. /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   427 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   427 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   427 : pipe_fds_{-1, -1} 143   427 : pipe_fds_{-1, -1}
HITCBC 144   427 , max_fd_(-1) 144   427 , max_fd_(-1)
145   { 145   {
HITCBC 146   427 if (::pipe(pipe_fds_) < 0) 146   427 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   1281 for (int i = 0; i < 2; ++i) 149   1281 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   854 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   854 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   854 if (flags == -1) 152   854 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   854 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   854 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   854 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   854 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   427 timer_svc_ = &get_timer_service(ctx, *this); 175   427 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   427 timer_svc_->set_on_earliest_changed( 176   427 timer_svc_->set_on_earliest_changed(
HITCBC 177   3890 timer_service::callback(this, [](void* p) { 177   2826 timer_service::callback(this, [](void* p) {
HITCBC 178   3463 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   2399 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3463 })); 179   2399 }));
180   180  
HITCBC 181   427 get_resolver_service(ctx, *this); 181   427 get_resolver_service(ctx, *this);
HITCBC 182   427 get_signal_service(ctx, *this); 182   427 get_signal_service(ctx, *this);
HITCBC 183   427 get_stream_file_service(ctx, *this); 183   427 get_stream_file_service(ctx, *this);
HITCBC 184   427 get_random_access_file_service(ctx, *this); 184   427 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   427 completed_ops_.push(&task_op_); 186   427 completed_ops_.push(&task_op_);
HITCBC 187   427 } 187   427 }
188   188  
HITCBC 189   854 inline select_scheduler::~select_scheduler() 189   854 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   427 if (pipe_fds_[0] >= 0) 191   427 if (pipe_fds_[0] >= 0)
HITCBC 192   427 ::close(pipe_fds_[0]); 192   427 ::close(pipe_fds_[0]);
HITCBC 193   427 if (pipe_fds_[1] >= 0) 193   427 if (pipe_fds_[1] >= 0)
HITCBC 194   427 ::close(pipe_fds_[1]); 194   427 ::close(pipe_fds_[1]);
HITCBC 195   854 } 195   854 }
196   196  
197   inline void 197   inline void
HITCBC 198   427 select_scheduler::shutdown() 198   427 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   427 shutdown_drain(); 200   427 shutdown_drain();
201   201  
HITCBC 202   427 if (pipe_fds_[1] >= 0) 202   427 if (pipe_fds_[1] >= 0)
HITCBC 203   427 interrupt_reactor(); 203   427 interrupt_reactor();
HITCBC 204   427 } 204   427 }
205   205  
206   inline void 206   inline void
HITCBC 207   6765 select_scheduler::register_descriptor( 207   4636 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   6765 if (fd < 0 || fd >= FD_SETSIZE) 210   4636 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   6765 desc->registered_events = reactor_event_read | reactor_event_write; 213   4636 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   6765 desc->fd = fd; 214   4636 desc->fd = fd;
HITCBC 215   6765 desc->scheduler_ = this; 215   4636 desc->scheduler_ = this;
HITCBC 216   6765 desc->mutex.set_enabled(!single_threaded_); 216   4636 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   6765 desc->ready_events_.store(0, std::memory_order_relaxed); 217   4636 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   6765 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   4636 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   6765 desc->impl_ref_.reset(); 221   4636 desc->impl_ref_.reset();
HITCBC 222   6765 desc->read_ready = false; 222   4636 desc->read_ready = false;
HITCBC 223   6765 desc->write_ready = false; 223   4636 desc->write_ready = false;
HITCBC 224   6765 } 224   4636 }
225   225  
226   { 226   {
HITCBC 227   6765 mutex_type::scoped_lock lock(mutex_); 227   4636 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   6765 registered_descs_[fd] = desc; 228   4636 registered_descs_[fd] = desc;
HITCBC 229   6765 if (fd > max_fd_) 229   4636 if (fd > max_fd_)
HITCBC 230   6761 max_fd_ = fd; 230   4632 max_fd_ = fd;
HITCBC 231   6765 } 231   4636 }
232   232  
HITCBC 233   6765 interrupt_reactor(); 233   4636 interrupt_reactor();
HITCBC 234   6765 } 234   4636 }
235   235  
236   inline void 236   inline void
