. /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   428 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 142   430 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 143   428 : pipe_fds_{-1, -1} 143   430 : pipe_fds_{-1, -1}
HITCBC 144   428 , max_fd_(-1) 144   430 , max_fd_(-1)
145   { 145   {
HITCBC 146   428 if (::pipe(pipe_fds_) < 0) 146   430 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   1284 for (int i = 0; i < 2; ++i) 149   1290 for (int i = 0; i < 2; ++i)
150   { 150   {
HITCBC 151   856 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 151   860 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 152   856 if (flags == -1) 152   860 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   856 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 159   860 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   856 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 166   860 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   428 timer_svc_ = &get_timer_service(ctx, *this); 175   430 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 176   428 timer_svc_->set_on_earliest_changed( 176   430 timer_svc_->set_on_earliest_changed(
HITCBC 177   3482 timer_service::callback(this, [](void* p) { 177   3507 timer_service::callback(this, [](void* p) {
HITCBC 178   3054 static_cast<select_scheduler*>(p)->interrupt_reactor(); 178   3077 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 179   3054 })); 179   3077 }));
180   180  
HITCBC 181   428 get_resolver_service(ctx, *this); 181   430 get_resolver_service(ctx, *this);
HITCBC 182   428 get_signal_service(ctx, *this); 182   430 get_signal_service(ctx, *this);
HITCBC 183   428 get_stream_file_service(ctx, *this); 183   430 get_stream_file_service(ctx, *this);
HITCBC 184   428 get_random_access_file_service(ctx, *this); 184   430 get_random_access_file_service(ctx, *this);
185   185  
HITCBC 186   428 completed_ops_.push(&task_op_); 186   430 completed_ops_.push(&task_op_);
HITCBC 187   428 } 187   430 }
188   188  
HITCBC 189   856 inline select_scheduler::~select_scheduler() 189   860 inline select_scheduler::~select_scheduler()
190   { 190   {
HITCBC 191   428 if (pipe_fds_[0] >= 0) 191   430 if (pipe_fds_[0] >= 0)
HITCBC 192   428 ::close(pipe_fds_[0]); 192   430 ::close(pipe_fds_[0]);
HITCBC 193   428 if (pipe_fds_[1] >= 0) 193   430 if (pipe_fds_[1] >= 0)
HITCBC 194   428 ::close(pipe_fds_[1]); 194   430 ::close(pipe_fds_[1]);
HITCBC 195   856 } 195   860 }
196   196  
197   inline void 197   inline void
HITCBC 198   428 select_scheduler::shutdown() 198   430 select_scheduler::shutdown()
199   { 199   {
HITCBC 200   428 shutdown_drain(); 200   430 shutdown_drain();
201   201  
HITCBC 202   428 if (pipe_fds_[1] >= 0) 202   430 if (pipe_fds_[1] >= 0)
HITCBC 203   428 interrupt_reactor(); 203   430 interrupt_reactor();
HITCBC 204   428 } 204   430 }
205   205  
206   inline void 206   inline void
HITCBC 207   5945 select_scheduler::register_descriptor( 207   5986 select_scheduler::register_descriptor(
208   int fd, reactor_descriptor_state* desc) const 208   int fd, reactor_descriptor_state* desc) const
209   { 209   {
HITCBC 210   5945 if (fd < 0 || fd >= FD_SETSIZE) 210   5986 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   5945 desc->registered_events = reactor_event_read | reactor_event_write; 213   5986 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 214   5945 desc->fd = fd; 214   5986 desc->fd = fd;
HITCBC 215   5945 desc->scheduler_ = this; 215   5986 desc->scheduler_ = this;
HITCBC 216   5945 desc->mutex.set_enabled(!single_threaded_); 216   5986 desc->mutex.set_enabled(!single_threaded_);
