. /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   5729 timer_service::callback(this, [](void* p) { 208   5617 timer_service::callback(this, [](void* p) {
HITCBC 209   4429 auto* self = static_cast<epoll_scheduler*>(p); 209   4317 auto* self = static_cast<epoll_scheduler*>(p);
HITCBC 210   4429 self->timerfd_stale_.store(true, std::memory_order_release); 210   4317 self->timerfd_stale_.store(true, std::memory_order_release);
HITCBC 211   4429 self->interrupt_reactor(); 211   4317 self->interrupt_reactor();
HITCBC 212   4429 })); 212   4317 }));
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   5987 epoll_scheduler::register_descriptor( 249   6028 epoll_scheduler::register_descriptor(
250   int fd, reactor_descriptor_state* desc) const 250   int fd, reactor_descriptor_state* desc) const
251   { 251   {
HITCBC 252   5987 epoll_event ev{}; 252   6028 epoll_event ev{};
HITCBC 253   5987 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP; 253   6028 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP;
HITCBC 254   5987 ev.data.ptr = desc; 254   6028 ev.data.ptr = desc;
255   255  
HITCBC 256   5987 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0) 256   6028 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   5980 desc->registered_events = ev.events; 259   6021 desc->registered_events = ev.events;
HITCBC 260   5980 desc->fd = fd; 260   6021 desc->fd = fd;
HITCBC 261   5980 desc->scheduler_ = this; 261   6021 desc->scheduler_ = this;
HITCBC 262   5980 desc->mutex.set_enabled(reactor_io_locking_); 262   6021 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 263   5980 desc->ready_events_.store(0, std::memory_order_relaxed); 263   6021 desc->ready_events_.store(0, std::memory_order_relaxed);
264   264  
HITCBC 265   5980 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 265   6021 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 266   5980 desc->impl_ref_.reset(); 266   6021 desc->impl_ref_.reset();
HITCBC 267   5980 desc->read_ready = false; 267   6021 desc->read_ready = false;
HITCBC 268   5980 desc->write_ready = false; 268   6021 desc->write_ready = false;
HITCBC 269   5980 return {}; 269   6021 return {};
HITCBC 270   5980 } 270   6021 }
271   271  
272   inline void 272   inline void
HITCBC 273   5905 epoll_scheduler::deregister_descriptor(int fd) const 273   5946 epoll_scheduler::deregister_descriptor(int fd) const
274   { 274   {
HITCBC 275   5905 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr); 275   5946 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr);
HITCBC 276   5905 } 276   5946 }
277   277  
278   inline void 278   inline void
HITCBC 279   7838 epoll_scheduler::interrupt_reactor() const 279   7715 epoll_scheduler::interrupt_reactor() const
280   { 280   {
HITCBC 281   7838 bool expected = false; 281   7715 bool expected = false;
HITCBC 282   7838 if (eventfd_armed_.compare_exchange_strong( 282   7715 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   6348 std::uint64_t val = 1; 286   6197 std::uint64_t val = 1;
HITCBC 287   6348 if (::write(event_fd_, &val, sizeof(val)) < 0) 287   6197 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   7838 } 299   7715 }
300   300  
301   inline void 301   inline void
HITCBC 302   11064 epoll_scheduler::update_timerfd() const 302   11302 epoll_scheduler::update_timerfd() const
303   { 303   {
HITCBC 304   11064 auto nearest = timer_svc_->nearest_expiry(); 304   11302 auto nearest = timer_svc_->nearest_expiry();
305   305  
HITCBC 306   11064 itimerspec ts{}; 306   11302 itimerspec ts{};
HITCBC 307   11064 int flags = 0; 307   11302 int flags = 0;
308   308  
HITCBC 309   11064 if (nearest == timer_service::time_point::max()) 309   11302 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   9878 auto now = std::chrono::steady_clock::now(); 315   10170 auto now = std::chrono::steady_clock::now();
HITCBC 316   9878 if (nearest <= now) 316   10170 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   1432 ts.it_value.tv_nsec = 1; 319   747 ts.it_value.tv_nsec = 1;
320   } 320   }
321   else 321   else
322   { 322   {
HITCBC 323   8446 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>( 323   9423 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(
HITCBC 324   8446 nearest - now) 324   9423 nearest - now)
HITCBC 325   8446 .count(); 325   9423 .count();
