. /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   3575 timer_service::callback(this, [](void* p) { 177   3811 timer_service::callback(this, [](void* p) {
HITCBC 178   3336 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3572 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3336 })); 179   3572 }));
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   6373 select_scheduler::register_descriptor( 207   6865 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6373 if (fd < 0 || fd >= FD_SETSIZE) 210   6865 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   6373 desc->registered_events = reactor_event_read | reactor_event_write; 213   6865 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6373 desc->fd = fd; 214   6865 desc->fd = fd;
HITCBC 215   6373 desc->scheduler_ = this; 215   6865 desc->scheduler_ = this;
HITCBC 216   6373 desc->mutex.set_enabled(!single_threaded_); 216   6865 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6373 desc->ready_events_.store(0, std::memory_order_relaxed); 217   6865 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6373 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   6865 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6373 desc->impl_ref_.reset(); 221   6865 desc->impl_ref_.reset();
HITCBC 222   6373 desc->read_ready = false; 222   6865 desc->read_ready = false;
HITCBC 223   6373 desc->write_ready = false; 223   6865 desc->write_ready = false;
HITCBC 224   6373 } 224   6865 }
225   225  
226   { 226   {
HITCBC 227   6373 mutex_type::scoped_lock lock(mutex_); 227   6865 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6373 registered_descs_[fd] = desc; 228   6865 registered_descs_[fd] = desc;
HITCBC 229   6373 if (fd > max_fd_) 229   6865 if (fd > max_fd_)
HITCBC 230   6369 max_fd_ = fd; 230   6861 max_fd_ = fd;
HITCBC 231   6373 } 231   6865 }
232   232  
HITCBC 233   6373 interrupt_reactor(); 233   6865 interrupt_reactor();
HITCBC 234   6373 } 234   6865 }
235   235  
236   inline void 236   inline void
HITCBC 237   6373 select_scheduler::deregister_descriptor(int fd) const 237   6865 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6373 mutex_type::scoped_lock lock(mutex_); 239   6865 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6373 auto it = registered_descs_.find(fd); 241   6865 auto it = registered_descs_.find(fd);
HITCBC 242   6373 if (it == registered_descs_.end()) 242   6865 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6373 registered_descs_.erase(it); 245   6865 registered_descs_.erase(it);
246   246  
HITCBC 247   6373 if (fd == max_fd_) 247   6865 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6310 max_fd_ = pipe_fds_[0]; 249   6802 max_fd_ = pipe_fds_[0];
HITCBC 250   12506 for (auto& [registered_fd, state] : registered_descs_) 250   13490 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6196 if (registered_fd > max_fd_) 252   6688 if (registered_fd > max_fd_)
HITCBC 253   6181 max_fd_ = registered_fd; 253   6673 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6373 } 256   6865 }
257   257  
258   inline void 258   inline void
HITCBC 259   3113 select_scheduler::notify_reactor() const 259   3359 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3113 interrupt_reactor(); 261   3359 interrupt_reactor();
HITCBC 262   3113 } 262   3359 }
263   263  
264   inline void 264   inline void
HITCBC 265   13226 select_scheduler::interrupt_reactor() const 265   14200 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   13226 char byte = 1; 267   14200 char byte = 1;
HITCBC 268   13226 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   14200 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   13226 } 269   14200 }
270   270  
271   inline long 271   inline long
HITCBC 272   200409 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   101589 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   200409 if (requested_timeout_us == 0) 274   101589 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   200409 auto nearest = timer_svc_->nearest_expiry(); 277   101589 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   200409 if (nearest == timer_service::time_point::max()) 278   101589 if (nearest == timer_service::time_point::max())
HITCBC 279   56 return requested_timeout_us; 279   56 return requested_timeout_us;
280   280  
HITCBC 281   200353 auto now = std::chrono::steady_clock::now(); 281   101533 auto now = std::chrono::steady_clock::now();
HITCBC 282   200353 if (nearest <= now) 282   101533 if (nearest <= now)
HITCBC 283   485 return 0; 283   506 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   199868 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   101027 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   199868 .count(); 287   101027 .count();
288   288  
HITCBC 289   199868 constexpr auto long_max = 289   101027 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   199868 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   101027 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   199868 static_cast<long long>(0)), 293   101027 static_cast<long long>(0)),
HITCBC 294   199868 long_max); 294   101027 long_max);
295   295  
HITCBC 296   199868 if (requested_timeout_us < 0) 296   101027 if (requested_timeout_us < 0)
HITCBC 297   199862 return static_cast<long>(capped_timer_us); 297   101021 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   236882 select_scheduler::run_task( 305   125374 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   236882 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   125374 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   236882 int snapshot_count = 0; 323   125374 int snapshot_count = 0;
