. /include/boost/corosio /native /detail /select /select_scheduler.hpp
86.83% Lines (145/167) 100.00% Functions (11/11)
[ ] prev/next file n p prev/next uncovered line
TLA Baseline Branch
Line Hits Code Line Hits Code
1   // 1   //
2   // Copyright (c) 2026 Steve Gerbino 2   // Copyright (c) 2026 Steve Gerbino
3   // Copyright (c) 2026 Michael Vandeberg 3   // Copyright (c) 2026 Michael Vandeberg
4   // 4   //
5   // Distributed under the Boost Software License, Version 1.0. (See accompanying 5   // Distributed under the Boost Software License, Version 1.0. (See accompanying
6   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7   // 7   //
8   // Official repository: https://github.com/cppalliance/corosio 8   // Official repository: https://github.com/cppalliance/corosio
9   // 9   //
10   10  
11   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 11   #ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
12   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 12   #define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
13   13  
14   #include <boost/corosio/detail/platform.hpp> 14   #include <boost/corosio/detail/platform.hpp>
15   15  
16   #if BOOST_COROSIO_HAS_SELECT 16   #if BOOST_COROSIO_HAS_SELECT
17   17  
18   #include <boost/corosio/detail/config.hpp> 18   #include <boost/corosio/detail/config.hpp>
19   #include <boost/capy/ex/execution_context.hpp> 19   #include <boost/capy/ex/execution_context.hpp>
20   20  
21   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp> 21   #include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
22   #include <boost/corosio/native/detail/reactor/reactor_signal_pipe.hpp> 22   #include <boost/corosio/native/detail/reactor/reactor_signal_pipe.hpp>
23   23  
24   #include <boost/corosio/native/detail/select/select_traits.hpp> 24   #include <boost/corosio/native/detail/select/select_traits.hpp>
25   #include <boost/corosio/detail/timer_service.hpp> 25   #include <boost/corosio/detail/timer_service.hpp>
26   #include <boost/corosio/native/detail/make_err.hpp> 26   #include <boost/corosio/native/detail/make_err.hpp>
27   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp> 27   #include <boost/corosio/native/detail/posix/posix_resolver_service.hpp>
28   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp> 28   #include <boost/corosio/native/detail/posix/posix_signal_service.hpp>
29   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp> 29   #include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
30   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp> 30   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
31   31  
32   #include <boost/corosio/detail/except.hpp> 32   #include <boost/corosio/detail/except.hpp>
33   33  
34   #include <sys/select.h> 34   #include <sys/select.h>
35   #include <unistd.h> 35   #include <unistd.h>
36   #include <errno.h> 36   #include <errno.h>
37   #include <fcntl.h> 37   #include <fcntl.h>
38   38  
39   #include <atomic> 39   #include <atomic>
40   #include <chrono> 40   #include <chrono>
41   #include <cstdint> 41   #include <cstdint>
42   #include <limits> 42   #include <limits>
43   #include <mutex> 43   #include <mutex>
44   #include <unordered_map> 44   #include <unordered_map>
45   45  
46   namespace boost::corosio::detail { 46   namespace boost::corosio::detail {
47   47  
48   struct select_op; 48   struct select_op;
49   49  
50   /** POSIX scheduler using select() for I/O multiplexing. 50   /** POSIX scheduler using select() for I/O multiplexing.
51   51  
52   This scheduler implements the scheduler interface using the POSIX select() 52   This scheduler implements the scheduler interface using the POSIX select()
53   call for I/O event notification. It inherits the shared reactor threading 53   call for I/O event notification. It inherits the shared reactor threading
54   model from reactor_scheduler: signal state machine, inline completion 54   model from reactor_scheduler: signal state machine, inline completion
55   budget, work counting, and the do_one event loop. 55   budget, work counting, and the do_one event loop.
