. /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   594 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   594 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   594 : pipe_fds_{-1, -1} 143   594 : pipe_fds_{-1, -1}
HITCBC 144   594 , max_fd_(-1) 144   594 , max_fd_(-1)
145   { 145   {
HITCBC 146   594 if (::pipe(pipe_fds_) < 0) 146   594 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   1782 for (int i = 0; i < 2; ++i) 149   1782 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   1188 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   1188 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   1188 if (flags == -1) 152   1188 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   1188 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   1188 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   1188 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   1188 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   594 timer_svc_ = &get_timer_service(ctx, *this); 175   594 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   594 timer_svc_->set_on_earliest_changed( 176   594 timer_svc_->set_on_earliest_changed(
HITCBC 177   4567 timer_service::callback(this, [](void* p) { 177   4351 timer_service::callback(this, [](void* p) {
HITCBC 178   3973 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3757 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3973 })); 179   3757 }));
180   180  
HITCBC 181   594 get_resolver_service(ctx, *this); 181   594 get_resolver_service(ctx, *this);
HITCBC 182   594 get_signal_service(ctx, *this); 182   594 get_signal_service(ctx, *this);
HITCBC 183   594 get_stream_file_service(ctx, *this); 183   594 get_stream_file_service(ctx, *this);
HITCBC 184   594 get_random_access_file_service(ctx, *this); 184   594 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   594 completed_ops_.push(&task_op_); 186   594 completed_ops_.push(&task_op_);
HITCBC 187   594 } 187   594 }
188   188  
HITCBC 189   1188 inline select_scheduler::~select_scheduler() 189   1188 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   594 if (pipe_fds_[0] >= 0) 191   594 if (pipe_fds_[0] >= 0)
HITCBC 192   594 ::close(pipe_fds_[0]); 192   594 ::close(pipe_fds_[0]);
HITCBC 193   594 if (pipe_fds_[1] >= 0) 193   594 if (pipe_fds_[1] >= 0)
HITCBC 194   594 ::close(pipe_fds_[1]); 194   594 ::close(pipe_fds_[1]);
HITCBC 195   1188 } 195   1188 }
196   196  
197   inline void 197   inline void
HITCBC 198   594 select_scheduler::shutdown() 198   594 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   594 shutdown_drain(); 200   594 shutdown_drain();
201   201  
HITCBC 202   594 if (pipe_fds_[1] >= 0) 202   594 if (pipe_fds_[1] >= 0)
HITCBC 203   594 interrupt_reactor(); 203   594 interrupt_reactor();
HITCBC 204   594 } 204   594 }
205   205  
206   inline void 206   inline void
HITCBC 207   7853 select_scheduler::register_descriptor( 207   7420 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7853 if (fd < 0 || fd >= FD_SETSIZE) 210   7420 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   7853 desc->registered_events = reactor_event_read | reactor_event_write; 213   7420 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7853 desc->fd = fd; 214   7420 desc->fd = fd;
HITCBC 215   7853 desc->scheduler_ = this; 215   7420 desc->scheduler_ = this;
HITCBC 216   7853 desc->mutex.set_enabled(!single_threaded_); 216   7420 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7853 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7420 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7853 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7420 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7853 desc->impl_ref_.reset(); 221   7420 desc->impl_ref_.reset();
HITCBC 222   7853 desc->read_ready = false; 222   7420 desc->read_ready = false;
HITCBC 223   7853 desc->write_ready = false; 223   7420 desc->write_ready = false;
HITCBC 224   7853 } 224   7420 }
225   225  
226   { 226   {
HITCBC 227   7853 mutex_type::scoped_lock lock(mutex_); 227   7420 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7853 registered_descs_[fd] = desc; 228   7420 registered_descs_[fd] = desc;
HITCBC 229   7853 if (fd > max_fd_) 229   7420 if (fd > max_fd_)
HITCBC 230   7848 max_fd_ = fd; 230   7415 max_fd_ = fd;
HITCBC 231   7853 } 231   7420 }
232   232  
HITCBC 233   7853 interrupt_reactor(); 233   7420 interrupt_reactor();
HITCBC 234   7853 } 234   7420 }
235   235  
236   inline void 236   inline void
HITCBC 237   7853 select_scheduler::deregister_descriptor(int fd) const 237   7420 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7853 mutex_type::scoped_lock lock(mutex_); 239   7420 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7853 auto it = registered_descs_.find(fd); 241   7420 auto it = registered_descs_.find(fd);
HITCBC 242   7853 if (it == registered_descs_.end()) 242   7420 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7853 registered_descs_.erase(it); 245   7420 registered_descs_.erase(it);
246   246  
HITCBC 247   7853 if (fd == max_fd_) 247   7420 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7740 max_fd_ = pipe_fds_[0]; 249   7306 max_fd_ = pipe_fds_[0];
HITCBC 250   15232 for (auto& [registered_fd, state] : registered_descs_) 250   14364 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7492 if (registered_fd > max_fd_) 252   7058 if (registered_fd > max_fd_)
HITCBC 253   7445 max_fd_ = registered_fd; 253   7011 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7853 } 256   7420 }
257   257  
258   inline void 258   inline void
HITCBC 259   3831 select_scheduler::notify_reactor() const 259   3615 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3831 interrupt_reactor(); 261   3615 interrupt_reactor();
HITCBC 262   3831 } 262   3615 }
263   263  
264   inline void 264   inline void
HITCBC 265   16685 select_scheduler::interrupt_reactor() const 265   15835 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   16685 char byte = 1; 267   15835 char byte = 1;
HITCBC 268   16685 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15835 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   16685 } 269   15835 }
270   270  
271   inline long 271   inline long
HITCBC 272   232940 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   212107 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   232940 if (requested_timeout_us == 0) 274   212107 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   232940 auto nearest = timer_svc_->nearest_expiry(); 277   212107 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   232940 if (nearest == timer_service::time_point::max()) 278   212107 if (nearest == timer_service::time_point::max())
HITCBC 279   404 return requested_timeout_us; 279   419 return requested_timeout_us;
280   280  
HITCBC 281   232536 auto now = std::chrono::steady_clock::now(); 281   211688 auto now = std::chrono::steady_clock::now();
HITCBC 282   232536 if (nearest <= now) 282   211688 if (nearest <= now)
HITCBC 283   1159 return 0; 283   586 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   231377 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   211102 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   231377 .count(); 287   211102 .count();
288   288  
HITCBC 289   231377 constexpr auto long_max = 289   211102 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   231377 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   211102 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   231377 static_cast<long long>(0)), 293   211102 static_cast<long long>(0)),
HITCBC 294   231377 long_max); 294   211102 long_max);
295   295  
HITCBC 296   231377 if (requested_timeout_us < 0) 296   211102 if (requested_timeout_us < 0)
HITCBC 297   231377 return static_cast<long>(capped_timer_us); 297   211102 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   259734 select_scheduler::run_task( 305   237085 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   259734 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   237085 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   259734 int snapshot_count = 0; 323   237085 int snapshot_count = 0;
324   324  
HITCBC 325   681443 for (auto& [fd, desc] : registered_descs_) 325   620293 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   421709 if (snapshot_count < FD_SETSIZE) 327   383208 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   421709 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   383208 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   421709 snapshot[snapshot_count].fd = fd; 330   383208 snapshot[snapshot_count].fd = fd;
HITCBC 331   421709 snapshot[snapshot_count].desc = desc; 331   383208 snapshot[snapshot_count].desc = desc;
HITCBC 332   421709 snapshot[snapshot_count].needs_write = 332   383208 snapshot[snapshot_count].needs_write =
HITCBC 333   421709 (desc->write_op || desc->connect_op); 333   383208 (desc->write_op || desc->connect_op);
HITCBC 334   421709 ++snapshot_count; 334   383208 ++snapshot_count;
HITCBC 335   421709 } 335   383208 }
336   } 336   }
337   337  
HITCBC 338   259734 if (lock.owns_lock()) 338   237085 if (lock.owns_lock())
HITCBC 339   232940 lock.unlock(); 339   212107 lock.unlock();
340   340  
HITCBC 341   259734 task_cleanup on_exit{this, &lock, ctx}; 341   237085 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   4415478 FD_ZERO(&read_fds); 344   4030445 FD_ZERO(&read_fds);
HITCBC 345   4415478 FD_ZERO(&write_fds); 345   4030445 FD_ZERO(&write_fds);
HITCBC 346   4415478 FD_ZERO(&except_fds); 346   4030445 FD_ZERO(&except_fds);
347   347  
HITCBC 348   259734 FD_SET(pipe_fds_[0], &read_fds); 348   237085 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   259734 int nfds = pipe_fds_[0]; 349   237085 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   681443 for (int i = 0; i < snapshot_count; ++i) 351   620293 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   421709 int fd = snapshot[i].fd; 353   383208 int fd = snapshot[i].fd;
HITCBC 354   421709 FD_SET(fd, &read_fds); 354   383208 FD_SET(fd, &read_fds);
HITCBC 355   421709 if (snapshot[i].needs_write) 355   383208 if (snapshot[i].needs_write)
HITCBC 356   12710 FD_SET(fd, &write_fds); 356   15410 FD_SET(fd, &write_fds);
HITCBC 357   421709 FD_SET(fd, &except_fds); 357   383208 FD_SET(fd, &except_fds);
HITCBC 358   421709 if (fd > nfds) 358   383208 if (fd > nfds)
HITCBC 359   259284 nfds = fd; 359   236622 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   259734 struct timeval* tv_ptr = nullptr; 363   237085 struct timeval* tv_ptr = nullptr;
HITCBC 364   259734 if (effective_timeout_us >= 0) 364   237085 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   259334 tv.tv_sec = effective_timeout_us / 1000000; 366   236670 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   259334 tv.tv_usec = effective_timeout_us % 1000000; 367   236670 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   259334 tv_ptr = &tv; 368   236670 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   259734 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   237085 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   259734 if (ready < 0) 376   237085 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   259734 timer_svc_->process_expired(); 384   237085 timer_svc_->process_expired();
385   385  
HITCBC 386   259734 op_queue local_ops; 386   237085 op_queue local_ops;
387   387  
HITCBC 388   259734 if (ready > 0) 388   237085 if (ready > 0)
389   { 389   {
HITCBC 390   239450 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   218144 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   16192 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   15356 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   605790 for (int i = 0; i < snapshot_count; ++i) 398   552415 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   366340 int fd = snapshot[i].fd; 400   334271 int fd = snapshot[i].fd;
HITCBC 401   366340 reactor_descriptor_state* desc = snapshot[i].desc; 401   334271 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   366340 std::uint32_t flags = 0; 403   334271 std::uint32_t flags = 0;
HITCBC 404   366340 if (FD_ISSET(fd, &read_fds)) 404   334271 if (FD_ISSET(fd, &read_fds))
HITCBC 405   235327 flags |= reactor_event_read; 405   214222 flags |= reactor_event_read;
HITCBC 406   366340 if (FD_ISSET(fd, &write_fds)) 406   334271 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3828 flags |= reactor_event_write; 407   3612 flags |= reactor_event_write;
HITCBC 408   366340 if (FD_ISSET(fd, &except_fds)) 408   334271 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   366340 if (flags == 0) 411   334271 if (flags == 0)
HITCBC 412   127194 continue; 412   116447 continue;
413   413  
HITCBC 414   239146 desc->add_ready_events(flags); 414   217824 desc->add_ready_events(flags);
415   415  
HITCBC 416   239146 bool expected = false; 416   217824 bool expected = false;
HITCBC 417   239146 if (desc->is_enqueued_.compare_exchange_strong( 417   217824 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   239146 local_ops.push(desc); 421   217824 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   259734 lock.lock(); 426   237085 lock.lock();
427   427  
HITCBC 428   259734 if (!local_ops.empty()) 428   237085 if (!local_ops.empty())
HITCBC 429   235409 completed_ops_.splice(local_ops); 429   214304 completed_ops_.splice(local_ops);
HITCBC 430   259734 } 430   237085 }
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