. /include/boost/corosio /native /detail /select /select_scheduler.hpp
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1   // 1   //
2   // Copyright (c) 2026 Steve Gerbino 2   // Copyright (c) 2026 Steve Gerbino
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 4   // Distributed under the Boost Software License, Version 1.0. (See accompanying
5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/corosio 7   // Official repository: https://github.com/cppalliance/corosio
8   // 8   //
9   9  
10   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 10   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
11   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 11   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
12   12  
13   #include <boost/corosio/detail/platform.hpp> 13   #include <boost/corosio/detail/platform.hpp>
14   14  
15   #if BOOST_COROSIO_HAS_SELECT 15   #if BOOST_COROSIO_HAS_SELECT
16   16  
17   #include <boost/corosio/detail/config.hpp> 17   #include <boost/corosio/detail/config.hpp>
18   #include <boost/capy/ex/execution_context.hpp> 18   #include <boost/capy/ex/execution_context.hpp>
19   19  
20   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp> 20   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
21   21  
22   #include <boost/corosio/native/detail/select/select_traits.hpp> 22   #include <boost/corosio/native/detail/select/select_traits.hpp>
23   #include <boost/corosio/detail/timer_service.hpp> 23   #include <boost/corosio/detail/timer_service.hpp>
24   #include <boost/corosio/native/detail/make_err.hpp> 24   #include <boost/corosio/native/detail/make_err.hpp>
25   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp> 25   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp>
26   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp> 26   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp>
27   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp> 27   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
28   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp> 28   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
29   29  
30   #include <boost/corosio/detail/except.hpp> 30   #include <boost/corosio/detail/except.hpp>
31   31  
32   #include <sys/select.h> 32   #include <sys/select.h>
33   #include <unistd.h> 33   #include <unistd.h>
34   #include <errno.h> 34   #include <errno.h>
35   #include <fcntl.h> 35   #include <fcntl.h>
36   36  
37   #include <atomic> 37   #include <atomic>
38   #include <chrono> 38   #include <chrono>
39   #include <cstdint> 39   #include <cstdint>
40   #include <limits> 40   #include <limits>
41   #include <mutex> 41   #include <mutex>
42   #include <unordered_map> 42   #include <unordered_map>
43   43  
44   namespace boost::corosio::detail { 44   namespace boost::corosio::detail {
45   45  
46   struct select_op; 46   struct select_op;
47   47  
48   /** POSIX scheduler using select() for I/O multiplexing. 48   /** POSIX scheduler using select() for I/O multiplexing.
49   49  
50   This scheduler implements the scheduler interface using the POSIX select() 50   This scheduler implements the scheduler interface using the POSIX select()
51   call for I/O event notification. It inherits the shared reactor threading 51   call for I/O event notification. It inherits the shared reactor threading
52   model from reactor_scheduler: signal state machine, inline completion 52   model from reactor_scheduler: signal state machine, inline completion
53   budget, work counting, and the do_one event loop. 53   budget, work counting, and the do_one event loop.
54   54  
55   The design mirrors epoll_scheduler for behavioral consistency: 55   The design mirrors epoll_scheduler for behavioral consistency:
56   - Same single-reactor thread coordination model 56   - Same single-reactor thread coordination model
57   - Same deferred I/O pattern (reactor marks ready; workers do I/O) 57   - Same deferred I/O pattern (reactor marks ready; workers do I/O)
58   - Same timer integration pattern 58   - Same timer integration pattern
59   59  
60   Known Limitations: 60   Known Limitations:
61   - FD_SETSIZE (~1024) limits maximum concurrent connections 61   - FD_SETSIZE (~1024) limits maximum concurrent connections
62   - O(n) scanning: rebuilds fd_sets each iteration 62   - O(n) scanning: rebuilds fd_sets each iteration
63   - Level-triggered only (no edge-triggered mode) 63   - Level-triggered only (no edge-triggered mode)
64   64  
65   @par Thread Safety 65   @par Thread Safety
66   All public member functions are thread-safe. 66   All public member functions are thread-safe.
67   */ 67   */
68   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler 68   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler
69   { 69   {
70   public: 70   public:
71   /** Construct the scheduler. 71   /** Construct the scheduler.
72   72  
73   Creates a self-pipe for reactor interruption. 73   Creates a self-pipe for reactor interruption.
74   74  
75   @param ctx Reference to the owning execution_context. 75   @param ctx Reference to the owning execution_context.
76   @param concurrency_hint Hint for expected thread count (unused). 76   @param concurrency_hint Hint for expected thread count (unused).
