. /include/boost/corosio /native /detail /select /select_scheduler.hpp
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1   // 1   //
2   // Copyright (c) 2026 Steve Gerbino 2   // Copyright (c) 2026 Steve Gerbino
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 4   // Distributed under the Boost Software License, Version 1.0. (See accompanying
5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/corosio 7   // Official repository: https://github.com/cppalliance/corosio
8   // 8   //
9   9  
10   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 10   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
11   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 11   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
12   12  
13   #include <boost/corosio/detail/platform.hpp> 13   #include <boost/corosio/detail/platform.hpp>
14   14  
15   #if BOOST_COROSIO_HAS_SELECT 15   #if BOOST_COROSIO_HAS_SELECT
16   16  
17   #include <boost/corosio/detail/config.hpp> 17   #include <boost/corosio/detail/config.hpp>
18   #include <boost/capy/ex/execution_context.hpp> 18   #include <boost/capy/ex/execution_context.hpp>
19   19  
20   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp> 20   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
21   21  
22   #include <boost/corosio/native/detail/select/select_traits.hpp> 22   #include <boost/corosio/native/detail/select/select_traits.hpp>
23   #include <boost/corosio/detail/timer_service.hpp> 23   #include <boost/corosio/detail/timer_service.hpp>
24   #include <boost/corosio/native/detail/make_err.hpp> 24   #include <boost/corosio/native/detail/make_err.hpp>
25   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp> 25   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp>
26   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp> 26   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp>
27   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp> 27   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
28   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp> 28   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
29   29  
30   #include <boost/corosio/detail/except.hpp> 30   #include <boost/corosio/detail/except.hpp>
31   31  
32   #include <sys/select.h> 32   #include <sys/select.h>
33   #include <unistd.h> 33   #include <unistd.h>
34   #include <errno.h> 34   #include <errno.h>
35   #include <fcntl.h> 35   #include <fcntl.h>
36   36  
37   #include <atomic> 37   #include <atomic>
38   #include <chrono> 38   #include <chrono>
39   #include <cstdint> 39   #include <cstdint>
40   #include <limits> 40   #include <limits>
41   #include <mutex> 41   #include <mutex>
42   #include <unordered_map> 42   #include <unordered_map>
43   43  
44   namespace boost::corosio::detail { 44   namespace boost::corosio::detail {
45   45  
46   struct select_op; 46   struct select_op;
47   47  
48   /** POSIX scheduler using select() for I/O multiplexing. 48   /** POSIX scheduler using select() for I/O multiplexing.
49   49  
50   This scheduler implements the scheduler interface using the POSIX select() 50   This scheduler implements the scheduler interface using the POSIX select()
51   call for I/O event notification. It inherits the shared reactor threading 51   call for I/O event notification. It inherits the shared reactor threading
52   model from reactor_scheduler: signal state machine, inline completion 52   model from reactor_scheduler: signal state machine, inline completion
53   budget, work counting, and the do_one event loop. 53   budget, work counting, and the do_one event loop.
54   54  
55   The design mirrors epoll_scheduler for behavioral consistency: 55   The design mirrors epoll_scheduler for behavioral consistency:
56   - Same single-reactor thread coordination model 56   - Same single-reactor thread coordination model
57   - Same deferred I/O pattern (reactor marks ready; workers do I/O) 57   - Same deferred I/O pattern (reactor marks ready; workers do I/O)
58   - Same timer integration pattern 58   - Same timer integration pattern
59   59  
60   Known Limitations: 60   Known Limitations:
61   - FD_SETSIZE (~1024) limits maximum concurrent connections 61   - FD_SETSIZE (~1024) limits maximum concurrent connections
62   - O(n) scanning: rebuilds fd_sets each iteration 62   - O(n) scanning: rebuilds fd_sets each iteration
63   - Level-triggered only (no edge-triggered mode) 63   - Level-triggered only (no edge-triggered mode)
64   64  
65   @par Thread Safety 65   @par Thread Safety
66   All public member functions are thread-safe. 66   All public member functions are thread-safe.
67   */ 67   */
68   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler 68   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler
69   { 69   {
70   public: 70   public:
71   /** Construct the scheduler. 71   /** Construct the scheduler.
72   72  
73   Creates a self-pipe for reactor interruption. 73   Creates a self-pipe for reactor interruption.
74   74  
75   @param ctx Reference to the owning execution_context. 75   @param ctx Reference to the owning execution_context.
76   @param concurrency_hint Hint for expected thread count (unused). 76   @param concurrency_hint Hint for expected thread count (unused).
