. /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   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   430 : pipe_fds_{-1, -1} 143   428 : pipe_fds_{-1, -1}
HITCBC 144   430 , max_fd_(-1) 144   428 , max_fd_(-1)
145   { 145   {
HITCBC 146   430 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   1290 for (int i = 0; i < 2; ++i) 149   1284 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   860 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   860 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   860 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   860 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   430 timer_svc_ = &get_timer_service(ctx, *this); 175   428 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   430 timer_svc_->set_on_earliest_changed( 176   428 timer_svc_->set_on_earliest_changed(
HITCBC 177   3055 timer_service::callback(this, [](void* p) { 177   4657 timer_service::callback(this, [](void* p) {
HITCBC 178   2625 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   4229 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   2625 })); 179   4229 }));
180   180  
HITCBC 181   430 get_resolver_service(ctx, *this); 181   428 get_resolver_service(ctx, *this);
HITCBC 182   430 get_signal_service(ctx, *this); 182   428 get_signal_service(ctx, *this);
HITCBC 183   430 get_stream_file_service(ctx, *this); 183   428 get_stream_file_service(ctx, *this);
HITCBC 184   430 get_random_access_file_service(ctx, *this); 184   428 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   430 completed_ops_.push(&task_op_); 186   428 completed_ops_.push(&task_op_);
HITCBC 187   430 } 187   428 }
188   188  
HITCBC 189   860 inline select_scheduler::~select_scheduler() 189   856 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   430 if (pipe_fds_[0] >= 0) 191   428 if (pipe_fds_[0] >= 0)
HITCBC 192   430 ::close(pipe_fds_[0]); 192   428 ::close(pipe_fds_[0]);
HITCBC 193   430 if (pipe_fds_[1] >= 0) 193   428 if (pipe_fds_[1] >= 0)
HITCBC 194   430 ::close(pipe_fds_[1]); 194   428 ::close(pipe_fds_[1]);
HITCBC 195   860 } 195   856 }
196   196  
197   inline void 197   inline void
HITCBC 198   430 select_scheduler::shutdown() 198   428 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   430 shutdown_drain(); 200   428 shutdown_drain();
201   201  
HITCBC 202   430 if (pipe_fds_[1] >= 0) 202   428 if (pipe_fds_[1] >= 0)
HITCBC 203   430 interrupt_reactor(); 203   428 interrupt_reactor();
HITCBC 204   430 } 204   428 }
205   205  
206   inline void 206   inline void
HITCBC 207   5083 select_scheduler::register_descriptor( 207   8298 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   5083 if (fd < 0 || fd >= FD_SETSIZE) 210   8298 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   5083 desc->registered_events = reactor_event_read | reactor_event_write; 213   8298 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   5083 desc->fd = fd; 214   8298 desc->fd = fd;
HITCBC 215   5083 desc->scheduler_ = this; 215   8298 desc->scheduler_ = this;
HITCBC 216   5083 desc->mutex.set_enabled(!single_threaded_); 216   8298 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   5083 desc->ready_events_.store(0, std::memory_order_relaxed); 217   8298 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   5083 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   8298 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   5083 desc->impl_ref_.reset(); 221   8298 desc->impl_ref_.reset();
HITCBC 222   5083 desc->read_ready = false; 222   8298 desc->read_ready = false;
HITCBC 223   5083 desc->write_ready = false; 223   8298 desc->write_ready = false;
HITCBC 224   5083 } 224   8298 }
225   225  
226   { 226   {
HITCBC 227   5083 mutex_type::scoped_lock lock(mutex_); 227   8298 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   5083 registered_descs_[fd] = desc; 228   8298 registered_descs_[fd] = desc;
HITCBC 229   5083 if (fd > max_fd_) 229   8298 if (fd > max_fd_)
HITCBC 230   5079 max_fd_ = fd; 230   8294 max_fd_ = fd;
HITCBC 231   5083 } 231   8298 }
232   232  
HITCBC 233   5083 interrupt_reactor(); 233   8298 interrupt_reactor();
HITCBC 234   5083 } 234   8298 }
235   235  
236   inline void 236   inline void
HITCBC 237   5083 select_scheduler::deregister_descriptor(int fd) const 237   8298 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   5083 mutex_type::scoped_lock lock(mutex_); 239   8298 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   5083 auto it = registered_descs_.find(fd); 241   8298 auto it = registered_descs_.find(fd);