HITCBC 217   5945 desc->ready_events_.store(0, std::memory_order_relaxed); 217   5986 desc->ready_events_.store(0, std::memory_order_relaxed);
218   218  
219   { 219   {
HITCBC 220   5945 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 220   5986 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 221   5945 desc->impl_ref_.reset(); 221   5986 desc->impl_ref_.reset();
HITCBC 222   5945 desc->read_ready = false; 222   5986 desc->read_ready = false;
HITCBC 223   5945 desc->write_ready = false; 223   5986 desc->write_ready = false;
HITCBC 224   5945 } 224   5986 }
225   225  
226   { 226   {
HITCBC 227   5945 mutex_type::scoped_lock lock(mutex_); 227   5986 mutex_type::scoped_lock lock(mutex_);
HITCBC 228   5945 registered_descs_[fd] = desc; 228   5986 registered_descs_[fd] = desc;
HITCBC 229   5945 if (fd > max_fd_) 229   5986 if (fd > max_fd_)
HITCBC 230   5941 max_fd_ = fd; 230   5982 max_fd_ = fd;
HITCBC 231   5945 } 231   5986 }
232   232  
HITCBC 233   5945 interrupt_reactor(); 233   5986 interrupt_reactor();
HITCBC 234   5945 } 234   5986 }
235   235  
236   inline void 236   inline void
HITCBC 237   5945 select_scheduler::deregister_descriptor(int fd) const 237   5986 select_scheduler::deregister_descriptor(int fd) const
238   { 238   {
HITCBC 239   5945 mutex_type::scoped_lock lock(mutex_); 239   5986 mutex_type::scoped_lock lock(mutex_);
240   240  
HITCBC 241   5945 auto it = registered_descs_.find(fd); 241   5986 auto it = registered_descs_.find(fd);
HITCBC 242   5945 if (it == registered_descs_.end()) 242   5986 if (it == registered_descs_.end())
MISUBC 243   ✗ return; 243   ✗ return;
244   244  
HITCBC 245   5945 registered_descs_.erase(it); 245   5986 registered_descs_.erase(it);
246   246  
HITCBC 247   5945 if (fd == max_fd_) 247   5986 if (fd == max_fd_)
248   { 248   {
HITCBC 249   5840 max_fd_ = pipe_fds_[0]; 249   5882 max_fd_ = pipe_fds_[0];
HITCBC 250   11469 for (auto& [registered_fd, state] : registered_descs_) 250   11553 for (auto& [registered_fd, state] : registered_descs_)
251   { 251   {
HITCBC 252   5629 if (registered_fd > max_fd_) 252   5671 if (registered_fd > max_fd_)
HITCBC 253   5604 max_fd_ = registered_fd; 253   5644 max_fd_ = registered_fd;
254   } 254   }
255   } 255   }
HITCBC 256   5945 } 256   5986 }
257   257  
258   inline void 258   inline void
HITCBC 259   2832 select_scheduler::notify_reactor() const 259   2851 select_scheduler::notify_reactor() const
260   { 260   {
HITCBC 261   2832 interrupt_reactor(); 261   2851 interrupt_reactor();
HITCBC 262   2832 } 262   2851 }
263   263  
264   inline void 264   inline void
HITCBC 265   12545 select_scheduler::interrupt_reactor() const 265   12632 select_scheduler::interrupt_reactor() const
266   { 266   {
HITCBC 267   12545 char byte = 1; 267   12632 char byte = 1;
HITCBC 268   12545 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 268   12632 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 269   12545 } 269   12632 }
270   270  
271   inline long 271   inline long
HITCBC 272   200955 select_scheduler::calculate_timeout(long requested_timeout_us) const 272   219340 select_scheduler::calculate_timeout(long requested_timeout_us) const
273   { 273   {
HITCBC 274   200955 if (requested_timeout_us == 0) 274   219340 if (requested_timeout_us == 0)
MISUBC 275   ✗ return 0; 275   ✗ return 0;
276   276  
HITCBC 277   200955 auto nearest = timer_svc_->nearest_expiry(); 277   219340 auto nearest = timer_svc_->nearest_expiry();
HITCBC 278   200955 if (nearest == timer_service::time_point::max()) 278   219340 if (nearest == timer_service::time_point::max())
