. /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   27  
28   #include <boost/corosio/detail/except.hpp> 28   #include <boost/corosio/detail/except.hpp>
29   29  
30   #include <atomic> 30   #include <atomic>
31   #include <chrono> 31   #include <chrono>
32   #include <cstdint> 32   #include <cstdint>
33   #include <mutex> 33   #include <mutex>
34   #include <vector> 34   #include <vector>
35   35  
36   #include <errno.h> 36   #include <errno.h>
37   #include <sys/epoll.h> 37   #include <sys/epoll.h>
38   #include <sys/eventfd.h> 38   #include <sys/eventfd.h>
39   #include <sys/timerfd.h> 39   #include <sys/timerfd.h>
40   #include <unistd.h> 40   #include <unistd.h>
41   41  
42   namespace boost::corosio::detail { 42   namespace boost::corosio::detail {
43   43  
44   /** Linux scheduler using epoll for I/O multiplexing. 44   /** Linux scheduler using epoll for I/O multiplexing.
45   45  
46   This scheduler implements the scheduler interface using Linux epoll 46   This scheduler implements the scheduler interface using Linux epoll
47   for efficient I/O event notification. It uses a single reactor model 47   for efficient I/O event notification. It uses a single reactor model
48   where one thread runs epoll_wait while other threads 48   where one thread runs epoll_wait while other threads
49   wait on a condition variable for handler work. This design provides: 49   wait on a condition variable for handler work. This design provides:
50   50  
51   - Handler parallelism: N posted handlers can execute on N threads 51   - Handler parallelism: N posted handlers can execute on N threads
52   - No thundering herd: condition_variable wakes exactly one thread 52   - No thundering herd: condition_variable wakes exactly one thread
53   - IOCP parity: Behavior matches Windows I/O completion port semantics 53   - IOCP parity: Behavior matches Windows I/O completion port semantics
54   54  
55   When threads call run(), they first try to execute queued handlers. 55   When threads call run(), they first try to execute queued handlers.
56   If the queue is empty and no reactor is running, one thread becomes 56   If the queue is empty and no reactor is running, one thread becomes
57   the reactor and runs epoll_wait. Other threads wait on a condition 57   the reactor and runs epoll_wait. Other threads wait on a condition
58   variable until handlers are available. 58   variable until handlers are available.
59   59  
60   @par Thread Safety 60   @par Thread Safety
61   All public member functions are thread-safe. 61   All public member functions are thread-safe.
62   */ 62   */
63   class BOOST_COROSIO_DECL epoll_scheduler final : public reactor_scheduler 63   class BOOST_COROSIO_DECL epoll_scheduler final : public reactor_scheduler
64   { 64   {
65   public: 65   public:
66   /** Construct the scheduler. 66   /** Construct the scheduler.
67   67  
68   Creates an epoll instance, eventfd for reactor interruption, 68   Creates an epoll instance, eventfd for reactor interruption,
69   and timerfd for kernel-managed timer expiry. 69   and timerfd for kernel-managed timer expiry.
70   70  
71   @param ctx Reference to the owning execution_context. 71   @param ctx Reference to the owning execution_context.
72   @param concurrency_hint Hint for expected thread count (unused). 72   @param concurrency_hint Hint for expected thread count (unused).
73   */ 73   */
74   epoll_scheduler(capy::execution_context& ctx, int concurrency_hint = -1); 74   epoll_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
75   75  
76   /// Destroy the scheduler. 76   /// Destroy the scheduler.
77   ~epoll_scheduler() override; 77   ~epoll_scheduler() override;
78   78  
79   epoll_scheduler(epoll_scheduler const&) = delete; 79   epoll_scheduler(epoll_scheduler const&) = delete;
80   epoll_scheduler& operator=(epoll_scheduler const&) = delete; 80   epoll_scheduler& operator=(epoll_scheduler const&) = delete;
81   81  
82   /// Shut down the scheduler, draining pending operations. 82   /// Shut down the scheduler, draining pending operations.