HITCBC 237   6765 select_scheduler::deregister_descriptor(int fd) const 237   4636 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   6765 mutex_type::scoped_lock lock(mutex_); 239   4636 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   6765 auto it = registered_descs_.find(fd); 241   4636 auto it = registered_descs_.find(fd);
HITCBC 242   6765 if (it == registered_descs_.end()) 242   4636 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   6765 registered_descs_.erase(it); 245   4636 registered_descs_.erase(it);
246   246  
HITCBC 247   6765 if (fd == max_fd_) 247   4636 if (fd == max_fd_)
248   { 248   {
HITCBC 249   6660 max_fd_ = pipe_fds_[0]; 249   4532 max_fd_ = pipe_fds_[0];
HITCBC 250   13109 for (auto& [registered_fd, state] : registered_descs_) 250   8853 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   6449 if (registered_fd > max_fd_) 252   4321 if (registered_fd > max_fd_)
HITCBC 253   6424 max_fd_ = registered_fd; 253   4296 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   6765 } 256   4636 }
257   257  
258   inline void 258   inline void
HITCBC 259   3242 select_scheduler::notify_reactor() const 259   2177 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3242 interrupt_reactor(); 261   2177 interrupt_reactor();
HITCBC 262   3242 } 262   2177 }
263   263  
264   inline void 264   inline void
HITCBC 265   14182 select_scheduler::interrupt_reactor() const 265   9924 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14182 char byte = 1; 267   9924 char byte = 1;
HITCBC 268   14182 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   9924 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14182 } 269   9924 }
270   270  
271   inline long 271   inline long
HITCBC 272   194643 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   218109 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   194643 if (requested_timeout_us == 0) 274   218109 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   194643 auto nearest = timer_svc_->nearest_expiry(); 277   218109 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   194643 if (nearest == timer_service::time_point::max()) 278   218109 if (nearest == timer_service::time_point::max())
HITCBC 279   175 return requested_timeout_us; 279   175 return requested_timeout_us;
280   280  
HITCBC 281   194468 auto now = std::chrono::steady_clock::now(); 281   217934 auto now = std::chrono::steady_clock::now();
HITCBC 282   194468 if (nearest <= now) 282   217934 if (nearest <= now)
HITCBC 283   667 return 0; 283   532 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   193801 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   217402 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   193801 .count(); 287   217402 .count();
288   288  
HITCBC 289   193801 constexpr auto long_max = 289   217402 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   193801 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   217402 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   193801 static_cast<long long>(0)), 293   217402 static_cast<long long>(0)),
HITCBC 294   193801 long_max); 294   217402 long_max);
295   295  
HITCBC 296   193801 if (requested_timeout_us < 0) 296   217402 if (requested_timeout_us < 0)
HITCBC 297   193801 return static_cast<long>(capped_timer_us); 297   217402 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   217618 select_scheduler::run_task( 305   241389 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   217618 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   241389 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   217618 int snapshot_count = 0; 323   241389 int snapshot_count = 0;
324   324  
HITCBC 325   576897 for (auto& [fd, desc] : registered_descs_) 325   624462 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   359279 if (snapshot_count < FD_SETSIZE) 327   383073 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   359279 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   383073 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   359279 snapshot[snapshot_count].fd = fd; 330   383073 snapshot[snapshot_count].fd = fd;
HITCBC 331   359279 snapshot[snapshot_count].desc = desc; 331   383073 snapshot[snapshot_count].desc = desc;
HITCBC 332   359279 snapshot[snapshot_count].needs_write = 332   383073 snapshot[snapshot_count].needs_write =
HITCBC 333   359279 (desc->write_op || desc->connect_op); 333   383073 (desc->write_op || desc->connect_op);
HITCBC 334   359279 ++snapshot_count; 334   383073 ++snapshot_count;