HITCBC 279   175 return requested_timeout_us; 279   177 return requested_timeout_us;
280   280  
HITCBC 281   200780 auto now = std::chrono::steady_clock::now(); 281   219163 auto now = std::chrono::steady_clock::now();
HITCBC 282   200780 if (nearest <= now) 282   219163 if (nearest <= now)
HITCBC 283   676 return 0; 283   683 return 0;
284   284  
285   auto timer_timeout_us = 285   auto timer_timeout_us =
HITCBC 286   200104 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 286   218480 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 287   200104 .count(); 287   218480 .count();
288   288  
HITCBC 289   200104 constexpr auto long_max = 289   218480 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   200104 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 292   218480 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 293   200104 static_cast<long long>(0)), 293   218480 static_cast<long long>(0)),
HITCBC 294   200104 long_max); 294   218480 long_max);
295   295  
HITCBC 296   200104 if (requested_timeout_us < 0) 296   218480 if (requested_timeout_us < 0)
HITCBC 297   200104 return static_cast<long>(capped_timer_us); 297   218480 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   224140 select_scheduler::run_task( 305   247844 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   224140 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 309   247844 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   224140 int snapshot_count = 0; 323   247844 int snapshot_count = 0;
324   324  
HITCBC 325   583452 for (auto& [fd, desc] : registered_descs_) 325   671522 for (auto& [fd, desc] : registered_descs_)
326   { 326   {
HITCBC 327   359312 if (snapshot_count < FD_SETSIZE) 327   423678 if (snapshot_count < FD_SETSIZE)
328   { 328   {
HITCBC 329   359312 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 329   423678 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 330   359312 snapshot[snapshot_count].fd = fd; 330   423678 snapshot[snapshot_count].fd = fd;
HITCBC 331   359312 snapshot[snapshot_count].desc = desc; 331   423678 snapshot[snapshot_count].desc = desc;
HITCBC 332   359312 snapshot[snapshot_count].needs_write = 332   423678 snapshot[snapshot_count].needs_write =
HITCBC 333   359312 (desc->write_op || desc->connect_op); 333   423678 (desc->write_op || desc->connect_op);
HITCBC 334   359312 ++snapshot_count; 334   423678 ++snapshot_count;
HITCBC 335   359312 } 335   423678 }
336   } 336   }
337   337  
HITCBC 338   224140 if (lock.owns_lock()) 338   247844 if (lock.owns_lock())
HITCBC 339   200955 lock.unlock(); 339   219340 lock.unlock();
340   340  
HITCBC 341   224140 task_cleanup on_exit{this, &lock, ctx}; 341   247844 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   3810380 FD_ZERO(&read_fds); 344   4213348 FD_ZERO(&read_fds);
HITCBC 345   3810380 FD_ZERO(&write_fds); 345   4213348 FD_ZERO(&write_fds);
HITCBC 346   3810380 FD_ZERO(&except_fds); 346   4213348 FD_ZERO(&except_fds);
347   347  
HITCBC 348   224140 FD_SET(pipe_fds_[0], &read_fds); 348   247844 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 349   224140 int nfds = pipe_fds_[0]; 349   247844 int nfds = pipe_fds_[0];
350   350  
HITCBC 351   583452 for (int i = 0; i < snapshot_count; ++i) 351   671522 for (int i = 0; i < snapshot_count; ++i)
352   { 352   {
HITCBC 353   359312 int fd = snapshot[i].fd; 353   423678 int fd = snapshot[i].fd;
HITCBC 354   359312 FD_SET(fd, &read_fds); 354   423678 FD_SET(fd, &read_fds);
HITCBC 355   359312 if (snapshot[i].needs_write) 355   423678 if (snapshot[i].needs_write)
HITCBC 356   2919 FD_SET(fd, &write_fds); 356   2938 FD_SET(fd, &write_fds);
