. /include/boost/corosio /native /detail /epoll /epoll_scheduler.hpp
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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_EPOLL_EPOLL_SCHEDULER_HPP 11   #ifndef BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_SCHEDULER_HPP
12   #define BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_SCHEDULER_HPP 12   #define BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_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_EPOLL 16   #if BOOST_COROSIO_HAS_EPOLL
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/epoll/epoll_traits.hpp> 24   #include <boost/corosio/native/detail/epoll/epoll_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 <atomic> 34   #include <atomic>
35   #include <chrono> 35   #include <chrono>
36   #include <cstdint> 36   #include <cstdint>
37   #include <mutex> 37   #include <mutex>
38   #include <vector> 38   #include <vector>
39   39  
40   #include <errno.h> 40   #include <errno.h>
41   #include <sys/epoll.h> 41   #include <sys/epoll.h>
42   #include <sys/eventfd.h> 42   #include <sys/eventfd.h>
43   #include <sys/timerfd.h> 43   #include <sys/timerfd.h>
44   #include <unistd.h> 44   #include <unistd.h>
45   45  
46   namespace boost::corosio::detail { 46   namespace boost::corosio::detail {
47   47  
48   /** Linux scheduler using epoll for I/O multiplexing. 48   /** Linux scheduler using epoll for I/O multiplexing.
49   49  
50   This scheduler implements the scheduler interface using Linux epoll 50   This scheduler implements the scheduler interface using Linux epoll
51   for efficient I/O event notification. It uses a single reactor model 51   for efficient I/O event notification. It uses a single reactor model
52   where one thread runs epoll_wait while other threads 52   where one thread runs epoll_wait while other threads
53   wait on a condition variable for handler work. This design provides: 53   wait on a condition variable for handler work. This design provides:
54   54  
55   - Handler parallelism: N posted handlers can execute on N threads 55   - Handler parallelism: N posted handlers can execute on N threads
56   - No thundering herd: condition_variable wakes exactly one thread 56   - No thundering herd: condition_variable wakes exactly one thread
57   - IOCP parity: Behavior matches Windows I/O completion port semantics 57   - IOCP parity: Behavior matches Windows I/O completion port semantics
58   58  
59   When threads call run(), they first try to execute queued handlers. 59   When threads call run(), they first try to execute queued handlers.
60   If the queue is empty and no reactor is running, one thread becomes 60   If the queue is empty and no reactor is running, one thread becomes
61   the reactor and runs epoll_wait. Other threads wait on a condition 61   the reactor and runs epoll_wait. Other threads wait on a condition
62   variable until handlers are available. 62   variable until handlers are available.
63   63  
64   @par Thread Safety 64   @par Thread Safety
65   All public member functions are thread-safe. 65   All public member functions are thread-safe.
66   */ 66   */
67   class BOOST_COROSIO_DECL epoll_scheduler final : public reactor_scheduler 67   class BOOST_COROSIO_DECL epoll_scheduler final : public reactor_scheduler
68   { 68   {
69   public: 69   public:
70   /** Construct the scheduler. 70   /** Construct the scheduler.
71   71  
72   Creates an epoll instance, eventfd for reactor interruption, 72   Creates an epoll instance, eventfd for reactor interruption,
73   and timerfd for kernel-managed timer expiry. 73   and timerfd for kernel-managed timer expiry.
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   epoll_scheduler(capy::execution_context& ctx, int concurrency_hint = -1); 78   epoll_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
79   79  
80   /// Destroy the scheduler. 80   /// Destroy the scheduler.
81   ~epoll_scheduler() override; 81   ~epoll_scheduler() override;
82   82  
83   epoll_scheduler(epoll_scheduler const&) = delete; 83   epoll_scheduler(epoll_scheduler const&) = delete;
84   epoll_scheduler& operator=(epoll_scheduler const&) = delete; 84   epoll_scheduler& operator=(epoll_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   /// Apply runtime configuration, resizing the event buffer. 89   /// Apply runtime configuration, resizing the event buffer.
90   void configure_reactor( 90   void configure_reactor(
91   unsigned max_events, 91   unsigned max_events,
92   unsigned budget_init, 92   unsigned budget_init,
93   unsigned budget_max, 93   unsigned budget_max,
94   unsigned unassisted) override; 94   unsigned unassisted) override;
95   95  
96   /** Return the epoll file descriptor. 96   /** Return the epoll file descriptor.
97   97  
98   Used by socket services to register file descriptors 98   Used by socket services to register file descriptors
99   for I/O event notification. 99   for I/O event notification.
100   100  
101   @return The epoll file descriptor. 101   @return The epoll file descriptor.
102   */ 102   */
103   int epoll_fd() const noexcept 103   int epoll_fd() const noexcept
104   { 104   {
105   return epoll_fd_; 105   return epoll_fd_;
106   } 106   }
107   107  
108   /** Register a descriptor for persistent monitoring. 108   /** Register a descriptor for persistent monitoring.
109   109  
110   The fd is registered once and stays registered until explicitly 110   The fd is registered once and stays registered until explicitly
111   deregistered. Events are dispatched via reactor_descriptor_state which 111   deregistered. Events are dispatched via reactor_descriptor_state which
112   tracks pending read/write/connect operations. 112   tracks pending read/write/connect operations.
113   113  
114   @param fd The file descriptor to register. 114   @param fd The file descriptor to register.
115   @param desc Pointer to descriptor data (stored in epoll_event.data.ptr). 115   @param desc Pointer to descriptor data (stored in epoll_event.data.ptr).
116   */ 116   */
117   void register_descriptor(int fd, reactor_descriptor_state* desc) const; 117   void register_descriptor(int fd, reactor_descriptor_state* desc) const;
118   118  
119   /** Deregister a persistently registered descriptor. 119   /** Deregister a persistently registered descriptor.
120   120  
121   @param fd The file descriptor to deregister. 121   @param fd The file descriptor to deregister.
122   */ 122   */
123   void deregister_descriptor(int fd) const; 123   void deregister_descriptor(int fd) const;
124   124  
125   /// Watch the read end of the POSIX signal self-pipe (see scheduler.hpp). 125   /// Watch the read end of the POSIX signal self-pipe (see scheduler.hpp).
HITCBC 126   41 void register_signal_reader(int read_fd) override 126   41 void register_signal_reader(int read_fd) override
127   { 127   {
HITCBC 128   41 register_descriptor(read_fd, signal_pipe_reader_.arm()); 128   41 register_descriptor(read_fd, signal_pipe_reader_.arm());
HITCBC 129   41 } 129   41 }
130   130  
131   private: 131   private:
132   void 132   void
133   run_task(lock_type& lock, context_type* ctx, 133   run_task(lock_type& lock, context_type* ctx,
134   long timeout_us) override; 134   long timeout_us) override;
135   void interrupt_reactor() const override; 135   void interrupt_reactor() const override;
136   void update_timerfd() const; 136   void update_timerfd() const;
137   137  
138   int epoll_fd_; 138   int epoll_fd_;
139   int event_fd_; 139   int event_fd_;
140   int timer_fd_; 140   int timer_fd_;
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   // Edge-triggered eventfd state 146   // Edge-triggered eventfd state
147   mutable std::atomic<bool> eventfd_armed_{false}; 147   mutable std::atomic<bool> eventfd_armed_{false};
148   148  
149   // Set when the earliest timer changes; flushed before epoll_wait 149   // Set when the earliest timer changes; flushed before epoll_wait
150   mutable std::atomic<bool> timerfd_stale_{false}; 150   mutable std::atomic<bool> timerfd_stale_{false};
151   151  
152   // Event buffer sized from max_events_per_poll_ (set at construction, 152   // Event buffer sized from max_events_per_poll_ (set at construction,
153   // resized by configure_reactor via io_context_options). 153   // resized by configure_reactor via io_context_options).
154   std::vector<epoll_event> event_buffer_; 154   std::vector<epoll_event> event_buffer_;
155   }; 155   };
156   156  
HITCBC 157   637 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int) 157   641 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int)
HITCBC 158   637 : epoll_fd_(-1) 158   641 : epoll_fd_(-1)
HITCBC 159   637 , event_fd_(-1) 159   641 , event_fd_(-1)
HITCBC 160   637 , timer_fd_(-1) 160   641 , timer_fd_(-1)
HITCBC 161   1274 , event_buffer_(max_events_per_poll_) 161   1282 , event_buffer_(max_events_per_poll_)
162   { 162   {
HITCBC 163   637 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC); 163   641 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC);
HITCBC 164   637 if (epoll_fd_ < 0) 164   641 if (epoll_fd_ < 0)
MISUBC 165   ✗ detail::throw_system_error(make_err(errno), "epoll_create1"); 165   ✗ detail::throw_system_error(make_err(errno), "epoll_create1");
166   166  
HITCBC 167   637 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); 167   641 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
HITCBC 168   637 if (event_fd_ < 0) 168   641 if (event_fd_ < 0)
169   { 169   {
MISUBC 170   ✗ int errn = errno; 170   ✗ int errn = errno;
MISUBC 171   ✗ ::close(epoll_fd_); 171   ✗ ::close(epoll_fd_);
MISUBC 172   ✗ detail::throw_system_error(make_err(errn), "eventfd"); 172   ✗ detail::throw_system_error(make_err(errn), "eventfd");
173   } 173   }
174   174  
HITCBC 175   637 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC); 175   641 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
HITCBC 176   637 if (timer_fd_ < 0) 176   641 if (timer_fd_ < 0)
177   { 177   {
MISUBC 178   ✗ int errn = errno; 178   ✗ int errn = errno;
MISUBC 179   ✗ ::close(event_fd_); 179   ✗ ::close(event_fd_);
MISUBC 180   ✗ ::close(epoll_fd_); 180   ✗ ::close(epoll_fd_);
MISUBC 181   ✗ detail::throw_system_error(make_err(errn), "timerfd_create"); 181   ✗ detail::throw_system_error(make_err(errn), "timerfd_create");
182   } 182   }
183   183  
HITCBC 184   637 epoll_event ev{}; 184   641 epoll_event ev{};
HITCBC 185   637 ev.events = EPOLLIN | EPOLLET; 185   641 ev.events = EPOLLIN | EPOLLET;
HITCBC 186   637 ev.data.ptr = nullptr; 186   641 ev.data.ptr = nullptr;
HITCBC 187   637 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0) 187   641 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0)
188   { 188   {
MISUBC 189   ✗ int errn = errno; 189   ✗ int errn = errno;
MISUBC 190   ✗ ::close(timer_fd_); 190   ✗ ::close(timer_fd_);
MISUBC 191   ✗ ::close(event_fd_); 191   ✗ ::close(event_fd_);
MISUBC 192   ✗ ::close(epoll_fd_); 192   ✗ ::close(epoll_fd_);
MISUBC 193   ✗ detail::throw_system_error(make_err(errn), "epoll_ctl"); 193   ✗ detail::throw_system_error(make_err(errn), "epoll_ctl");
194   } 194   }
195   195  
HITCBC 196   637 epoll_event timer_ev{}; 196   641 epoll_event timer_ev{};
HITCBC 197   637 timer_ev.events = EPOLLIN | EPOLLERR; 197   641 timer_ev.events = EPOLLIN | EPOLLERR;
HITCBC 198   637 timer_ev.data.ptr = &timer_fd_; 198   641 timer_ev.data.ptr = &timer_fd_;
HITCBC 199   637 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0) 199   641 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0)
200   { 200   {
MISUBC 201   ✗ int errn = errno; 201   ✗ int errn = errno;
MISUBC 202   ✗ ::close(timer_fd_); 202   ✗ ::close(timer_fd_);
MISUBC 203   ✗ ::close(event_fd_); 203   ✗ ::close(event_fd_);
MISUBC 204   ✗ ::close(epoll_fd_); 204   ✗ ::close(epoll_fd_);
MISUBC 205   ✗ detail::throw_system_error(make_err(errn), "epoll_ctl (timerfd)"); 205   ✗ detail::throw_system_error(make_err(errn), "epoll_ctl (timerfd)");
206   } 206   }
207   207  
HITCBC 208   637 timer_svc_ = &get_timer_service(ctx, *this); 208   641 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 209   637 timer_svc_->set_on_earliest_changed( 209   641 timer_svc_->set_on_earliest_changed(
HITCBC 210   5210 timer_service::callback(this, [](void* p) { 210   5213 timer_service::callback(this, [](void* p) {
HITCBC 211   4573 auto* self = static_cast<epoll_scheduler*>(p); 211   4572 auto* self = static_cast<epoll_scheduler*>(p);
HITCBC 212   4573 self->timerfd_stale_.store(true, std::memory_order_release); 212   4572 self->timerfd_stale_.store(true, std::memory_order_release);
HITCBC 213   4573 self->interrupt_reactor(); 213   4572 self->interrupt_reactor();
HITCBC 214   4573 })); 214   4572 }));
215   215  
HITCBC 216   637 get_resolver_service(ctx, *this); 216   641 get_resolver_service(ctx, *this);
HITCBC 217   637 get_signal_service(ctx, *this); 217   641 get_signal_service(ctx, *this);
HITCBC 218   637 get_stream_file_service(ctx, *this); 218   641 get_stream_file_service(ctx, *this);
HITCBC 219   637 get_random_access_file_service(ctx, *this); 219   641 get_random_access_file_service(ctx, *this);
220   220  
HITCBC 221   637 completed_ops_.push(&task_op_); 221   641 completed_ops_.push(&task_op_);
HITCBC 222   637 } 222   641 }
223   223  
HITCBC 224   1274 inline epoll_scheduler::~epoll_scheduler() 224   1282 inline epoll_scheduler::~epoll_scheduler()
225   { 225   {
HITCBC 226   637 if (timer_fd_ >= 0) 226   641 if (timer_fd_ >= 0)
HITCBC 227   637 ::close(timer_fd_); 227   641 ::close(timer_fd_);
HITCBC 228   637 if (event_fd_ >= 0) 228   641 if (event_fd_ >= 0)
HITCBC 229   637 ::close(event_fd_); 229   641 ::close(event_fd_);
HITCBC 230   637 if (epoll_fd_ >= 0) 230   641 if (epoll_fd_ >= 0)
HITCBC 231   637 ::close(epoll_fd_); 231   641 ::close(epoll_fd_);
HITCBC 232   1274 } 232   1282 }
233   233  
234   inline void 234   inline void
HITCBC 235   637 epoll_scheduler::shutdown() 235   641 epoll_scheduler::shutdown()
236   { 236   {
HITCBC 237   637 shutdown_drain(); 237   641 shutdown_drain();
238   238  
HITCBC 239   637 if (event_fd_ >= 0) 239   641 if (event_fd_ >= 0)
HITCBC 240   637 interrupt_reactor(); 240   641 interrupt_reactor();
HITCBC 241   637 } 241   641 }
242   242  
243   inline void 243   inline void
HITCBC 244   16 epoll_scheduler::configure_reactor( 244   16 epoll_scheduler::configure_reactor(
245   unsigned max_events, 245   unsigned max_events,
246   unsigned budget_init, 246   unsigned budget_init,
247   unsigned budget_max, 247   unsigned budget_max,
248   unsigned unassisted) 248   unsigned unassisted)
249   { 249   {
HITCBC 250   16 reactor_scheduler::configure_reactor( 250   16 reactor_scheduler::configure_reactor(
251   max_events, budget_init, budget_max, unassisted); 251   max_events, budget_init, budget_max, unassisted);
HITCBC 252   15 event_buffer_.resize(max_events_per_poll_); 252   15 event_buffer_.resize(max_events_per_poll_);
HITCBC 253   15 } 253   15 }
254   254  
255   inline void 255   inline void
HITCBC 256   7791 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const 256   7804 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const
257   { 257   {
HITCBC 258   7791 epoll_event ev{}; 258   7804 epoll_event ev{};
HITCBC 259   7791 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP; 259   7804 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP;
HITCBC 260   7791 ev.data.ptr = desc; 260   7804 ev.data.ptr = desc;
261   261  
HITCBC 262   7791 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0) 262   7804 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0)
MISUBC 263   ✗ detail::throw_system_error(make_err(errno), "epoll_ctl (register)"); 263   ✗ detail::throw_system_error(make_err(errno), "epoll_ctl (register)");
264   264  
HITCBC 265   7791 desc->registered_events = ev.events; 265   7804 desc->registered_events = ev.events;
HITCBC 266   7791 desc->fd = fd; 266   7804 desc->fd = fd;
HITCBC 267   7791 desc->scheduler_ = this; 267   7804 desc->scheduler_ = this;
HITCBC 268   7791 desc->mutex.set_enabled(reactor_io_locking_); 268   7804 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 269   7791 desc->ready_events_.store(0, std::memory_order_relaxed); 269   7804 desc->ready_events_.store(0, std::memory_order_relaxed);
270   270  
HITCBC 271   7791 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 271   7804 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 272   7791 desc->impl_ref_.reset(); 272   7804 desc->impl_ref_.reset();
HITCBC 273   7791 desc->read_ready = false; 273   7804 desc->read_ready = false;
HITCBC 274   7791 desc->write_ready = false; 274   7804 desc->write_ready = false;
HITCBC 275   7791 } 275   7804 }
276   276  
277   inline void 277   inline void
HITCBC 278   7750 epoll_scheduler::deregister_descriptor(int fd) const 278   7763 epoll_scheduler::deregister_descriptor(int fd) const
279   { 279   {
HITCBC 280   7750 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr); 280   7763 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr);
HITCBC 281   7750 } 281   7763 }
282   282  
283   inline void 283   inline void
HITCBC 284   5726 epoll_scheduler::interrupt_reactor() const 284   5735 epoll_scheduler::interrupt_reactor() const
285   { 285   {
HITCBC 286   5726 bool expected = false; 286   5735 bool expected = false;
HITCBC 287   5726 if (eventfd_armed_.compare_exchange_strong( 287   5735 if (eventfd_armed_.compare_exchange_strong(
288   expected, true, std::memory_order_release, 288   expected, true, std::memory_order_release,
289   std::memory_order_relaxed)) 289   std::memory_order_relaxed))
290   { 290   {
HITCBC 291   4692 std::uint64_t val = 1; 291   4696 std::uint64_t val = 1;
HITCBC 292   4692 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val)); 292   4696 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val));
293   } 293   }
HITCBC 294   5726 } 294   5735 }
295   295  
296   inline void 296   inline void
HITCBC 297   7795 epoll_scheduler::update_timerfd() const 297   7794 epoll_scheduler::update_timerfd() const
298   { 298   {
HITCBC 299   7795 auto nearest = timer_svc_->nearest_expiry(); 299   7794 auto nearest = timer_svc_->nearest_expiry();
300   300  
HITCBC 301   7795 itimerspec ts{}; 301   7794 itimerspec ts{};
HITCBC 302   7795 int flags = 0; 302   7794 int flags = 0;
303   303  
HITCBC 304   7795 if (nearest == timer_service::time_point::max()) 304   7794 if (nearest == timer_service::time_point::max())
305   { 305   {
306   // No timers — disarm by setting to 0 (relative) 306   // No timers — disarm by setting to 0 (relative)
307   } 307   }
308   else 308   else
309   { 309   {
HITCBC 310   7660 auto now = std::chrono::steady_clock::now(); 310   7660 auto now = std::chrono::steady_clock::now();
HITCBC 311   7660 if (nearest <= now) 311   7660 if (nearest <= now)
312   { 312   {
313   // Use 1ns instead of 0 — zero disarms the timerfd 313   // Use 1ns instead of 0 — zero disarms the timerfd
HITCBC 314   1171 ts.it_value.tv_nsec = 1; 314   540 ts.it_value.tv_nsec = 1;
315   } 315   }
316   else 316   else
317   { 317   {
HITCBC 318   6489 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>( 318   7120 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(
HITCBC 319   6489 nearest - now) 319   7120 nearest - now)
HITCBC 320   6489 .count(); 320   7120 .count();
HITCBC 321   6489 ts.it_value.tv_sec = nsec / 1000000000; 321   7120 ts.it_value.tv_sec = nsec / 1000000000;
HITCBC 322   6489 ts.it_value.tv_nsec = nsec % 1000000000; 322   7120 ts.it_value.tv_nsec = nsec % 1000000000;
HITCBC 323   6489 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0) 323   7120 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0)
MISUBC 324   ✗ ts.it_value.tv_nsec = 1; 324   ✗ ts.it_value.tv_nsec = 1;
325   } 325   }
326   } 326   }
327   327  
HITCBC 328   7795 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0) 328   7794 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0)
MISUBC 329   ✗ detail::throw_system_error(make_err(errno), "timerfd_settime"); 329   ✗ detail::throw_system_error(make_err(errno), "timerfd_settime");
HITCBC 330   7795 } 330   7794 }
331   331  
332   inline void 332   inline void
HITCBC 333   43806 epoll_scheduler::run_task( 333   36184 epoll_scheduler::run_task(
334   lock_type& lock, context_type* ctx, long timeout_us) 334   lock_type& lock, context_type* ctx, long timeout_us)
335   { 335   {
336   int timeout_ms; 336   int timeout_ms;
HITCBC 337   43806 if (task_interrupted_) 337   36184 if (task_interrupted_)
HITCBC 338   33638 timeout_ms = 0; 338   25139 timeout_ms = 0;
HITCBC 339   10168 else if (timeout_us < 0) 339   11045 else if (timeout_us < 0)
HITCBC 340   10164 timeout_ms = -1; 340   11041 timeout_ms = -1;
341   else 341   else
HITCBC 342   4 timeout_ms = static_cast<int>((timeout_us + 999) / 1000); 342   4 timeout_ms = static_cast<int>((timeout_us + 999) / 1000);
343   343  
HITCBC 344   43806 if (lock.owns_lock()) 344   36184 if (lock.owns_lock())
HITCBC 345   10170 lock.unlock(); 345   11047 lock.unlock();
346   346  
HITCBC 347   43806 task_cleanup on_exit{this, &lock, ctx}; 347   36184 task_cleanup on_exit{this, &lock, ctx};
348   348  
349   // Flush deferred timerfd programming before blocking 349   // Flush deferred timerfd programming before blocking
HITCBC 350   43806 if (timerfd_stale_.exchange(false, std::memory_order_acquire)) 350   36184 if (timerfd_stale_.exchange(false, std::memory_order_acquire))
HITCBC 351   3904 update_timerfd(); 351   3903 update_timerfd();
352   352  
HITCBC 353   43806 int nfds = ::epoll_wait( 353   36184 int nfds = ::epoll_wait(
354   epoll_fd_, event_buffer_.data(), 354   epoll_fd_, event_buffer_.data(),
HITCBC 355   43806 static_cast<int>(event_buffer_.size()), timeout_ms); 355   36184 static_cast<int>(event_buffer_.size()), timeout_ms);
356   356  
HITCBC 357   43806 if (nfds < 0 && errno != EINTR) 357   36184 if (nfds < 0 && errno != EINTR)
MISUBC 358   ✗ detail::throw_system_error(make_err(errno), "epoll_wait"); 358   ✗ detail::throw_system_error(make_err(errno), "epoll_wait");
359   359  
HITCBC 360   43806 bool check_timers = false; 360   36184 bool check_timers = false;
HITCBC 361   43806 ready_queue local_ops; 361   36184 ready_queue local_ops;
362   362  
HITCBC 363   100079 for (int i = 0; i < nfds; ++i) 363   83339 for (int i = 0; i < nfds; ++i)
364   { 364   {
HITCBC 365   56273 if (event_buffer_[i].data.ptr == nullptr) 365   47155 if (event_buffer_[i].data.ptr == nullptr)
366   { 366   {
367   std::uint64_t val; 367   std::uint64_t val;
368   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection) 368   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection)
HITCBC 369   4055 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val)); 369   4055 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val));
HITCBC 370   4055 eventfd_armed_.store(false, std::memory_order_relaxed); 370   4055 eventfd_armed_.store(false, std::memory_order_relaxed);
HITCBC 371   4055 continue; 371   4055 continue;
HITCBC 372   4055 } 372   4055 }
373   373  
HITCBC 374   52218 if (event_buffer_[i].data.ptr == &timer_fd_) 374   43100 if (event_buffer_[i].data.ptr == &timer_fd_)
375   { 375   {
376   std::uint64_t expirations; 376   std::uint64_t expirations;
377   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection) 377   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection)
378   [[maybe_unused]] auto r = 378   [[maybe_unused]] auto r =
HITCBC 379   3891 ::read(timer_fd_, &expirations, sizeof(expirations)); 379   3891 ::read(timer_fd_, &expirations, sizeof(expirations));
HITCBC 380   3891 check_timers = true; 380   3891 check_timers = true;
HITCBC 381   3891 continue; 381   3891 continue;
HITCBC 382   3891 } 382   3891 }
383   383  
384   auto* desc = 384   auto* desc =
HITCBC 385   48327 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr); 385   39209 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr);
HITCBC 386   48327 desc->add_ready_events(event_buffer_[i].events); 386   39209 desc->add_ready_events(event_buffer_[i].events);
387   387  
HITCBC 388   48327 bool expected = false; 388   39209 bool expected = false;
HITCBC 389   48327 if (desc->is_enqueued_.compare_exchange_strong( 389   39209 if (desc->is_enqueued_.compare_exchange_strong(
390   expected, true, std::memory_order_release, 390   expected, true, std::memory_order_release,
391   std::memory_order_relaxed)) 391   std::memory_order_relaxed))
392   { 392   {
HITCBC 393   48327 local_ops.push(desc); 393   39209 local_ops.push(desc);
394   } 394   }
395   } 395   }
396   396  
HITCBC 397   43806 if (check_timers) 397   36184 if (check_timers)
398   { 398   {
HITCBC 399   3891 timer_svc_->process_expired(); 399   3891 timer_svc_->process_expired();
HITCBC 400   3891 update_timerfd(); 400   3891 update_timerfd();
401   } 401   }
402   402  
HITCBC 403   43806 lock.lock(); 403   36184 lock.lock();
404   404  
HITCBC 405   43806 completed_ops_.splice(local_ops); 405   36184 completed_ops_.splice(local_ops);
HITCBC 406   43806 } 406   36184 }
407   407  
408   } // namespace boost::corosio::detail 408   } // namespace boost::corosio::detail
409   409  
410   #endif // BOOST_COROSIO_HAS_EPOLL 410   #endif // BOOST_COROSIO_HAS_EPOLL
411   411  
412   #endif // BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_SCHEDULER_HPP 412   #endif // BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_SCHEDULER_HPP