. /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   239 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   239 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   239 : pipe_fds_{-1, -1} 143   239 : pipe_fds_{-1, -1}
HITCBC 144   239 , max_fd_(-1) 144   239 , max_fd_(-1)
145   { 145   {
HITCBC 146   239 if (::pipe(pipe_fds_) < 0) 146   239 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   717 for (int i = 0; i < 2; ++i) 149   717 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   478 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   478 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   478 if (flags == -1) 152   478 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   478 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   478 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   478 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   478 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   239 timer_svc_ = &get_timer_service(ctx, *this); 175   239 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   239 timer_svc_->set_on_earliest_changed( 176   239 timer_svc_->set_on_earliest_changed(
HITCBC 177   3930 timer_service::callback(this, [](void* p) { 177   3896 timer_service::callback(this, [](void* p) {
HITCBC 178   3691 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3657 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3691 })); 179   3657 }));
180   180  
HITCBC 181   239 get_resolver_service(ctx, *this); 181   239 get_resolver_service(ctx, *this);
HITCBC 182   239 get_signal_service(ctx, *this); 182   239 get_signal_service(ctx, *this);
HITCBC 183   239 get_stream_file_service(ctx, *this); 183   239 get_stream_file_service(ctx, *this);
HITCBC 184   239 get_random_access_file_service(ctx, *this); 184   239 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   239 completed_ops_.push(&task_op_); 186   239 completed_ops_.push(&task_op_);
HITCBC 187   239 } 187   239 }
188   188  
HITCBC 189   478 inline select_scheduler::~select_scheduler() 189   478 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   239 if (pipe_fds_[0] >= 0) 191   239 if (pipe_fds_[0] >= 0)
HITCBC 192   239 ::close(pipe_fds_[0]); 192   239 ::close(pipe_fds_[0]);
HITCBC 193   239 if (pipe_fds_[1] >= 0) 193   239 if (pipe_fds_[1] >= 0)
HITCBC 194   239 ::close(pipe_fds_[1]); 194   239 ::close(pipe_fds_[1]);
HITCBC 195   478 } 195   478 }
196   196  
197   inline void 197   inline void
HITCBC 198   239 select_scheduler::shutdown() 198   239 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   239 shutdown_drain(); 200   239 shutdown_drain();
201   201  
HITCBC 202   239 if (pipe_fds_[1] >= 0) 202   239 if (pipe_fds_[1] >= 0)
HITCBC 203   239 interrupt_reactor(); 203   239 interrupt_reactor();
HITCBC 204   239 } 204   239 }
205   205  
206   inline void 206   inline void
HITCBC 207   7075 select_scheduler::register_descriptor( 207   7035 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7075 if (fd < 0 || fd >= FD_SETSIZE) 210   7035 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   7075 desc->registered_events = reactor_event_read | reactor_event_write; 213   7035 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7075 desc->fd = fd; 214   7035 desc->fd = fd;
HITCBC 215   7075 desc->scheduler_ = this; 215   7035 desc->scheduler_ = this;
HITCBC 216   7075 desc->mutex.set_enabled(!single_threaded_); 216   7035 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7075 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7035 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7075 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7035 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7075 desc->impl_ref_.reset(); 221   7035 desc->impl_ref_.reset();
HITCBC 222   7075 desc->read_ready = false; 222   7035 desc->read_ready = false;
HITCBC 223   7075 desc->write_ready = false; 223   7035 desc->write_ready = false;
HITCBC 224   7075 } 224   7035 }
225   225  
226   { 226   {
HITCBC 227   7075 mutex_type::scoped_lock lock(mutex_); 227   7035 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7075 registered_descs_[fd] = desc; 228   7035 registered_descs_[fd] = desc;
HITCBC 229   7075 if (fd > max_fd_) 229   7035 if (fd > max_fd_)
HITCBC 230   7071 max_fd_ = fd; 230   7031 max_fd_ = fd;
HITCBC 231   7075 } 231   7035 }
232   232  
HITCBC 233   7075 interrupt_reactor(); 233   7035 interrupt_reactor();
HITCBC 234   7075 } 234   7035 }
235   235  
236   inline void 236   inline void
