. /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   246 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   427 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   246 : pipe_fds_{-1, -1} 143   427 : pipe_fds_{-1, -1}
HITCBC 144   246 , max_fd_(-1) 144   427 , max_fd_(-1)
145   { 145   {
HITCBC 146   246 if (::pipe(pipe_fds_) < 0) 146   427 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   738 for (int i = 0; i < 2; ++i) 149   1281 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   492 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   854 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   492 if (flags == -1) 152   854 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   492 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   854 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   492 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   854 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   246 timer_svc_ = &get_timer_service(ctx, *this); 175   427 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   246 timer_svc_->set_on_earliest_changed( 176   427 timer_svc_->set_on_earliest_changed(
HITCBC 177   4015 timer_service::callback(this, [](void* p) { 177   4128 timer_service::callback(this, [](void* p) {
HITCBC 178   3769 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3701 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3769 })); 179   3701 }));
180   180  
HITCBC 181   246 get_resolver_service(ctx, *this); 181   427 get_resolver_service(ctx, *this);
HITCBC 182   246 get_signal_service(ctx, *this); 182   427 get_signal_service(ctx, *this);
HITCBC 183   246 get_stream_file_service(ctx, *this); 183   427 get_stream_file_service(ctx, *this);
HITCBC 184   246 get_random_access_file_service(ctx, *this); 184   427 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   246 completed_ops_.push(&task_op_); 186   427 completed_ops_.push(&task_op_);
HITCBC 187   246 } 187   427 }
188   188  
HITCBC 189   492 inline select_scheduler::~select_scheduler() 189   854 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   246 if (pipe_fds_[0] >= 0) 191   427 if (pipe_fds_[0] >= 0)
HITCBC 192   246 ::close(pipe_fds_[0]); 192   427 ::close(pipe_fds_[0]);
HITCBC 193   246 if (pipe_fds_[1] >= 0) 193   427 if (pipe_fds_[1] >= 0)
HITCBC 194   246 ::close(pipe_fds_[1]); 194   427 ::close(pipe_fds_[1]);
HITCBC 195   492 } 195   854 }
196   196  
197   inline void 197   inline void
HITCBC 198   246 select_scheduler::shutdown() 198   427 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   246 shutdown_drain(); 200   427 shutdown_drain();
201   201  
HITCBC 202   246 if (pipe_fds_[1] >= 0) 202   427 if (pipe_fds_[1] >= 0)
HITCBC 203   246 interrupt_reactor(); 203   427 interrupt_reactor();
HITCBC 204   246 } 204   427 }
205   205  
206   inline void 206   inline void
HITCBC 207   7278 select_scheduler::register_descriptor( 207   7236 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7278 if (fd < 0 || fd >= FD_SETSIZE) 210   7236 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   7278 desc->registered_events = reactor_event_read | reactor_event_write; 213   7236 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7278 desc->fd = fd; 214   7236 desc->fd = fd;
HITCBC 215   7278 desc->scheduler_ = this; 215   7236 desc->scheduler_ = this;
HITCBC 216   7278 desc->mutex.set_enabled(!single_threaded_); 216   7236 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7278 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7236 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7278 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7236 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7278 desc->impl_ref_.reset(); 221   7236 desc->impl_ref_.reset();
HITCBC 222   7278 desc->read_ready = false; 222   7236 desc->read_ready = false;
HITCBC 223   7278 desc->write_ready = false; 223   7236 desc->write_ready = false;
HITCBC 224   7278 } 224   7236 }
225   225  
226   { 226   {
HITCBC 227   7278 mutex_type::scoped_lock lock(mutex_); 227   7236 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7278 registered_descs_[fd] = desc; 228   7236 registered_descs_[fd] = desc;
HITCBC 229   7278 if (fd > max_fd_) 229   7236 if (fd > max_fd_)
HITCBC 230   7274 max_fd_ = fd; 230   7232 max_fd_ = fd;
HITCBC 231   7278 } 231   7236 }
232   232  
HITCBC 233   7278 interrupt_reactor(); 233   7236 interrupt_reactor();
HITCBC 234   7278 } 234   7236 }
235   235  
236   inline void 236   inline void