56   56  
57   The design mirrors epoll_scheduler for behavioral consistency: 57   The design mirrors epoll_scheduler for behavioral consistency:
58   - Same single-reactor thread coordination model 58   - Same single-reactor thread coordination model
59   - Same deferred I/O pattern (reactor marks ready; workers do I/O) 59   - Same deferred I/O pattern (reactor marks ready; workers do I/O)
60   - Same timer integration pattern 60   - Same timer integration pattern
61   61  
62   Known Limitations: 62   Known Limitations:
63   - FD_SETSIZE (~1024) limits maximum concurrent connections 63   - FD_SETSIZE (~1024) limits maximum concurrent connections
64   - O(n) scanning: rebuilds fd_sets each iteration 64   - O(n) scanning: rebuilds fd_sets each iteration
65   - Level-triggered only (no edge-triggered mode) 65   - Level-triggered only (no edge-triggered mode)
66   66  
67   @par Thread Safety 67   @par Thread Safety
68   All public member functions are thread-safe. 68   All public member functions are thread-safe.
69   */ 69   */
70   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler 70   class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler
71   { 71   {
72   public: 72   public:
73   /** Construct the scheduler. 73   /** Construct the scheduler.
74   74  
75   Creates a self-pipe for reactor interruption. 75   Creates a self-pipe for reactor interruption.
76   76  
77   @param ctx Reference to the owning execution_context. 77   @param ctx Reference to the owning execution_context.
78   @param concurrency_hint Hint for expected thread count (unused). 78   @param concurrency_hint Hint for expected thread count (unused).
79   */ 79   */
80   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1); 80   select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
81   81  
82   /// Destroy the scheduler. 82   /// Destroy the scheduler.
83   ~select_scheduler() override; 83   ~select_scheduler() override;
84   84  
85   select_scheduler(select_scheduler const&) = delete; 85   select_scheduler(select_scheduler const&) = delete;
86   select_scheduler& operator=(select_scheduler const&) = delete; 86   select_scheduler& operator=(select_scheduler const&) = delete;
87   87  
88   /// Shut down the scheduler, draining pending operations. 88   /// Shut down the scheduler, draining pending operations.
89   void shutdown() override; 89   void shutdown() override;
90   90  
91   /** Return the maximum file descriptor value supported. 91   /** Return the maximum file descriptor value supported.
92   92  
93   Returns FD_SETSIZE - 1, the maximum fd value that can be 93   Returns FD_SETSIZE - 1, the maximum fd value that can be
94   monitored by select(). Operations with fd >= FD_SETSIZE 94   monitored by select(). Operations with fd >= FD_SETSIZE
95   will fail with EINVAL. 95   will fail with EINVAL.
96   96  
97   @return The maximum supported file descriptor value. 97   @return The maximum supported file descriptor value.
98   */ 98   */
99   static constexpr int max_fd() noexcept 99   static constexpr int max_fd() noexcept
100   { 100   {
101   return FD_SETSIZE - 1; 101   return FD_SETSIZE - 1;
102   } 102   }
103   103  
104   /** Register a descriptor for persistent monitoring. 104   /** Register a descriptor for persistent monitoring.
105   105  
106   The fd is added to the registered_descs_ map and will be 106   The fd is added to the registered_descs_ map and will be
107   included in subsequent select() calls. The reactor is 107   included in subsequent select() calls. The reactor is
108   interrupted so a blocked select() rebuilds its fd_sets. 108   interrupted so a blocked select() rebuilds its fd_sets.
109   109  
110   @param fd The file descriptor to register. 110   @param fd The file descriptor to register.
111   @param desc Pointer to descriptor state for this fd. 111   @param desc Pointer to descriptor state for this fd.
112   */ 112   */
113   void register_descriptor(int fd, reactor_descriptor_state* desc) const; 113   void register_descriptor(int fd, reactor_descriptor_state* desc) const;
114   114  
115   /** Deregister a persistently registered descriptor. 115   /** Deregister a persistently registered descriptor.
116   116  
117   @param fd The file descriptor to deregister. 117   @param fd The file descriptor to deregister.