77   */ 77   */
78   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1); 78   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
79   79  
80   /// Destroy the scheduler. 80   /// Destroy the scheduler.
81   ~select_scheduler() override; 81   ~select_scheduler() override;
82   82  
83   select_scheduler(select_scheduler const&) = delete; 83   select_scheduler(select_scheduler const&) = delete;
84   select_scheduler& operator=(select_scheduler const&) = delete; 84   select_scheduler& operator=(select_scheduler const&) = delete;
85   85  
86   /// Shut down the scheduler, draining pending operations. 86   /// Shut down the scheduler, draining pending operations.
87   void shutdown() override; 87   void shutdown() override;
88   88  
89   /** Return the maximum file descriptor value supported. 89   /** Return the maximum file descriptor value supported.
90   90  
91   Returns FD_SETSIZE - 1, the maximum fd value that can be 91   Returns FD_SETSIZE - 1, the maximum fd value that can be
92   monitored by select(). Operations with fd >= FD_SETSIZE 92   monitored by select(). Operations with fd >= FD_SETSIZE
93   will fail with EINVAL. 93   will fail with EINVAL.
94   94  
95   @return The maximum supported file descriptor value. 95   @return The maximum supported file descriptor value.
96   */ 96   */
97   static constexpr int max_fd() noexcept 97   static constexpr int max_fd() noexcept
98   { 98   {
99   return FD_SETSIZE - 1; 99   return FD_SETSIZE - 1;
100   } 100   }
101   101  
102   /** Register a descriptor for persistent monitoring. 102   /** Register a descriptor for persistent monitoring.
103   103  
104   The fd is added to the registered_descs_ map and will be 104   The fd is added to the registered_descs_ map and will be
105   included in subsequent select() calls. The reactor is 105   included in subsequent select() calls. The reactor is
106   interrupted so a blocked select() rebuilds its fd_sets. 106   interrupted so a blocked select() rebuilds its fd_sets.
107   107  
108   @param fd The file descriptor to register. 108   @param fd The file descriptor to register.
109   @param desc Pointer to descriptor state for this fd. 109   @param desc Pointer to descriptor state for this fd.
110   */ 110   */
111   void register_descriptor(int fd, reactor_descriptor_state* desc) const; 111   void register_descriptor(int fd, reactor_descriptor_state* desc) const;
112   112  
113   /** Deregister a persistently registered descriptor. 113   /** Deregister a persistently registered descriptor.
114   114  
115   @param fd The file descriptor to deregister. 115   @param fd The file descriptor to deregister.
116   */ 116   */
117   void deregister_descriptor(int fd) const; 117   void deregister_descriptor(int fd) const;
118   118  
119   /** Interrupt the reactor so it rebuilds its fd_sets. 119   /** Interrupt the reactor so it rebuilds its fd_sets.
120   120  
121   Called when a write or connect op is registered after 121   Called when a write or connect op is registered after
122   the reactor's snapshot was taken. Without this, select() 122   the reactor's snapshot was taken. Without this, select()
123   may block not watching for writability on the fd. 123   may block not watching for writability on the fd.
124   */ 124   */
125   void notify_reactor() const; 125   void notify_reactor() const;
126   126  
127   private: 127   private:
128   void 128   void
129   run_task(lock_type& lock, context_type* ctx, 129   run_task(lock_type& lock, context_type* ctx,
130   long timeout_us) override; 130   long timeout_us) override;
131   void interrupt_reactor() const override; 131   void interrupt_reactor() const override;
132   long calculate_timeout(long requested_timeout_us) const; 132   long calculate_timeout(long requested_timeout_us) const;
133   133  
134   // Self-pipe for interrupting select() 134   // Self-pipe for interrupting select()
135   int pipe_fds_[2]; // [0]=read, [1]=write 135   int pipe_fds_[2]; // [0]=read, [1]=write
136   136  
137   // Per-fd tracking for fd_set building 137   // Per-fd tracking for fd_set building
138   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_; 138   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_;
139   mutable int max_fd_ = -1; 139   mutable int max_fd_ = -1;
140   }; 140   };
141   141  
HITCBC 142   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   428 : pipe_fds_{-1, -1} 143   428 : pipe_fds_{-1, -1}
HITCBC 144   428 , max_fd_(-1) 144   428 , max_fd_(-1)
145   { 145   {
HITCBC 146   428 if (::pipe(pipe_fds_) < 0) 146   428 if (::pipe(pipe_fds_) < 0)
MISUBC 147   ✗ detail::throw_system_error(make_err(errno), "pipe"); 147   ✗ detail::throw_system_error(make_err(errno), "pipe");
