. /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   588 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   590 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   588 : pipe_fds_{-1, -1} 143   590 : pipe_fds_{-1, -1}
HITCBC 144   588 , max_fd_(-1) 144   590 , max_fd_(-1)
145   { 145   {
HITCBC 146   588 if (::pipe(pipe_fds_) < 0) 146   590 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   1764 for (int i = 0; i < 2; ++i) 149   1770 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   1176 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   1180 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   1176 if (flags == -1) 152   1180 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   1176 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   1180 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   1176 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   1180 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   588 timer_svc_ = &get_timer_service(ctx, *this); 175   590 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   588 timer_svc_->set_on_earliest_changed( 176   590 timer_svc_->set_on_earliest_changed(
HITCBC 177   4288 timer_service::callback(this, [](void* p) { 177   4206 timer_service::callback(this, [](void* p) {
HITCBC 178   3700 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3616 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3700 })); 179   3616 }));
180   180  
HITCBC 181   588 get_resolver_service(ctx, *this); 181   590 get_resolver_service(ctx, *this);
HITCBC 182   588 get_signal_service(ctx, *this); 182   590 get_signal_service(ctx, *this);
HITCBC 183   588 get_stream_file_service(ctx, *this); 183   590 get_stream_file_service(ctx, *this);
HITCBC 184   588 get_random_access_file_service(ctx, *this); 184   590 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   588 completed_ops_.push(&task_op_); 186   590 completed_ops_.push(&task_op_);
HITCBC 187   588 } 187   590 }
188   188  
HITCBC 189   1176 inline select_scheduler::~select_scheduler() 189   1180 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   588 if (pipe_fds_[0] >= 0) 191   590 if (pipe_fds_[0] >= 0)
HITCBC 192   588 ::close(pipe_fds_[0]); 192   590 ::close(pipe_fds_[0]);
HITCBC 193   588 if (pipe_fds_[1] >= 0) 193   590 if (pipe_fds_[1] >= 0)
HITCBC 194   588 ::close(pipe_fds_[1]); 194   590 ::close(pipe_fds_[1]);
HITCBC 195   1176 } 195   1180 }
196   196  
197   inline void 197   inline void
HITCBC 198   588 select_scheduler::shutdown() 198   590 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   588 shutdown_drain(); 200   590 shutdown_drain();
201   201  
HITCBC 202   588 if (pipe_fds_[1] >= 0) 202   590 if (pipe_fds_[1] >= 0)
HITCBC 203   588 interrupt_reactor(); 203   590 interrupt_reactor();
HITCBC 204   588 } 204   590 }
205   205  
206   inline void 206   inline void
HITCBC 207   7319 select_scheduler::register_descriptor( 207   7110 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7319 if (fd < 0 || fd >= FD_SETSIZE) 210   7110 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   7319 desc->registered_events = reactor_event_read | reactor_event_write; 213   7110 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7319 desc->fd = fd; 214   7110 desc->fd = fd;
HITCBC 215   7319 desc->scheduler_ = this; 215   7110 desc->scheduler_ = this;
HITCBC 216   7319 desc->mutex.set_enabled(!single_threaded_); 216   7110 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7319 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7110 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7319 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7110 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7319 desc->impl_ref_.reset(); 221   7110 desc->impl_ref_.reset();
HITCBC 222   7319 desc->read_ready = false; 222   7110 desc->read_ready = false;
HITCBC 223   7319 desc->write_ready = false; 223   7110 desc->write_ready = false;
HITCBC 224   7319 } 224   7110 }
225   225  
226   { 226   {
HITCBC 227   7319 mutex_type::scoped_lock lock(mutex_); 227   7110 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7319 registered_descs_[fd] = desc; 228   7110 registered_descs_[fd] = desc;
HITCBC 229   7319 if (fd > max_fd_) 229   7110 if (fd > max_fd_)
HITCBC 230   7314 max_fd_ = fd; 230   7105 max_fd_ = fd;
HITCBC 231   7319 } 231   7110 }
232   232  
HITCBC 233   7319 interrupt_reactor(); 233   7110 interrupt_reactor();
HITCBC 234   7319 } 234   7110 }
235   235  
236   inline void 236   inline void