HITCBC 237   7278 select_scheduler::deregister_descriptor(int fd) const 237   7236 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7278 mutex_type::scoped_lock lock(mutex_); 239   7236 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7278 auto it = registered_descs_.find(fd); 241   7236 auto it = registered_descs_.find(fd);
HITCBC 242   7278 if (it == registered_descs_.end()) 242   7236 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7278 registered_descs_.erase(it); 245   7236 registered_descs_.erase(it);
246   246  
HITCBC 247   7278 if (fd == max_fd_) 247   7236 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7208 max_fd_ = pipe_fds_[0]; 249   7132 max_fd_ = pipe_fds_[0];
HITCBC 250   14295 for (auto& [registered_fd, state] : registered_descs_) 250   14053 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7087 if (registered_fd > max_fd_) 252   6921 if (registered_fd > max_fd_)
HITCBC 253   7072 max_fd_ = registered_fd; 253   6896 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7278 } 256   7236 }
257   257  
258   inline void 258   inline void
HITCBC 259   3560 select_scheduler::notify_reactor() const 259   3477 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3560 interrupt_reactor(); 261   3477 interrupt_reactor();
HITCBC 262   3560 } 262   3477 }
263   263  
264   inline void 264   inline void
HITCBC 265   15029 select_scheduler::interrupt_reactor() const 265   15126 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   15029 char byte = 1; 267   15126 char byte = 1;
HITCBC 268   15029 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15126 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   15029 } 269   15126 }
270   270  
271   inline long 271   inline long
HITCBC 272   126982 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   219314 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   126982 if (requested_timeout_us == 0) 274   219314 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   126982 auto nearest = timer_svc_->nearest_expiry(); 277   219314 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   126982 if (nearest == timer_service::time_point::max()) 278   219314 if (nearest == timer_service::time_point::max())
HITCBC 279   60 return requested_timeout_us; 279   175 return requested_timeout_us;
280   280  
HITCBC 281   126922 auto now = std::chrono::steady_clock::now(); 281   219139 auto now = std::chrono::steady_clock::now();
HITCBC 282   126922 if (nearest <= now) 282   219139 if (nearest <= now)
HITCBC 283   584 return 0; 283   522 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   126338 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   218617 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   126338 .count(); 287   218617 .count();
288   288  
HITCBC 289   126338 constexpr auto long_max = 289   218617 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   126338 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   218617 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   126338 static_cast<long long>(0)), 293   218617 static_cast<long long>(0)),
HITCBC 294   126338 long_max); 294   218617 long_max);
295   295  
HITCBC 296   126338 if (requested_timeout_us < 0) 296   218617 if (requested_timeout_us < 0)
HITCBC 297   126336 return static_cast<long>(capped_timer_us); 297   218617 return static_cast<long>(capped_timer_us);
298   298  
299   return static_cast<long>( 299   return static_cast<long>(
MISLBC 300   2 (std::min)(static_cast<long long>(requested_timeout_us), 300   ✗ (std::min)(static_cast<long long>(requested_timeout_us),
MISLBC 301   2 capped_timer_us)); 301   ✗ capped_timer_us));
302   } 302   }
303   303  
304   inline void 304   inline void
HITCBC 305   148826 select_scheduler::run_task( 305   243414 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   148826 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   243414 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   148826 int snapshot_count = 0; 323   243414 int snapshot_count = 0;
324   324  
HITCBC 325   438313 for (auto& [fd, desc] : registered_descs_) 325   630127 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   289487 if (snapshot_count < FD_SETSIZE) 327   386713 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   289487 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   386713 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   289487 snapshot[snapshot_count].fd = fd; 330   386713 snapshot[snapshot_count].fd = fd;
HITCBC 331   289487 snapshot[snapshot_count].desc = desc; 331   386713 snapshot[snapshot_count].desc = desc;
HITCBC 332   289487 snapshot[snapshot_count].needs_write = 332   386713 snapshot[snapshot_count].needs_write =