77   */ 77   */
78   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1); 78   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
79   79  
80   /// Destroy the scheduler. 80   /// Destroy the scheduler.
81   ~select_scheduler() override; 81   ~select_scheduler() override;
82   82  
83   select_scheduler(select_scheduler const&) = delete; 83   select_scheduler(select_scheduler const&) = delete;
84   select_scheduler& operator=(select_scheduler const&) = delete; 84   select_scheduler& operator=(select_scheduler const&) = delete;
85   85  
86   /// Shut down the scheduler, draining pending operations. 86   /// Shut down the scheduler, draining pending operations.
87   void shutdown() override; 87   void shutdown() override;
88   88  
89   /** Return the maximum file descriptor value supported. 89   /** Return the maximum file descriptor value supported.
90   90  
91   Returns FD_SETSIZE - 1, the maximum fd value that can be 91   Returns FD_SETSIZE - 1, the maximum fd value that can be
92   monitored by select(). Operations with fd >= FD_SETSIZE 92   monitored by select(). Operations with fd >= FD_SETSIZE
93   will fail with EINVAL. 93   will fail with EINVAL.
94   94  
95   @return The maximum supported file descriptor value. 95   @return The maximum supported file descriptor value.
96   */ 96   */
97   static constexpr int max_fd() noexcept 97   static constexpr int max_fd() noexcept
98   { 98   {
99   return FD_SETSIZE - 1; 99   return FD_SETSIZE - 1;
100   } 100   }
101   101  
102   /** Register a descriptor for persistent monitoring. 102   /** Register a descriptor for persistent monitoring.
103   103  
104   The fd is added to the registered_descs_ map and will be 104   The fd is added to the registered_descs_ map and will be
105   included in subsequent select() calls. The reactor is 105   included in subsequent select() calls. The reactor is
106   interrupted so a blocked select() rebuilds its fd_sets. 106   interrupted so a blocked select() rebuilds its fd_sets.
107   107  
108   @param fd The file descriptor to register. 108   @param fd The file descriptor to register.
109   @param desc Pointer to descriptor state for this fd. 109   @param desc Pointer to descriptor state for this fd.
110   */ 110   */
111   void register_descriptor(int fd, reactor_descriptor_state* desc) const; 111   void register_descriptor(int fd, reactor_descriptor_state* desc) const;
112   112  
113   /** Deregister a persistently registered descriptor. 113   /** Deregister a persistently registered descriptor.
114   114  
115   @param fd The file descriptor to deregister. 115   @param fd The file descriptor to deregister.
116   */ 116   */
117   void deregister_descriptor(int fd) const; 117   void deregister_descriptor(int fd) const;
118   118  
119   /** Interrupt the reactor so it rebuilds its fd_sets. 119   /** Interrupt the reactor so it rebuilds its fd_sets.
120   120  
121   Called when a write or connect op is registered after 121   Called when a write or connect op is registered after
122   the reactor's snapshot was taken. Without this, select() 122   the reactor's snapshot was taken. Without this, select()
123   may block not watching for writability on the fd. 123   may block not watching for writability on the fd.
124   */ 124   */
125   void notify_reactor() const; 125   void notify_reactor() const;
126   126  
127   private: 127   private:
128   void 128   void
129   run_task(lock_type& lock, context_type* ctx, 129   run_task(lock_type& lock, context_type* ctx,
130   long timeout_us) override; 130   long timeout_us) override;
131   void interrupt_reactor() const override; 131   void interrupt_reactor() const override;
132   long calculate_timeout(long requested_timeout_us) const; 132   long calculate_timeout(long requested_timeout_us) const;
133   133  
134   // Self-pipe for interrupting select() 134   // Self-pipe for interrupting select()
135   int pipe_fds_[2]; // [0]=read, [1]=write 135   int pipe_fds_[2]; // [0]=read, [1]=write
136   136  
137   // Per-fd tracking for fd_set building 137   // Per-fd tracking for fd_set building
138   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_; 138   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_;
139   mutable int max_fd_ = -1; 139   mutable int max_fd_ = -1;
140   }; 140   };
141   141  
HITCBC 142   239 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   239 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   239 : pipe_fds_{-1, -1} 143   239 : pipe_fds_{-1, -1}
HITCBC 144   239 , max_fd_(-1) 144   239 , max_fd_(-1)
145   { 145   {
HITCBC 146   239 if (::pipe(pipe_fds_) < 0) 146   239 if (::pipe(pipe_fds_) < 0)
MISUBC 147   ✗ detail::throw_system_error(make_err(errno), "pipe"); 147   ✗ detail::throw_system_error(make_err(errno), "pipe");
