. /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   3613 timer_service::callback(this, [](void* p) { 177   3954 timer_service::callback(this, [](void* p) {
HITCBC 178   3374 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3715 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3374 })); 179   3715 }));
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   6469 select_scheduler::register_descriptor( 207   7154 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6469 if (fd < 0 || fd >= FD_SETSIZE) 210   7154 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   6469 desc->registered_events = reactor_event_read | reactor_event_write; 213   7154 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6469 desc->fd = fd; 214   7154 desc->fd = fd;
HITCBC 215   6469 desc->scheduler_ = this; 215   7154 desc->scheduler_ = this;
HITCBC 216   6469 desc->mutex.set_enabled(!single_threaded_); 216   7154 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6469 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7154 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6469 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7154 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6469 desc->impl_ref_.reset(); 221   7154 desc->impl_ref_.reset();
HITCBC 222   6469 desc->read_ready = false; 222   7154 desc->read_ready = false;
HITCBC 223   6469 desc->write_ready = false; 223   7154 desc->write_ready = false;
HITCBC 224   6469 } 224   7154 }
225   225  
226   { 226   {
HITCBC 227   6469 mutex_type::scoped_lock lock(mutex_); 227   7154 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6469 registered_descs_[fd] = desc; 228   7154 registered_descs_[fd] = desc;
HITCBC 229   6469 if (fd > max_fd_) 229   7154 if (fd > max_fd_)
HITCBC 230   6465 max_fd_ = fd; 230   7150 max_fd_ = fd;
HITCBC 231   6469 } 231   7154 }
232   232  
HITCBC 233   6469 interrupt_reactor(); 233   7154 interrupt_reactor();
HITCBC 234   6469 } 234   7154 }
235   235  
236   inline void 236   inline void
HITCBC 237   6469 select_scheduler::deregister_descriptor(int fd) const 237   7154 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6469 mutex_type::scoped_lock lock(mutex_); 239   7154 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6469 auto it = registered_descs_.find(fd); 241   7154 auto it = registered_descs_.find(fd);
HITCBC 242   6469 if (it == registered_descs_.end()) 242   7154 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6469 registered_descs_.erase(it); 245   7154 registered_descs_.erase(it);
246   246  
HITCBC 247   6469 if (fd == max_fd_) 247   7154 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6406 max_fd_ = pipe_fds_[0]; 249   7092 max_fd_ = pipe_fds_[0];
HITCBC 250   12698 for (auto& [registered_fd, state] : registered_descs_) 250   14070 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6292 if (registered_fd > max_fd_) 252   6978 if (registered_fd > max_fd_)
HITCBC 253   6277 max_fd_ = registered_fd; 253   6963 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6469 } 256   7154 }
257   257  
258   inline void 258   inline void
HITCBC 259   3161 select_scheduler::notify_reactor() const 259   3503 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3161 interrupt_reactor(); 261   3503 interrupt_reactor();
HITCBC 262   3161 } 262   3503 }
263   263  
264   inline void 264   inline void
HITCBC 265   13408 select_scheduler::interrupt_reactor() const 265   14776 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   13408 char byte = 1; 267   14776 char byte = 1;
HITCBC 268   13408 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   14776 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   13408 } 269   14776 }
270   270  
271   inline long 271   inline long
HITCBC 272   120159 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   125782 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   120159 if (requested_timeout_us == 0) 274   125782 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   120159 auto nearest = timer_svc_->nearest_expiry(); 277   125782 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   120159 if (nearest == timer_service::time_point::max()) 278   125782 if (nearest == timer_service::time_point::max())
HITCBC 279   56 return requested_timeout_us; 279   56 return requested_timeout_us;
280   280  
HITCBC 281   120103 auto now = std::chrono::steady_clock::now(); 281   125726 auto now = std::chrono::steady_clock::now();
HITCBC 282   120103 if (nearest <= now) 282   125726 if (nearest <= now)
HITCBC 283   340 return 0; 283   389 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   119763 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   125337 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   119763 .count(); 287   125337 .count();
288   288  
HITCBC 289   119763 constexpr auto long_max = 289   125337 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   119763 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   125337 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   119763 static_cast<long long>(0)), 293   125337 static_cast<long long>(0)),
HITCBC 294   119763 long_max); 294   125337 long_max);
295   295  
HITCBC 296   119763 if (requested_timeout_us < 0) 296   125337 if (requested_timeout_us < 0)
HITCBC 297   119757 return static_cast<long>(capped_timer_us); 297   125331 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   144597 select_scheduler::run_task( 305   150265 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   144597 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   150265 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   144597 int snapshot_count = 0; 323   150265 int snapshot_count = 0;