HITCBC 237   7319 select_scheduler::deregister_descriptor(int fd) const 237   7110 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7319 mutex_type::scoped_lock lock(mutex_); 239   7110 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7319 auto it = registered_descs_.find(fd); 241   7110 auto it = registered_descs_.find(fd);
HITCBC 242   7319 if (it == registered_descs_.end()) 242   7110 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7319 registered_descs_.erase(it); 245   7110 registered_descs_.erase(it);
246   246  
HITCBC 247   7319 if (fd == max_fd_) 247   7110 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7206 max_fd_ = pipe_fds_[0]; 249   6996 max_fd_ = pipe_fds_[0];
HITCBC 250   14164 for (auto& [registered_fd, state] : registered_descs_) 250   13744 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6958 if (registered_fd > max_fd_) 252   6748 if (registered_fd > max_fd_)
HITCBC 253   6911 max_fd_ = registered_fd; 253   6701 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7319 } 256   7110 }
257   257  
258   inline void 258   inline void
HITCBC 259   3564 select_scheduler::notify_reactor() const 259   3460 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3564 interrupt_reactor(); 261   3460 interrupt_reactor();
HITCBC 262   3564 } 262   3460 }
263   263  
264   inline void 264   inline void
HITCBC 265   15604 select_scheduler::interrupt_reactor() const 265   15208 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   15604 char byte = 1; 267   15208 char byte = 1;
HITCBC 268   15604 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15208 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   15604 } 269   15208 }
270   270  
271   inline long 271   inline long
HITCBC 272   212421 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   333161 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   212421 if (requested_timeout_us == 0) 274   333161 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   212421 auto nearest = timer_svc_->nearest_expiry(); 277   333161 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   212421 if (nearest == timer_service::time_point::max()) 278   333161 if (nearest == timer_service::time_point::max())
HITCBC 279   402 return requested_timeout_us; 279   407 return requested_timeout_us;
280   280  
HITCBC 281   212019 auto now = std::chrono::steady_clock::now(); 281   332754 auto now = std::chrono::steady_clock::now();
HITCBC 282   212019 if (nearest <= now) 282   332754 if (nearest <= now)
HITCBC 283   783 return 0; 283   788 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   211236 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   331966 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   211236 .count(); 287   331966 .count();
288   288  
HITCBC 289   211236 constexpr auto long_max = 289   331966 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   211236 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   331966 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   211236 static_cast<long long>(0)), 293   331966 static_cast<long long>(0)),
HITCBC 294   211236 long_max); 294   331966 long_max);
295   295  
HITCBC 296   211236 if (requested_timeout_us < 0) 296   331966 if (requested_timeout_us < 0)
HITCBC 297   211236 return static_cast<long>(capped_timer_us); 297   331966 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   236364 select_scheduler::run_task( 305   368851 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   236364 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   368851 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   236364 int snapshot_count = 0; 323   368851 int snapshot_count = 0;
324   324  
HITCBC 325   615065 for (auto& [fd, desc] : registered_descs_) 325   985005 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   378701 if (snapshot_count < FD_SETSIZE) 327   616154 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   378701 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   616154 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   378701 snapshot[snapshot_count].fd = fd; 330   616154 snapshot[snapshot_count].fd = fd;
HITCBC 331   378701 snapshot[snapshot_count].desc = desc; 331   616154 snapshot[snapshot_count].desc = desc;
HITCBC 332   378701 snapshot[snapshot_count].needs_write = 332   616154 snapshot[snapshot_count].needs_write =
HITCBC 333   378701 (desc->write_op || desc->connect_op); 333   616154 (desc->write_op || desc->connect_op);
HITCBC 334   378701 ++snapshot_count; 334   616154 ++snapshot_count;
