. /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   4033 timer_service::callback(this, [](void* p) { 177   4072 timer_service::callback(this, [](void* p) {
HITCBC 178   3794 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3833 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3794 })); 179   3833 }));
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   7302 select_scheduler::register_descriptor( 207   7378 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7302 if (fd < 0 || fd >= FD_SETSIZE) 210   7378 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   7302 desc->registered_events = reactor_event_read | reactor_event_write; 213   7378 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7302 desc->fd = fd; 214   7378 desc->fd = fd;
HITCBC 215   7302 desc->scheduler_ = this; 215   7378 desc->scheduler_ = this;
HITCBC 216   7302 desc->mutex.set_enabled(!single_threaded_); 216   7378 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7302 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7378 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7302 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7378 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7302 desc->impl_ref_.reset(); 221   7378 desc->impl_ref_.reset();
HITCBC 222   7302 desc->read_ready = false; 222   7378 desc->read_ready = false;
HITCBC 223   7302 desc->write_ready = false; 223   7378 desc->write_ready = false;
HITCBC 224   7302 } 224   7378 }
225   225  
226   { 226   {
HITCBC 227   7302 mutex_type::scoped_lock lock(mutex_); 227   7378 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7302 registered_descs_[fd] = desc; 228   7378 registered_descs_[fd] = desc;
HITCBC 229   7302 if (fd > max_fd_) 229   7378 if (fd > max_fd_)
HITCBC 230   7298 max_fd_ = fd; 230   7374 max_fd_ = fd;
HITCBC 231   7302 } 231   7378 }
232   232  
HITCBC 233   7302 interrupt_reactor(); 233   7378 interrupt_reactor();
HITCBC 234   7302 } 234   7378 }
235   235  
236   inline void 236   inline void
HITCBC 237   7302 select_scheduler::deregister_descriptor(int fd) const 237   7378 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7302 mutex_type::scoped_lock lock(mutex_); 239   7378 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7302 auto it = registered_descs_.find(fd); 241   7378 auto it = registered_descs_.find(fd);
HITCBC 242   7302 if (it == registered_descs_.end()) 242   7378 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7302 registered_descs_.erase(it); 245   7378 registered_descs_.erase(it);
246   246  
HITCBC 247   7302 if (fd == max_fd_) 247   7378 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7240 max_fd_ = pipe_fds_[0]; 249   7316 max_fd_ = pipe_fds_[0];
HITCBC 250   14366 for (auto& [registered_fd, state] : registered_descs_) 250   14518 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7126 if (registered_fd > max_fd_) 252   7202 if (registered_fd > max_fd_)
HITCBC 253   7111 max_fd_ = registered_fd; 253   7187 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7302 } 256   7378 }
257   257  
258   inline void 258   inline void
HITCBC 259   3577 select_scheduler::notify_reactor() const 259   3615 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3577 interrupt_reactor(); 261   3615 interrupt_reactor();
HITCBC 262   3577 } 262   3615 }
263   263  
264   inline void 264   inline void
HITCBC 265   15077 select_scheduler::interrupt_reactor() const 265   15230 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   15077 char byte = 1; 267   15230 char byte = 1;
HITCBC 268   15077 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15230 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   15077 } 269   15230 }
270   270  
271   inline long 271   inline long
HITCBC 272   128301 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   132151 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   128301 if (requested_timeout_us == 0) 274   132151 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   128301 auto nearest = timer_svc_->nearest_expiry(); 277   132151 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   128301 if (nearest == timer_service::time_point::max()) 278   132151 if (nearest == timer_service::time_point::max())
HITCBC 279   56 return requested_timeout_us; 279   56 return requested_timeout_us;
280   280  
HITCBC 281   128245 auto now = std::chrono::steady_clock::now(); 281   132095 auto now = std::chrono::steady_clock::now();
HITCBC 282   128245 if (nearest <= now) 282   132095 if (nearest <= now)
HITCBC 283   345 return 0; 283   394 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   127900 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   131701 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   127900 .count(); 287   131701 .count();
288   288  
HITCBC 289   127900 constexpr auto long_max = 289   131701 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   127900 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   131701 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   127900 static_cast<long long>(0)), 293   131701 static_cast<long long>(0)),
HITCBC 294   127900 long_max); 294   131701 long_max);
295   295  
HITCBC 296   127900 if (requested_timeout_us < 0) 296   131701 if (requested_timeout_us < 0)
HITCBC 297   127894 return static_cast<long>(capped_timer_us); 297   131695 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   153291 select_scheduler::run_task( 305   156450 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   153291 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   156450 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   153291 int snapshot_count = 0; 323   156450 int snapshot_count = 0;
