 325   401709 for (auto& [fd, desc] : registered_descs_) 325   420634 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   266058 if (snapshot_count < FD_SETSIZE) 327   278962 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   266058 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   278962 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   266058 snapshot[snapshot_count].fd = fd; 330   278962 snapshot[snapshot_count].fd = fd;
HITCBC 331   266058 snapshot[snapshot_count].desc = desc; 331   278962 snapshot[snapshot_count].desc = desc;
HITCBC 332   266058 snapshot[snapshot_count].needs_write = 332   278962 snapshot[snapshot_count].needs_write =
HITCBC 333   266058 (desc->write_op || desc->connect_op); 333   278962 (desc->write_op || desc->connect_op);
HITCBC 334   266058 ++snapshot_count; 334   278962 ++snapshot_count;
HITCBC 335   266058 } 335   278962 }
336   } 336   }
337   337  
HITCBC 338   135651 if (lock.owns_lock()) 338   141672 if (lock.owns_lock())
HITCBC 339   114437 lock.unlock(); 339   117408 lock.unlock();
340   340  
HITCBC 341   135651 task_cleanup on_exit{this, &lock, ctx}; 341   141672 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   2306067 FD_ZERO(&read_fds); 344   2408424 FD_ZERO(&read_fds);
HITCBC 345   2306067 FD_ZERO(&write_fds); 345   2408424 FD_ZERO(&write_fds);
HITCBC 346   2306067 FD_ZERO(&except_fds); 346   2408424 FD_ZERO(&except_fds);
347   347  
HITCBC 348   135651 FD_SET(pipe_fds_[0], &read_fds); 348   141672 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   135651 int nfds = pipe_fds_[0]; 349   141672 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   401709 for (int i = 0; i < snapshot_count; ++i) 351   420634 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   266058 int fd = snapshot[i].fd; 353   278962 int fd = snapshot[i].fd;
HITCBC 354   266058 FD_SET(fd, &read_fds); 354   278962 FD_SET(fd, &read_fds);
HITCBC 355   266058 if (snapshot[i].needs_write) 355   278962 if (snapshot[i].needs_write)
HITCBC 356   3366 FD_SET(fd, &write_fds); 356   3449 FD_SET(fd, &write_fds);
HITCBC 357   266058 FD_SET(fd, &except_fds); 357   278962 FD_SET(fd, &except_fds);
HITCBC 358   266058 if (fd > nfds) 358   278962 if (fd > nfds)
HITCBC 359   135380 nfds = fd; 359   141402 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   135651 struct timeval* tv_ptr = nullptr; 363   141672 struct timeval* tv_ptr = nullptr;
HITCBC 364   135651 if (effective_timeout_us >= 0) 364   141672 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   135595 tv.tv_sec = effective_timeout_us / 1000000; 366   141616 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   135595 tv.tv_usec = effective_timeout_us % 1000000; 367   141616 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   135595 tv_ptr = &tv; 368   141616 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   135651 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   141672 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   135651 if (ready < 0) 376   141672 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   135651 timer_svc_->process_expired(); 384   141672 timer_svc_->process_expired();
385   385  
HITCBC 386   135651 op_queue local_ops; 386   141672 op_queue local_ops;
387   387  
HITCBC 388   135651 if (ready > 0) 388   141672 if (ready > 0)
389   { 389   {
HITCBC 390   118618 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   122896 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14070 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14404 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   337355 for (int i = 0; i < snapshot_count; ++i) 398   349994 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   218737 int fd = snapshot[i].fd; 400   227098 int fd = snapshot[i].fd;
HITCBC 401   218737 reactor_descriptor_state* desc = snapshot[i].desc; 401   227098 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   218737 std::uint32_t flags = 0; 403   227098 std::uint32_t flags = 0;
HITCBC 404   218737 if (FD_ISSET(fd, &read_fds)) 404   227098 if (FD_ISSET(fd, &read_fds))
HITCBC 405   115124 flags |= reactor_event_read; 405   119319 flags |= reactor_event_read;
HITCBC 406   218737 if (FD_ISSET(fd, &write_fds)) 406   227098 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3363 flags |= reactor_event_write; 407   3446 flags |= reactor_event_write;
HITCBC 408   218737 if (FD_ISSET(fd, &except_fds)) 408   227098 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   218737 if (flags == 0) 411   227098 if (flags == 0)
HITCBC 412   100258 continue; 412   104340 continue;
413   413  
HITCBC 414   118479 desc->add_ready_events(flags); 414   122758 desc->add_ready_events(flags);
415   415  
HITCBC 416   118479 bool expected = false; 416   122758 bool expected = false;
HITCBC 417   118479 if (desc->is_enqueued_.compare_exchange_strong( 417   122758 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   118479 local_ops.push(desc); 421   122758 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   135651 lock.lock(); 426   141672 lock.lock();
427   427  
HITCBC 428   135651 if (!local_ops.empty()) 428   141672 if (!local_ops.empty())
HITCBC 429   115125 completed_ops_.splice(local_ops); 429   119320 completed_ops_.splice(local_ops);
HITCBC 430   135651 } 430   141672 }
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