. /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   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   428 : pipe_fds_{-1, -1} 143   428 : pipe_fds_{-1, -1}
HITCBC 144   428 , max_fd_(-1) 144   428 , max_fd_(-1)
145   { 145   {
HITCBC 146   428 if (::pipe(pipe_fds_) < 0) 146   428 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   1284 for (int i = 0; i < 2; ++i) 149   1284 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   856 if (flags == -1) 152   856 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   856 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   856 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   856 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   856 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   428 timer_svc_ = &get_timer_service(ctx, *this); 175   428 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   428 timer_svc_->set_on_earliest_changed( 176   428 timer_svc_->set_on_earliest_changed(
HITCBC 177   4031 timer_service::callback(this, [](void* p) { 177   3914 timer_service::callback(this, [](void* p) {
HITCBC 178   3603 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3486 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3603 })); 179   3486 }));
180   180  
HITCBC 181   428 get_resolver_service(ctx, *this); 181   428 get_resolver_service(ctx, *this);
HITCBC 182   428 get_signal_service(ctx, *this); 182   428 get_signal_service(ctx, *this);
HITCBC 183   428 get_stream_file_service(ctx, *this); 183   428 get_stream_file_service(ctx, *this);
HITCBC 184   428 get_random_access_file_service(ctx, *this); 184   428 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   428 completed_ops_.push(&task_op_); 186   428 completed_ops_.push(&task_op_);
HITCBC 187   428 } 187   428 }
188   188  
HITCBC 189   856 inline select_scheduler::~select_scheduler() 189   856 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   428 if (pipe_fds_[0] >= 0) 191   428 if (pipe_fds_[0] >= 0)
HITCBC 192   428 ::close(pipe_fds_[0]); 192   428 ::close(pipe_fds_[0]);
HITCBC 193   428 if (pipe_fds_[1] >= 0) 193   428 if (pipe_fds_[1] >= 0)
HITCBC 194   428 ::close(pipe_fds_[1]); 194   428 ::close(pipe_fds_[1]);
HITCBC 195   856 } 195   856 }
196   196  
197   inline void 197   inline void
HITCBC 198   428 select_scheduler::shutdown() 198   428 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   428 shutdown_drain(); 200   428 shutdown_drain();
201   201  
HITCBC 202   428 if (pipe_fds_[1] >= 0) 202   428 if (pipe_fds_[1] >= 0)
HITCBC 203   428 interrupt_reactor(); 203   428 interrupt_reactor();
HITCBC 204   428 } 204   428 }
205   205  
206   inline void 206   inline void
HITCBC 207   7041 select_scheduler::register_descriptor( 207   6805 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7041 if (fd < 0 || fd >= FD_SETSIZE) 210   6805 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   7041 desc->registered_events = reactor_event_read | reactor_event_write; 213   6805 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7041 desc->fd = fd; 214   6805 desc->fd = fd;
HITCBC 215   7041 desc->scheduler_ = this; 215   6805 desc->scheduler_ = this;
HITCBC 216   7041 desc->mutex.set_enabled(!single_threaded_); 216   6805 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7041 desc->ready_events_.store(0, std::memory_order_relaxed); 217   6805 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7041 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   6805 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7041 desc->impl_ref_.reset(); 221   6805 desc->impl_ref_.reset();
HITCBC 222   7041 desc->read_ready = false; 222   6805 desc->read_ready = false;
HITCBC 223   7041 desc->write_ready = false; 223   6805 desc->write_ready = false;
HITCBC 224   7041 } 224   6805 }
225   225  
226   { 226   {
HITCBC 227   7041 mutex_type::scoped_lock lock(mutex_); 227   6805 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7041 registered_descs_[fd] = desc; 228   6805 registered_descs_[fd] = desc;
HITCBC 229   7041 if (fd > max_fd_) 229   6805 if (fd > max_fd_)
HITCBC 230   7037 max_fd_ = fd; 230   6801 max_fd_ = fd;
HITCBC 231   7041 } 231   6805 }
232   232  
HITCBC 233   7041 interrupt_reactor(); 233   6805 interrupt_reactor();
HITCBC 234   7041 } 234   6805 }
235   235  
236   inline void 236   inline void