83   void shutdown() override; 83   void shutdown() override;
84   84  
85   /// Apply runtime configuration, resizing the event buffer. 85   /// Apply runtime configuration, resizing the event buffer.
86   void configure_reactor( 86   void configure_reactor(
87   unsigned max_events, 87   unsigned max_events,
88   unsigned budget_init, 88   unsigned budget_init,
89   unsigned budget_max, 89   unsigned budget_max,
90   unsigned unassisted) override; 90   unsigned unassisted) override;
91   91  
92   /** Return the epoll file descriptor. 92   /** Return the epoll file descriptor.
93   93  
94   Used by socket services to register file descriptors 94   Used by socket services to register file descriptors
95   for I/O event notification. 95   for I/O event notification.
96   96  
97   @return The epoll file descriptor. 97   @return The epoll file descriptor.
98   */ 98   */
99   int epoll_fd() const noexcept 99   int epoll_fd() const noexcept
100   { 100   {
101   return epoll_fd_; 101   return epoll_fd_;
102   } 102   }
103   103  
104   /** Register a descriptor for persistent monitoring. 104   /** Register a descriptor for persistent monitoring.
105   105  
106   The fd is registered once and stays registered until explicitly 106   The fd is registered once and stays registered until explicitly
107   deregistered. Events are dispatched via reactor_descriptor_state which 107   deregistered. Events are dispatched via reactor_descriptor_state which
108   tracks pending read/write/connect operations. 108   tracks pending read/write/connect operations.
109   109  
110   @param fd The file descriptor to register. 110   @param fd The file descriptor to register.
111   @param desc Pointer to descriptor data (stored in epoll_event.data.ptr). 111   @param desc Pointer to descriptor data (stored in epoll_event.data.ptr).
112   112  
113   @return The error if registration fails, otherwise a default 113   @return The error if registration fails, otherwise a default
114   constructed error code. 114   constructed error code.
115   */ 115   */
116   std::error_code 116   std::error_code
117   register_descriptor(int fd, reactor_descriptor_state* desc) const; 117   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   76 [[nodiscard]] std::error_code register_signal_reader(int read_fd) override 126   76 [[nodiscard]] std::error_code register_signal_reader(int read_fd) override
127   { 127   {
HITCBC 128   76 return register_descriptor(read_fd, signal_pipe_reader_.arm()); 128   76 return register_descriptor(read_fd, signal_pipe_reader_.arm());
129   } 129   }
130   130  
131   private: 131   private:
132   void run_task(lock_type& lock, context_type& ctx, long timeout_us) override; 132   void run_task(lock_type& lock, context_type& ctx, long timeout_us) override;
133   void interrupt_reactor() const override; 133   void interrupt_reactor() const override;
134   void update_timerfd() const; 134   void update_timerfd() const;
135   135  
136   int epoll_fd_; 136   int epoll_fd_;
137   int event_fd_; 137   int event_fd_;
138   int timer_fd_; 138   int timer_fd_;
139   139  
140   // Watches the global signal self-pipe's read end (armed lazily by 140   // Watches the global signal self-pipe's read end (armed lazily by
141   // register_signal_reader on the first signal registration). 141   // register_signal_reader on the first signal registration).
142   reactor_signal_pipe_reader signal_pipe_reader_; 142   reactor_signal_pipe_reader signal_pipe_reader_;
143   143  
144   // Edge-triggered eventfd state 144   // Edge-triggered eventfd state
145   mutable std::atomic<bool> eventfd_armed_{false}; 145   mutable std::atomic<bool> eventfd_armed_{false};
146   146  
147   // Set when the earliest timer changes; flushed before epoll_wait 147   // Set when the earliest timer changes; flushed before epoll_wait
148   mutable std::atomic<bool> timerfd_stale_{false}; 148   mutable std::atomic<bool> timerfd_stale_{false};
149   149  
150   // Event buffer sized from max_events_per_poll_ (set at construction, 150   // Event buffer sized from max_events_per_poll_ (set at construction,
151   // resized by configure_reactor via io_context_options). 151   // resized by configure_reactor via io_context_options).