HITCBC 357   359312 FD_SET(fd, &except_fds); 357   423678 FD_SET(fd, &except_fds);
HITCBC 358   359312 if (fd > nfds) 358   423678 if (fd > nfds)
HITCBC 359   223789 nfds = fd; 359   247490 nfds = fd;
360   } 360   }
361   361  
362   struct timeval tv; 362   struct timeval tv;
HITCBC 363   224140 struct timeval* tv_ptr = nullptr; 363   247844 struct timeval* tv_ptr = nullptr;
HITCBC 364   224140 if (effective_timeout_us >= 0) 364   247844 if (effective_timeout_us >= 0)
365   { 365   {
HITCBC 366   223966 tv.tv_sec = effective_timeout_us / 1000000; 366   247668 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 367   223966 tv.tv_usec = effective_timeout_us % 1000000; 367   247668 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 368   223966 tv_ptr = &tv; 368   247668 tv_ptr = &tv;
369   } 369   }
370   370  
HITCBC 371   224140 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 371   247844 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   224140 if (ready < 0) 376   247844 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   224140 timer_svc_->process_expired(); 384   247844 timer_svc_->process_expired();
385   385  
HITCBC 386   224140 op_queue local_ops; 386   247844 op_queue local_ops;
387   387  
HITCBC 388   224140 if (ready > 0) 388   247844 if (ready > 0)
389   { 389   {
HITCBC 390   207268 if (FD_ISSET(pipe_fds_[0], &read_fds)) 390   227668 if (FD_ISSET(pipe_fds_[0], &read_fds))
391   { 391   {
392   char buf[256]; 392   char buf[256];
HITCBC 393   12158 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 393   12250 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
394   { 394   {
395   } 395   }
396   } 396   }
397   397  
HITCBC 398   520791 for (int i = 0; i < snapshot_count; ++i) 398   591336 for (int i = 0; i < snapshot_count; ++i)
399   { 399   {
HITCBC 400   313523 int fd = snapshot[i].fd; 400   363668 int fd = snapshot[i].fd;
HITCBC 401   313523 reactor_descriptor_state* desc = snapshot[i].desc; 401   363668 reactor_descriptor_state* desc = snapshot[i].desc;
402   402  
HITCBC 403   313523 std::uint32_t flags = 0; 403   363668 std::uint32_t flags = 0;
HITCBC 404   313523 if (FD_ISSET(fd, &read_fds)) 404   363668 if (FD_ISSET(fd, &read_fds))
HITCBC 405   204227 flags |= reactor_event_read; 405   224604 flags |= reactor_event_read;
HITCBC 406   313523 if (FD_ISSET(fd, &write_fds)) 406   363668 if (FD_ISSET(fd, &write_fds))
HITCBC 407   2831 flags |= reactor_event_write; 407   2850 flags |= reactor_event_write;
HITCBC 408   313523 if (FD_ISSET(fd, &except_fds)) 408   363668 if (FD_ISSET(fd, &except_fds))
MISUBC 409   ✗ flags |= reactor_event_error; 409   ✗ flags |= reactor_event_error;
410   410  
HITCBC 411   313523 if (flags == 0) 411   363668 if (flags == 0)
HITCBC 412   106475 continue; 412   136223 continue;
413   413  
HITCBC 414   207048 desc->add_ready_events(flags); 414   227445 desc->add_ready_events(flags);
415   415  
HITCBC 416   207048 bool expected = false; 416   227445 bool expected = false;
HITCBC 417   207048 if (desc->is_enqueued_.compare_exchange_strong( 417   227445 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   207048 local_ops.push(desc); 421   227445 local_ops.push(desc);
422   } 422   }
423   } 423   }
424   } 424   }
425   425  
HITCBC 426   224140 lock.lock(); 426   247844 lock.lock();
427   427  
HITCBC 428   224140 if (!local_ops.empty()) 428   247844 if (!local_ops.empty())
HITCBC 429   204223 completed_ops_.splice(local_ops); 429   224600 completed_ops_.splice(local_ops);
HITCBC 430   224140 } 430   247844 }
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