148   148  
HITCBC 149   1284 for (int i = 0; i < 2; ++i) 149   1284 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   856 if (flags == -1) 152   856 if (flags == -1)
153   { 153   {
MISUBC 154   ✗ int errn = errno; 154   ✗ int errn = errno;
MISUBC 155   ✗ ::close(pipe_fds_[0]); 155   ✗ ::close(pipe_fds_[0]);
MISUBC 156   ✗ ::close(pipe_fds_[1]); 156   ✗ ::close(pipe_fds_[1]);
MISUBC 157   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL"); 157   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
158   } 158   }
HITCBC 159   856 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   856 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
160   { 160   {
MISUBC 161   ✗ int errn = errno; 161   ✗ int errn = errno;
MISUBC 162   ✗ ::close(pipe_fds_[0]); 162   ✗ ::close(pipe_fds_[0]);
MISUBC 163   ✗ ::close(pipe_fds_[1]); 163   ✗ ::close(pipe_fds_[1]);
MISUBC 164   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL"); 164   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
165   } 165   }
HITCBC 166   856 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   856 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
167   { 167   {
MISUBC 168   ✗ int errn = errno; 168   ✗ int errn = errno;
MISUBC 169   ✗ ::close(pipe_fds_[0]); 169   ✗ ::close(pipe_fds_[0]);
MISUBC 170   ✗ ::close(pipe_fds_[1]); 170   ✗ ::close(pipe_fds_[1]);
MISUBC 171   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD"); 171   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
172   } 172   }
173   } 173   }
174   174  
HITCBC 175   428 timer_svc_ = &get_timer_service(ctx, *this); 175   428 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   428 timer_svc_->set_on_earliest_changed( 176   428 timer_svc_->set_on_earliest_changed(
HITCBC 177   3949 timer_service::callback(this, [](void* p) { 177   2353 timer_service::callback(this, [](void* p) {
HITCBC 178   3521 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   1925 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3521 })); 179   1925 }));
180   180  
HITCBC 181   428 get_resolver_service(ctx, *this); 181   428 get_resolver_service(ctx, *this);
HITCBC 182   428 get_signal_service(ctx, *this); 182   428 get_signal_service(ctx, *this);
HITCBC 183   428 get_stream_file_service(ctx, *this); 183   428 get_stream_file_service(ctx, *this);
HITCBC 184   428 get_random_access_file_service(ctx, *this); 184   428 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   428 completed_ops_.push(&task_op_); 186   428 completed_ops_.push(&task_op_);
HITCBC 187   428 } 187   428 }
188   188  
HITCBC 189   856 inline select_scheduler::~select_scheduler() 189   856 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   428 if (pipe_fds_[0] >= 0) 191   428 if (pipe_fds_[0] >= 0)
HITCBC 192   428 ::close(pipe_fds_[0]); 192   428 ::close(pipe_fds_[0]);
HITCBC 193   428 if (pipe_fds_[1] >= 0) 193   428 if (pipe_fds_[1] >= 0)
HITCBC 194   428 ::close(pipe_fds_[1]); 194   428 ::close(pipe_fds_[1]);
HITCBC 195   856 } 195   856 }
196   196  
197   inline void 197   inline void
HITCBC 198   428 select_scheduler::shutdown() 198   428 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   428 shutdown_drain(); 200   428 shutdown_drain();
201   201  
HITCBC 202   428 if (pipe_fds_[1] >= 0) 202   428 if (pipe_fds_[1] >= 0)
HITCBC 203   428 interrupt_reactor(); 203   428 interrupt_reactor();
HITCBC 204   428 } 204   428 }
205   205  
206   inline void 206   inline void
HITCBC 207   6876 select_scheduler::register_descriptor( 207   3706 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6876 if (fd < 0 || fd >= FD_SETSIZE) 210   3706 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   6876 desc->registered_events = reactor_event_read | reactor_event_write; 213   3706 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6876 desc->fd = fd; 214   3706 desc->fd = fd;
HITCBC 215   6876 desc->scheduler_ = this; 215   3706 desc->scheduler_ = this;
HITCBC 216   6876 desc->mutex.set_enabled(!single_threaded_); 216   3706 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6876 desc->ready_events_.store(0, std::memory_order_relaxed); 217   3706 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6876 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   3706 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6876 desc->impl_ref_.reset(); 221   3706 desc->impl_ref_.reset();
HITCBC 222   6876 desc->read_ready = false; 222   3706 desc->read_ready = false;
HITCBC 223   6876 desc->write_ready = false; 223   3706 desc->write_ready = false;
HITCBC 224   6876 } 224   3706 }
225   225  
226   { 226   {
HITCBC 227   6876 mutex_type::scoped_lock lock(mutex_); 227   3706 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6876 registered_descs_[fd] = desc; 228   3706 registered_descs_[fd] = desc;
HITCBC 229   6876 if (fd > max_fd_) 229   3706 if (fd > max_fd_)
HITCBC 230   6872 max_fd_ = fd; 230   3702 max_fd_ = fd;
HITCBC 231   6876 } 231   3706 }
232   232  
HITCBC 233   6876 interrupt_reactor(); 233   3706 interrupt_reactor();
HITCBC 234   6876 } 234   3706 }
235   235  
236   inline void 236   inline void
HITCBC 237   6876 select_scheduler::deregister_descriptor(int fd) const 237   3706 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6876 mutex_type::scoped_lock lock(mutex_); 239   3706 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6876 auto it = registered_descs_.find(fd); 241   3706 auto it = registered_descs_.find(fd);
HITCBC 242   6876 if (it == registered_descs_.end()) 242   3706 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6876 registered_descs_.erase(it); 245   3706 registered_descs_.erase(it);
246   246  
HITCBC 247   6876 if (fd == max_fd_) 247   3706 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6772 max_fd_ = pipe_fds_[0]; 249   3602 max_fd_ = pipe_fds_[0];
HITCBC 250   13333 for (auto& [registered_fd, state] : registered_descs_) 250   6993 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6561 if (registered_fd > max_fd_) 252   3391 if (registered_fd > max_fd_)
HITCBC 253   6536 max_fd_ = registered_fd; 253   3366 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6876 } 256   3706 }
257   257  
258   inline void 258   inline void
HITCBC 259   3297 select_scheduler::notify_reactor() const 259   1712 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3297 interrupt_reactor(); 261   1712 interrupt_reactor();
HITCBC 262   3297 } 262   1712 }
263   263  
264   inline void 264   inline void
HITCBC 265   14408 select_scheduler::interrupt_reactor() const 265   8057 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14408 char byte = 1; 267   8057 char byte = 1;
HITCBC 268   14408 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   8057 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14408 } 269   8057 }
270   270  
271   inline long 271   inline long
HITCBC 272   202635 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   188756 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   202635 if (requested_timeout_us == 0) 274   188756 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   202635 auto nearest = timer_svc_->nearest_expiry(); 277   188756 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   202635 if (nearest == timer_service::time_point::max()) 278   188756 if (nearest == timer_service::time_point::max())
HITCBC 279   175 return requested_timeout_us; 279   175 return requested_timeout_us;
280   280  
HITCBC 281   202460 auto now = std::chrono::steady_clock::now(); 281   188581 auto now = std::chrono::steady_clock::now();
HITCBC 282   202460 if (nearest <= now) 282   188581 if (nearest <= now)
HITCBC 283   644 return 0; 283   659 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   201816 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   187922 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   201816 .count(); 287   187922 .count();
288   288  
HITCBC 289   201816 constexpr auto long_max = 289   187922 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   201816 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   187922 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   201816 static_cast<long long>(0)), 293   187922 static_cast<long long>(0)),
HITCBC 294   201816 long_max); 294   187922 long_max);
295   295  
HITCBC 296   201816 if (requested_timeout_us < 0) 296   187922 if (requested_timeout_us < 0)
HITCBC 297   201816 return static_cast<long>(capped_timer_us); 297   187922 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   228499 select_scheduler::run_task( 305   213122 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   228499 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   213122 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   228499 int snapshot_count = 0; 323   213122 int snapshot_count = 0;
324   324  
HITCBC 325   606132 for (auto& [fd, desc] : registered_descs_) 325   568198 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   377633 if (snapshot_count < FD_SETSIZE) 327   355076 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   377633 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   355076 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   377633 snapshot[snapshot_count].fd = fd; 330   355076 snapshot[snapshot_count].fd = fd;
HITCBC 331   377633 snapshot[snapshot_count].desc = desc; 331   355076 snapshot[snapshot_count].desc = desc;
HITCBC 332   377633 snapshot[snapshot_count].needs_write = 332   355076 snapshot[snapshot_count].needs_write =
HITCBC 333   377633 (desc->write_op || desc->connect_op); 333   355076 (desc->write_op || desc->connect_op);
HITCBC 334   377633 ++snapshot_count; 334   355076 ++snapshot_count;
HITCBC 335   377633 } 335   355076 }
336   } 336   }
337   337  
HITCBC 338   228499 if (lock.owns_lock()) 338   213122 if (lock.owns_lock())
HITCBC 339   202635 lock.unlock(); 339   188756 lock.unlock();
340   340  
HITCBC 341   228499 task_cleanup on_exit{this, &lock, ctx}; 341   213122 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   3884483 FD_ZERO(&read_fds); 344   3623074 FD_ZERO(&read_fds);
HITCBC 345   3884483 FD_ZERO(&write_fds); 345   3623074 FD_ZERO(&write_fds);
HITCBC 346   3884483 FD_ZERO(&except_fds); 346   3623074 FD_ZERO(&except_fds);
347   347  
HITCBC 348   228499 FD_SET(pipe_fds_[0], &read_fds); 348   213122 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   228499 int nfds = pipe_fds_[0]; 349   213122 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   606132 for (int i = 0; i < snapshot_count; ++i) 351   568198 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   377633 int fd = snapshot[i].fd; 353   355076 int fd = snapshot[i].fd;
HITCBC 354   377633 FD_SET(fd, &read_fds); 354   355076 FD_SET(fd, &read_fds);
HITCBC 355   377633 if (snapshot[i].needs_write) 355   355076 if (snapshot[i].needs_write)
HITCBC 356   3384 FD_SET(fd, &write_fds); 356   1799 FD_SET(fd, &write_fds);
HITCBC 357   377633 FD_SET(fd, &except_fds); 357   355076 FD_SET(fd, &except_fds);
HITCBC 358   377633 if (fd > nfds) 358   355076 if (fd > nfds)
HITCBC 359   228148 nfds = fd; 359   212773 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   228499 struct timeval* tv_ptr = nullptr; 363   213122 struct timeval* tv_ptr = nullptr;
HITCBC 364   228499 if (effective_timeout_us >= 0) 364   213122 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   228325 tv.tv_sec = effective_timeout_us / 1000000; 366   212948 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   228325 tv.tv_usec = effective_timeout_us % 1000000; 367   212948 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   228325 tv_ptr = &tv; 368   212948 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   228499 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   213122 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   228499 if (ready < 0) 376   213122 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   228499 timer_svc_->process_expired(); 384   213122 timer_svc_->process_expired();
385   385  
HITCBC 386   228499 op_queue local_ops; 386   213122 op_queue local_ops;
387   387  
HITCBC 388   228499 if (ready > 0) 388   213122 if (ready > 0)
389   { 389   {
HITCBC 390   209278 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   197071 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14026 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   7674 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   533307 for (int i = 0; i < snapshot_count; ++i) 398   500109 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   324029 int fd = snapshot[i].fd; 400   303038 int fd = snapshot[i].fd;
HITCBC 401   324029 reactor_descriptor_state* desc = snapshot[i].desc; 401   303038 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   324029 std::uint32_t flags = 0; 403   303038 std::uint32_t flags = 0;
HITCBC 404   324029 if (FD_ISSET(fd, &read_fds)) 404   303038 if (FD_ISSET(fd, &read_fds))
HITCBC 405   205770 flags |= reactor_event_read; 405   195148 flags |= reactor_event_read;
HITCBC 406   324029 if (FD_ISSET(fd, &write_fds)) 406   303038 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3296 flags |= reactor_event_write; 407   1711 flags |= reactor_event_write;
HITCBC 408   324029 if (FD_ISSET(fd, &except_fds)) 408   303038 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   324029 if (flags == 0) 411   303038 if (flags == 0)
HITCBC 412   114972 continue; 412   106188 continue;
413   413  
HITCBC 414   209057 desc->add_ready_events(flags); 414   196850 desc->add_ready_events(flags);
415   415  
HITCBC 416   209057 bool expected = false; 416   196850 bool expected = false;
HITCBC 417   209057 if (desc->is_enqueued_.compare_exchange_strong( 417   196850 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   209057 local_ops.push(desc); 421   196850 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   228499 lock.lock(); 426   213122 lock.lock();
427   427  
HITCBC 428   228499 if (!local_ops.empty()) 428   213122 if (!local_ops.empty())
HITCBC 429   205766 completed_ops_.splice(local_ops); 429   195144 completed_ops_.splice(local_ops);
HITCBC 430   228499 } 430   213122 }
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