. /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   585 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int) 154   585 inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
HITCBC 155   585 : pipe_fds_{-1, -1} 155   585 : pipe_fds_{-1, -1}
HITCBC 156   585 , max_fd_(-1) 156   585 , max_fd_(-1)
157   { 157   {
HITCBC 158   585 if (::pipe(pipe_fds_) < 0) 158   585 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   1755 for (int i = 0; i < 2; ++i) 161   1755 for (int i = 0; i < 2; ++i)
162   { 162   {
HITCBC 163   1170 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0); 163   1170 int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
HITCBC 164   1170 if (flags == -1) 164   1170 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   1170 if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1) 171   1170 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   1170 if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1) 178   1170 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   585 timer_svc_ = &get_timer_service(ctx, *this); 187   585 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 188   585 timer_svc_->set_on_earliest_changed( 188   585 timer_svc_->set_on_earliest_changed(
HITCBC 189   3420 timer_service::callback(this, [](void* p) { 189   3576 timer_service::callback(this, [](void* p) {
HITCBC 190   2835 static_cast<select_scheduler*>(p)->interrupt_reactor(); 190   2991 static_cast<select_scheduler*>(p)->interrupt_reactor();
HITCBC 191   2835 })); 191   2991 }));
192   192  
HITCBC 193   585 get_resolver_service(ctx, *this); 193   585 get_resolver_service(ctx, *this);
HITCBC 194   585 get_signal_service(ctx, *this); 194   585 get_signal_service(ctx, *this);
HITCBC 195   585 get_stream_file_service(ctx, *this); 195   585 get_stream_file_service(ctx, *this);
HITCBC 196   585 get_random_access_file_service(ctx, *this); 196   585 get_random_access_file_service(ctx, *this);
197   197  
HITCBC 198   585 completed_ops_.push(&task_op_); 198   585 completed_ops_.push(&task_op_);
HITCBC 199   585 } 199   585 }
200   200  
HITCBC 201   1170 inline select_scheduler::~select_scheduler() 201   1170 inline select_scheduler::~select_scheduler()
202   { 202   {
HITCBC 203   585 if (pipe_fds_[0] >= 0) 203   585 if (pipe_fds_[0] >= 0)
HITCBC 204   585 ::close(pipe_fds_[0]); 204   585 ::close(pipe_fds_[0]);
HITCBC 205   585 if (pipe_fds_[1] >= 0) 205   585 if (pipe_fds_[1] >= 0)
HITCBC 206   585 ::close(pipe_fds_[1]); 206   585 ::close(pipe_fds_[1]);
HITCBC 207   1170 } 207   1170 }
208   208  
209   inline void 209   inline void
HITCBC 210   585 select_scheduler::shutdown() 210   585 select_scheduler::shutdown()
211   { 211   {
HITCBC 212   585 shutdown_drain(); 212   585 shutdown_drain();
213   213  
HITCBC 214   585 if (pipe_fds_[1] >= 0) 214   585 if (pipe_fds_[1] >= 0)
HITCBC 215   585 interrupt_reactor(); 215   585 interrupt_reactor();
HITCBC 216   585 } 216   585 }
217   217  
218   inline void 218   inline void
HITCBC 219   4495 select_scheduler::register_descriptor( 219   4685 select_scheduler::register_descriptor(
220   int fd, reactor_descriptor_state* desc) const 220   int fd, reactor_descriptor_state* desc) const
221   { 221   {
HITCBC 222   4495 if (fd < 0 || fd >= FD_SETSIZE) 222   4685 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   4495 desc->registered_events = reactor_event_read | reactor_event_write; 225   4685 desc->registered_events = reactor_event_read | reactor_event_write;
HITCBC 226   4495 desc->fd = fd; 226   4685 desc->fd = fd;
HITCBC 227   4495 desc->scheduler_ = this; 227   4685 desc->scheduler_ = this;