152   std::vector<epoll_event> event_buffer_; 152   std::vector<epoll_event> event_buffer_;
153   }; 153   };
154   154  
HITCBC 155   1305 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int) 155   1305 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int)
HITCBC 156   1305 : epoll_fd_(-1) 156   1305 : epoll_fd_(-1)
HITCBC 157   1305 , event_fd_(-1) 157   1305 , event_fd_(-1)
HITCBC 158   1305 , timer_fd_(-1) 158   1305 , timer_fd_(-1)
HITCBC 159   2610 , event_buffer_(max_events_per_poll_) 159   2610 , event_buffer_(max_events_per_poll_)
160   { 160   {
HITCBC 161   1305 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC); 161   1305 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC);
HITCBC 162   1305 if (epoll_fd_ < 0) 162   1305 if (epoll_fd_ < 0)
HITCBC 163   1 detail::throw_system_error(make_err(errno), "epoll_create1"); 163   1 detail::throw_system_error(make_err(errno), "epoll_create1");
164   164  
HITCBC 165   1304 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); 165   1304 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
HITCBC 166   1304 if (event_fd_ < 0) 166   1304 if (event_fd_ < 0)
167   { 167   {
HITCBC 168   1 int errn = errno; 168   1 int errn = errno;
HITCBC 169   1 ::close(epoll_fd_); 169   1 ::close(epoll_fd_);
HITCBC 170   1 detail::throw_system_error(make_err(errn), "eventfd"); 170   1 detail::throw_system_error(make_err(errn), "eventfd");
171   } 171   }
172   172  
HITCBC 173   1303 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC); 173   1303 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
HITCBC 174   1303 if (timer_fd_ < 0) 174   1303 if (timer_fd_ < 0)
175   { 175   {
HITCBC 176   1 int errn = errno; 176   1 int errn = errno;
HITCBC 177   1 ::close(event_fd_); 177   1 ::close(event_fd_);
HITCBC 178   1 ::close(epoll_fd_); 178   1 ::close(epoll_fd_);
HITCBC 179   1 detail::throw_system_error(make_err(errn), "timerfd_create"); 179   1 detail::throw_system_error(make_err(errn), "timerfd_create");
180   } 180   }
181   181  
HITCBC 182   1302 epoll_event ev{}; 182   1302 epoll_event ev{};
HITCBC 183   1302 ev.events = EPOLLIN | EPOLLET; 183   1302 ev.events = EPOLLIN | EPOLLET;
HITCBC 184   1302 ev.data.ptr = nullptr; 184   1302 ev.data.ptr = nullptr;
HITCBC 185   1302 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0) 185   1302 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0)
186   { 186   {
HITCBC 187   1 int errn = errno; 187   1 int errn = errno;
HITCBC 188   1 ::close(timer_fd_); 188   1 ::close(timer_fd_);
HITCBC 189   1 ::close(event_fd_); 189   1 ::close(event_fd_);
HITCBC 190   1 ::close(epoll_fd_); 190   1 ::close(epoll_fd_);
HITCBC 191   1 detail::throw_system_error(make_err(errn), "epoll_ctl"); 191   1 detail::throw_system_error(make_err(errn), "epoll_ctl");
192   } 192   }
193   193  
HITCBC 194   1301 epoll_event timer_ev{}; 194   1301 epoll_event timer_ev{};
HITCBC 195   1301 timer_ev.events = EPOLLIN | EPOLLERR; 195   1301 timer_ev.events = EPOLLIN | EPOLLERR;
HITCBC 196   1301 timer_ev.data.ptr = &timer_fd_; 196   1301 timer_ev.data.ptr = &timer_fd_;
HITCBC 197   1301 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0) 197   1301 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0)
198   { 198   {
HITCBC 199   1 int errn = errno; 199   1 int errn = errno;
HITCBC 200   1 ::close(timer_fd_); 200   1 ::close(timer_fd_);