324   324  
HITCBC 325   428420 for (auto& [fd, desc] : registered_descs_) 325   446734 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   283823 if (snapshot_count < FD_SETSIZE) 327   296469 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   283823 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   296469 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   283823 snapshot[snapshot_count].fd = fd; 330   296469 snapshot[snapshot_count].fd = fd;
HITCBC 331   283823 snapshot[snapshot_count].desc = desc; 331   296469 snapshot[snapshot_count].desc = desc;
HITCBC 332   283823 snapshot[snapshot_count].needs_write = 332   296469 snapshot[snapshot_count].needs_write =
HITCBC 333   283823 (desc->write_op || desc->connect_op); 333   296469 (desc->write_op || desc->connect_op);
HITCBC 334   283823 ++snapshot_count; 334   296469 ++snapshot_count;
HITCBC 335   283823 } 335   296469 }
336   } 336   }
337   337  
HITCBC 338   144597 if (lock.owns_lock()) 338   150265 if (lock.owns_lock())
HITCBC 339   120159 lock.unlock(); 339   125782 lock.unlock();
340   340  
HITCBC 341   144597 task_cleanup on_exit{this, &lock, ctx}; 341   150265 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   2458149 FD_ZERO(&read_fds); 344   2554505 FD_ZERO(&read_fds);
HITCBC 345   2458149 FD_ZERO(&write_fds); 345   2554505 FD_ZERO(&write_fds);
HITCBC 346   2458149 FD_ZERO(&except_fds); 346   2554505 FD_ZERO(&except_fds);
347   347  
HITCBC 348   144597 FD_SET(pipe_fds_[0], &read_fds); 348   150265 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   144597 int nfds = pipe_fds_[0]; 349   150265 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   428420 for (int i = 0; i < snapshot_count; ++i) 351   446734 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   283823 int fd = snapshot[i].fd; 353   296469 int fd = snapshot[i].fd;
HITCBC 354   283823 FD_SET(fd, &read_fds); 354   296469 FD_SET(fd, &read_fds);
HITCBC 355   283823 if (snapshot[i].needs_write) 355   296469 if (snapshot[i].needs_write)
HITCBC 356   3163 FD_SET(fd, &write_fds); 356   3505 FD_SET(fd, &write_fds);
HITCBC 357   283823 FD_SET(fd, &except_fds); 357   296469 FD_SET(fd, &except_fds);
HITCBC 358   283823 if (fd > nfds) 358   296469 if (fd > nfds)
HITCBC 359   144326 nfds = fd; 359   149995 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   144597 struct timeval* tv_ptr = nullptr; 363   150265 struct timeval* tv_ptr = nullptr;
HITCBC 364   144597 if (effective_timeout_us >= 0) 364   150265 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   144541 tv.tv_sec = effective_timeout_us / 1000000; 366   150209 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   144541 tv.tv_usec = effective_timeout_us % 1000000; 367   150209 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   144541 tv_ptr = &tv; 368   150209 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   144597 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   150265 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   144597 if (ready < 0) 376   150265 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   144597 timer_svc_->process_expired(); 384   150265 timer_svc_->process_expired();
385   385  
HITCBC 386   144597 op_queue local_ops; 386   150265 op_queue local_ops;
387   387  
HITCBC 388   144597 if (ready > 0) 388   150265 if (ready > 0)
389   { 389   {
HITCBC 390   126316 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   131285 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   13256 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14626 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   361170 for (int i = 0; i < snapshot_count; ++i) 398   375362 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   234854 int fd = snapshot[i].fd; 400   244077 int fd = snapshot[i].fd;
HITCBC 401   234854 reactor_descriptor_state* desc = snapshot[i].desc; 401   244077 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   234854 std::uint32_t flags = 0; 403   244077 std::uint32_t flags = 0;
HITCBC 404   234854 if (FD_ISSET(fd, &read_fds)) 404   244077 if (FD_ISSET(fd, &read_fds))
HITCBC 405   123025 flags |= reactor_event_read; 405   127652 flags |= reactor_event_read;
HITCBC 406   234854 if (FD_ISSET(fd, &write_fds)) 406   244077 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3160 flags |= reactor_event_write; 407   3502 flags |= reactor_event_write;
HITCBC 408   234854 if (FD_ISSET(fd, &except_fds)) 408   244077 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   234854 if (flags == 0) 411   244077 if (flags == 0)
HITCBC 412   108677 continue; 412   112930 continue;
413   413  
HITCBC 414   126177 desc->add_ready_events(flags); 414   131147 desc->add_ready_events(flags);
415   415  
HITCBC 416   126177 bool expected = false; 416   131147 bool expected = false;
HITCBC 417   126177 if (desc->is_enqueued_.compare_exchange_strong( 417   131147 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   126177 local_ops.push(desc); 421   131147 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   144597 lock.lock(); 426   150265 lock.lock();
427   427  
HITCBC 428   144597 if (!local_ops.empty()) 428   150265 if (!local_ops.empty())
HITCBC 429   123026 completed_ops_.splice(local_ops); 429   127653 completed_ops_.splice(local_ops);
HITCBC 430   144597 } 430   150265 }
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