. /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   430 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   588 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   430 : pipe_fds_{-1, -1} 143   588 : pipe_fds_{-1, -1}
HITCBC 144   430 , max_fd_(-1) 144   588 , max_fd_(-1)
145   { 145   {
HITCBC 146   430 if (::pipe(pipe_fds_) < 0) 146   588 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   1290 for (int i = 0; i < 2; ++i) 149   1764 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   860 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   1176 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   860 if (flags == -1) 152   1176 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   860 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   1176 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   860 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   1176 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   430 timer_svc_ = &get_timer_service(ctx, *this); 175   588 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   430 timer_svc_->set_on_earliest_changed( 176   588 timer_svc_->set_on_earliest_changed(
HITCBC 177   3954 timer_service::callback(this, [](void* p) { 177   4418 timer_service::callback(this, [](void* p) {
HITCBC 178   3524 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3830 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3524 })); 179   3830 }));
180   180  
HITCBC 181   430 get_resolver_service(ctx, *this); 181   588 get_resolver_service(ctx, *this);
HITCBC 182   430 get_signal_service(ctx, *this); 182   588 get_signal_service(ctx, *this);
HITCBC 183   430 get_stream_file_service(ctx, *this); 183   588 get_stream_file_service(ctx, *this);
HITCBC 184   430 get_random_access_file_service(ctx, *this); 184   588 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   430 completed_ops_.push(&task_op_); 186   588 completed_ops_.push(&task_op_);
HITCBC 187   430 } 187   588 }
188   188  
HITCBC 189   860 inline select_scheduler::~select_scheduler() 189   1176 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   430 if (pipe_fds_[0] >= 0) 191   588 if (pipe_fds_[0] >= 0)
HITCBC 192   430 ::close(pipe_fds_[0]); 192   588 ::close(pipe_fds_[0]);
HITCBC 193   430 if (pipe_fds_[1] >= 0) 193   588 if (pipe_fds_[1] >= 0)
HITCBC 194   430 ::close(pipe_fds_[1]); 194   588 ::close(pipe_fds_[1]);
HITCBC 195   860 } 195   1176 }
196   196  
197   inline void 197   inline void
HITCBC 198   430 select_scheduler::shutdown() 198   588 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   430 shutdown_drain(); 200   588 shutdown_drain();
201   201  
HITCBC 202   430 if (pipe_fds_[1] >= 0) 202   588 if (pipe_fds_[1] >= 0)
HITCBC 203   430 interrupt_reactor(); 203   588 interrupt_reactor();
HITCBC 204   430 } 204   588 }
205   205  
206   inline void 206   inline void
HITCBC 207   6885 select_scheduler::register_descriptor( 207   7565 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6885 if (fd < 0 || fd >= FD_SETSIZE) 210   7565 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   6885 desc->registered_events = reactor_event_read | reactor_event_write; 213   7565 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6885 desc->fd = fd; 214   7565 desc->fd = fd;
HITCBC 215   6885 desc->scheduler_ = this; 215   7565 desc->scheduler_ = this;
HITCBC 216   6885 desc->mutex.set_enabled(!single_threaded_); 216   7565 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6885 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7565 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6885 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7565 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6885 desc->impl_ref_.reset(); 221   7565 desc->impl_ref_.reset();
HITCBC 222   6885 desc->read_ready = false; 222   7565 desc->read_ready = false;
HITCBC 223   6885 desc->write_ready = false; 223   7565 desc->write_ready = false;
HITCBC 224   6885 } 224   7565 }
225   225  
226   { 226   {
HITCBC 227   6885 mutex_type::scoped_lock lock(mutex_); 227   7565 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6885 registered_descs_[fd] = desc; 228   7565 registered_descs_[fd] = desc;
HITCBC 229   6885 if (fd > max_fd_) 229   7565 if (fd > max_fd_)
HITCBC 230   6881 max_fd_ = fd; 230   7560 max_fd_ = fd;
HITCBC 231   6885 } 231   7565 }
232   232  
HITCBC 233   6885 interrupt_reactor(); 233   7565 interrupt_reactor();
HITCBC 234   6885 } 234   7565 }
235   235  
236   inline void 236   inline void
