. /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   4475 timer_service::callback(this, [](void* p) { 177   4403 timer_service::callback(this, [](void* p) {
HITCBC 178   3881 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3809 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3881 })); 179   3809 }));
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   7666 select_scheduler::register_descriptor( 207   7523 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7666 if (fd < 0 || fd >= FD_SETSIZE) 210   7523 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   7666 desc->registered_events = reactor_event_read | reactor_event_write; 213   7523 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7666 desc->fd = fd; 214   7523 desc->fd = fd;
HITCBC 215   7666 desc->scheduler_ = this; 215   7523 desc->scheduler_ = this;
HITCBC 216   7666 desc->mutex.set_enabled(!single_threaded_); 216   7523 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7666 desc->ready_events_.store(0, std::memory_order_relaxed); 217   7523 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7666 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   7523 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7666 desc->impl_ref_.reset(); 221   7523 desc->impl_ref_.reset();
HITCBC 222   7666 desc->read_ready = false; 222   7523 desc->read_ready = false;
HITCBC 223   7666 desc->write_ready = false; 223   7523 desc->write_ready = false;
HITCBC 224   7666 } 224   7523 }
225   225  
226   { 226   {
HITCBC 227   7666 mutex_type::scoped_lock lock(mutex_); 227   7523 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7666 registered_descs_[fd] = desc; 228   7523 registered_descs_[fd] = desc;
HITCBC 229   7666 if (fd > max_fd_) 229   7523 if (fd > max_fd_)
HITCBC 230   7661 max_fd_ = fd; 230   7518 max_fd_ = fd;
HITCBC 231   7666 } 231   7523 }
232   232  
HITCBC 233   7666 interrupt_reactor(); 233   7523 interrupt_reactor();
HITCBC 234   7666 } 234   7523 }
235   235  
236   inline void 236   inline void
HITCBC 237   7666 select_scheduler::deregister_descriptor(int fd) const 237   7523 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7666 mutex_type::scoped_lock lock(mutex_); 239   7523 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7666 auto it = registered_descs_.find(fd); 241   7523 auto it = registered_descs_.find(fd);
HITCBC 242   7666 if (it == registered_descs_.end()) 242   7523 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7666 registered_descs_.erase(it); 245   7523 registered_descs_.erase(it);
246   246  
HITCBC 247   7666 if (fd == max_fd_) 247   7523 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7552 max_fd_ = pipe_fds_[0]; 249   7410 max_fd_ = pipe_fds_[0];
HITCBC 250   14856 for (auto& [registered_fd, state] : registered_descs_) 250   14572 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7304 if (registered_fd > max_fd_) 252   7162 if (registered_fd > max_fd_)
HITCBC 253   7257 max_fd_ = registered_fd; 253   7115 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7666 } 256   7523 }
257   257  
258   inline void 258   inline void
HITCBC 259   3738 select_scheduler::notify_reactor() const 259   3666 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3738 interrupt_reactor(); 261   3666 interrupt_reactor();
HITCBC 262   3738 } 262   3666 }
263   263  
264   inline void 264   inline void
HITCBC 265   16313 select_scheduler::interrupt_reactor() const 265   16023 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   16313 char byte = 1; 267   16023 char byte = 1;
HITCBC 268   16313 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   16023 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   16313 } 269   16023 }
270   270  
271   inline long 271   inline long
HITCBC 272   230282 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   231008 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   230282 if (requested_timeout_us == 0) 274   231008 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   230282 auto nearest = timer_svc_->nearest_expiry(); 277   231008 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   230282 if (nearest == timer_service::time_point::max()) 278   231008 if (nearest == timer_service::time_point::max())
HITCBC 279   405 return requested_timeout_us; 279   402 return requested_timeout_us;
280   280  
HITCBC 281   229877 auto now = std::chrono::steady_clock::now(); 281   230606 auto now = std::chrono::steady_clock::now();
HITCBC 282   229877 if (nearest <= now) 282   230606 if (nearest <= now)
HITCBC 283   563 return 0; 283   660 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   229314 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   229946 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   229314 .count(); 287   229946 .count();
288   288  
HITCBC 289   229314 constexpr auto long_max = 289   229946 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   229314 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   229946 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   229314 static_cast<long long>(0)), 293   229946 static_cast<long long>(0)),
HITCBC 294   229314 long_max); 294   229946 long_max);
295   295  
HITCBC 296   229314 if (requested_timeout_us < 0) 296   229946 if (requested_timeout_us < 0)
HITCBC 297   229314 return static_cast<long>(capped_timer_us); 297   229946 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   255725 select_scheduler::run_task( 305   253359 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   255725 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   253359 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   255725 int snapshot_count = 0; 323   253359 int snapshot_count = 0;