HITCBC 201   1 ::close(event_fd_); 201   1 ::close(event_fd_);
HITCBC 202   1 ::close(epoll_fd_); 202   1 ::close(epoll_fd_);
HITCBC 203   1 detail::throw_system_error(make_err(errn), "epoll_ctl (timerfd)"); 203   1 detail::throw_system_error(make_err(errn), "epoll_ctl (timerfd)");
204   } 204   }
205   205  
HITCBC 206   1300 timer_svc_ = &get_timer_service(ctx, *this); 206   1300 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 207   1300 timer_svc_->set_on_earliest_changed( 207   1300 timer_svc_->set_on_earliest_changed(
HITCBC 208   5493 timer_service::callback(this, [](void* p) { 208   4662 timer_service::callback(this, [](void* p) {
HITCBC 209   4193 auto* self = static_cast<epoll_scheduler*>(p); 209   3362 auto* self = static_cast<epoll_scheduler*>(p);
HITCBC 210   4193 self->timerfd_stale_.store(true, std::memory_order_release); 210   3362 self->timerfd_stale_.store(true, std::memory_order_release);
HITCBC 211   4193 self->interrupt_reactor(); 211   3362 self->interrupt_reactor();
HITCBC 212   4193 })); 212   3362 }));
213   213  
HITCBC 214   1300 completed_ops_.push(&task_op_); 214   1300 completed_ops_.push(&task_op_);
HITCBC 215   1315 } 215   1315 }
216   216  
HITCBC 217   2600 inline epoll_scheduler::~epoll_scheduler() 217   2600 inline epoll_scheduler::~epoll_scheduler()
218   { 218   {
HITCBC 219   1300 if (timer_fd_ >= 0) 219   1300 if (timer_fd_ >= 0)
HITCBC 220   1300 ::close(timer_fd_); 220   1300 ::close(timer_fd_);
HITCBC 221   1300 if (event_fd_ >= 0) 221   1300 if (event_fd_ >= 0)
HITCBC 222   1300 ::close(event_fd_); 222   1300 ::close(event_fd_);
HITCBC 223   1300 if (epoll_fd_ >= 0) 223   1300 if (epoll_fd_ >= 0)
HITCBC 224   1300 ::close(epoll_fd_); 224   1300 ::close(epoll_fd_);
HITCBC 225   2600 } 225   2600 }
226   226  
227   inline void 227   inline void
HITCBC 228   1300 epoll_scheduler::shutdown() 228   1300 epoll_scheduler::shutdown()
229   { 229   {
HITCBC 230   1300 shutdown_drain(); 230   1300 shutdown_drain();
231   231  
HITCBC 232   1300 if (event_fd_ >= 0) 232   1300 if (event_fd_ >= 0)
HITCBC 233   1300 interrupt_reactor(); 233   1300 interrupt_reactor();
HITCBC 234   1300 } 234   1300 }
235   235  
236   inline void 236   inline void
HITCBC 237   27 epoll_scheduler::configure_reactor( 237   27 epoll_scheduler::configure_reactor(
238   unsigned max_events, 238   unsigned max_events,
239   unsigned budget_init, 239   unsigned budget_init,
240   unsigned budget_max, 240   unsigned budget_max,
241   unsigned unassisted) 241   unsigned unassisted)
242   { 242   {
HITCBC 243   27 reactor_scheduler::configure_reactor( 243   27 reactor_scheduler::configure_reactor(
244   max_events, budget_init, budget_max, unassisted); 244   max_events, budget_init, budget_max, unassisted);
HITCBC 245   25 event_buffer_.resize(max_events_per_poll_); 245   25 event_buffer_.resize(max_events_per_poll_);
HITCBC 246   25 } 246   25 }
247   247  
248   inline std::error_code 248   inline std::error_code
HITCBC 249   5551 epoll_scheduler::register_descriptor( 249   4351 epoll_scheduler::register_descriptor(
250   int fd, reactor_descriptor_state* desc) const 250   int fd, reactor_descriptor_state* desc) const
251   { 251   {
HITCBC 252   5551 epoll_event ev{}; 252   4351 epoll_event ev{};