HITCBC 228   4495 desc->mutex.set_enabled(reactor_io_locking_); 228   4685 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 229   4495 desc->ready_events_.store(0, std::memory_order_relaxed); 229   4685 desc->ready_events_.store(0, std::memory_order_relaxed);
230   230  
231   { 231   {
HITCBC 232   4495 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 232   4685 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 233   4495 desc->impl_ref_.reset(); 233   4685 desc->impl_ref_.reset();
HITCBC 234   4495 desc->read_ready = false; 234   4685 desc->read_ready = false;
HITCBC 235   4495 desc->write_ready = false; 235   4685 desc->write_ready = false;
HITCBC 236   4495 } 236   4685 }
237   237  
238   { 238   {
HITCBC 239   4495 mutex_type::scoped_lock lock(mutex_); 239   4685 mutex_type::scoped_lock lock(mutex_);
HITCBC 240   4495 registered_descs_[fd] = desc; 240   4685 registered_descs_[fd] = desc;
HITCBC 241   4495 if (fd > max_fd_) 241   4685 if (fd > max_fd_)
HITCBC 242   4490 max_fd_ = fd; 242   4680 max_fd_ = fd;
HITCBC 243   4495 } 243   4685 }
244   244  
HITCBC 245   4495 interrupt_reactor(); 245   4685 interrupt_reactor();
HITCBC 246   4495 } 246   4685 }
247   247  
248   inline void 248   inline void
HITCBC 249   4454 select_scheduler::deregister_descriptor(int fd) const 249   4644 select_scheduler::deregister_descriptor(int fd) const
250   { 250   {
HITCBC 251   4454 mutex_type::scoped_lock lock(mutex_); 251   4644 mutex_type::scoped_lock lock(mutex_);
252   252  
HITCBC 253   4454 auto it = registered_descs_.find(fd); 253   4644 auto it = registered_descs_.find(fd);
HITCBC 254   4454 if (it == registered_descs_.end()) 254   4644 if (it == registered_descs_.end())
MISUBC 255   ✗ return; 255   ✗ return;
256   256  
HITCBC 257   4454 registered_descs_.erase(it); 257   4644 registered_descs_.erase(it);
258   258  
HITCBC 259   4454 if (fd == max_fd_) 259   4644 if (fd == max_fd_)
260   { 260   {
HITCBC 261   4335 max_fd_ = pipe_fds_[0]; 261   4525 max_fd_ = pipe_fds_[0];
HITCBC 262   8417 for (auto& [registered_fd, state] : registered_descs_) 262   8797 for (auto& [registered_fd, state] : registered_descs_)
263   { 263   {
HITCBC 264   4082 if (registered_fd > max_fd_) 264   4272 if (registered_fd > max_fd_)
HITCBC 265   4035 max_fd_ = registered_fd; 265   4225 max_fd_ = registered_fd;
266   } 266   }
267   } 267   }
HITCBC 268   4454 } 268   4644 }
269   269  
270   inline void 270   inline void
HITCBC 271   2130 select_scheduler::notify_reactor() const 271   2225 select_scheduler::notify_reactor() const
272   { 272   {
HITCBC 273   2130 interrupt_reactor(); 273   2225 interrupt_reactor();
HITCBC 274   2130 } 274   2225 }
275   275  
276   inline void 276   inline void
HITCBC 277   10496 select_scheduler::interrupt_reactor() const 277   10937 select_scheduler::interrupt_reactor() const
278   { 278   {
HITCBC 279   10496 char byte = 1; 279   10937 char byte = 1;
HITCBC 280   10496 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1); 280   10937 [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
HITCBC 281   10496 } 281   10937 }
282   282  
283   inline long 283   inline long
HITCBC 284   175189 select_scheduler::calculate_timeout(long requested_timeout_us) const 284   176671 select_scheduler::calculate_timeout(long requested_timeout_us) const
285   { 285   {
HITCBC 286   175189 if (requested_timeout_us == 0) 286   176671 if (requested_timeout_us == 0)
MISUBC 287   ✗ return 0; 287   ✗ return 0;
288   288  
HITCBC 289   175189 auto nearest = timer_svc_->nearest_expiry(); 289   176671 auto nearest = timer_svc_->nearest_expiry();