148   148  
HITCBC 149   717 for (int i = 0; i < 2; ++i) 149   717 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   478 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   478 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   478 if (flags == -1) 152   478 if (flags == -1)
153   { 153   {
MISUBC 154   ✗ int errn = errno; 154   ✗ int errn = errno;
MISUBC 155   ✗ ::close(pipe_fds_[0]); 155   ✗ ::close(pipe_fds_[0]);
MISUBC 156   ✗ ::close(pipe_fds_[1]); 156   ✗ ::close(pipe_fds_[1]);
MISUBC 157   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL"); 157   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
158   } 158   }
HITCBC 159   478 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   478 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
160   { 160   {
MISUBC 161   ✗ int errn = errno; 161   ✗ int errn = errno;
MISUBC 162   ✗ ::close(pipe_fds_[0]); 162   ✗ ::close(pipe_fds_[0]);
MISUBC 163   ✗ ::close(pipe_fds_[1]); 163   ✗ ::close(pipe_fds_[1]);
MISUBC 164   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL"); 164   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
165   } 165   }
HITCBC 166   478 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   478 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
167   { 167   {
MISUBC 168   ✗ int errn = errno; 168   ✗ int errn = errno;
MISUBC 169   ✗ ::close(pipe_fds_[0]); 169   ✗ ::close(pipe_fds_[0]);
MISUBC 170   ✗ ::close(pipe_fds_[1]); 170   ✗ ::close(pipe_fds_[1]);
MISUBC 171   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD"); 171   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
172   } 172   }
173   } 173   }
174   174  
HITCBC 175   239 timer_svc_ = &get_timer_service(ctx, *this); 175   239 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   239 timer_svc_->set_on_earliest_changed( 176   239 timer_svc_->set_on_earliest_changed(
HITCBC 177   4006 timer_service::callback(this, [](void* p) { 177   3347 timer_service::callback(this, [](void* p) {
HITCBC 178   3767 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3108 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3767 })); 179   3108 }));
180   180  
HITCBC 181   239 get_resolver_service(ctx, *this); 181   239 get_resolver_service(ctx, *this);
HITCBC 182   239 get_signal_service(ctx, *this); 182   239 get_signal_service(ctx, *this);
HITCBC 183   239 get_stream_file_service(ctx, *this); 183   239 get_stream_file_service(ctx, *this);
HITCBC 184   239 get_random_access_file_service(ctx, *this); 184   239 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   239 completed_ops_.push(&task_op_); 186   239 completed_ops_.push(&task_op_);
HITCBC 187   239 } 187   239 }
188   188  
HITCBC 189   478 inline select_scheduler::~select_scheduler() 189   478 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   239 if (pipe_fds_[0] >= 0) 191   239 if (pipe_fds_[0] >= 0)
HITCBC 192   239 ::close(pipe_fds_[0]); 192   239 ::close(pipe_fds_[0]);
HITCBC 193   239 if (pipe_fds_[1] >= 0) 193   239 if (pipe_fds_[1] >= 0)
HITCBC 194   239 ::close(pipe_fds_[1]); 194   239 ::close(pipe_fds_[1]);
HITCBC 195   478 } 195   478 }
196   196  
197   inline void 197   inline void
HITCBC 198   239 select_scheduler::shutdown() 198   239 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   239 shutdown_drain(); 200   239 shutdown_drain();
201   201  
HITCBC 202   239 if (pipe_fds_[1] >= 0) 202   239 if (pipe_fds_[1] >= 0)
HITCBC 203   239 interrupt_reactor(); 203   239 interrupt_reactor();
HITCBC 204   239 } 204   239 }
205   205  
206   inline void 206   inline void
HITCBC 207   7246 select_scheduler::register_descriptor( 207   5915 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   7246 if (fd < 0 || fd >= FD_SETSIZE) 210   5915 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   7246 desc->registered_events = reactor_event_read | reactor_event_write; 213   5915 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   7246 desc->fd = fd; 214   5915 desc->fd = fd;
HITCBC 215   7246 desc->scheduler_ = this; 215   5915 desc->scheduler_ = this;
HITCBC 216   7246 desc->mutex.set_enabled(!single_threaded_); 216   5915 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   7246 desc->ready_events_.store(0, std::memory_order_relaxed); 217   5915 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   7246 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   5915 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   7246 desc->impl_ref_.reset(); 221   5915 desc->impl_ref_.reset();
HITCBC 222   7246 desc->read_ready = false; 222   5915 desc->read_ready = false;
HITCBC 223   7246 desc->write_ready = false; 223   5915 desc->write_ready = false;
HITCBC 224   7246 } 224   5915 }
225   225  
226   { 226   {