HITCBC 253   5551 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP; 253   4351 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP;
HITCBC 254   5551 ev.data.ptr = desc; 254   4351 ev.data.ptr = desc;
255   255  
HITCBC 256   5551 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0) 256   4351 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0)
HITCBC 257   7 return make_err(errno); 257   7 return make_err(errno);
258   258  
HITCBC 259   5544 desc->registered_events = ev.events; 259   4344 desc->registered_events = ev.events;
HITCBC 260   5544 desc->fd = fd; 260   4344 desc->fd = fd;
HITCBC 261   5544 desc->scheduler_ = this; 261   4344 desc->scheduler_ = this;
HITCBC 262   5544 desc->mutex.set_enabled(reactor_io_locking_); 262   4344 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 263   5544 desc->ready_events_.store(0, std::memory_order_relaxed); 263   4344 desc->ready_events_.store(0, std::memory_order_relaxed);
264   264  
HITCBC 265   5544 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 265   4344 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 266   5544 desc->impl_ref_.reset(); 266   4344 desc->impl_ref_.reset();
HITCBC 267   5544 desc->read_ready = false; 267   4344 desc->read_ready = false;
HITCBC 268   5544 desc->write_ready = false; 268   4344 desc->write_ready = false;
HITCBC 269   5544 return {}; 269   4344 return {};
HITCBC 270   5544 } 270   4344 }
271   271  
272   inline void 272   inline void
HITCBC 273   5469 epoll_scheduler::deregister_descriptor(int fd) const 273   4269 epoll_scheduler::deregister_descriptor(int fd) const
274   { 274   {
HITCBC 275   5469 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr); 275   4269 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr);
HITCBC 276   5469 } 276   4269 }
277   277  
278   inline void 278   inline void
HITCBC 279   7582 epoll_scheduler::interrupt_reactor() const 279   6674 epoll_scheduler::interrupt_reactor() const
280   { 280   {
HITCBC 281   7582 bool expected = false; 281   6674 bool expected = false;
HITCBC 282   7582 if (eventfd_armed_.compare_exchange_strong( 282   6674 if (eventfd_armed_.compare_exchange_strong(
283   expected, true, std::memory_order_release, 283   expected, true, std::memory_order_release,
284   std::memory_order_relaxed)) 284   std::memory_order_relaxed))
285   { 285   {
HITCBC 286   6115 std::uint64_t val = 1; 286   5268 std::uint64_t val = 1;
HITCBC 287   6115 if (::write(event_fd_, &val, sizeof(val)) < 0) 287   5268 if (::write(event_fd_, &val, sizeof(val)) < 0)
288   { 288   {
289   // The flag is what coalesces later interrupts into a byte 289   // The flag is what coalesces later interrupts into a byte
290   // already in the eventfd; a write that failed put no byte 290   // already in the eventfd; a write that failed put no byte
291   // there, so leaving it armed would swallow every interrupt 291   // there, so leaving it armed would swallow every interrupt
292   // that follows. Disarming keeps the cost to the interrupts 292   // that follows. Disarming keeps the cost to the interrupts
293   // already in flight -- the next one arms and writes again, 293   // already in flight -- the next one arms and writes again,
294   // instead of every one after this coalescing into a byte 294   // instead of every one after this coalescing into a byte
295   // that does not exist. 295   // that does not exist.
HITCBC 296   2 eventfd_armed_.store(false, std::memory_order_release); 296   2 eventfd_armed_.store(false, std::memory_order_release);
297   } 297   }
298   } 298   }
HITCBC 299   7582 } 299   6674 }
300   300  
301   inline void 301   inline void
HITCBC 302   10416 epoll_scheduler::update_timerfd() const 302   9187 epoll_scheduler::update_timerfd() const
303   { 303   {
HITCBC 304   10416 auto nearest = timer_svc_->nearest_expiry(); 304   9187 auto nearest = timer_svc_->nearest_expiry();
305   305  
HITCBC 306   10416 itimerspec ts{}; 306   9187 itimerspec ts{};
HITCBC 307   10416 int flags = 0; 307   9187 int flags = 0;
308   308  
HITCBC 309   10416 if (nearest == timer_service::time_point::max()) 309   9187 if (nearest == timer_service::time_point::max())
310   { 310   {
311   // No timers — disarm by setting to 0 (relative) 311   // No timers — disarm by setting to 0 (relative)
312   } 312   }
313   else 313   else
314   { 314   {
HITCBC 315   9238 auto now = std::chrono::steady_clock::now(); 315   8068 auto now = std::chrono::steady_clock::now();
HITCBC 316   9238 if (nearest <= now) 316   8068 if (nearest <= now)
317   { 317   {
318   // Use 1ns instead of 0 — zero disarms the timerfd 318   // Use 1ns instead of 0 — zero disarms the timerfd
HITCBC 319   1667 ts.it_value.tv_nsec = 1; 319   1655 ts.it_value.tv_nsec = 1;
320   } 320   }
321   else 321   else
322   { 322   {
HITCBC 323   7571 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>( 323   6413 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(
HITCBC 324   7571 nearest - now) 324   6413 nearest - now)
HITCBC 325   7571 .count(); 325   6413 .count();
HITCBC 326   7571 ts.it_value.tv_sec = nsec / 1000000000; 326   6413 ts.it_value.tv_sec = nsec / 1000000000;
HITCBC 327   7571 ts.it_value.tv_nsec = nsec % 1000000000; 327   6413 ts.it_value.tv_nsec = nsec % 1000000000;
HITCBC 328   7571 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0) 328   6413 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0)
MISUBC 329   ✗ ts.it_value.tv_nsec = 1; 329   ✗ ts.it_value.tv_nsec = 1;
330   } 330   }
331   } 331   }
332   332  
HITCBC 333   10416 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0) 333   9187 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0)
HITCBC 334   1 detail::throw_system_error(make_err(errno), "timerfd_settime"); 334   1 detail::throw_system_error(make_err(errno), "timerfd_settime");
HITCBC 335   10415 } 335   9186 }
336   336  
337   inline void 337   inline void
HITCBC 338   41904 epoll_scheduler::run_task(lock_type& lock, context_type& ctx, long timeout_us) 338   33477 epoll_scheduler::run_task(lock_type& lock, context_type& ctx, long timeout_us)
339   { 339   {
340   int timeout_ms; 340   int timeout_ms;
HITCBC 341   41904 if (task_interrupted_) 341   33477 if (task_interrupted_)
HITCBC 342   31297 timeout_ms = 0; 342   24485 timeout_ms = 0;
HITCBC 343   10607 else if (timeout_us < 0) 343   8992 else if (timeout_us < 0)
HITCBC 344   10200 timeout_ms = -1; 344   8795 timeout_ms = -1;
345   else 345   else
HITCBC 346   407 timeout_ms = static_cast<int>((timeout_us + 999) / 1000); 346   197 timeout_ms = static_cast<int>((timeout_us + 999) / 1000);
347   347  
HITCBC 348   41904 if (lock.owns_lock()) 348   33477 if (lock.owns_lock())
HITCBC 349   10609 lock.unlock(); 349   8994 lock.unlock();
350   350  
HITCBC 351   41904 task_cleanup on_exit{this, &lock, ctx}; 351   33477 task_cleanup on_exit{this, &lock, ctx};
352   352  
353   // Flush deferred timerfd programming before blocking 353   // Flush deferred timerfd programming before blocking
HITCBC 354   41904 if (timerfd_stale_.exchange(false, std::memory_order_acquire)) 354   33477 if (timerfd_stale_.exchange(false, std::memory_order_acquire))
HITCBC 355   3615 update_timerfd(); 355   2841 update_timerfd();
356   356  