118   */ 118   */
119   void deregister_descriptor(int fd) const; 119   void deregister_descriptor(int fd) const;
120   120  
121   /** Interrupt the reactor so it rebuilds its fd_sets. 121   /** Interrupt the reactor so it rebuilds its fd_sets.
122   122  
123   Called when a write or connect op is registered after 123   Called when a write or connect op is registered after
124   the reactor's snapshot was taken. Without this, select() 124   the reactor's snapshot was taken. Without this, select()
125   may block not watching for writability on the fd. 125   may block not watching for writability on the fd.
126   */ 126   */
127   void notify_reactor() const; 127   void notify_reactor() const;
128   128  
129   /// Watch the read end of the POSIX signal self-pipe (see scheduler.hpp). 129   /// Watch the read end of the POSIX signal self-pipe (see scheduler.hpp).
HITCBC 130   41 void register_signal_reader(int read_fd) override 130   41 void register_signal_reader(int read_fd) override
131   { 131   {
HITCBC 132   41 register_descriptor(read_fd, signal_pipe_reader_.arm()); 132   41 register_descriptor(read_fd, signal_pipe_reader_.arm());
HITCBC 133   41 } 133   41 }
134   134  
135   private: 135   private:
136   void 136   void
137   run_task(lock_type& lock, context_type* ctx, 137   run_task(lock_type& lock, context_type* ctx,
138   long timeout_us) override; 138   long timeout_us) override;
139   void interrupt_reactor() const override; 139   void interrupt_reactor() const override;
140   long calculate_timeout(long requested_timeout_us) const; 140   long calculate_timeout(long requested_timeout_us) const;
141   141  
142   // Watches the global signal self-pipe's read end (armed lazily by 142   // Watches the global signal self-pipe's read end (armed lazily by
143   // register_signal_reader on the first signal registration). 143   // register_signal_reader on the first signal registration).
144   reactor_signal_pipe_reader signal_pipe_reader_; 144   reactor_signal_pipe_reader signal_pipe_reader_;
145   145  
146   // Self-pipe for interrupting select() 146   // Self-pipe for interrupting select()
147   int pipe_fds_[2]; // [0]=read, [1]=write 147   int pipe_fds_[2]; // [0]=read, [1]=write
148   148  
149   // Per-fd tracking for fd_set building 149   // Per-fd tracking for fd_set building
150   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_; 150   mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_;
151   mutable int max_fd_ = -1; 151   mutable int max_fd_ = -1;
152   }; 152   };
153   153  
HITCBC 154   584 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 154   581 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 155   584 : pipe_fds_{-1, -1} 155   581 : pipe_fds_{-1, -1}
HITCBC 156   584 , max_fd_(-1) 156   581 , max_fd_(-1)
157   { 157   {
HITCBC 158   584 if (::pipe(pipe_fds_) < 0) 158   581 if (::pipe(pipe_fds_) < 0)
MISUBC 159   ✗ detail::throw_system_error(make_err(errno), "pipe"); 159   ✗ detail::throw_system_error(make_err(errno), "pipe");
160   160  
HITCBC 161   1752 for (int i = 0; i < 2; ++i) 161   1743 for (int i = 0; i < 2; ++i)
162   { 162   {
HITCBC 163   1168 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 163   1162 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 164   1168 if (flags == -1) 164   1162 if (flags == -1)
165   { 165   {
MISUBC 166   ✗ int errn = errno; 166   ✗ int errn = errno;
MISUBC 167   ✗ ::close(pipe_fds_[0]); 167   ✗ ::close(pipe_fds_[0]);