HITCBC 290   175189 if (nearest == timer_service::time_point::max()) 290   176671 if (nearest == timer_service::time_point::max())
HITCBC 291   571 return requested_timeout_us; 291   566 return requested_timeout_us;
292   292  
HITCBC 293   174618 auto now = std::chrono::steady_clock::now(); 293   176105 auto now = std::chrono::steady_clock::now();
HITCBC 294   174618 if (nearest <= now) 294   176105 if (nearest <= now)
HITCBC 295   900 return 0; 295   849 return 0;
296   296  
297   auto timer_timeout_us = 297   auto timer_timeout_us =
HITCBC 298   173718 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now) 298   175256 std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
HITCBC 299   173718 .count(); 299   175256 .count();
300   300  
HITCBC 301   173718 constexpr auto long_max = 301   175256 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   173718 (std::min)((std::max)(static_cast<long long>(timer_timeout_us), 304   175256 (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
HITCBC 305   173718 static_cast<long long>(0)), 305   175256 static_cast<long long>(0)),
HITCBC 306   173718 long_max); 306   175256 long_max);
307   307  
HITCBC 308   173718 if (requested_timeout_us < 0) 308   175256 if (requested_timeout_us < 0)
HITCBC 309   173718 return static_cast<long>(capped_timer_us); 309   175256 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   197239 select_scheduler::run_task( 317   199249 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   197239 task_interrupted_ ? 0 : calculate_timeout(timeout_us); 321   199249 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   197239 int snapshot_count = 0; 335   199249 int snapshot_count = 0;
336   336  
HITCBC 337   512784 for (auto& [fd, desc] : registered_descs_) 337   521867 for (auto& [fd, desc] : registered_descs_)
338   { 338   {
HITCBC 339   315545 if (snapshot_count < FD_SETSIZE) 339   322618 if (snapshot_count < FD_SETSIZE)
340   { 340   {
HITCBC 341   315545 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex); 341   322618 conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
HITCBC 342   315545 snapshot[snapshot_count].fd = fd; 342   322618 snapshot[snapshot_count].fd = fd;
HITCBC 343   315545 snapshot[snapshot_count].desc = desc; 343   322618 snapshot[snapshot_count].desc = desc;
HITCBC 344   315545 snapshot[snapshot_count].needs_write = 344   322618 snapshot[snapshot_count].needs_write =
HITCBC 345   315545 (desc->write_op || desc->connect_op); 345   322618 (desc->write_op || desc->connect_op);
HITCBC 346   315545 ++snapshot_count; 346   322618 ++snapshot_count;
HITCBC 347   315545 } 347   322618 }
348   } 348   }
349   349  
HITCBC 350   197239 if (lock.owns_lock()) 350   199249 if (lock.owns_lock())
HITCBC 351   175190 lock.unlock(); 351   176672 lock.unlock();
352   352  
HITCBC 353   197239 task_cleanup on_exit{this, &lock, ctx}; 353   199249 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   3353063 FD_ZERO(&read_fds); 356   3387233 FD_ZERO(&read_fds);
HITCBC 357   3353063 FD_ZERO(&write_fds); 357   3387233 FD_ZERO(&write_fds);
HITCBC 358   3353063 FD_ZERO(&except_fds); 358   3387233 FD_ZERO(&except_fds);
359   359  
HITCBC 360   197239 FD_SET(pipe_fds_[0], &read_fds); 360   199249 FD_SET(pipe_fds_[0], &read_fds);
HITCBC 361   197239 int nfds = pipe_fds_[0]; 361   199249 int nfds = pipe_fds_[0];
362   362  
HITCBC 363   512784 for (int i = 0; i < snapshot_count; ++i) 363   521867 for (int i = 0; i < snapshot_count; ++i)
364   { 364   {
HITCBC 365   315545 int fd = snapshot[i].fd; 365   322618 int fd = snapshot[i].fd;
HITCBC 366   315545 FD_SET(fd, &read_fds); 366   322618 FD_SET(fd, &read_fds);
HITCBC 367   315545 if (snapshot[i].needs_write) 367   322618 if (snapshot[i].needs_write)