HITCBC 242   5083 if (it == registered_descs_.end()) 242   8298 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   5083 registered_descs_.erase(it); 245   8298 registered_descs_.erase(it);
246   246  
HITCBC 247   5083 if (fd == max_fd_) 247   8298 if (fd == max_fd_)
248   { 248   {
HITCBC 249   4978 max_fd_ = pipe_fds_[0]; 249   8194 max_fd_ = pipe_fds_[0];
HITCBC 250   9745 for (auto& [registered_fd, state] : registered_descs_) 250   16177 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   4767 if (registered_fd > max_fd_) 252   7983 if (registered_fd > max_fd_)
HITCBC 253   4740 max_fd_ = registered_fd; 253   7958 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   5083 } 256   8298 }
257   257  
258   inline void 258   inline void
HITCBC 259   2400 select_scheduler::notify_reactor() const 259   4008 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   2400 interrupt_reactor(); 261   4008 interrupt_reactor();
HITCBC 262   2400 } 262   4008 }
263   263  
264   inline void 264   inline void
HITCBC 265   10826 select_scheduler::interrupt_reactor() const 265   17249 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   10826 char byte = 1; 267   17249 char byte = 1;
HITCBC 268   10826 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   17249 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   10826 } 269   17249 }
270   270  
271   inline long 271   inline long
HITCBC 272   229038 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   212821 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   229038 if (requested_timeout_us == 0) 274   212821 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   229038 auto nearest = timer_svc_->nearest_expiry(); 277   212821 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   229038 if (nearest == timer_service::time_point::max()) 278   212821 if (nearest == timer_service::time_point::max())
HITCBC 279   177 return requested_timeout_us; 279   175 return requested_timeout_us;
280   280  
HITCBC 281   228861 auto now = std::chrono::steady_clock::now(); 281   212646 auto now = std::chrono::steady_clock::now();
HITCBC 282   228861 if (nearest <= now) 282   212646 if (nearest <= now)
HITCBC 283   673 return 0; 283   1899 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   228188 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   210747 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   228188 .count(); 287   210747 .count();
288   288  
HITCBC 289   228188 constexpr auto long_max = 289   210747 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   228188 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   210747 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   228188 static_cast<long long>(0)), 293   210747 static_cast<long long>(0)),
HITCBC 294   228188 long_max); 294   210747 long_max);
295   295  
HITCBC 296   228188 if (requested_timeout_us < 0) 296   210747 if (requested_timeout_us < 0)
HITCBC 297   228188 return static_cast<long>(capped_timer_us); 297   210747 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   255038 select_scheduler::run_task( 305   236718 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   255038 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   236718 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   255038 int snapshot_count = 0; 323   236718 int snapshot_count = 0;
324   324  
HITCBC 325   683218 for (auto& [fd, desc] : registered_descs_) 325   612204 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   428180 if (snapshot_count < FD_SETSIZE) 327   375486 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   428180 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   375486 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   428180 snapshot[snapshot_count].fd = fd; 330   375486 snapshot[snapshot_count].fd = fd;
HITCBC 331   428180 snapshot[snapshot_count].desc = desc; 331   375486 snapshot[snapshot_count].desc = desc;
HITCBC 332   428180 snapshot[snapshot_count].needs_write = 332   375486 snapshot[snapshot_count].needs_write =
HITCBC 333   428180 (desc->write_op || desc->connect_op); 333   375486 (desc->write_op || desc->connect_op);
HITCBC 334   428180 ++snapshot_count; 334   375486 ++snapshot_count;
HITCBC 335   428180 } 335   375486 }
336   } 336   }
337   337  