MISUBC 168   ✗ ::close(pipe_fds_[1]); 168   ✗ ::close(pipe_fds_[1]);
MISUBC 169   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL"); 169   ✗ detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
170   } 170   }
HITCBC 171   1168 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 171   1162 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
172   { 172   {
MISUBC 173   ✗ int errn = errno; 173   ✗ int errn = errno;
MISUBC 174   ✗ ::close(pipe_fds_[0]); 174   ✗ ::close(pipe_fds_[0]);
MISUBC 175   ✗ ::close(pipe_fds_[1]); 175   ✗ ::close(pipe_fds_[1]);
MISUBC 176   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL"); 176   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
177   } 177   }
HITCBC 178   1168 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 178   1162 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
179   { 179   {
MISUBC 180   ✗ int errn = errno; 180   ✗ int errn = errno;
MISUBC 181   ✗ ::close(pipe_fds_[0]); 181   ✗ ::close(pipe_fds_[0]);
MISUBC 182   ✗ ::close(pipe_fds_[1]); 182   ✗ ::close(pipe_fds_[1]);
MISUBC 183   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD"); 183   ✗ detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
184   } 184   }
185   } 185   }
186   186  
HITCBC 187   584 timer_svc_ = &get_timer_service(ctx, *this); 187   581 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 188   584 timer_svc_->set_on_earliest_changed( 188   581 timer_svc_->set_on_earliest_changed(
HITCBC 189   3891 timer_service::callback(this, [](void* p) { 189   4328 timer_service::callback(this, [](void* p) {
HITCBC 190   3307 static_cast<select_scheduler*>(p)->interrupt_reactor(); 190   3747 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 191   3307 })); 191   3747 }));
192   192  
HITCBC 193   584 get_resolver_service(ctx, *this); 193   581 get_resolver_service(ctx, *this);
HITCBC 194   584 get_signal_service(ctx, *this); 194   581 get_signal_service(ctx, *this);
HITCBC 195   584 get_stream_file_service(ctx, *this); 195   581 get_stream_file_service(ctx, *this);
HITCBC 196   584 get_random_access_file_service(ctx, *this); 196   581 get_random_access_file_service(ctx, *this);
197   197  
HITCBC 198   584 completed_ops_.push(&task_op_); 198   581 completed_ops_.push(&task_op_);
HITCBC 199   584 } 199   581 }
200   200  
HITCBC 201   1168 inline select_scheduler::~select_scheduler() 201   1162 inline select_scheduler::~select_scheduler()
202   { 202   {
HITCBC 203   584 if (pipe_fds_[0] >= 0) 203   581 if (pipe_fds_[0] >= 0)
HITCBC 204   584 ::close(pipe_fds_[0]); 204   581 ::close(pipe_fds_[0]);
HITCBC 205   584 if (pipe_fds_[1] >= 0) 205   581 if (pipe_fds_[1] >= 0)
HITCBC 206   584 ::close(pipe_fds_[1]); 206   581 ::close(pipe_fds_[1]);
HITCBC 207   1168 } 207   1162 }
208   208  
209   inline void 209   inline void
HITCBC 210   584 select_scheduler::shutdown() 210   581 select_scheduler::shutdown()
211   { 211   {
HITCBC 212   584 shutdown_drain(); 212   581 shutdown_drain();
213   213  
HITCBC 214   584 if (pipe_fds_[1] >= 0) 214   581 if (pipe_fds_[1] >= 0)
HITCBC 215   584 interrupt_reactor(); 215   581 interrupt_reactor();
HITCBC 216   584 } 216   581 }
217   217  
218   inline void 218   inline void
HITCBC 219   5489 select_scheduler::register_descriptor( 219   6168 select_scheduler::register_descriptor(
220   int fd, reactor_descriptor_state* desc) const 220   int fd, reactor_descriptor_state* desc) const
221   { 221   {
HITCBC 222   5489 if (fd < 0 || fd >= FD_SETSIZE) 222   6168 if (fd < 0 || fd >= FD_SETSIZE)