HITCBC 227   7246 mutex_type::scoped_lock lock(mutex_); 227   5915 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   7246 registered_descs_[fd] = desc; 228   5915 registered_descs_[fd] = desc;
HITCBC 229   7246 if (fd > max_fd_) 229   5915 if (fd > max_fd_)
HITCBC 230   7242 max_fd_ = fd; 230   5911 max_fd_ = fd;
HITCBC 231   7246 } 231   5915 }
232   232  
HITCBC 233   7246 interrupt_reactor(); 233   5915 interrupt_reactor();
HITCBC 234   7246 } 234   5915 }
235   235  
236   inline void 236   inline void
HITCBC 237   7246 select_scheduler::deregister_descriptor(int fd) const 237   5915 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   7246 mutex_type::scoped_lock lock(mutex_); 239   5915 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   7246 auto it = registered_descs_.find(fd); 241   5915 auto it = registered_descs_.find(fd);
HITCBC 242   7246 if (it == registered_descs_.end()) 242   5915 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   7246 registered_descs_.erase(it); 245   5915 registered_descs_.erase(it);
246   246  
HITCBC 247   7246 if (fd == max_fd_) 247   5915 if (fd == max_fd_)
248   { 248   {
HITCBC 249   7184 max_fd_ = pipe_fds_[0]; 249   5852 max_fd_ = pipe_fds_[0];
HITCBC 250   14254 for (auto& [registered_fd, state] : registered_descs_) 250   11590 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   7070 if (registered_fd > max_fd_) 252   5738 if (registered_fd > max_fd_)
HITCBC 253   7055 max_fd_ = registered_fd; 253   5723 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   7246 } 256   5915 }
257   257  
258   inline void 258   inline void
HITCBC 259   3549 select_scheduler::notify_reactor() const 259   2884 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   3549 interrupt_reactor(); 261   2884 interrupt_reactor();
HITCBC 262   3549 } 262   2884 }
263   263  
264   inline void 264   inline void
HITCBC 265   14966 select_scheduler::interrupt_reactor() const 265   12311 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   14966 char byte = 1; 267   12311 char byte = 1;
HITCBC 268   14966 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   12311 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   14966 } 269   12311 }
270   270  
271   inline long 271   inline long
HITCBC 272   131579 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   191307 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   131579 if (requested_timeout_us == 0) 274   191307 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   131579 auto nearest = timer_svc_->nearest_expiry(); 277   191307 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   131579 if (nearest == timer_service::time_point::max()) 278   191307 if (nearest == timer_service::time_point::max())
HITCBC 279   56 return requested_timeout_us; 279   56 return requested_timeout_us;
280   280  
HITCBC 281   131523 auto now = std::chrono::steady_clock::now(); 281   191251 auto now = std::chrono::steady_clock::now();
HITCBC 282   131523 if (nearest <= now) 282   191251 if (nearest <= now)
HITCBC 283   456 return 0; 283   536 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   131067 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   190715 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   131067 .count(); 287   190715 .count();
288   288  
HITCBC 289   131067 constexpr auto long_max = 289   190715 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   131067 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   190715 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   131067 static_cast<long long>(0)), 293   190715 static_cast<long long>(0)),
HITCBC 294   131067 long_max); 294   190715 long_max);
295   295  
HITCBC 296   131067 if (requested_timeout_us < 0) 296   190715 if (requested_timeout_us < 0)
HITCBC 297   131061 return static_cast<long>(capped_timer_us); 297   190709 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   156050 select_scheduler::run_task( 305   227189 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   156050 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   227189 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   156050 int snapshot_count = 0; 323   227189 int snapshot_count = 0;
324   324  
HITCBC 325   459181 for (auto& [fd, desc] : registered_descs_) 325   687846 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   303131 if (snapshot_count < FD_SETSIZE) 327   460657 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   303131 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   460657 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   303131 snapshot[snapshot_count].fd = fd; 330   460657 snapshot[snapshot_count].fd = fd;
HITCBC 331   303131 snapshot[snapshot_count].desc = desc; 331   460657 snapshot[snapshot_count].desc = desc;
