. /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   2389 timer_service::callback(this, [](void* p) { 177   2338 timer_service::callback(this, [](void* p) {
HITCBC 178   1795 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   1744 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   1795 })); 179   1744 }));
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   3536 select_scheduler::register_descriptor( 207   3497 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   3536 if (fd < 0 || fd >= FD_SETSIZE) 210   3497 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   3536 desc->registered_events = reactor_event_read | reactor_event_write; 213   3497 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   3536 desc->fd = fd; 214   3497 desc->fd = fd;
HITCBC 215   3536 desc->scheduler_ = this; 215   3497 desc->scheduler_ = this;
HITCBC 216   3536 desc->mutex.set_enabled(!single_threaded_); 216   3497 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   3536 desc->ready_events_.store(0, std::memory_order_relaxed); 217   3497 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   3536 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   3497 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   3536 desc->impl_ref_.reset(); 221   3497 desc->impl_ref_.reset();
HITCBC 222   3536 desc->read_ready = false; 222   3497 desc->read_ready = false;
HITCBC 223   3536 desc->write_ready = false; 223   3497 desc->write_ready = false;
HITCBC 224   3536 } 224   3497 }
225   225  
226   { 226   {
HITCBC 227   3536 mutex_type::scoped_lock lock(mutex_); 227   3497 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   3536 registered_descs_[fd] = desc; 228   3497 registered_descs_[fd] = desc;
HITCBC 229   3536 if (fd > max_fd_) 229   3497 if (fd > max_fd_)
HITCBC 230   3531 max_fd_ = fd; 230   3492 max_fd_ = fd;
HITCBC 231   3536 } 231   3497 }
232   232  
HITCBC 233   3536 interrupt_reactor(); 233   3497 interrupt_reactor();
HITCBC 234   3536 } 234   3497 }
235   235  
236   inline void 236   inline void
HITCBC 237   3536 select_scheduler::deregister_descriptor(int fd) const 237   3497 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   3536 mutex_type::scoped_lock lock(mutex_); 239   3497 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   3536 auto it = registered_descs_.find(fd); 241   3497 auto it = registered_descs_.find(fd);
HITCBC 242   3536 if (it == registered_descs_.end()) 242   3497 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   3536 registered_descs_.erase(it); 245   3497 registered_descs_.erase(it);
246   246  
HITCBC 247   3536 if (fd == max_fd_) 247   3497 if (fd == max_fd_)
248   { 248   {
HITCBC 249   3422 max_fd_ = pipe_fds_[0]; 249   3384 max_fd_ = pipe_fds_[0];
HITCBC 250   6596 for (auto& [registered_fd, state] : registered_descs_) 250   6520 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   3174 if (registered_fd > max_fd_) 252   3136 if (registered_fd > max_fd_)
HITCBC 253   3127 max_fd_ = registered_fd; 253   3089 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   3536 } 256   3497 }
257   257  
258   inline void 258   inline void
HITCBC 259   1673 select_scheduler::notify_reactor() const 259   1653 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   1673 interrupt_reactor(); 261   1653 interrupt_reactor();
HITCBC 262   1673 } 262   1653 }
263   263  
264   inline void 264   inline void
HITCBC 265   8032 select_scheduler::interrupt_reactor() const 265   7917 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   8032 char byte = 1; 267   7917 char byte = 1;
HITCBC 268   8032 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   7917 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   8032 } 269   7917 }
270   270  
271   inline long 271   inline long
HITCBC 272   132616 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   127384 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   132616 if (requested_timeout_us == 0) 274   127384 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   132616 auto nearest = timer_svc_->nearest_expiry(); 277   127384 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   132616 if (nearest == timer_service::time_point::max()) 278   127384 if (nearest == timer_service::time_point::max())
HITCBC 279   403 return requested_timeout_us; 279   403 return requested_timeout_us;
280   280  
HITCBC 281   132213 auto now = std::chrono::steady_clock::now(); 281   126981 auto now = std::chrono::steady_clock::now();
HITCBC 282   132213 if (nearest <= now) 282   126981 if (nearest <= now)
HITCBC 283   456 return 0; 283   518 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   131757 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   126463 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   131757 .count(); 287   126463 .count();
288   288  
HITCBC 289   131757 constexpr auto long_max = 289   126463 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   131757 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   126463 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   131757 static_cast<long long>(0)), 293   126463 static_cast<long long>(0)),
HITCBC 294   131757 long_max); 294   126463 long_max);
295   295  
HITCBC 296   131757 if (requested_timeout_us < 0) 296   126463 if (requested_timeout_us < 0)
HITCBC 297   131757 return static_cast<long>(capped_timer_us); 297   126463 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   152412 select_scheduler::run_task( 305   143121 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   152412 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   143121 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   152412 int snapshot_count = 0; 323   143121 int snapshot_count = 0;