HITCBC 237   7075 select_scheduler::deregister_descriptor(int fd) const 237   7035 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7075 mutex_type::scoped_lock lock(mutex_); 239   7035 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7075 auto it = registered_descs_.find(fd); 241   7035 auto it = registered_descs_.find(fd);
HITCBC 242   7075 if (it == registered_descs_.end()) 242   7035 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7075 registered_descs_.erase(it); 245   7035 registered_descs_.erase(it);
246   246  
HITCBC 247   7075 if (fd == max_fd_) 247   7035 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7012 max_fd_ = pipe_fds_[0]; 249   6972 max_fd_ = pipe_fds_[0];
HITCBC 250   13910 for (auto& [registered_fd, state] : registered_descs_) 250   13830 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6898 if (registered_fd > max_fd_) 252   6858 if (registered_fd > max_fd_)
HITCBC 253   6883 max_fd_ = registered_fd; 253   6843 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7075 } 256   7035 }
257   257  
258   inline void 258   inline void
HITCBC 259   3464 select_scheduler::notify_reactor() const 259   3444 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3464 interrupt_reactor(); 261   3444 interrupt_reactor();
HITCBC 262   3464 } 262   3444 }
263   263  
264   inline void 264   inline void
HITCBC 265   14634 select_scheduler::interrupt_reactor() const 265   14540 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14634 char byte = 1; 267   14540 char byte = 1;
HITCBC 268   14634 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   14540 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14634 } 269   14540 }
270   270  
271   inline long 271   inline long
HITCBC 272   210052 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   118486 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   210052 if (requested_timeout_us == 0) 274   118486 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   210052 auto nearest = timer_svc_->nearest_expiry(); 277   118486 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   210052 if (nearest == timer_service::time_point::max()) 278   118486 if (nearest == timer_service::time_point::max())
HITCBC 279   56 return requested_timeout_us; 279   56 return requested_timeout_us;
280   280  
HITCBC 281   209996 auto now = std::chrono::steady_clock::now(); 281   118430 auto now = std::chrono::steady_clock::now();
HITCBC 282   209996 if (nearest <= now) 282   118430 if (nearest <= now)
HITCBC 283   386 return 0; 283   457 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   209610 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   117973 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   209610 .count(); 287   117973 .count();
288   288  
HITCBC 289   209610 constexpr auto long_max = 289   117973 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   209610 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   117973 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   209610 static_cast<long long>(0)), 293   117973 static_cast<long long>(0)),
HITCBC 294   209610 long_max); 294   117973 long_max);
295   295  
HITCBC 296   209610 if (requested_timeout_us < 0) 296   117973 if (requested_timeout_us < 0)
HITCBC 297   209604 return static_cast<long>(capped_timer_us); 297   117967 return static_cast<long>(capped_timer_us);
298   298  
299   return static_cast<long>( 299   return static_cast<long>(
HITCBC 300   6 (std::min)(static_cast<long long>(requested_timeout_us), 300   6 (std::min)(static_cast<long long>(requested_timeout_us),
HITCBC 301   6 capped_timer_us)); 301   6 capped_timer_us));
302   } 302   }
303   303  
304   inline void 304   inline void
HITCBC 305   248679 select_scheduler::run_task( 305   139612 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   248679 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   139612 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   248679 int snapshot_count = 0; 323   139612 int snapshot_count = 0;
324   324  
HITCBC 325   752972 for (auto& [fd, desc] : registered_descs_) 325   412141 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   504293 if (snapshot_count < FD_SETSIZE) 327   272529 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   504293 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   272529 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   504293 snapshot[snapshot_count].fd = fd; 330   272529 snapshot[snapshot_count].fd = fd;
HITCBC 331   504293 snapshot[snapshot_count].desc = desc; 331   272529 snapshot[snapshot_count].desc = desc;
HITCBC 332   504293 snapshot[snapshot_count].needs_write = 332   272529 snapshot[snapshot_count].needs_write =