HITCBC 237   6885 select_scheduler::deregister_descriptor(int fd) const 237   7565 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6885 mutex_type::scoped_lock lock(mutex_); 239   7565 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6885 auto it = registered_descs_.find(fd); 241   7565 auto it = registered_descs_.find(fd);
HITCBC 242   6885 if (it == registered_descs_.end()) 242   7565 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6885 registered_descs_.erase(it); 245   7565 registered_descs_.erase(it);
246   246  
HITCBC 247   6885 if (fd == max_fd_) 247   7565 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6780 max_fd_ = pipe_fds_[0]; 249   7452 max_fd_ = pipe_fds_[0];
HITCBC 250   13349 for (auto& [registered_fd, state] : registered_descs_) 250   14656 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6569 if (registered_fd > max_fd_) 252   7204 if (registered_fd > max_fd_)
HITCBC 253   6542 max_fd_ = registered_fd; 253   7157 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6885 } 256   7565 }
257   257  
258   inline void 258   inline void
HITCBC 259   3301 select_scheduler::notify_reactor() const 259   3687 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3301 interrupt_reactor(); 261   3687 interrupt_reactor();
HITCBC 262   3301 } 262   3687 }
263   263  
264   inline void 264   inline void
HITCBC 265   14427 select_scheduler::interrupt_reactor() const 265   16107 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14427 char byte = 1; 267   16107 char byte = 1;
HITCBC 268   14427 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   16107 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14427 } 269   16107 }
270   270  
271   inline long 271   inline long
HITCBC 272   206934 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   220614 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   206934 if (requested_timeout_us == 0) 274   220614 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   206934 auto nearest = timer_svc_->nearest_expiry(); 277   220614 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   206934 if (nearest == timer_service::time_point::max()) 278   220614 if (nearest == timer_service::time_point::max())
HITCBC 279   176 return requested_timeout_us; 279   408 return requested_timeout_us;
280   280  
HITCBC 281   206758 auto now = std::chrono::steady_clock::now(); 281   220206 auto now = std::chrono::steady_clock::now();
HITCBC 282   206758 if (nearest <= now) 282   220206 if (nearest <= now)
HITCBC 283   610 return 0; 283   658 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   206148 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   219548 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   206148 .count(); 287   219548 .count();
288   288  
HITCBC 289   206148 constexpr auto long_max = 289   219548 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   206148 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   219548 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   206148 static_cast<long long>(0)), 293   219548 static_cast<long long>(0)),
HITCBC 294   206148 long_max); 294   219548 long_max);
295   295  
HITCBC 296   206148 if (requested_timeout_us < 0) 296   219548 if (requested_timeout_us < 0)
HITCBC 297   206148 return static_cast<long>(capped_timer_us); 297   219548 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   230651 select_scheduler::run_task( 305   244058 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   230651 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   244058 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   230651 int snapshot_count = 0; 323   244058 int snapshot_count = 0;
324   324  
HITCBC 325   601502 for (auto& [fd, desc] : registered_descs_) 325   647082 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   370851 if (snapshot_count < FD_SETSIZE) 327   403024 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   370851 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   403024 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   370851 snapshot[snapshot_count].fd = fd; 330   403024 snapshot[snapshot_count].fd = fd;
HITCBC 331   370851 snapshot[snapshot_count].desc = desc; 331   403024 snapshot[snapshot_count].desc = desc;
HITCBC 332   370851 snapshot[snapshot_count].needs_write = 332   403024 snapshot[snapshot_count].needs_write =
HITCBC 333   370851 (desc->write_op || desc->connect_op); 333   403024 (desc->write_op || desc->connect_op);
HITCBC 334   370851 ++snapshot_count; 334   403024 ++snapshot_count;