MISUBC 223   ✗ detail::throw_system_error(make_err(EINVAL), "select: fd out of range"); 223   ✗ detail::throw_system_error(make_err(EINVAL), "select: fd out of range");
224   224  
HITCBC 225   5489 desc->registered_events = reactor_event_read | reactor_event_write; 225   6168 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 226   5489 desc->fd = fd; 226   6168 desc->fd = fd;
HITCBC 227   5489 desc->scheduler_ = this; 227   6168 desc->scheduler_ = this;
HITCBC 228   5489 desc->mutex.set_enabled(reactor_io_locking_); 228   6168 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 229   5489 desc->ready_events_.store(0, std::memory_order_relaxed); 229   6168 desc->ready_events_.store(0, std::memory_order_relaxed);
230   230  
231   { 231   {
HITCBC 232   5489 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 232   6168 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 233   5489 desc->impl_ref_.reset(); 233   6168 desc->impl_ref_.reset();
HITCBC 234   5489 desc->read_ready = false; 234   6168 desc->read_ready = false;
HITCBC 235   5489 desc->write_ready = false; 235   6168 desc->write_ready = false;
HITCBC 236   5489 } 236   6168 }
237   237  
238   { 238   {
HITCBC 239   5489 mutex_type::scoped_lock lock(mutex_); 239   6168 mutex_type::scoped_lock lock(mutex_);
HITCBC 240   5489 registered_descs_[fd] = desc; 240   6168 registered_descs_[fd] = desc;
HITCBC 241   5489 if (fd > max_fd_) 241   6168 if (fd > max_fd_)
HITCBC 242   5484 max_fd_ = fd; 242   6163 max_fd_ = fd;
HITCBC 243   5489 } 243   6168 }
244   244  
HITCBC 245   5489 interrupt_reactor(); 245   6168 interrupt_reactor();
HITCBC 246   5489 } 246   6168 }
247   247  
248   inline void 248   inline void
HITCBC 249   5448 select_scheduler::deregister_descriptor(int fd) const 249   6127 select_scheduler::deregister_descriptor(int fd) const
250   { 250   {
HITCBC 251   5448 mutex_type::scoped_lock lock(mutex_); 251   6127 mutex_type::scoped_lock lock(mutex_);
252   252  
HITCBC 253   5448 auto it = registered_descs_.find(fd); 253   6127 auto it = registered_descs_.find(fd);
HITCBC 254   5448 if (it == registered_descs_.end()) 254   6127 if (it == registered_descs_.end())
MISUBC 255   ✗ return; 255   ✗ return;
256   256  
HITCBC 257   5448 registered_descs_.erase(it); 257   6127 registered_descs_.erase(it);
258   258  
HITCBC 259   5448 if (fd == max_fd_) 259   6127 if (fd == max_fd_)
260   { 260   {
HITCBC 261   5329 max_fd_ = pipe_fds_[0]; 261   6011 max_fd_ = pipe_fds_[0];
HITCBC 262   10405 for (auto& [registered_fd, state] : registered_descs_) 262   11773 for (auto& [registered_fd, state] : registered_descs_)
263   { 263   {
HITCBC 264   5076 if (registered_fd > max_fd_) 264   5762 if (registered_fd > max_fd_)
HITCBC 265   5029 max_fd_ = registered_fd; 265   5715 max_fd_ = registered_fd;
266   } 266   }
267   } 267   }
HITCBC 268   5448 } 268   6127 }
269   269  
270   inline void 270   inline void
HITCBC 271   2627 select_scheduler::notify_reactor() const 271   2968 select_scheduler::notify_reactor() const
272   { 272   {
HITCBC 273   2627 interrupt_reactor(); 273   2968 interrupt_reactor();
HITCBC 274   2627 } 274   2968 }
275   275  
276   inline void 276   inline void
HITCBC 277   12460 select_scheduler::interrupt_reactor() const 277   13910 select_scheduler::interrupt_reactor() const
278   { 278   {
HITCBC 279   12460 char byte = 1; 279   13910 char byte = 1;
HITCBC 280   12460 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 280   13910 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 281   12460 } 281   13910 }
