. /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   4365 timer_service::callback(this, [](void* p) { 177   4244 timer_service::callback(this, [](void* p) {
HITCBC 178   3771 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3650 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3771 })); 179   3650 }));
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   7454 select_scheduler::register_descriptor( 207   7212 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7454 if (fd < 0 || fd >= FD_SETSIZE) 210   7212 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   7454 desc->registered_events = reactor_event_read | reactor_event_write; 213   7212 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7454 desc->fd = fd; 214   7212 desc->fd = fd;
HITCBC 215   7454 desc->scheduler_ = this; 215   7212 desc->scheduler_ = this;
HITCBC 216   7454 desc->mutex.set_enabled(!single_threaded_); 216   7212 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7454 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7212 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7454 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7212 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7454 desc->impl_ref_.reset(); 221   7212 desc->impl_ref_.reset();
HITCBC 222   7454 desc->read_ready = false; 222   7212 desc->read_ready = false;
HITCBC 223   7454 desc->write_ready = false; 223   7212 desc->write_ready = false;
HITCBC 224   7454 } 224   7212 }
225   225  
226   { 226   {
HITCBC 227   7454 mutex_type::scoped_lock lock(mutex_); 227   7212 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7454 registered_descs_[fd] = desc; 228   7212 registered_descs_[fd] = desc;
HITCBC 229   7454 if (fd > max_fd_) 229   7212 if (fd > max_fd_)
HITCBC 230   7449 max_fd_ = fd; 230   7207 max_fd_ = fd;
HITCBC 231   7454 } 231   7212 }
232   232  
HITCBC 233   7454 interrupt_reactor(); 233   7212 interrupt_reactor();
HITCBC 234   7454 } 234   7212 }
235   235  
236   inline void 236   inline void
HITCBC 237   7454 select_scheduler::deregister_descriptor(int fd) const 237   7212 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7454 mutex_type::scoped_lock lock(mutex_); 239   7212 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7454 auto it = registered_descs_.find(fd); 241   7212 auto it = registered_descs_.find(fd);
HITCBC 242   7454 if (it == registered_descs_.end()) 242   7212 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7454 registered_descs_.erase(it); 245   7212 registered_descs_.erase(it);
246   246  
HITCBC 247   7454 if (fd == max_fd_) 247   7212 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7340 max_fd_ = pipe_fds_[0]; 249   7098 max_fd_ = pipe_fds_[0];
HITCBC 250   14432 for (auto& [registered_fd, state] : registered_descs_) 250   13948 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7092 if (registered_fd > max_fd_) 252   6850 if (registered_fd > max_fd_)
HITCBC 253   7045 max_fd_ = registered_fd; 253   6803 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7454 } 256   7212 }
257   257  
258   inline void 258   inline void
HITCBC 259   3632 select_scheduler::notify_reactor() const 259   3511 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3632 interrupt_reactor(); 261   3511 interrupt_reactor();
HITCBC 262   3632 } 262   3511 }
263   263  
264   inline void 264   inline void
HITCBC 265   15880 select_scheduler::interrupt_reactor() const 265   15401 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   15880 char byte = 1; 267   15401 char byte = 1;
HITCBC 268   15880 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15401 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   15880 } 269   15401 }
270   270  
271   inline long 271   inline long
HITCBC 272   219414 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   213276 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   219414 if (requested_timeout_us == 0) 274   213276 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   219414 auto nearest = timer_svc_->nearest_expiry(); 277   213276 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   219414 if (nearest == timer_service::time_point::max()) 278   213276 if (nearest == timer_service::time_point::max())
HITCBC 279   398 return requested_timeout_us; 279   403 return requested_timeout_us;
280   280  
HITCBC 281   219016 auto now = std::chrono::steady_clock::now(); 281   212873 auto now = std::chrono::steady_clock::now();
HITCBC 282   219016 if (nearest <= now) 282   212873 if (nearest <= now)
HITCBC 283   534 return 0; 283   672 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   218482 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   212201 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   218482 .count(); 287   212201 .count();
288   288  
HITCBC 289   218482 constexpr auto long_max = 289   212201 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   218482 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   212201 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   218482 static_cast<long long>(0)), 293   212201 static_cast<long long>(0)),
HITCBC 294   218482 long_max); 294   212201 long_max);
295   295  
HITCBC 296   218482 if (requested_timeout_us < 0) 296   212201 if (requested_timeout_us < 0)
HITCBC 297   218482 return static_cast<long>(capped_timer_us); 297   212201 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   243766 select_scheduler::run_task( 305   237377 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   243766 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   237377 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   243766 int snapshot_count = 0; 323   237377 int snapshot_count = 0;