HITCBC 338   255038 if (lock.owns_lock()) 338   236718 if (lock.owns_lock())
HITCBC 339   229038 lock.unlock(); 339   212821 lock.unlock();
340   340  
HITCBC 341   255038 task_cleanup on_exit{this, &lock, ctx}; 341   236718 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   4335646 FD_ZERO(&read_fds); 344   4024206 FD_ZERO(&read_fds);
HITCBC 345   4335646 FD_ZERO(&write_fds); 345   4024206 FD_ZERO(&write_fds);
HITCBC 346   4335646 FD_ZERO(&except_fds); 346   4024206 FD_ZERO(&except_fds);
347   347  
HITCBC 348   255038 FD_SET(pipe_fds_[0], &read_fds); 348   236718 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   255038 int nfds = pipe_fds_[0]; 349   236718 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   683218 for (int i = 0; i < snapshot_count; ++i) 351   612204 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   428180 int fd = snapshot[i].fd; 353   375486 int fd = snapshot[i].fd;
HITCBC 354   428180 FD_SET(fd, &read_fds); 354   375486 FD_SET(fd, &read_fds);
HITCBC 355   428180 if (snapshot[i].needs_write) 355   375486 if (snapshot[i].needs_write)
HITCBC 356   2487 FD_SET(fd, &write_fds); 356   4095 FD_SET(fd, &write_fds);
HITCBC 357   428180 FD_SET(fd, &except_fds); 357   375486 FD_SET(fd, &except_fds);
HITCBC 358   428180 if (fd > nfds) 358   375486 if (fd > nfds)
HITCBC 359   254683 nfds = fd; 359   236370 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   255038 struct timeval* tv_ptr = nullptr; 363   236718 struct timeval* tv_ptr = nullptr;
HITCBC 364   255038 if (effective_timeout_us >= 0) 364   236718 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   254862 tv.tv_sec = effective_timeout_us / 1000000; 366   236544 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   254862 tv.tv_usec = effective_timeout_us % 1000000; 367   236544 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   254862 tv_ptr = &tv; 368   236544 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   255038 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   236718 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   255038 if (ready < 0) 376   236718 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   255038 timer_svc_->process_expired(); 384   236718 timer_svc_->process_expired();
385   385  
HITCBC 386   255038 op_queue local_ops; 386   236718 op_queue local_ops;
387   387  
HITCBC 388   255038 if (ready > 0) 388   236718 if (ready > 0)
389   { 389   {
HITCBC 390   236856 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   219614 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   10442 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   16864 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   608756 for (int i = 0; i < snapshot_count; ++i) 398   550843 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   371900 int fd = snapshot[i].fd; 400   331229 int fd = snapshot[i].fd;
HITCBC 401   371900 reactor_descriptor_state* desc = snapshot[i].desc; 401   331229 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   371900 std::uint32_t flags = 0; 403   331229 std::uint32_t flags = 0;
HITCBC 404   371900 if (FD_ISSET(fd, &read_fds)) 404   331229 if (FD_ISSET(fd, &read_fds))
HITCBC 405   234243 flags |= reactor_event_read; 405   215395 flags |= reactor_event_read;
HITCBC 406   371900 if (FD_ISSET(fd, &write_fds)) 406   331229 if (FD_ISSET(fd, &write_fds))
HITCBC 407   2399 flags |= reactor_event_write; 407   4007 flags |= reactor_event_write;
HITCBC 408   371900 if (FD_ISSET(fd, &except_fds)) 408   331229 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   371900 if (flags == 0) 411   331229 if (flags == 0)
HITCBC 412   135268 continue; 412   111836 continue;
413   413  
HITCBC 414   236632 desc->add_ready_events(flags); 414   219393 desc->add_ready_events(flags);
415   415  
HITCBC 416   236632 bool expected = false; 416   219393 bool expected = false;
HITCBC 417   236632 if (desc->is_enqueued_.compare_exchange_strong( 417   219393 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   236632 local_ops.push(desc); 421   219393 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   255038 lock.lock(); 426   236718 lock.lock();
427   427  
HITCBC 428   255038 if (!local_ops.empty()) 428   236718 if (!local_ops.empty())
HITCBC 429   234239 completed_ops_.splice(local_ops); 429   215391 completed_ops_.splice(local_ops);
HITCBC 430   255038 } 430   236718 }
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