282   282  
283   inline long 283   inline long
HITCBC 284   220623 select_scheduler::calculate_timeout(long requested_timeout_us) const 284   212427 select_scheduler::calculate_timeout(long requested_timeout_us) const
285   { 285   {
HITCBC 286   220623 if (requested_timeout_us == 0) 286   212427 if (requested_timeout_us == 0)
MISUBC 287   ✗ return 0; 287   ✗ return 0;
288   288  
HITCBC 289   220623 auto nearest = timer_svc_->nearest_expiry(); 289   212427 auto nearest = timer_svc_->nearest_expiry();
HITCBC 290   220623 if (nearest == timer_service::time_point::max()) 290   212427 if (nearest == timer_service::time_point::max())
HITCBC 291   566 return requested_timeout_us; 291   565 return requested_timeout_us;
292   292  
HITCBC 293   220057 auto now = std::chrono::steady_clock::now(); 293   211862 auto now = std::chrono::steady_clock::now();
HITCBC 294   220057 if (nearest <= now) 294   211862 if (nearest <= now)
HITCBC 295   1359 return 0; 295   1559 return 0;
296   296  
297   auto timer_timeout_us = 297   auto timer_timeout_us =
HITCBC 298   218698 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 298   210303 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 299   218698 .count(); 299   210303 .count();
300   300  
HITCBC 301   218698 constexpr auto long_max = 301   210303 constexpr auto long_max =
302   static_cast<long long>((std::numeric_limits<long>::max)()); 302   static_cast<long long>((std::numeric_limits<long>::max)());
303   auto capped_timer_us = 303   auto capped_timer_us =
HITCBC 304   218698 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 304   210303 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 305   218698 static_cast<long long>(0)), 305   210303 static_cast<long long>(0)),
HITCBC 306   218698 long_max); 306   210303 long_max);
307   307  
HITCBC 308   218698 if (requested_timeout_us < 0) 308   210303 if (requested_timeout_us < 0)
HITCBC 309   218698 return static_cast<long>(capped_timer_us); 309   210303 return static_cast<long>(capped_timer_us);
310   310  
311   return static_cast<long>( 311   return static_cast<long>(
MISUBC 312   ✗ (std::min)(static_cast<long long>(requested_timeout_us), 312   ✗ (std::min)(static_cast<long long>(requested_timeout_us),
MISUBC 313   ✗ capped_timer_us)); 313   ✗ capped_timer_us));
314   } 314   }
315   315  
316   inline void 316   inline void
HITCBC 317   244315 select_scheduler::run_task( 317   236937 select_scheduler::run_task(
318   lock_type& lock, context_type* ctx, long timeout_us) 318   lock_type& lock, context_type* ctx, long timeout_us)
319   { 319   {
320   long effective_timeout_us = 320   long effective_timeout_us =
HITCBC 321   244315 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 321   236937 task_interrupted_ ? 0 : calculate_timeout(timeout_us);
322   322  
323   // Snapshot registered descriptors while holding lock. 323   // Snapshot registered descriptors while holding lock.
324   // Record which fds need write monitoring to avoid a hot loop: 324   // Record which fds need write monitoring to avoid a hot loop:
325   // select is level-triggered so writable sockets (nearly always 325   // select is level-triggered so writable sockets (nearly always
326   // writable) would cause select() to return immediately every 326   // writable) would cause select() to return immediately every
327   // iteration if unconditionally added to write_fds. 327   // iteration if unconditionally added to write_fds.
