. /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   430 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   430 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   430 : pipe_fds_{-1, -1} 143   430 : pipe_fds_{-1, -1}
HITCBC 144   430 , max_fd_(-1) 144   430 , max_fd_(-1)
145   { 145   {
HITCBC 146   430 if (::pipe(pipe_fds_) < 0) 146   430 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   1290 for (int i = 0; i < 2; ++i) 149   1290 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   860 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   860 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   860 if (flags == -1) 152   860 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   860 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   860 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   860 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   860 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   430 timer_svc_ = &get_timer_service(ctx, *this); 175   430 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   430 timer_svc_->set_on_earliest_changed( 176   430 timer_svc_->set_on_earliest_changed(
HITCBC 177   4378 timer_service::callback(this, [](void* p) { 177   4627 timer_service::callback(this, [](void* p) {
HITCBC 178   3948 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   4197 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3948 })); 179   4197 }));
180   180  
HITCBC 181   430 get_resolver_service(ctx, *this); 181   430 get_resolver_service(ctx, *this);
HITCBC 182   430 get_signal_service(ctx, *this); 182   430 get_signal_service(ctx, *this);
HITCBC 183   430 get_stream_file_service(ctx, *this); 183   430 get_stream_file_service(ctx, *this);
HITCBC 184   430 get_random_access_file_service(ctx, *this); 184   430 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   430 completed_ops_.push(&task_op_); 186   430 completed_ops_.push(&task_op_);
HITCBC 187   430 } 187   430 }
188   188  
HITCBC 189   860 inline select_scheduler::~select_scheduler() 189   860 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   430 if (pipe_fds_[0] >= 0) 191   430 if (pipe_fds_[0] >= 0)
HITCBC 192   430 ::close(pipe_fds_[0]); 192   430 ::close(pipe_fds_[0]);
HITCBC 193   430 if (pipe_fds_[1] >= 0) 193   430 if (pipe_fds_[1] >= 0)
HITCBC 194   430 ::close(pipe_fds_[1]); 194   430 ::close(pipe_fds_[1]);
HITCBC 195   860 } 195   860 }
196   196  
197   inline void 197   inline void
HITCBC 198   430 select_scheduler::shutdown() 198   430 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   430 shutdown_drain(); 200   430 shutdown_drain();
201   201  
HITCBC 202   430 if (pipe_fds_[1] >= 0) 202   430 if (pipe_fds_[1] >= 0)
HITCBC 203   430 interrupt_reactor(); 203   430 interrupt_reactor();
HITCBC 204   430 } 204   430 }
205   205  
206   inline void 206   inline void
HITCBC 207   7715 select_scheduler::register_descriptor( 207   8228 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7715 if (fd < 0 || fd >= FD_SETSIZE) 210   8228 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   7715 desc->registered_events = reactor_event_read | reactor_event_write; 213   8228 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7715 desc->fd = fd; 214   8228 desc->fd = fd;
HITCBC 215   7715 desc->scheduler_ = this; 215   8228 desc->scheduler_ = this;
HITCBC 216   7715 desc->mutex.set_enabled(!single_threaded_); 216   8228 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7715 desc->ready_events_.store(0, std::memory_order_relaxed); 217   8228 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7715 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   8228 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7715 desc->impl_ref_.reset(); 221   8228 desc->impl_ref_.reset();
HITCBC 222   7715 desc->read_ready = false; 222   8228 desc->read_ready = false;
HITCBC 223   7715 desc->write_ready = false; 223   8228 desc->write_ready = false;
HITCBC 224   7715 } 224   8228 }
225   225  
226   { 226   {
HITCBC 227   7715 mutex_type::scoped_lock lock(mutex_); 227   8228 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7715 registered_descs_[fd] = desc; 228   8228 registered_descs_[fd] = desc;
HITCBC 229   7715 if (fd > max_fd_) 229   8228 if (fd > max_fd_)
HITCBC 230   7711 max_fd_ = fd; 230   8224 max_fd_ = fd;
HITCBC 231   7715 } 231   8228 }
232   232  
HITCBC 233   7715 interrupt_reactor(); 233   8228 interrupt_reactor();
HITCBC 234   7715 } 234   8228 }
235   235  
236   inline void 236   inline void