HITCBC 335   370851 } 335   403024 }
336   } 336   }
337   337  
HITCBC 338   230651 if (lock.owns_lock()) 338   244058 if (lock.owns_lock())
HITCBC 339   206934 lock.unlock(); 339   220614 lock.unlock();
340   340  
HITCBC 341   230651 task_cleanup on_exit{this, &lock, ctx}; 341   244058 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   3921067 FD_ZERO(&read_fds); 344   4148986 FD_ZERO(&read_fds);
HITCBC 345   3921067 FD_ZERO(&write_fds); 345   4148986 FD_ZERO(&write_fds);
HITCBC 346   3921067 FD_ZERO(&except_fds); 346   4148986 FD_ZERO(&except_fds);
347   347  
HITCBC 348   230651 FD_SET(pipe_fds_[0], &read_fds); 348   244058 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   230651 int nfds = pipe_fds_[0]; 349   244058 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   601502 for (int i = 0; i < snapshot_count; ++i) 351   647082 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   370851 int fd = snapshot[i].fd; 353   403024 int fd = snapshot[i].fd;
HITCBC 354   370851 FD_SET(fd, &read_fds); 354   403024 FD_SET(fd, &read_fds);
HITCBC 355   370851 if (snapshot[i].needs_write) 355   403024 if (snapshot[i].needs_write)
HITCBC 356   3388 FD_SET(fd, &write_fds); 356   14952 FD_SET(fd, &write_fds);
HITCBC 357   370851 FD_SET(fd, &except_fds); 357   403024 FD_SET(fd, &except_fds);
HITCBC 358   370851 if (fd > nfds) 358   403024 if (fd > nfds)
HITCBC 359   230299 nfds = fd; 359   243603 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   230651 struct timeval* tv_ptr = nullptr; 363   244058 struct timeval* tv_ptr = nullptr;
HITCBC 364   230651 if (effective_timeout_us >= 0) 364   244058 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   230476 tv.tv_sec = effective_timeout_us / 1000000; 366   243654 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   230476 tv.tv_usec = effective_timeout_us % 1000000; 367   243654 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   230476 tv_ptr = &tv; 368   243654 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   230651 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   244058 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   230651 if (ready < 0) 376   244058 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   230651 timer_svc_->process_expired(); 384   244058 timer_svc_->process_expired();
385   385  
HITCBC 386   230651 op_queue local_ops; 386   244058 op_queue local_ops;
387   387  
HITCBC 388   230651 if (ready > 0) 388   244058 if (ready > 0)
389   { 389   {
HITCBC 390   212575 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   225536 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14040 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   15626 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   534101 for (int i = 0; i < snapshot_count; ++i) 398   577848 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   321526 int fd = snapshot[i].fd; 400   352312 int fd = snapshot[i].fd;
HITCBC 401   321526 reactor_descriptor_state* desc = snapshot[i].desc; 401   352312 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   321526 std::uint32_t flags = 0; 403   352312 std::uint32_t flags = 0;
HITCBC 404   321526 if (FD_ISSET(fd, &read_fds)) 404   352312 if (FD_ISSET(fd, &read_fds))
HITCBC 405   209064 flags |= reactor_event_read; 405   221553 flags |= reactor_event_read;
HITCBC 406   321526 if (FD_ISSET(fd, &write_fds)) 406   352312 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3300 flags |= reactor_event_write; 407   3684 flags |= reactor_event_write;
HITCBC 408   321526 if (FD_ISSET(fd, &except_fds)) 408   352312 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   321526 if (flags == 0) 411   352312 if (flags == 0)
HITCBC 412   109172 continue; 412   127084 continue;
413   413  
HITCBC 414   212354 desc->add_ready_events(flags); 414   225228 desc->add_ready_events(flags);
415   415  
HITCBC 416   212354 bool expected = false; 416   225228 bool expected = false;
HITCBC 417   212354 if (desc->is_enqueued_.compare_exchange_strong( 417   225228 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   212354 local_ops.push(desc); 421   225228 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   230651 lock.lock(); 426   244058 lock.lock();
427   427  
HITCBC 428   230651 if (!local_ops.empty()) 428   244058 if (!local_ops.empty())
HITCBC 429   209060 completed_ops_.splice(local_ops); 429   221635 completed_ops_.splice(local_ops);
HITCBC 430   230651 } 430   244058 }
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