HITCBC 333   504293 (desc->write_op || desc->connect_op); 333   272529 (desc->write_op || desc->connect_op);
HITCBC 334   504293 ++snapshot_count; 334   272529 ++snapshot_count;
HITCBC 335   504293 } 335   272529 }
336   } 336   }
337   337  
HITCBC 338   248679 if (lock.owns_lock()) 338   139612 if (lock.owns_lock())
HITCBC 339   210052 lock.unlock(); 339   118486 lock.unlock();
340   340  
HITCBC 341   248679 task_cleanup on_exit{this, &lock, ctx}; 341   139612 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   4227543 FD_ZERO(&read_fds); 344   2373404 FD_ZERO(&read_fds);
HITCBC 345   4227543 FD_ZERO(&write_fds); 345   2373404 FD_ZERO(&write_fds);
HITCBC 346   4227543 FD_ZERO(&except_fds); 346   2373404 FD_ZERO(&except_fds);
347   347  
HITCBC 348   248679 FD_SET(pipe_fds_[0], &read_fds); 348   139612 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   248679 int nfds = pipe_fds_[0]; 349   139612 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   752972 for (int i = 0; i < snapshot_count; ++i) 351   412141 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   504293 int fd = snapshot[i].fd; 353   272529 int fd = snapshot[i].fd;
HITCBC 354   504293 FD_SET(fd, &read_fds); 354   272529 FD_SET(fd, &read_fds);
HITCBC 355   504293 if (snapshot[i].needs_write) 355   272529 if (snapshot[i].needs_write)
HITCBC 356   3466 FD_SET(fd, &write_fds); 356   3446 FD_SET(fd, &write_fds);
HITCBC 357   504293 FD_SET(fd, &except_fds); 357   272529 FD_SET(fd, &except_fds);
HITCBC 358   504293 if (fd > nfds) 358   272529 if (fd > nfds)
HITCBC 359   248408 nfds = fd; 359   139341 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   248679 struct timeval* tv_ptr = nullptr; 363   139612 struct timeval* tv_ptr = nullptr;
HITCBC 364   248679 if (effective_timeout_us >= 0) 364   139612 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   248623 tv.tv_sec = effective_timeout_us / 1000000; 366   139556 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   248623 tv.tv_usec = effective_timeout_us % 1000000; 367   139556 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   248623 tv_ptr = &tv; 368   139556 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   248679 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   139612 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   248679 if (ready < 0) 376   139612 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   248679 timer_svc_->process_expired(); 384   139612 timer_svc_->process_expired();
385   385  
HITCBC 386   248679 op_queue local_ops; 386   139612 op_queue local_ops;
387   387  
HITCBC 388   248679 if (ready > 0) 388   139612 if (ready > 0)
389   { 389   {
HITCBC 390   221645 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   122598 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14500 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14388 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   645552 for (int i = 0; i < snapshot_count; ++i) 398   348107 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   423907 int fd = snapshot[i].fd; 400   225509 int fd = snapshot[i].fd;
HITCBC 401   423907 reactor_descriptor_state* desc = snapshot[i].desc; 401   225509 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   423907 std::uint32_t flags = 0; 403   225509 std::uint32_t flags = 0;
HITCBC 404   423907 if (FD_ISSET(fd, &read_fds)) 404   225509 if (FD_ISSET(fd, &read_fds))
HITCBC 405   218048 flags |= reactor_event_read; 405   119025 flags |= reactor_event_read;
HITCBC 406   423907 if (FD_ISSET(fd, &write_fds)) 406   225509 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3463 flags |= reactor_event_write; 407   3443 flags |= reactor_event_write;
HITCBC 408   423907 if (FD_ISSET(fd, &except_fds)) 408   225509 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   423907 if (flags == 0) 411   225509 if (flags == 0)
HITCBC 412   202404 continue; 412   103049 continue;
413   413  
HITCBC 414   221503 desc->add_ready_events(flags); 414   122460 desc->add_ready_events(flags);
415   415  
HITCBC 416   221503 bool expected = false; 416   122460 bool expected = false;
HITCBC 417   221503 if (desc->is_enqueued_.compare_exchange_strong( 417   122460 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   221503 local_ops.push(desc); 421   122460 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   248679 lock.lock(); 426   139612 lock.lock();
427   427  
HITCBC 428   248679 if (!local_ops.empty()) 428   139612 if (!local_ops.empty())
HITCBC 429   218049 completed_ops_.splice(local_ops); 429   119026 completed_ops_.splice(local_ops);
HITCBC 430   248679 } 430   139612 }
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