HITCBC 368   8763 FD_SET(fd, &write_fds); 368   7683 FD_SET(fd, &write_fds);
HITCBC 369   315545 FD_SET(fd, &except_fds); 369   322618 FD_SET(fd, &except_fds);
HITCBC 370   315545 if (fd > nfds) 370   322618 if (fd > nfds)
HITCBC 371   196922 nfds = fd; 371   198937 nfds = fd;
372   } 372   }
373   373  
374   struct timeval tv; 374   struct timeval tv;
HITCBC 375   197239 struct timeval* tv_ptr = nullptr; 375   199249 struct timeval* tv_ptr = nullptr;
HITCBC 376   197239 if (effective_timeout_us >= 0) 376   199249 if (effective_timeout_us >= 0)
377   { 377   {
HITCBC 378   196671 tv.tv_sec = effective_timeout_us / 1000000; 378   198687 tv.tv_sec = effective_timeout_us / 1000000;
HITCBC 379   196671 tv.tv_usec = effective_timeout_us % 1000000; 379   198687 tv.tv_usec = effective_timeout_us % 1000000;
HITCBC 380   196671 tv_ptr = &tv; 380   198687 tv_ptr = &tv;
381   } 381   }
382   382  
HITCBC 383   197239 int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr); 383   199249 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   197239 if (ready < 0) 388   199249 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   197239 timer_svc_->process_expired(); 396   199249 timer_svc_->process_expired();
397   397  
HITCBC 398   197239 ready_queue local_ops; 398   199249 ready_queue local_ops;
399   399  
HITCBC 400   197239 if (ready > 0) 400   199249 if (ready > 0)
401   { 401   {
HITCBC 402   182735 if (FD_ISSET(pipe_fds_[0], &read_fds)) 402   184149 if (FD_ISSET(pipe_fds_[0], &read_fds))
403   { 403   {
404   char buf[256]; 404   char buf[256];
HITCBC 405   9452 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0) 405   9828 while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
406   { 406   {
407   } 407   }
408   } 408   }
409   409  
HITCBC 410   459776 for (int i = 0; i < snapshot_count; ++i) 410   464991 for (int i = 0; i < snapshot_count; ++i)
411   { 411   {
HITCBC 412   277041 int fd = snapshot[i].fd; 412   280842 int fd = snapshot[i].fd;
HITCBC 413   277041 reactor_descriptor_state* desc = snapshot[i].desc; 413   280842 reactor_descriptor_state* desc = snapshot[i].desc;
414   414  
HITCBC 415   277041 std::uint32_t flags = 0; 415   280842 std::uint32_t flags = 0;
HITCBC 416   277041 if (FD_ISSET(fd, &read_fds)) 416   280842 if (FD_ISSET(fd, &read_fds))
HITCBC 417   180284 flags |= reactor_event_read; 417   181605 flags |= reactor_event_read;
HITCBC 418   277041 if (FD_ISSET(fd, &write_fds)) 418   280842 if (FD_ISSET(fd, &write_fds))
HITCBC 419   2127 flags |= reactor_event_write; 419   2222 flags |= reactor_event_write;
HITCBC 420   277041 if (FD_ISSET(fd, &except_fds)) 420   280842 if (FD_ISSET(fd, &except_fds))
MISUBC 421   ✗ flags |= reactor_event_error; 421   ✗ flags |= reactor_event_error;
422   422  
HITCBC 423   277041 if (flags == 0) 423   280842 if (flags == 0)
HITCBC 424   94640 continue; 424   97025 continue;
425   425  
HITCBC 426   182401 desc->add_ready_events(flags); 426   183817 desc->add_ready_events(flags);
427   427  
HITCBC 428   182401 bool expected = false; 428   183817 bool expected = false;
HITCBC 429   182401 if (desc->is_enqueued_.compare_exchange_strong( 429   183817 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   182401 local_ops.push(desc); 433   183817 local_ops.push(desc);
434   } 434   }
435   } 435   }
436   } 436   }
437   437  
HITCBC 438   197239 lock.lock(); 438   199249 lock.lock();
439   439  
HITCBC 440   197239 completed_ops_.splice(local_ops); 440   199249 completed_ops_.splice(local_ops);
HITCBC 441   197239 } 441   199249 }
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