HITCBC 333   289487 (desc->write_op || desc->connect_op); 333   386713 (desc->write_op || desc->connect_op);
HITCBC 334   289487 ++snapshot_count; 334   386713 ++snapshot_count;
HITCBC 335   289487 } 335   386713 }
336   } 336   }
337   337  
HITCBC 338   148826 if (lock.owns_lock()) 338   243414 if (lock.owns_lock())
HITCBC 339   126982 lock.unlock(); 339   219314 lock.unlock();
340   340  
HITCBC 341   148826 task_cleanup on_exit{this, &lock, ctx}; 341   243414 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   2530042 FD_ZERO(&read_fds); 344   4138038 FD_ZERO(&read_fds);
HITCBC 345   2530042 FD_ZERO(&write_fds); 345   4138038 FD_ZERO(&write_fds);
HITCBC 346   2530042 FD_ZERO(&except_fds); 346   4138038 FD_ZERO(&except_fds);
347   347  
HITCBC 348   148826 FD_SET(pipe_fds_[0], &read_fds); 348   243414 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   148826 int nfds = pipe_fds_[0]; 349   243414 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   438313 for (int i = 0; i < snapshot_count; ++i) 351   630127 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   289487 int fd = snapshot[i].fd; 353   386713 int fd = snapshot[i].fd;
HITCBC 354   289487 FD_SET(fd, &read_fds); 354   386713 FD_SET(fd, &read_fds);
HITCBC 355   289487 if (snapshot[i].needs_write) 355   386713 if (snapshot[i].needs_write)
HITCBC 356   3562 FD_SET(fd, &write_fds); 356   3564 FD_SET(fd, &write_fds);
HITCBC 357   289487 FD_SET(fd, &except_fds); 357   386713 FD_SET(fd, &except_fds);
HITCBC 358   289487 if (fd > nfds) 358   386713 if (fd > nfds)
HITCBC 359   148562 nfds = fd; 359   243060 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   148826 struct timeval* tv_ptr = nullptr; 363   243414 struct timeval* tv_ptr = nullptr;
HITCBC 364   148826 if (effective_timeout_us >= 0) 364   243414 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   148766 tv.tv_sec = effective_timeout_us / 1000000; 366   243240 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   148766 tv.tv_usec = effective_timeout_us % 1000000; 367   243240 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   148766 tv_ptr = &tv; 368   243240 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   148826 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   243414 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   148826 if (ready < 0) 376   243414 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   148826 timer_svc_->process_expired(); 384   243414 timer_svc_->process_expired();
385   385  
HITCBC 386   148826 op_queue local_ops; 386   243414 op_queue local_ops;
387   387  
HITCBC 388   148826 if (ready > 0) 388   243414 if (ready > 0)
389   { 389   {
HITCBC 390   131617 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   224821 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14872 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14744 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   376385 for (int i = 0; i < snapshot_count; ++i) 398   561211 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   244768 int fd = snapshot[i].fd; 400   336390 int fd = snapshot[i].fd;
HITCBC 401   244768 reactor_descriptor_state* desc = snapshot[i].desc; 401   336390 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   244768 std::uint32_t flags = 0; 403   336390 std::uint32_t flags = 0;
HITCBC 404   244768 if (FD_ISSET(fd, &read_fds)) 404   336390 if (FD_ISSET(fd, &read_fds))
HITCBC 405   127924 flags |= reactor_event_read; 405   221132 flags |= reactor_event_read;
HITCBC 406   244768 if (FD_ISSET(fd, &write_fds)) 406   336390 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3559 flags |= reactor_event_write; 407   3476 flags |= reactor_event_write;
HITCBC 408   244768 if (FD_ISSET(fd, &except_fds)) 408   336390 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   244768 if (flags == 0) 411   336390 if (flags == 0)
HITCBC 412   113292 continue; 412   111791 continue;
413   413  
HITCBC 414   131476 desc->add_ready_events(flags); 414   224599 desc->add_ready_events(flags);
415   415  
HITCBC 416   131476 bool expected = false; 416   224599 bool expected = false;
HITCBC 417   131476 if (desc->is_enqueued_.compare_exchange_strong( 417   224599 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   131476 local_ops.push(desc); 421   224599 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   148826 lock.lock(); 426   243414 lock.lock();
427   427  
HITCBC 428   148826 if (!local_ops.empty()) 428   243414 if (!local_ops.empty())
HITCBC 429   127925 completed_ops_.splice(local_ops); 429   221128 completed_ops_.splice(local_ops);
HITCBC 430   148826 } 430   243414 }
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