HITCBC 335   378701 } 335   616154 }
336   } 336   }
337   337  
HITCBC 338   236364 if (lock.owns_lock()) 338   368851 if (lock.owns_lock())
HITCBC 339   212421 lock.unlock(); 339   333161 lock.unlock();
340   340  
HITCBC 341   236364 task_cleanup on_exit{this, &lock, ctx}; 341   368851 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   4018188 FD_ZERO(&read_fds); 344   6270467 FD_ZERO(&read_fds);
HITCBC 345   4018188 FD_ZERO(&write_fds); 345   6270467 FD_ZERO(&write_fds);
HITCBC 346   4018188 FD_ZERO(&except_fds); 346   6270467 FD_ZERO(&except_fds);
347   347  
HITCBC 348   236364 FD_SET(pipe_fds_[0], &read_fds); 348   368851 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   236364 int nfds = pipe_fds_[0]; 349   368851 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   615065 for (int i = 0; i < snapshot_count; ++i) 351   985005 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   378701 int fd = snapshot[i].fd; 353   616154 int fd = snapshot[i].fd;
HITCBC 354   378701 FD_SET(fd, &read_fds); 354   616154 FD_SET(fd, &read_fds);
HITCBC 355   378701 if (snapshot[i].needs_write) 355   616154 if (snapshot[i].needs_write)
HITCBC 356   13834 FD_SET(fd, &write_fds); 356   15884 FD_SET(fd, &write_fds);
HITCBC 357   378701 FD_SET(fd, &except_fds); 357   616154 FD_SET(fd, &except_fds);
HITCBC 358   378701 if (fd > nfds) 358   616154 if (fd > nfds)
HITCBC 359   235917 nfds = fd; 359   368396 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   236364 struct timeval* tv_ptr = nullptr; 363   368851 struct timeval* tv_ptr = nullptr;
HITCBC 364   236364 if (effective_timeout_us >= 0) 364   368851 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   235966 tv.tv_sec = effective_timeout_us / 1000000; 366   368447 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   235966 tv.tv_usec = effective_timeout_us % 1000000; 367   368447 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   235966 tv_ptr = &tv; 368   368447 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   236364 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   368851 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   236364 if (ready < 0) 376   368851 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   236364 timer_svc_->process_expired(); 384   368851 timer_svc_->process_expired();
385   385  
HITCBC 386   236364 op_queue local_ops; 386   368851 op_queue local_ops;
387   387  
HITCBC 388   236364 if (ready > 0) 388   368851 if (ready > 0)
389   { 389   {
HITCBC 390   218374 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   344277 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   15108 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14740 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   551620 for (int i = 0; i < snapshot_count; ++i) 398   889431 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   333246 int fd = snapshot[i].fd; 400   545154 int fd = snapshot[i].fd;
HITCBC 401   333246 reactor_descriptor_state* desc = snapshot[i].desc; 401   545154 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   333246 std::uint32_t flags = 0; 403   545154 std::uint32_t flags = 0;
HITCBC 404   333246 if (FD_ISSET(fd, &read_fds)) 404   545154 if (FD_ISSET(fd, &read_fds))
HITCBC 405   214524 flags |= reactor_event_read; 405   340518 flags |= reactor_event_read;
HITCBC 406   333246 if (FD_ISSET(fd, &write_fds)) 406   545154 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3561 flags |= reactor_event_write; 407   3457 flags |= reactor_event_write;
HITCBC 408   333246 if (FD_ISSET(fd, &except_fds)) 408   545154 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   333246 if (flags == 0) 411   545154 if (flags == 0)
HITCBC 412   115170 continue; 412   201189 continue;
413   413  
HITCBC 414   218076 desc->add_ready_events(flags); 414   343965 desc->add_ready_events(flags);
415   415  
HITCBC 416   218076 bool expected = false; 416   343965 bool expected = false;
HITCBC 417   218076 if (desc->is_enqueued_.compare_exchange_strong( 417   343965 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   218076 local_ops.push(desc); 421   343965 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   236364 lock.lock(); 426   368851 lock.lock();
427   427  
HITCBC 428   236364 if (!local_ops.empty()) 428   368851 if (!local_ops.empty())
HITCBC 429   214606 completed_ops_.splice(local_ops); 429   340600 completed_ops_.splice(local_ops);
HITCBC 430   236364 } 430   368851 }
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