324   324  
HITCBC 325   452110 for (auto& [fd, desc] : registered_descs_) 325   461833 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   298819 if (snapshot_count < FD_SETSIZE) 327   305383 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   298819 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   305383 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   298819 snapshot[snapshot_count].fd = fd; 330   305383 snapshot[snapshot_count].fd = fd;
HITCBC 331   298819 snapshot[snapshot_count].desc = desc; 331   305383 snapshot[snapshot_count].desc = desc;
HITCBC 332   298819 snapshot[snapshot_count].needs_write = 332   305383 snapshot[snapshot_count].needs_write =
HITCBC 333   298819 (desc->write_op || desc->connect_op); 333   305383 (desc->write_op || desc->connect_op);
HITCBC 334   298819 ++snapshot_count; 334   305383 ++snapshot_count;
HITCBC 335   298819 } 335   305383 }
336   } 336   }
337   337  
HITCBC 338   153291 if (lock.owns_lock()) 338   156450 if (lock.owns_lock())
HITCBC 339   128301 lock.unlock(); 339   132151 lock.unlock();
340   340  
HITCBC 341   153291 task_cleanup on_exit{this, &lock, ctx}; 341   156450 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   2605947 FD_ZERO(&read_fds); 344   2659650 FD_ZERO(&read_fds);
HITCBC 345   2605947 FD_ZERO(&write_fds); 345   2659650 FD_ZERO(&write_fds);
HITCBC 346   2605947 FD_ZERO(&except_fds); 346   2659650 FD_ZERO(&except_fds);
347   347  
HITCBC 348   153291 FD_SET(pipe_fds_[0], &read_fds); 348   156450 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   153291 int nfds = pipe_fds_[0]; 349   156450 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   452110 for (int i = 0; i < snapshot_count; ++i) 351   461833 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   298819 int fd = snapshot[i].fd; 353   305383 int fd = snapshot[i].fd;
HITCBC 354   298819 FD_SET(fd, &read_fds); 354   305383 FD_SET(fd, &read_fds);
HITCBC 355   298819 if (snapshot[i].needs_write) 355   305383 if (snapshot[i].needs_write)
HITCBC 356   3579 FD_SET(fd, &write_fds); 356   3617 FD_SET(fd, &write_fds);
HITCBC 357   298819 FD_SET(fd, &except_fds); 357   305383 FD_SET(fd, &except_fds);
HITCBC 358   298819 if (fd > nfds) 358   305383 if (fd > nfds)
HITCBC 359   153021 nfds = fd; 359   156180 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   153291 struct timeval* tv_ptr = nullptr; 363   156450 struct timeval* tv_ptr = nullptr;
HITCBC 364   153291 if (effective_timeout_us >= 0) 364   156450 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   153235 tv.tv_sec = effective_timeout_us / 1000000; 366   156394 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   153235 tv.tv_usec = effective_timeout_us % 1000000; 367   156394 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   153235 tv_ptr = &tv; 368   156394 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   153291 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   156450 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   153291 if (ready < 0) 376   156450 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   153291 timer_svc_->process_expired(); 384   156450 timer_svc_->process_expired();
385   385  
HITCBC 386   153291 op_queue local_ops; 386   156450 op_queue local_ops;
387   387  
HITCBC 388   153291 if (ready > 0) 388   156450 if (ready > 0)
389   { 389   {
HITCBC 390   134019 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   137560 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14928 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   15082 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   381557 for (int i = 0; i < snapshot_count; ++i) 398   393237 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   247538 int fd = snapshot[i].fd; 400   255677 int fd = snapshot[i].fd;
HITCBC 401   247538 reactor_descriptor_state* desc = snapshot[i].desc; 401   255677 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   247538 std::uint32_t flags = 0; 403   255677 std::uint32_t flags = 0;
HITCBC 404   247538 if (FD_ISSET(fd, &read_fds)) 404   255677 if (FD_ISSET(fd, &read_fds))
HITCBC 405   130312 flags |= reactor_event_read; 405   133814 flags |= reactor_event_read;
HITCBC 406   247538 if (FD_ISSET(fd, &write_fds)) 406   255677 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3576 flags |= reactor_event_write; 407   3614 flags |= reactor_event_write;
HITCBC 408   247538 if (FD_ISSET(fd, &except_fds)) 408   255677 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   247538 if (flags == 0) 411   255677 if (flags == 0)
HITCBC 412   113657 continue; 412   118256 continue;
413   413  
HITCBC 414   133881 desc->add_ready_events(flags); 414   137421 desc->add_ready_events(flags);
415   415  
HITCBC 416   133881 bool expected = false; 416   137421 bool expected = false;
HITCBC 417   133881 if (desc->is_enqueued_.compare_exchange_strong( 417   137421 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   133881 local_ops.push(desc); 421   137421 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   153291 lock.lock(); 426   156450 lock.lock();
427   427  
HITCBC 428   153291 if (!local_ops.empty()) 428   156450 if (!local_ops.empty())
HITCBC 429   130313 completed_ops_.splice(local_ops); 429   133815 completed_ops_.splice(local_ops);
HITCBC 430   153291 } 430   156450 }
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