HITCBC 237   7715 select_scheduler::deregister_descriptor(int fd) const 237   8228 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7715 mutex_type::scoped_lock lock(mutex_); 239   8228 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7715 auto it = registered_descs_.find(fd); 241   8228 auto it = registered_descs_.find(fd);
HITCBC 242   7715 if (it == registered_descs_.end()) 242   8228 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7715 registered_descs_.erase(it); 245   8228 registered_descs_.erase(it);
246   246  
HITCBC 247   7715 if (fd == max_fd_) 247   8228 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7610 max_fd_ = pipe_fds_[0]; 249   8124 max_fd_ = pipe_fds_[0];
HITCBC 250   15009 for (auto& [registered_fd, state] : registered_descs_) 250   16037 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7399 if (registered_fd > max_fd_) 252   7913 if (registered_fd > max_fd_)
HITCBC 253   7372 max_fd_ = registered_fd; 253   7886 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7715 } 256   8228 }
257   257  
258   inline void 258   inline void
HITCBC 259   3716 select_scheduler::notify_reactor() const 259   3972 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3716 interrupt_reactor(); 261   3972 interrupt_reactor();
HITCBC 262   3716 } 262   3972 }
263   263  
264   inline void 264   inline void
HITCBC 265   16097 select_scheduler::interrupt_reactor() const 265   17115 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   16097 char byte = 1; 267   17115 char byte = 1;
HITCBC 268   16097 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   17115 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   16097 } 269   17115 }
270   270  
271   inline long 271   inline long
HITCBC 272   245399 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   220526 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   245399 if (requested_timeout_us == 0) 274   220526 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   245399 auto nearest = timer_svc_->nearest_expiry(); 277   220526 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   245399 if (nearest == timer_service::time_point::max()) 278   220526 if (nearest == timer_service::time_point::max())
HITCBC 279   177 return requested_timeout_us; 279   177 return requested_timeout_us;
280   280  
HITCBC 281   245222 auto now = std::chrono::steady_clock::now(); 281   220349 auto now = std::chrono::steady_clock::now();
HITCBC 282   245222 if (nearest <= now) 282   220349 if (nearest <= now)
HITCBC 283   1555 return 0; 283   1968 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   243667 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   218381 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   243667 .count(); 287   218381 .count();
288   288  
HITCBC 289   243667 constexpr auto long_max = 289   218381 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   243667 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   218381 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   243667 static_cast<long long>(0)), 293   218381 static_cast<long long>(0)),
HITCBC 294   243667 long_max); 294   218381 long_max);
295   295  
HITCBC 296   243667 if (requested_timeout_us < 0) 296   218381 if (requested_timeout_us < 0)
HITCBC 297   243667 return static_cast<long>(capped_timer_us); 297   218381 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   276492 select_scheduler::run_task( 305   251112 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   276492 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   251112 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   276492 int snapshot_count = 0; 323   251112 int snapshot_count = 0;
324   324  
HITCBC 325   765490 for (auto& [fd, desc] : registered_descs_) 325   674926 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   488998 if (snapshot_count < FD_SETSIZE) 327   423814 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   488998 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   423814 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   488998 snapshot[snapshot_count].fd = fd; 330   423814 snapshot[snapshot_count].fd = fd;
HITCBC 331   488998 snapshot[snapshot_count].desc = desc; 331   423814 snapshot[snapshot_count].desc = desc;
HITCBC 332   488998 snapshot[snapshot_count].needs_write = 332   423814 snapshot[snapshot_count].needs_write =
HITCBC 333   488998 (desc->write_op || desc->connect_op); 333   423814 (desc->write_op || desc->connect_op);
HITCBC 334   488998 ++snapshot_count; 334   423814 ++snapshot_count;
HITCBC 335   488998 } 335   423814 }
336   } 336   }
337   337  
HITCBC 338   276492 if (lock.owns_lock()) 338   251112 if (lock.owns_lock())
HITCBC 339   245399 lock.unlock(); 339   220526 lock.unlock();
340   340  
HITCBC 341   276492 task_cleanup on_exit{this, &lock, ctx}; 341   251112 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   4700364 FD_ZERO(&read_fds); 344   4268904 FD_ZERO(&read_fds);
HITCBC 345   4700364 FD_ZERO(&write_fds); 345   4268904 FD_ZERO(&write_fds);
HITCBC 346   4700364 FD_ZERO(&except_fds); 346   4268904 FD_ZERO(&except_fds);
347   347  
HITCBC 348   276492 FD_SET(pipe_fds_[0], &read_fds); 348   251112 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   276492 int nfds = pipe_fds_[0]; 349   251112 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   765490 for (int i = 0; i < snapshot_count; ++i) 351   674926 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   488998 int fd = snapshot[i].fd; 353   423814 int fd = snapshot[i].fd;
HITCBC 354   488998 FD_SET(fd, &read_fds); 354   423814 FD_SET(fd, &read_fds);
HITCBC 355   488998 if (snapshot[i].needs_write) 355   423814 if (snapshot[i].needs_write)
HITCBC 356   3803 FD_SET(fd, &write_fds); 356   4059 FD_SET(fd, &write_fds);
HITCBC 357   488998 FD_SET(fd, &except_fds); 357   423814 FD_SET(fd, &except_fds);
HITCBC 358   488998 if (fd > nfds) 358   423814 if (fd > nfds)
HITCBC 359   276142 nfds = fd; 359   250763 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   276492 struct timeval* tv_ptr = nullptr; 363   251112 struct timeval* tv_ptr = nullptr;
HITCBC 364   276492 if (effective_timeout_us >= 0) 364   251112 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   276316 tv.tv_sec = effective_timeout_us / 1000000; 366   250936 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   276316 tv.tv_usec = effective_timeout_us % 1000000; 367   250936 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   276316 tv_ptr = &tv; 368   250936 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   276492 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   251112 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   276492 if (ready < 0) 376   251112 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   276492 timer_svc_->process_expired(); 384   251112 timer_svc_->process_expired();
385   385  
HITCBC 386   276492 op_queue local_ops; 386   251112 op_queue local_ops;
387   387  
HITCBC 388   276492 if (ready > 0) 388   251112 if (ready > 0)
389   { 389   {
HITCBC 390   255279 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   230089 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   15722 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   16732 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   681870 for (int i = 0; i < snapshot_count; ++i) 398   593525 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   426591 int fd = snapshot[i].fd; 400   363436 int fd = snapshot[i].fd;
HITCBC 401   426591 reactor_descriptor_state* desc = snapshot[i].desc; 401   363436 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   426591 std::uint32_t flags = 0; 403   363436 std::uint32_t flags = 0;
HITCBC 404   426591 if (FD_ISSET(fd, &read_fds)) 404   363436 if (FD_ISSET(fd, &read_fds))
HITCBC 405   251350 flags |= reactor_event_read; 405   225904 flags |= reactor_event_read;
HITCBC 406   426591 if (FD_ISSET(fd, &write_fds)) 406   363436 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3715 flags |= reactor_event_write; 407   3971 flags |= reactor_event_write;
HITCBC 408   426591 if (FD_ISSET(fd, &except_fds)) 408   363436 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   426591 if (flags == 0) 411   363436 if (flags == 0)
HITCBC 412   171536 continue; 412   133570 continue;
413   413  
HITCBC 414   255055 desc->add_ready_events(flags); 414   229866 desc->add_ready_events(flags);
415   415  
HITCBC 416   255055 bool expected = false; 416   229866 bool expected = false;
HITCBC 417   255055 if (desc->is_enqueued_.compare_exchange_strong( 417   229866 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   255055 local_ops.push(desc); 421   229866 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   276492 lock.lock(); 426   251112 lock.lock();
427   427  
HITCBC 428   276492 if (!local_ops.empty()) 428   251112 if (!local_ops.empty())
HITCBC 429   251346 completed_ops_.splice(local_ops); 429   225900 completed_ops_.splice(local_ops);
HITCBC 430   276492 } 430   251112 }
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