324   324  
HITCBC 325   640193 for (auto& [fd, desc] : registered_descs_) 325   625598 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   396427 if (snapshot_count < FD_SETSIZE) 327   388221 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   396427 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   388221 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   396427 snapshot[snapshot_count].fd = fd; 330   388221 snapshot[snapshot_count].fd = fd;
HITCBC 331   396427 snapshot[snapshot_count].desc = desc; 331   388221 snapshot[snapshot_count].desc = desc;
HITCBC 332   396427 snapshot[snapshot_count].needs_write = 332   388221 snapshot[snapshot_count].needs_write =
HITCBC 333   396427 (desc->write_op || desc->connect_op); 333   388221 (desc->write_op || desc->connect_op);
HITCBC 334   396427 ++snapshot_count; 334   388221 ++snapshot_count;
HITCBC 335   396427 } 335   388221 }
336   } 336   }
337   337  
HITCBC 338   243766 if (lock.owns_lock()) 338   237377 if (lock.owns_lock())
HITCBC 339   219414 lock.unlock(); 339   213276 lock.unlock();
340   340  
HITCBC 341   243766 task_cleanup on_exit{this, &lock, ctx}; 341   237377 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   4144022 FD_ZERO(&read_fds); 344   4035409 FD_ZERO(&read_fds);
HITCBC 345   4144022 FD_ZERO(&write_fds); 345   4035409 FD_ZERO(&write_fds);
HITCBC 346   4144022 FD_ZERO(&except_fds); 346   4035409 FD_ZERO(&except_fds);
347   347  
HITCBC 348   243766 FD_SET(pipe_fds_[0], &read_fds); 348   237377 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   243766 int nfds = pipe_fds_[0]; 349   237377 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   640193 for (int i = 0; i < snapshot_count; ++i) 351   625598 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   396427 int fd = snapshot[i].fd; 353   388221 int fd = snapshot[i].fd;
HITCBC 354   396427 FD_SET(fd, &read_fds); 354   388221 FD_SET(fd, &read_fds);
HITCBC 355   396427 if (snapshot[i].needs_write) 355   388221 if (snapshot[i].needs_write)
HITCBC 356   14993 FD_SET(fd, &write_fds); 356   14886 FD_SET(fd, &write_fds);
HITCBC 357   396427 FD_SET(fd, &except_fds); 357   388221 FD_SET(fd, &except_fds);
HITCBC 358   396427 if (fd > nfds) 358   388221 if (fd > nfds)
HITCBC 359   243323 nfds = fd; 359   236929 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   243766 struct timeval* tv_ptr = nullptr; 363   237377 struct timeval* tv_ptr = nullptr;
HITCBC 364   243766 if (effective_timeout_us >= 0) 364   237377 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   243372 tv.tv_sec = effective_timeout_us / 1000000; 366   236978 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   243372 tv.tv_usec = effective_timeout_us % 1000000; 367   236978 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   243372 tv_ptr = &tv; 368   236978 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   243766 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   237377 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   243766 if (ready < 0) 376   237377 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   243766 timer_svc_->process_expired(); 384   237377 timer_svc_->process_expired();
385   385  
HITCBC 386   243766 op_queue local_ops; 386   237377 op_queue local_ops;
387   387  
HITCBC 388   243766 if (ready > 0) 388   237377 if (ready > 0)
389   { 389   {
HITCBC 390   225251 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   219029 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   15376 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14908 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   575539 for (int i = 0; i < snapshot_count; ++i) 398   558651 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   350288 int fd = snapshot[i].fd; 400   339622 int fd = snapshot[i].fd;
HITCBC 401   350288 reactor_descriptor_state* desc = snapshot[i].desc; 401   339622 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   350288 std::uint32_t flags = 0; 403   339622 std::uint32_t flags = 0;
HITCBC 404   350288 if (FD_ISSET(fd, &read_fds)) 404   339622 if (FD_ISSET(fd, &read_fds))
HITCBC 405   221335 flags |= reactor_event_read; 405   215227 flags |= reactor_event_read;
HITCBC 406   350288 if (FD_ISSET(fd, &write_fds)) 406   339622 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3629 flags |= reactor_event_write; 407   3508 flags |= reactor_event_write;
HITCBC 408   350288 if (FD_ISSET(fd, &except_fds)) 408   339622 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   350288 if (flags == 0) 411   339622 if (flags == 0)
HITCBC 412   125334 continue; 412   120897 continue;
413   413  
HITCBC 414   224954 desc->add_ready_events(flags); 414   218725 desc->add_ready_events(flags);
415   415  
HITCBC 416   224954 bool expected = false; 416   218725 bool expected = false;
HITCBC 417   224954 if (desc->is_enqueued_.compare_exchange_strong( 417   218725 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   224954 local_ops.push(desc); 421   218725 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   243766 lock.lock(); 426   237377 lock.lock();
427   427  
HITCBC 428   243766 if (!local_ops.empty()) 428   237377 if (!local_ops.empty())
HITCBC 429   221417 completed_ops_.splice(local_ops); 429   215309 completed_ops_.splice(local_ops);
HITCBC 430   243766 } 430   237377 }
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