324   324  
HITCBC 325   717663 for (auto& [fd, desc] : registered_descs_) 325   375242 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   480781 if (snapshot_count < FD_SETSIZE) 327   249868 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   480781 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   249868 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   480781 snapshot[snapshot_count].fd = fd; 330   249868 snapshot[snapshot_count].fd = fd;
HITCBC 331   480781 snapshot[snapshot_count].desc = desc; 331   249868 snapshot[snapshot_count].desc = desc;
HITCBC 332   480781 snapshot[snapshot_count].needs_write = 332   249868 snapshot[snapshot_count].needs_write =
HITCBC 333   480781 (desc->write_op || desc->connect_op); 333   249868 (desc->write_op || desc->connect_op);
HITCBC 334   480781 ++snapshot_count; 334   249868 ++snapshot_count;
HITCBC 335   480781 } 335   249868 }
336   } 336   }
337   337  
HITCBC 338   236882 if (lock.owns_lock()) 338   125374 if (lock.owns_lock())
HITCBC 339   200409 lock.unlock(); 339   101589 lock.unlock();
340   340  
HITCBC 341   236882 task_cleanup on_exit{this, &lock, ctx}; 341   125374 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   4026994 FD_ZERO(&read_fds); 344   2131358 FD_ZERO(&read_fds);
HITCBC 345   4026994 FD_ZERO(&write_fds); 345   2131358 FD_ZERO(&write_fds);
HITCBC 346   4026994 FD_ZERO(&except_fds); 346   2131358 FD_ZERO(&except_fds);
347   347  
HITCBC 348   236882 FD_SET(pipe_fds_[0], &read_fds); 348   125374 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   236882 int nfds = pipe_fds_[0]; 349   125374 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   717663 for (int i = 0; i < snapshot_count; ++i) 351   375242 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   480781 int fd = snapshot[i].fd; 353   249868 int fd = snapshot[i].fd;
HITCBC 354   480781 FD_SET(fd, &read_fds); 354   249868 FD_SET(fd, &read_fds);
HITCBC 355   480781 if (snapshot[i].needs_write) 355   249868 if (snapshot[i].needs_write)
HITCBC 356   3115 FD_SET(fd, &write_fds); 356   3361 FD_SET(fd, &write_fds);
HITCBC 357   480781 FD_SET(fd, &except_fds); 357   249868 FD_SET(fd, &except_fds);
HITCBC 358   480781 if (fd > nfds) 358   249868 if (fd > nfds)
HITCBC 359   236611 nfds = fd; 359   125103 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   236882 struct timeval* tv_ptr = nullptr; 363   125374 struct timeval* tv_ptr = nullptr;
HITCBC 364   236882 if (effective_timeout_us >= 0) 364   125374 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   236826 tv.tv_sec = effective_timeout_us / 1000000; 366   125318 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   236826 tv.tv_usec = effective_timeout_us % 1000000; 367   125318 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   236826 tv_ptr = &tv; 368   125318 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   236882 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   125374 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   236882 if (ready < 0) 376   125374 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   236882 timer_svc_->process_expired(); 384   125374 timer_svc_->process_expired();
385   385  
HITCBC 386   236882 op_queue local_ops; 386   125374 op_queue local_ops;
387   387  
HITCBC 388   236882 if (ready > 0) 388   125374 if (ready > 0)
389   { 389   {
HITCBC 390   211653 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   107397 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   13092 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14052 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   615816 for (int i = 0; i < snapshot_count; ++i) 398   310035 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   404163 int fd = snapshot[i].fd; 400   202638 int fd = snapshot[i].fd;
HITCBC 401   404163 reactor_descriptor_state* desc = snapshot[i].desc; 401   202638 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   404163 std::uint32_t flags = 0; 403   202638 std::uint32_t flags = 0;
HITCBC 404   404163 if (FD_ISSET(fd, &read_fds)) 404   202638 if (FD_ISSET(fd, &read_fds))
HITCBC 405   208407 flags |= reactor_event_read; 405   103908 flags |= reactor_event_read;
HITCBC 406   404163 if (FD_ISSET(fd, &write_fds)) 406   202638 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3112 flags |= reactor_event_write; 407   3358 flags |= reactor_event_write;
HITCBC 408   404163 if (FD_ISSET(fd, &except_fds)) 408   202638 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   404163 if (flags == 0) 411   202638 if (flags == 0)
HITCBC 412   192652 continue; 412   95380 continue;
413   413  
HITCBC 414   211511 desc->add_ready_events(flags); 414   107258 desc->add_ready_events(flags);
415   415  
HITCBC 416   211511 bool expected = false; 416   107258 bool expected = false;
HITCBC 417   211511 if (desc->is_enqueued_.compare_exchange_strong( 417   107258 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   211511 local_ops.push(desc); 421   107258 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   236882 lock.lock(); 426   125374 lock.lock();
427   427  
HITCBC 428   236882 if (!local_ops.empty()) 428   125374 if (!local_ops.empty())
HITCBC 429   208408 completed_ops_.splice(local_ops); 429   103909 completed_ops_.splice(local_ops);
HITCBC 430   236882 } 430   125374 }
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