HITCBC 237   7041 select_scheduler::deregister_descriptor(int fd) const 237   6805 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7041 mutex_type::scoped_lock lock(mutex_); 239   6805 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7041 auto it = registered_descs_.find(fd); 241   6805 auto it = registered_descs_.find(fd);
HITCBC 242   7041 if (it == registered_descs_.end()) 242   6805 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7041 registered_descs_.erase(it); 245   6805 registered_descs_.erase(it);
246   246  
HITCBC 247   7041 if (fd == max_fd_) 247   6805 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6936 max_fd_ = pipe_fds_[0]; 249   6700 max_fd_ = pipe_fds_[0];
HITCBC 250   13661 for (auto& [registered_fd, state] : registered_descs_) 250   13189 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6725 if (registered_fd > max_fd_) 252   6489 if (registered_fd > max_fd_)
HITCBC 253   6700 max_fd_ = registered_fd; 253   6464 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7041 } 256   6805 }
257   257  
258   inline void 258   inline void
HITCBC 259   3380 select_scheduler::notify_reactor() const 259   3262 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3380 interrupt_reactor(); 261   3262 interrupt_reactor();
HITCBC 262   3380 } 262   3262 }
263   263  
264   inline void 264   inline void
HITCBC 265   14738 select_scheduler::interrupt_reactor() const 265   14267 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14738 char byte = 1; 267   14267 char byte = 1;
HITCBC 268   14738 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   14267 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14738 } 269   14267 }
270   270  
271   inline long 271   inline long
HITCBC 272   201599 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   197246 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   201599 if (requested_timeout_us == 0) 274   197246 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   201599 auto nearest = timer_svc_->nearest_expiry(); 277   197246 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   201599 if (nearest == timer_service::time_point::max()) 278   197246 if (nearest == timer_service::time_point::max())
HITCBC 279   175 return requested_timeout_us; 279   175 return requested_timeout_us;
280   280  
HITCBC 281   201424 auto now = std::chrono::steady_clock::now(); 281   197071 auto now = std::chrono::steady_clock::now();
HITCBC 282   201424 if (nearest <= now) 282   197071 if (nearest <= now)
HITCBC 283   642 return 0; 283   710 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   200782 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   196361 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   200782 .count(); 287   196361 .count();
288   288  
HITCBC 289   200782 constexpr auto long_max = 289   196361 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   200782 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   196361 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   200782 static_cast<long long>(0)), 293   196361 static_cast<long long>(0)),
HITCBC 294   200782 long_max); 294   196361 long_max);
295   295  
HITCBC 296   200782 if (requested_timeout_us < 0) 296   196361 if (requested_timeout_us < 0)
HITCBC 297   200782 return static_cast<long>(capped_timer_us); 297   196361 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   228298 select_scheduler::run_task( 305   223168 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   228298 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   223168 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   228298 int snapshot_count = 0; 323   223168 int snapshot_count = 0;
324   324  
HITCBC 325   600946 for (auto& [fd, desc] : registered_descs_) 325   586972 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   372648 if (snapshot_count < FD_SETSIZE) 327   363804 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   372648 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   363804 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   372648 snapshot[snapshot_count].fd = fd; 330   363804 snapshot[snapshot_count].fd = fd;
HITCBC 331   372648 snapshot[snapshot_count].desc = desc; 331   363804 snapshot[snapshot_count].desc = desc;
HITCBC 332   372648 snapshot[snapshot_count].needs_write = 332   363804 snapshot[snapshot_count].needs_write =
HITCBC 333   372648 (desc->write_op || desc->connect_op); 333   363804 (desc->write_op || desc->connect_op);
HITCBC 334   372648 ++snapshot_count; 334   363804 ++snapshot_count;
HITCBC 335   372648 } 335   363804 }