328   struct fd_entry 328   struct fd_entry
329   { 329   {
330   int fd; 330   int fd;
331   reactor_descriptor_state* desc; 331   reactor_descriptor_state* desc;
332   bool needs_write; 332   bool needs_write;
333   }; 333   };
334   fd_entry snapshot[FD_SETSIZE]; 334   fd_entry snapshot[FD_SETSIZE];
HITCBC 335   244315 int snapshot_count = 0; 335   236937 int snapshot_count = 0;
336   336  
HITCBC 337   633188 for (auto& [fd, desc] : registered_descs_) 337   615082 for (auto& [fd, desc] : registered_descs_)
338   { 338   {
HITCBC 339   388873 if (snapshot_count < FD_SETSIZE) 339   378145 if (snapshot_count < FD_SETSIZE)
340   { 340   {
HITCBC 341   388873 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 341   378145 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 342   388873 snapshot[snapshot_count].fd = fd; 342   378145 snapshot[snapshot_count].fd = fd;
HITCBC 343   388873 snapshot[snapshot_count].desc = desc; 343   378145 snapshot[snapshot_count].desc = desc;
HITCBC 344   388873 snapshot[snapshot_count].needs_write = 344   378145 snapshot[snapshot_count].needs_write =
HITCBC 345   388873 (desc->write_op || desc->connect_op); 345   378145 (desc->write_op || desc->connect_op);
HITCBC 346   388873 ++snapshot_count; 346   378145 ++snapshot_count;
HITCBC 347   388873 } 347   378145 }
348   } 348   }
349   349  
HITCBC 350   244315 if (lock.owns_lock()) 350   236937 if (lock.owns_lock())
HITCBC 351   220624 lock.unlock(); 351   212428 lock.unlock();
352   352  
HITCBC 353   244315 task_cleanup on_exit{this, &lock, ctx}; 353   236937 task_cleanup on_exit{this, &lock, ctx};
354   354  
355   fd_set read_fds, write_fds, except_fds; 355   fd_set read_fds, write_fds, except_fds;
HITCBC 356   4153355 FD_ZERO(&read_fds); 356   4027929 FD_ZERO(&read_fds);
HITCBC 357   4153355 FD_ZERO(&write_fds); 357   4027929 FD_ZERO(&write_fds);
HITCBC 358   4153355 FD_ZERO(&except_fds); 358   4027929 FD_ZERO(&except_fds);
359   359  
HITCBC 360   244315 FD_SET(pipe_fds_[0], &read_fds); 360   236937 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 361   244315 int nfds = pipe_fds_[0]; 361   236937 int nfds = pipe_fds_[0];
362   362  
HITCBC 363   633188 for (int i = 0; i < snapshot_count; ++i) 363   615082 for (int i = 0; i < snapshot_count; ++i)
364   { 364   {
HITCBC 365   388873 int fd = snapshot[i].fd; 365   378145 int fd = snapshot[i].fd;
HITCBC 366   388873 FD_SET(fd, &read_fds); 366   378145 FD_SET(fd, &read_fds);
HITCBC 367   388873 if (snapshot[i].needs_write) 367   378145 if (snapshot[i].needs_write)
HITCBC 368   10927 FD_SET(fd, &write_fds); 368   10626 FD_SET(fd, &write_fds);
HITCBC 369   388873 FD_SET(fd, &except_fds); 369   378145 FD_SET(fd, &except_fds);
HITCBC 370   388873 if (fd > nfds) 370   378145 if (fd > nfds)
HITCBC 371   244009 nfds = fd; 371   236619 nfds = fd;
372   } 372   }
373   373  
374   struct timeval tv; 374   struct timeval tv;
HITCBC 375   244315 struct timeval* tv_ptr = nullptr; 375   236937 struct timeval* tv_ptr = nullptr;
HITCBC 376   244315 if (effective_timeout_us >= 0) 376   236937 if (effective_timeout_us >= 0)
377   { 377   {
HITCBC 378   243752 tv.tv_sec = effective_timeout_us / 1000000; 378   236376 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 379   243752 tv.tv_usec = effective_timeout_us % 1000000; 379   236376 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 380   243752 tv_ptr = &tv; 380   236376 tv_ptr = &tv;
381   } 381   }
382   382  
HITCBC 383   244315 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 383   236937 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr);
384   384  
385   // EINTR: signal interrupted select(), just retry. 385   // EINTR: signal interrupted select(), just retry.
386   // EBADF: an fd was closed between snapshot and select(); retry 386   // EBADF: an fd was closed between snapshot and select(); retry
387   // with a fresh snapshot from registered_descs_. 387   // with a fresh snapshot from registered_descs_.