324   324  
HITCBC 325   670211 for (auto& [fd, desc] : registered_descs_) 325   658015 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   414486 if (snapshot_count < FD_SETSIZE) 327   404656 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   414486 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   404656 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   414486 snapshot[snapshot_count].fd = fd; 330   404656 snapshot[snapshot_count].fd = fd;
HITCBC 331   414486 snapshot[snapshot_count].desc = desc; 331   404656 snapshot[snapshot_count].desc = desc;
HITCBC 332   414486 snapshot[snapshot_count].needs_write = 332   404656 snapshot[snapshot_count].needs_write =
HITCBC 333   414486 (desc->write_op || desc->connect_op); 333   404656 (desc->write_op || desc->connect_op);
HITCBC 334   414486 ++snapshot_count; 334   404656 ++snapshot_count;
HITCBC 335   414486 } 335   404656 }
336   } 336   }
337   337  
HITCBC 338   255725 if (lock.owns_lock()) 338   253359 if (lock.owns_lock())
HITCBC 339   230282 lock.unlock(); 339   231008 lock.unlock();
340   340  
HITCBC 341   255725 task_cleanup on_exit{this, &lock, ctx}; 341   253359 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   4347325 FD_ZERO(&read_fds); 344   4307103 FD_ZERO(&read_fds);
HITCBC 345   4347325 FD_ZERO(&write_fds); 345   4307103 FD_ZERO(&write_fds);
HITCBC 346   4347325 FD_ZERO(&except_fds); 346   4307103 FD_ZERO(&except_fds);
347   347  
HITCBC 348   255725 FD_SET(pipe_fds_[0], &read_fds); 348   253359 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   255725 int nfds = pipe_fds_[0]; 349   253359 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   670211 for (int i = 0; i < snapshot_count; ++i) 351   658015 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   414486 int fd = snapshot[i].fd; 353   404656 int fd = snapshot[i].fd;
HITCBC 354   414486 FD_SET(fd, &read_fds); 354   404656 FD_SET(fd, &read_fds);
HITCBC 355   414486 if (snapshot[i].needs_write) 355   404656 if (snapshot[i].needs_write)
HITCBC 356   15297 FD_SET(fd, &write_fds); 356   9005 FD_SET(fd, &write_fds);
HITCBC 357   414486 FD_SET(fd, &except_fds); 357   404656 FD_SET(fd, &except_fds);
HITCBC 358   414486 if (fd > nfds) 358   404656 if (fd > nfds)
HITCBC 359   255275 nfds = fd; 359   252912 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   255725 struct timeval* tv_ptr = nullptr; 363   253359 struct timeval* tv_ptr = nullptr;
HITCBC 364   255725 if (effective_timeout_us >= 0) 364   253359 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   255324 tv.tv_sec = effective_timeout_us / 1000000; 366   252961 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   255324 tv.tv_usec = effective_timeout_us % 1000000; 367   252961 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   255324 tv_ptr = &tv; 368   252961 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   255725 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   253359 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   255725 if (ready < 0) 376   253359 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   255725 timer_svc_->process_expired(); 384   253359 timer_svc_->process_expired();
385   385  
HITCBC 386   255725 op_queue local_ops; 386   253359 op_queue local_ops;
387   387  
HITCBC 388   255725 if (ready > 0) 388   253359 if (ready > 0)
389   { 389   {
HITCBC 390   236137 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   235652 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   15822 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   15532 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   596787 for (int i = 0; i < snapshot_count; ++i) 398   593172 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   360650 int fd = snapshot[i].fd; 400   357520 int fd = snapshot[i].fd;
HITCBC 401   360650 reactor_descriptor_state* desc = snapshot[i].desc; 401   357520 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   360650 std::uint32_t flags = 0; 403   357520 std::uint32_t flags = 0;
HITCBC 404   360650 if (FD_ISSET(fd, &read_fds)) 404   357520 if (FD_ISSET(fd, &read_fds))
HITCBC 405   232106 flags |= reactor_event_read; 405   231695 flags |= reactor_event_read;
HITCBC 406   360650 if (FD_ISSET(fd, &write_fds)) 406   357520 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3735 flags |= reactor_event_write; 407   3663 flags |= reactor_event_write;
HITCBC 408   360650 if (FD_ISSET(fd, &except_fds)) 408   357520 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   360650 if (flags == 0) 411   357520 if (flags == 0)
HITCBC 412   124819 continue; 412   122171 continue;
413   413  
HITCBC 414   235831 desc->add_ready_events(flags); 414   235349 desc->add_ready_events(flags);
415   415  
HITCBC 416   235831 bool expected = false; 416   235349 bool expected = false;
HITCBC 417   235831 if (desc->is_enqueued_.compare_exchange_strong( 417   235349 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   235831 local_ops.push(desc); 421   235349 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   255725 lock.lock(); 426   253359 lock.lock();
427   427  
HITCBC 428   255725 if (!local_ops.empty()) 428   253359 if (!local_ops.empty())
HITCBC 429   232188 completed_ops_.splice(local_ops); 429   231777 completed_ops_.splice(local_ops);
HITCBC 430   255725 } 430   253359 }
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