HITCBC 357   41903 int nfds = ::epoll_wait( 357   33476 int nfds = ::epoll_wait(
HITCBC 358   41903 epoll_fd_, event_buffer_.data(), static_cast<int>(event_buffer_.size()), 358   33476 epoll_fd_, event_buffer_.data(), static_cast<int>(event_buffer_.size()),
359   timeout_ms); 359   timeout_ms);
360   360  
HITCBC 361   41903 if (nfds < 0 && errno != EINTR) 361   33476 if (nfds < 0 && errno != EINTR)
HITCBC 362   1 detail::throw_system_error(make_err(errno), "epoll_wait"); 362   1 detail::throw_system_error(make_err(errno), "epoll_wait");
363   363  
HITCBC 364   41902 bool check_timers = false; 364   33475 bool check_timers = false;
HITCBC 365   41902 ready_queue local_ops; 365   33475 ready_queue local_ops;
366   366  
HITCBC 367   92057 for (int i = 0; i < nfds; ++i) 367   70609 for (int i = 0; i < nfds; ++i)
368   { 368   {
HITCBC 369   50155 if (event_buffer_[i].data.ptr == nullptr) 369   37134 if (event_buffer_[i].data.ptr == nullptr)
370   { 370   {
371   std::uint64_t val; 371   std::uint64_t val;
372   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection) 372   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection)
HITCBC 373   4813 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val)); 373   3966 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val));
HITCBC 374   4813 eventfd_armed_.store(false, std::memory_order_relaxed); 374   3966 eventfd_armed_.store(false, std::memory_order_relaxed);
HITCBC 375   4813 continue; 375   3966 continue;
HITCBC 376   4813 } 376   3966 }
377   377  
HITCBC 378   45342 if (event_buffer_[i].data.ptr == &timer_fd_) 378   33168 if (event_buffer_[i].data.ptr == &timer_fd_)
379   { 379   {
380   std::uint64_t expirations; 380   std::uint64_t expirations;
381   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection) 381   // NOLINTNEXTLINE(clang-analyzer-unix.BlockInCriticalSection)
382   [[maybe_unused]] auto r = 382   [[maybe_unused]] auto r =
HITCBC 383   6801 ::read(timer_fd_, &expirations, sizeof(expirations)); 383   6346 ::read(timer_fd_, &expirations, sizeof(expirations));
HITCBC 384   6801 check_timers = true; 384   6346 check_timers = true;
HITCBC 385   6801 continue; 385   6346 continue;
HITCBC 386   6801 } 386   6346 }
387   387  
388   auto* desc = 388   auto* desc =
HITCBC 389   38541 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr); 389   26822 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr);
HITCBC 390   38541 desc->add_ready_events(event_buffer_[i].events); 390   26822 desc->add_ready_events(event_buffer_[i].events);
391   391  
HITCBC 392   38541 bool expected = false; 392   26822 bool expected = false;
HITCBC 393   38541 if (desc->is_enqueued_.compare_exchange_strong( 393   26822 if (desc->is_enqueued_.compare_exchange_strong(
394   expected, true, std::memory_order_release, 394   expected, true, std::memory_order_release,
395   std::memory_order_relaxed)) 395   std::memory_order_relaxed))
396   { 396   {
HITCBC 397   38541 local_ops.push(desc); 397   26822 local_ops.push(desc);
398   } 398   }
399   } 399   }
400   400  
HITCBC 401   41902 if (check_timers) 401   33475 if (check_timers)
402   { 402   {
HITCBC 403   6801 timer_svc_->process_expired(); 403   6346 timer_svc_->process_expired();
HITCBC 404   6801 update_timerfd(); 404   6346 update_timerfd();
405   } 405   }
406   406  
HITCBC 407   41902 lock.lock(); 407   33475 lock.lock();
408   408  
HITCBC 409   41902 completed_ops_.splice(local_ops); 409   33475 completed_ops_.splice(local_ops);
HITCBC 410   41904 } 410   33477 }
411   411  
412   } // namespace boost::corosio::detail 412   } // namespace boost::corosio::detail
413   413  
414   #endif // BOOST_COROSIO_HAS_EPOLL 414   #endif // BOOST_COROSIO_HAS_EPOLL
415   415  
416   #endif // BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_SCHEDULER_HPP 416   #endif // BOOST_COROSIO_NATIVE_DETAIL_EPOLL_EPOLL_SCHEDULER_HPP