HITCBC 388   244315 if (ready < 0) 388   236937 if (ready < 0)
389   { 389   {
MISUBC 390   ✗ if (errno == EINTR || errno == EBADF) 390   ✗ if (errno == EINTR || errno == EBADF)
MISUBC 391   ✗ return; 391   ✗ return;
MISUBC 392   ✗ detail::throw_system_error(make_err(errno), "select"); 392   ✗ detail::throw_system_error(make_err(errno), "select");
393   } 393   }
394   394  
395   // Process timers outside the lock 395   // Process timers outside the lock
HITCBC 396   244315 timer_svc_->process_expired(); 396   236937 timer_svc_->process_expired();
397   397  
HITCBC 398   244315 ready_queue local_ops; 398   236937 ready_queue local_ops;
399   399  
HITCBC 400   244315 if (ready > 0) 400   236937 if (ready > 0)
401   { 401   {
HITCBC 402   228635 if (FD_ISSET(pipe_fds_[0], &read_fds)) 402   220722 if (FD_ISSET(pipe_fds_[0], &read_fds))
403   { 403   {
404   char buf[256]; 404   char buf[256];
HITCBC 405   11440 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 405   12807 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
406   { 406   {
407   } 407   }
408   } 408   }
409   409  
HITCBC 410   569334 for (int i = 0; i < snapshot_count; ++i) 410   549516 for (int i = 0; i < snapshot_count; ++i)
411   { 411   {
HITCBC 412   340699 int fd = snapshot[i].fd; 412   328794 int fd = snapshot[i].fd;
HITCBC 413   340699 reactor_descriptor_state* desc = snapshot[i].desc; 413   328794 reactor_descriptor_state* desc = snapshot[i].desc;
414   414  
HITCBC 415   340699 std::uint32_t flags = 0; 415   328794 std::uint32_t flags = 0;
HITCBC 416   340699 if (FD_ISSET(fd, &read_fds)) 416   328794 if (FD_ISSET(fd, &read_fds))
HITCBC 417   225690 flags |= reactor_event_read; 417   217430 flags |= reactor_event_read;
HITCBC 418   340699 if (FD_ISSET(fd, &write_fds)) 418   328794 if (FD_ISSET(fd, &write_fds))
HITCBC 419   2624 flags |= reactor_event_write; 419   2965 flags |= reactor_event_write;
HITCBC 420   340699 if (FD_ISSET(fd, &except_fds)) 420   328794 if (FD_ISSET(fd, &except_fds))
MISUBC 421   ✗ flags |= reactor_event_error; 421   ✗ flags |= reactor_event_error;
422   422  
HITCBC 423   340699 if (flags == 0) 423   328794 if (flags == 0)
HITCBC 424   112395 continue; 424   108409 continue;
425   425  
HITCBC 426   228304 desc->add_ready_events(flags); 426   220385 desc->add_ready_events(flags);
427   427  
HITCBC 428   228304 bool expected = false; 428   220385 bool expected = false;
HITCBC 429   228304 if (desc->is_enqueued_.compare_exchange_strong( 429   220385 if (desc->is_enqueued_.compare_exchange_strong(
430   expected, true, std::memory_order_release, 430   expected, true, std::memory_order_release,
431   std::memory_order_relaxed)) 431   std::memory_order_relaxed))
432   { 432   {
HITCBC 433   228304 local_ops.push(desc); 433   220385 local_ops.push(desc);
434   } 434   }
435   } 435   }
436   } 436   }
437   437  
HITCBC 438   244315 lock.lock(); 438   236937 lock.lock();
439   439  
HITCBC 440   244315 completed_ops_.splice(local_ops); 440   236937 completed_ops_.splice(local_ops);
HITCBC 441   244315 } 441   236937 }
442   442  
443   } // namespace boost::corosio::detail 443   } // namespace boost::corosio::detail
444   444  
445   #endif // BOOST_COROSIO_HAS_SELECT 445   #endif // BOOST_COROSIO_HAS_SELECT
446   446  
447   #endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP 447   #endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP