. /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   246 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   246 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   246 : pipe_fds_{-1, -1} 143   246 : pipe_fds_{-1, -1}
HITCBC 144   246 , max_fd_(-1) 144   246 , max_fd_(-1)
145   { 145   {
HITCBC 146   246 if (::pipe(pipe_fds_) < 0) 146   246 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   738 for (int i = 0; i < 2; ++i) 149   738 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   492 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   492 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   492 if (flags == -1) 152   492 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   492 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   492 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   492 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   492 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   246 timer_svc_ = &get_timer_service(ctx, *this); 175   246 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   246 timer_svc_->set_on_earliest_changed( 176   246 timer_svc_->set_on_earliest_changed(
HITCBC 177   4583 timer_service::callback(this, [](void* p) { 177   4037 timer_service::callback(this, [](void* p) {
HITCBC 178   4337 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3791 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   4337 })); 179   3791 }));
180   180  
HITCBC 181   246 get_resolver_service(ctx, *this); 181   246 get_resolver_service(ctx, *this);
HITCBC 182   246 get_signal_service(ctx, *this); 182   246 get_signal_service(ctx, *this);
HITCBC 183   246 get_stream_file_service(ctx, *this); 183   246 get_stream_file_service(ctx, *this);
HITCBC 184   246 get_random_access_file_service(ctx, *this); 184   246 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   246 completed_ops_.push(&task_op_); 186   246 completed_ops_.push(&task_op_);
HITCBC 187   246 } 187   246 }
188   188  
HITCBC 189   492 inline select_scheduler::~select_scheduler() 189   492 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   246 if (pipe_fds_[0] >= 0) 191   246 if (pipe_fds_[0] >= 0)
HITCBC 192   246 ::close(pipe_fds_[0]); 192   246 ::close(pipe_fds_[0]);
HITCBC 193   246 if (pipe_fds_[1] >= 0) 193   246 if (pipe_fds_[1] >= 0)
HITCBC 194   246 ::close(pipe_fds_[1]); 194   246 ::close(pipe_fds_[1]);
HITCBC 195   492 } 195   492 }
196   196  
197   inline void 197   inline void
HITCBC 198   246 select_scheduler::shutdown() 198   246 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   246 shutdown_drain(); 200   246 shutdown_drain();
201   201  
HITCBC 202   246 if (pipe_fds_[1] >= 0) 202   246 if (pipe_fds_[1] >= 0)
HITCBC 203   246 interrupt_reactor(); 203   246 interrupt_reactor();
HITCBC 204   246 } 204   246 }
205   205  
206   inline void 206   inline void
HITCBC 207   8408 select_scheduler::register_descriptor( 207   7318 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   8408 if (fd < 0 || fd >= FD_SETSIZE) 210   7318 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   8408 desc->registered_events = reactor_event_read | reactor_event_write; 213   7318 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   8408 desc->fd = fd; 214   7318 desc->fd = fd;
HITCBC 215   8408 desc->scheduler_ = this; 215   7318 desc->scheduler_ = this;
HITCBC 216   8408 desc->mutex.set_enabled(!single_threaded_); 216   7318 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   8408 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7318 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   8408 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7318 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   8408 desc->impl_ref_.reset(); 221   7318 desc->impl_ref_.reset();
HITCBC 222   8408 desc->read_ready = false; 222   7318 desc->read_ready = false;
HITCBC 223   8408 desc->write_ready = false; 223   7318 desc->write_ready = false;
HITCBC 224   8408 } 224   7318 }
225   225  
226   { 226   {
HITCBC 227   8408 mutex_type::scoped_lock lock(mutex_); 227   7318 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   8408 registered_descs_[fd] = desc; 228   7318 registered_descs_[fd] = desc;
HITCBC 229   8408 if (fd > max_fd_) 229   7318 if (fd > max_fd_)
HITCBC 230   8404 max_fd_ = fd; 230   7314 max_fd_ = fd;
HITCBC 231   8408 } 231   7318 }
232   232  
HITCBC 233   8408 interrupt_reactor(); 233   7318 interrupt_reactor();
HITCBC 234   8408 } 234   7318 }
235   235  
236   inline void 236   inline void
HITCBC 237   8408 select_scheduler::deregister_descriptor(int fd) const 237   7318 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   8408 mutex_type::scoped_lock lock(mutex_); 239   7318 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   8408 auto it = registered_descs_.find(fd); 241   7318 auto it = registered_descs_.find(fd);
HITCBC 242   8408 if (it == registered_descs_.end()) 242   7318 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   8408 registered_descs_.erase(it); 245   7318 registered_descs_.erase(it);
246   246  
HITCBC 247   8408 if (fd == max_fd_) 247   7318 if (fd == max_fd_)
248   { 248   {
HITCBC 249   8338 max_fd_ = pipe_fds_[0]; 249   7248 max_fd_ = pipe_fds_[0];
HITCBC 250   16555 for (auto& [registered_fd, state] : registered_descs_) 250   14375 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   8217 if (registered_fd > max_fd_) 252   7127 if (registered_fd > max_fd_)
HITCBC 253   8202 max_fd_ = registered_fd; 253   7112 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   8408 } 256   7318 }
257   257  
258   inline void 258   inline void
HITCBC 259   4125 select_scheduler::notify_reactor() const 259   3580 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   4125 interrupt_reactor(); 261   3580 interrupt_reactor();
HITCBC 262   4125 } 262   3580 }
263   263  
264   inline void 264   inline void
HITCBC 265   17292 select_scheduler::interrupt_reactor() const 265   15111 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   17292 char byte = 1; 267   15111 char byte = 1;
HITCBC 268   17292 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   15111 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   17292 } 269   15111 }
270   270  
271   inline long 271   inline long
HITCBC 272   118214 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   127216 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   118214 if (requested_timeout_us == 0) 274   127216 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   118214 auto nearest = timer_svc_->nearest_expiry(); 277   127216 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   118214 if (nearest == timer_service::time_point::max()) 278   127216 if (nearest == timer_service::time_point::max())
HITCBC 279   60 return requested_timeout_us; 279   60 return requested_timeout_us;
280   280  
HITCBC 281   118154 auto now = std::chrono::steady_clock::now(); 281   127156 auto now = std::chrono::steady_clock::now();
HITCBC 282   118154 if (nearest <= now) 282   127156 if (nearest <= now)
HITCBC 283   2173 return 0; 283   540 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   115981 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   126616 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   115981 .count(); 287   126616 .count();
288   288  
HITCBC 289   115981 constexpr auto long_max = 289   126616 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   115981 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   126616 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   115981 static_cast<long long>(0)), 293   126616 static_cast<long long>(0)),
HITCBC 294   115981 long_max); 294   126616 long_max);
295   295  
HITCBC 296   115981 if (requested_timeout_us < 0) 296   126616 if (requested_timeout_us < 0)
HITCBC 297   115975 return static_cast<long>(capped_timer_us); 297   126610 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   141085 select_scheduler::run_task( 305   154374 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   141085 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   154374 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   141085 int snapshot_count = 0; 323   154374 int snapshot_count = 0;
324   324  
HITCBC 325   417147 for (auto& [fd, desc] : registered_descs_) 325   458265 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   276062 if (snapshot_count < FD_SETSIZE) 327   303891 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   276062 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   303891 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   276062 snapshot[snapshot_count].fd = fd; 330   303891 snapshot[snapshot_count].fd = fd;
HITCBC 331   276062 snapshot[snapshot_count].desc = desc; 331   303891 snapshot[snapshot_count].desc = desc;
HITCBC 332   276062 snapshot[snapshot_count].needs_write = 332   303891 snapshot[snapshot_count].needs_write =
HITCBC 333   276062 (desc->write_op || desc->connect_op); 333   303891 (desc->write_op || desc->connect_op);
HITCBC 334   276062 ++snapshot_count; 334   303891 ++snapshot_count;
HITCBC 335   276062 } 335   303891 }
336   } 336   }
337   337  
HITCBC 338   141085 if (lock.owns_lock()) 338   154374 if (lock.owns_lock())
HITCBC 339   118214 lock.unlock(); 339   127216 lock.unlock();
340   340  
HITCBC 341   141085 task_cleanup on_exit{this, &lock, ctx}; 341   154374 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   2398445 FD_ZERO(&read_fds); 344   2624358 FD_ZERO(&read_fds);
HITCBC 345   2398445 FD_ZERO(&write_fds); 345   2624358 FD_ZERO(&write_fds);
HITCBC 346   2398445 FD_ZERO(&except_fds); 346   2624358 FD_ZERO(&except_fds);
347   347  
HITCBC 348   141085 FD_SET(pipe_fds_[0], &read_fds); 348   154374 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   141085 int nfds = pipe_fds_[0]; 349   154374 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   417147 for (int i = 0; i < snapshot_count; ++i) 351   458265 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   276062 int fd = snapshot[i].fd; 353   303891 int fd = snapshot[i].fd;
HITCBC 354   276062 FD_SET(fd, &read_fds); 354   303891 FD_SET(fd, &read_fds);
HITCBC 355   276062 if (snapshot[i].needs_write) 355   303891 if (snapshot[i].needs_write)
HITCBC 356   4127 FD_SET(fd, &write_fds); 356   3582 FD_SET(fd, &write_fds);
HITCBC 357   276062 FD_SET(fd, &except_fds); 357   303891 FD_SET(fd, &except_fds);
HITCBC 358   276062 if (fd > nfds) 358   303891 if (fd > nfds)
HITCBC 359   140816 nfds = fd; 359   154104 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   141085 struct timeval* tv_ptr = nullptr; 363   154374 struct timeval* tv_ptr = nullptr;
HITCBC 364   141085 if (effective_timeout_us >= 0) 364   154374 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   141025 tv.tv_sec = effective_timeout_us / 1000000; 366   154314 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   141025 tv.tv_usec = effective_timeout_us % 1000000; 367   154314 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   141025 tv_ptr = &tv; 368   154314 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   141085 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   154374 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   141085 if (ready < 0) 376   154374 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   141085 timer_svc_->process_expired(); 384   154374 timer_svc_->process_expired();
385   385  
HITCBC 386   141085 op_queue local_ops; 386   154374 op_queue local_ops;
387   387  
HITCBC 388   141085 if (ready > 0) 388   154374 if (ready > 0)
389   { 389   {
HITCBC 390   122894 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   133944 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   17134 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   14952 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   350958 for (int i = 0; i < snapshot_count; ++i) 398   381768 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   228064 int fd = snapshot[i].fd; 400   247824 int fd = snapshot[i].fd;
HITCBC 401   228064 reactor_descriptor_state* desc = snapshot[i].desc; 401   247824 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   228064 std::uint32_t flags = 0; 403   247824 std::uint32_t flags = 0;
HITCBC 404   228064 if (FD_ISSET(fd, &read_fds)) 404   247824 if (FD_ISSET(fd, &read_fds))
HITCBC 405   118634 flags |= reactor_event_read; 405   130229 flags |= reactor_event_read;
HITCBC 406   228064 if (FD_ISSET(fd, &write_fds)) 406   247824 if (FD_ISSET(fd, &write_fds))
HITCBC 407   4124 flags |= reactor_event_write; 407   3579 flags |= reactor_event_write;
HITCBC 408   228064 if (FD_ISSET(fd, &except_fds)) 408   247824 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   228064 if (flags == 0) 411   247824 if (flags == 0)
HITCBC 412   105313 continue; 412   114023 continue;
413   413  
HITCBC 414   122751 desc->add_ready_events(flags); 414   133801 desc->add_ready_events(flags);
415   415  
HITCBC 416   122751 bool expected = false; 416   133801 bool expected = false;
HITCBC 417   122751 if (desc->is_enqueued_.compare_exchange_strong( 417   133801 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   122751 local_ops.push(desc); 421   133801 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   141085 lock.lock(); 426   154374 lock.lock();
427   427  
HITCBC 428   141085 if (!local_ops.empty()) 428   154374 if (!local_ops.empty())
HITCBC 429   118635 completed_ops_.splice(local_ops); 429   130230 completed_ops_.splice(local_ops);
HITCBC 430   141085 } 430   154374 }
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