324   324  
HITCBC 325   413800 for (auto& [fd, desc] : registered_descs_) 325   371115 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   261388 if (snapshot_count < FD_SETSIZE) 327   227994 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   261388 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   227994 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   261388 snapshot[snapshot_count].fd = fd; 330   227994 snapshot[snapshot_count].fd = fd;
HITCBC 331   261388 snapshot[snapshot_count].desc = desc; 331   227994 snapshot[snapshot_count].desc = desc;
HITCBC 332   261388 snapshot[snapshot_count].needs_write = 332   227994 snapshot[snapshot_count].needs_write =
HITCBC 333   261388 (desc->write_op || desc->connect_op); 333   227994 (desc->write_op || desc->connect_op);
HITCBC 334   261388 ++snapshot_count; 334   227994 ++snapshot_count;
HITCBC 335   261388 } 335   227994 }
336   } 336   }
337   337  
HITCBC 338   152412 if (lock.owns_lock()) 338   143121 if (lock.owns_lock())
HITCBC 339   132616 lock.unlock(); 339   127384 lock.unlock();
340   340  
HITCBC 341   152412 task_cleanup on_exit{this, &lock, ctx}; 341   143121 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   2591004 FD_ZERO(&read_fds); 344   2433057 FD_ZERO(&read_fds);
HITCBC 345   2591004 FD_ZERO(&write_fds); 345   2433057 FD_ZERO(&write_fds);
HITCBC 346   2591004 FD_ZERO(&except_fds); 346   2433057 FD_ZERO(&except_fds);
347   347  
HITCBC 348   152412 FD_SET(pipe_fds_[0], &read_fds); 348   143121 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   152412 int nfds = pipe_fds_[0]; 349   143121 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   413800 for (int i = 0; i < snapshot_count; ++i) 351   371115 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   261388 int fd = snapshot[i].fd; 353   227994 int fd = snapshot[i].fd;
HITCBC 354   261388 FD_SET(fd, &read_fds); 354   227994 FD_SET(fd, &read_fds);
HITCBC 355   261388 if (snapshot[i].needs_write) 355   227994 if (snapshot[i].needs_write)
HITCBC 356   8988 FD_SET(fd, &write_fds); 356   8301 FD_SET(fd, &write_fds);
HITCBC 357   261388 FD_SET(fd, &except_fds); 357   227994 FD_SET(fd, &except_fds);
HITCBC 358   261388 if (fd > nfds) 358   227994 if (fd > nfds)
HITCBC 359   151961 nfds = fd; 359   142669 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   152412 struct timeval* tv_ptr = nullptr; 363   143121 struct timeval* tv_ptr = nullptr;
HITCBC 364   152412 if (effective_timeout_us >= 0) 364   143121 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   152012 tv.tv_sec = effective_timeout_us / 1000000; 366   142722 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   152012 tv.tv_usec = effective_timeout_us % 1000000; 367   142722 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   152012 tv_ptr = &tv; 368   142722 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   152412 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   143121 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   152412 if (ready < 0) 376   143121 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   152412 timer_svc_->process_expired(); 384   143121 timer_svc_->process_expired();
385   385  
HITCBC 386   152412 op_queue local_ops; 386   143121 op_queue local_ops;
387   387  
HITCBC 388   152412 if (ready > 0) 388   143121 if (ready > 0)
389   { 389   {
HITCBC 390   139387 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   132304 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   7522 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   7378 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   364679 for (int i = 0; i < snapshot_count; ++i) 398   329588 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   225292 int fd = snapshot[i].fd; 400   197284 int fd = snapshot[i].fd;
HITCBC 401   225292 reactor_descriptor_state* desc = snapshot[i].desc; 401   197284 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   225292 std::uint32_t flags = 0; 403   197284 std::uint32_t flags = 0;
HITCBC 404   225292 if (FD_ISSET(fd, &read_fds)) 404   197284 if (FD_ISSET(fd, &read_fds))
HITCBC 405   137430 flags |= reactor_event_read; 405   130369 flags |= reactor_event_read;
HITCBC 406   225292 if (FD_ISSET(fd, &write_fds)) 406   197284 if (FD_ISSET(fd, &write_fds))
HITCBC 407   1670 flags |= reactor_event_write; 407   1650 flags |= reactor_event_write;
HITCBC 408   225292 if (FD_ISSET(fd, &except_fds)) 408   197284 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   225292 if (flags == 0) 411   197284 if (flags == 0)
HITCBC 412   86202 continue; 412   65274 continue;
413   413  
HITCBC 414   139090 desc->add_ready_events(flags); 414   132010 desc->add_ready_events(flags);
415   415  
HITCBC 416   139090 bool expected = false; 416   132010 bool expected = false;
HITCBC 417   139090 if (desc->is_enqueued_.compare_exchange_strong( 417   132010 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   139090 local_ops.push(desc); 421   132010 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   152412 lock.lock(); 426   143121 lock.lock();
427   427  
HITCBC 428   152412 if (!local_ops.empty()) 428   143121 if (!local_ops.empty())
HITCBC 429   137512 completed_ops_.splice(local_ops); 429   130451 completed_ops_.splice(local_ops);
HITCBC 430   152412 } 430   143121 }
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