HITCBC 335   359279 } 335   383073 }
336   } 336   }
337   337  
HITCBC 338   217618 if (lock.owns_lock()) 338   241389 if (lock.owns_lock())
HITCBC 339   194643 lock.unlock(); 339   218109 lock.unlock();
340   340  
HITCBC 341   217618 task_cleanup on_exit{this, &lock, ctx}; 341   241389 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   3699506 FD_ZERO(&read_fds); 344   4103613 FD_ZERO(&read_fds);
HITCBC 345   3699506 FD_ZERO(&write_fds); 345   4103613 FD_ZERO(&write_fds);
HITCBC 346   3699506 FD_ZERO(&except_fds); 346   4103613 FD_ZERO(&except_fds);
347   347  
HITCBC 348   217618 FD_SET(pipe_fds_[0], &read_fds); 348   241389 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   217618 int nfds = pipe_fds_[0]; 349   241389 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   576897 for (int i = 0; i < snapshot_count; ++i) 351   624462 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   359279 int fd = snapshot[i].fd; 353   383073 int fd = snapshot[i].fd;
HITCBC 354   359279 FD_SET(fd, &read_fds); 354   383073 FD_SET(fd, &read_fds);
HITCBC 355   359279 if (snapshot[i].needs_write) 355   383073 if (snapshot[i].needs_write)
HITCBC 356   3329 FD_SET(fd, &write_fds); 356   2264 FD_SET(fd, &write_fds);
HITCBC 357   359279 FD_SET(fd, &except_fds); 357   383073 FD_SET(fd, &except_fds);
HITCBC 358   359279 if (fd > nfds) 358   383073 if (fd > nfds)
HITCBC 359   217267 nfds = fd; 359   241035 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   217618 struct timeval* tv_ptr = nullptr; 363   241389 struct timeval* tv_ptr = nullptr;
HITCBC 364   217618 if (effective_timeout_us >= 0) 364   241389 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   217444 tv.tv_sec = effective_timeout_us / 1000000; 366   241215 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   217444 tv.tv_usec = effective_timeout_us % 1000000; 367   241215 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   217444 tv_ptr = &tv; 368   241215 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   217618 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   241389 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   217618 if (ready < 0) 376   241389 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   217618 timer_svc_->process_expired(); 384   241389 timer_svc_->process_expired();
385   385  
HITCBC 386   217618 op_queue local_ops; 386   241389 op_queue local_ops;
387   387  
HITCBC 388   217618 if (ready > 0) 388   241389 if (ready > 0)
389   { 389   {
HITCBC 390   200024 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   225193 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   13798 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   9538 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   509886 for (int i = 0; i < snapshot_count; ++i) 398   560521 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   309862 int fd = snapshot[i].fd; 400   335328 int fd = snapshot[i].fd;
HITCBC 401   309862 reactor_descriptor_state* desc = snapshot[i].desc; 401   335328 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   309862 std::uint32_t flags = 0; 403   335328 std::uint32_t flags = 0;
HITCBC 404   309862 if (FD_ISSET(fd, &read_fds)) 404   335328 if (FD_ISSET(fd, &read_fds))
HITCBC 405   196572 flags |= reactor_event_read; 405   222804 flags |= reactor_event_read;
HITCBC 406   309862 if (FD_ISSET(fd, &write_fds)) 406   335328 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3241 flags |= reactor_event_write; 407   2176 flags |= reactor_event_write;
HITCBC 408   309862 if (FD_ISSET(fd, &except_fds)) 408   335328 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   309862 if (flags == 0) 411   335328 if (flags == 0)
HITCBC 412   110059 continue; 412   110357 continue;
413   413  
HITCBC 414   199803 desc->add_ready_events(flags); 414   224971 desc->add_ready_events(flags);
415   415  
HITCBC 416   199803 bool expected = false; 416   224971 bool expected = false;
HITCBC 417   199803 if (desc->is_enqueued_.compare_exchange_strong( 417   224971 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   199803 local_ops.push(desc); 421   224971 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   217618 lock.lock(); 426   241389 lock.lock();
427   427  
HITCBC 428   217618 if (!local_ops.empty()) 428   241389 if (!local_ops.empty())
HITCBC 429   196568 completed_ops_.splice(local_ops); 429   222800 completed_ops_.splice(local_ops);
HITCBC 430   217618 } 430   241389 }
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