HITCBC 332   303131 snapshot[snapshot_count].needs_write = 332   460657 snapshot[snapshot_count].needs_write =
HITCBC 333   303131 (desc->write_op || desc->connect_op); 333   460657 (desc->write_op || desc->connect_op);
HITCBC 334   303131 ++snapshot_count; 334   460657 ++snapshot_count;
HITCBC 335   303131 } 335   460657 }
336   } 336   }
337   337  
HITCBC 338   156050 if (lock.owns_lock()) 338   227189 if (lock.owns_lock())
HITCBC 339   131579 lock.unlock(); 339   191307 lock.unlock();
340   340  
HITCBC 341   156050 task_cleanup on_exit{this, &lock, ctx}; 341   227189 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   2652850 FD_ZERO(&read_fds); 344   3862213 FD_ZERO(&read_fds);
HITCBC 345   2652850 FD_ZERO(&write_fds); 345   3862213 FD_ZERO(&write_fds);
HITCBC 346   2652850 FD_ZERO(&except_fds); 346   3862213 FD_ZERO(&except_fds);
347   347  
HITCBC 348   156050 FD_SET(pipe_fds_[0], &read_fds); 348   227189 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   156050 int nfds = pipe_fds_[0]; 349   227189 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   459181 for (int i = 0; i < snapshot_count; ++i) 351   687846 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   303131 int fd = snapshot[i].fd; 353   460657 int fd = snapshot[i].fd;
HITCBC 354   303131 FD_SET(fd, &read_fds); 354   460657 FD_SET(fd, &read_fds);
HITCBC 355   303131 if (snapshot[i].needs_write) 355   460657 if (snapshot[i].needs_write)
HITCBC 356   3551 FD_SET(fd, &write_fds); 356   2886 FD_SET(fd, &write_fds);
HITCBC 357   303131 FD_SET(fd, &except_fds); 357   460657 FD_SET(fd, &except_fds);
HITCBC 358   303131 if (fd > nfds) 358   460657 if (fd > nfds)
HITCBC 359   155780 nfds = fd; 359   226918 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   156050 struct timeval* tv_ptr = nullptr; 363   227189 struct timeval* tv_ptr = nullptr;
HITCBC 364   156050 if (effective_timeout_us >= 0) 364   227189 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   155994 tv.tv_sec = effective_timeout_us / 1000000; 366   227133 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   155994 tv.tv_usec = effective_timeout_us % 1000000; 367   227133 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   155994 tv_ptr = &tv; 368   227133 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   156050 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   227189 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   156050 if (ready < 0) 376   227189 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   156050 timer_svc_->process_expired(); 384   227189 timer_svc_->process_expired();
385   385  
HITCBC 386   156050 op_queue local_ops; 386   227189 op_queue local_ops;
387   387  
HITCBC 388   156050 if (ready > 0) 388   227189 if (ready > 0)
389   { 389   {
HITCBC 390   137310 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   202703 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   14820 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   12174 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   391646 for (int i = 0; i < snapshot_count; ++i) 398   588799 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   254336 int fd = snapshot[i].fd; 400   386096 int fd = snapshot[i].fd;
HITCBC 401   254336 reactor_descriptor_state* desc = snapshot[i].desc; 401   386096 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   254336 std::uint32_t flags = 0; 403   386096 std::uint32_t flags = 0;
HITCBC 404   254336 if (FD_ISSET(fd, &read_fds)) 404   386096 if (FD_ISSET(fd, &read_fds))
HITCBC 405   133629 flags |= reactor_event_read; 405   199687 flags |= reactor_event_read;
HITCBC 406   254336 if (FD_ISSET(fd, &write_fds)) 406   386096 if (FD_ISSET(fd, &write_fds))
HITCBC 407   3548 flags |= reactor_event_write; 407   2883 flags |= reactor_event_write;
HITCBC 408   254336 if (FD_ISSET(fd, &except_fds)) 408   386096 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   254336 if (flags == 0) 411   386096 if (flags == 0)
HITCBC 412   117166 continue; 412   183534 continue;
413   413  
HITCBC 414   137170 desc->add_ready_events(flags); 414   202562 desc->add_ready_events(flags);
415   415  
HITCBC 416   137170 bool expected = false; 416   202562 bool expected = false;
HITCBC 417   137170 if (desc->is_enqueued_.compare_exchange_strong( 417   202562 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   137170 local_ops.push(desc); 421   202562 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   156050 lock.lock(); 426   227189 lock.lock();
427   427  
HITCBC 428   156050 if (!local_ops.empty()) 428   227189 if (!local_ops.empty())
HITCBC 429   133630 completed_ops_.splice(local_ops); 429   199688 completed_ops_.splice(local_ops);
HITCBC 430   156050 } 430   227189 }
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