336   } 336   }
337   337  
HITCBC 338   228298 if (lock.owns_lock()) 338   223168 if (lock.owns_lock())
HITCBC 339   201599 lock.unlock(); 339   197246 lock.unlock();
340   340  
HITCBC 341   228298 task_cleanup on_exit{this, &lock, ctx}; 341   223168 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   3881066 FD_ZERO(&read_fds); 344   3793856 FD_ZERO(&read_fds);
HITCBC 345   3881066 FD_ZERO(&write_fds); 345   3793856 FD_ZERO(&write_fds);
HITCBC 346   3881066 FD_ZERO(&except_fds); 346   3793856 FD_ZERO(&except_fds);
347   347  
HITCBC 348   228298 FD_SET(pipe_fds_[0], &read_fds); 348   223168 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   228298 int nfds = pipe_fds_[0]; 349   223168 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   600946 for (int i = 0; i < snapshot_count; ++i) 351   586972 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   372648 int fd = snapshot[i].fd; 353   363804 int fd = snapshot[i].fd;
HITCBC 354   372648 FD_SET(fd, &read_fds); 354   363804 FD_SET(fd, &read_fds);
HITCBC 355   372648 if (snapshot[i].needs_write) 355   363804 if (snapshot[i].needs_write)
HITCBC 356   3467 FD_SET(fd, &write_fds); 356   3349 FD_SET(fd, &write_fds);
HITCBC 357   372648 FD_SET(fd, &except_fds); 357   363804 FD_SET(fd, &except_fds);
HITCBC 358   372648 if (fd > nfds) 358   363804 if (fd > nfds)
HITCBC 359   227945 nfds = fd; 359   222813 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   228298 struct timeval* tv_ptr = nullptr; 363   223168 struct timeval* tv_ptr = nullptr;
HITCBC 364   228298 if (effective_timeout_us >= 0) 364   223168 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   228124 tv.tv_sec = effective_timeout_us / 1000000; 366   222994 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   228124 tv.tv_usec = effective_timeout_us % 1000000; 367   222994 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   228124 tv_ptr = &tv; 368   222994 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   228298 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   223168 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   228298 if (ready < 0) 376   223168 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   228298 timer_svc_->process_expired(); 384   223168 timer_svc_->process_expired();
385   385  
HITCBC 386   228298 op_queue local_ops; 386   223168 op_queue local_ops;
387   387  
HITCBC 388   228298 if (ready > 0) 388   223168 if (ready > 0)
389   { 389   {
HITCBC 390   208753 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   204364 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14352 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   13882 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   529067 for (int i = 0; i < snapshot_count; ++i) 398   519018 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   320314 int fd = snapshot[i].fd; 400   314654 int fd = snapshot[i].fd;
HITCBC 401   320314 reactor_descriptor_state* desc = snapshot[i].desc; 401   314654 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   320314 std::uint32_t flags = 0; 403   314654 std::uint32_t flags = 0;
HITCBC 404   320314 if (FD_ISSET(fd, &read_fds)) 404   314654 if (FD_ISSET(fd, &read_fds))
HITCBC 405   205162 flags |= reactor_event_read; 405   200890 flags |= reactor_event_read;
HITCBC 406   320314 if (FD_ISSET(fd, &write_fds)) 406   314654 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3379 flags |= reactor_event_write; 407   3261 flags |= reactor_event_write;
HITCBC 408   320314 if (FD_ISSET(fd, &except_fds)) 408   314654 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   320314 if (flags == 0) 411   314654 if (flags == 0)
HITCBC 412   111783 continue; 412   110513 continue;
413   413  
HITCBC 414   208531 desc->add_ready_events(flags); 414   204141 desc->add_ready_events(flags);
415   415  
HITCBC 416   208531 bool expected = false; 416   204141 bool expected = false;
HITCBC 417   208531 if (desc->is_enqueued_.compare_exchange_strong( 417   204141 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   208531 local_ops.push(desc); 421   204141 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   228298 lock.lock(); 426   223168 lock.lock();
427   427  
HITCBC 428   228298 if (!local_ops.empty()) 428   223168 if (!local_ops.empty())
HITCBC 429   205158 completed_ops_.splice(local_ops); 429   200886 completed_ops_.splice(local_ops);
HITCBC 430   228298 } 430   223168 }
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