HITCBC 326   8446 ts.it_value.tv_sec = nsec / 1000000000; 326   9423 ts.it_value.tv_sec = nsec / 1000000000;
HITCBC 327   8446 ts.it_value.tv_nsec = nsec % 1000000000; 327   9423 ts.it_value.tv_nsec = nsec % 1000000000;
HITCBC 328   8446 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0) 328   9423 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   11064 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0) 333   11302 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   11063 } 335   11301 }
336   336  
337   inline void 337   inline void
HITCBC 338   40629 epoll_scheduler::run_task(lock_type& lock, context_type& ctx, long timeout_us) 338   41247 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   40629 if (task_interrupted_) 341   41247 if (task_interrupted_)
HITCBC 342   28746 timeout_ms = 0; 342   29512 timeout_ms = 0;
HITCBC 343   11883 else if (timeout_us < 0) 343   11735 else if (timeout_us < 0)
HITCBC 344   11461 timeout_ms = -1; 344   11462 timeout_ms = -1;
345   else 345   else
HITCBC 346   422 timeout_ms = static_cast<int>((timeout_us + 999) / 1000); 346   273 timeout_ms = static_cast<int>((timeout_us + 999) / 1000);
347   347  
HITCBC 348   40629 if (lock.owns_lock()) 348   41247 if (lock.owns_lock())
HITCBC 349   11885 lock.unlock(); 349   11737 lock.unlock();
350   350  
HITCBC 351   40629 task_cleanup on_exit{this, &lock, ctx}; 351   41247 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   40629 if (timerfd_stale_.exchange(false, std::memory_order_acquire)) 354   41247 if (timerfd_stale_.exchange(false, std::memory_order_acquire))
HITCBC 355   3829 update_timerfd(); 355   3689 update_timerfd();
356   356  
HITCBC 357   40628 int nfds = ::epoll_wait( 357   41246 int nfds = ::epoll_wait(
HITCBC 358   40628 epoll_fd_, event_buffer_.data(), static_cast<int>(event_buffer_.size()), 358   41246 epoll_fd_, event_buffer_.data(), static_cast<int>(event_buffer_.size()),
359   timeout_ms); 359   timeout_ms);
360   360  
HITCBC 361   40628 if (nfds < 0 && errno != EINTR) 361   41246 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   40627 bool check_timers = false; 364   41245 bool check_timers = false;
HITCBC 365   40627 ready_queue local_ops; 365   41245 ready_queue local_ops;
366   366  
HITCBC 367   90833 for (int i = 0; i < nfds; ++i) 367   90472 for (int i = 0; i < nfds; ++i)
368   { 368   {
HITCBC 369   50206 if (event_buffer_[i].data.ptr == nullptr) 369   49227 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   5046 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val)); 373   4895 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val));
HITCBC 374   5046 eventfd_armed_.store(false, std::memory_order_relaxed); 374   4895 eventfd_armed_.store(false, std::memory_order_relaxed);
HITCBC 375   5046 continue; 375   4895 continue;
HITCBC 376   5046 } 376   4895 }
377   377  
HITCBC 378   45160 if (event_buffer_[i].data.ptr == &timer_fd_) 378   44332 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   7235 ::read(timer_fd_, &expirations, sizeof(expirations)); 383   7613 ::read(timer_fd_, &expirations, sizeof(expirations));
HITCBC 384   7235 check_timers = true; 384   7613 check_timers = true;
HITCBC 385   7235 continue; 385   7613 continue;
HITCBC 386   7235 } 386   7613 }
387   387  
388   auto* desc = 388   auto* desc =
HITCBC 389   37925 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr); 389   36719 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr);
HITCBC 390   37925 desc->add_ready_events(event_buffer_[i].events); 390   36719 desc->add_ready_events(event_buffer_[i].events);
391   391  
HITCBC 392   37925 bool expected = false; 392   36719 bool expected = false;
HITCBC 393   37925 if (desc->is_enqueued_.compare_exchange_strong( 393   36719 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   37925 local_ops.push(desc); 397   36719 local_ops.push(desc);
398   } 398   }
399   } 399   }
400   400  
HITCBC 401   40627 if (check_timers) 401   41245 if (check_timers)
402   { 402   {
HITCBC 403   7235 timer_svc_->process_expired(); 403   7613 timer_svc_->process_expired();
HITCBC 404   7235 update_timerfd(); 404   7613 update_timerfd();
405   } 405   }
406   406  
HITCBC 407   40627 lock.lock(); 407   41245 lock.lock();
408   408  
HITCBC 409   40627 completed_ops_.splice(local_ops); 409   41245 completed_ops_.splice(local_ops);
HITCBC 410   40629 } 410   41247 }
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