. /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   51 void register_signal_reader(int read_fd) override 126   51 void register_signal_reader(int read_fd) override
127   { 127   {
HITCBC 128   51 register_descriptor(read_fd, signal_pipe_reader_.arm()); 128   51 register_descriptor(read_fd, signal_pipe_reader_.arm());
HITCBC 129   51 } 129   51 }
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   791 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int) 157   791 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int)
HITCBC 158   791 : epoll_fd_(-1) 158   791 : epoll_fd_(-1)
HITCBC 159   791 , event_fd_(-1) 159   791 , event_fd_(-1)
HITCBC 160   791 , timer_fd_(-1) 160   791 , timer_fd_(-1)
HITCBC 161   1582 , event_buffer_(max_events_per_poll_) 161   1582 , event_buffer_(max_events_per_poll_)
162   { 162   {
HITCBC 163   791 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC); 163   791 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC);
HITCBC 164   791 if (epoll_fd_ < 0) 164   791 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   791 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); 167   791 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
HITCBC 168   791 if (event_fd_ < 0) 168   791 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   791 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC); 175   791 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
HITCBC 176   791 if (timer_fd_ < 0) 176   791 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   791 epoll_event ev{}; 184   791 epoll_event ev{};
HITCBC 185   791 ev.events = EPOLLIN | EPOLLET; 185   791 ev.events = EPOLLIN | EPOLLET;
HITCBC 186   791 ev.data.ptr = nullptr; 186   791 ev.data.ptr = nullptr;
HITCBC 187   791 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0) 187   791 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   791 epoll_event timer_ev{}; 196   791 epoll_event timer_ev{};
HITCBC 197   791 timer_ev.events = EPOLLIN | EPOLLERR; 197   791 timer_ev.events = EPOLLIN | EPOLLERR;
HITCBC 198   791 timer_ev.data.ptr = &timer_fd_; 198   791 timer_ev.data.ptr = &timer_fd_;
HITCBC 199   791 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0) 199   791 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   791 timer_svc_ = &get_timer_service(ctx, *this); 208   791 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 209   791 timer_svc_->set_on_earliest_changed( 209   791 timer_svc_->set_on_earliest_changed(
HITCBC 210   3985 timer_service::callback(this, [](void* p) { 210   3903 timer_service::callback(this, [](void* p) {
HITCBC 211   3194 auto* self = static_cast<epoll_scheduler*>(p); 211   3112 auto* self = static_cast<epoll_scheduler*>(p);
HITCBC 212   3194 self->timerfd_stale_.store(true, std::memory_order_release); 212   3112 self->timerfd_stale_.store(true, std::memory_order_release);
HITCBC 213   3194 self->interrupt_reactor(); 213   3112 self->interrupt_reactor();
HITCBC 214   3194 })); 214   3112 }));
215   215  
HITCBC 216   791 get_resolver_service(ctx, *this); 216   791 get_resolver_service(ctx, *this);
HITCBC 217   791 get_signal_service(ctx, *this); 217   791 get_signal_service(ctx, *this);
HITCBC 218   791 get_stream_file_service(ctx, *this); 218   791 get_stream_file_service(ctx, *this);
HITCBC 219   791 get_random_access_file_service(ctx, *this); 219   791 get_random_access_file_service(ctx, *this);
220   220  
HITCBC 221   791 completed_ops_.push(&task_op_); 221   791 completed_ops_.push(&task_op_);
HITCBC 222   791 } 222   791 }
223   223  
HITCBC 224   1582 inline epoll_scheduler::~epoll_scheduler() 224   1582 inline epoll_scheduler::~epoll_scheduler()
225   { 225   {
HITCBC 226   791 if (timer_fd_ >= 0) 226   791 if (timer_fd_ >= 0)
HITCBC 227   791 ::close(timer_fd_); 227   791 ::close(timer_fd_);
HITCBC 228   791 if (event_fd_ >= 0) 228   791 if (event_fd_ >= 0)
HITCBC 229   791 ::close(event_fd_); 229   791 ::close(event_fd_);
HITCBC 230   791 if (epoll_fd_ >= 0) 230   791 if (epoll_fd_ >= 0)
HITCBC 231   791 ::close(epoll_fd_); 231   791 ::close(epoll_fd_);
HITCBC 232   1582 } 232   1582 }
233   233  
234   inline void 234   inline void
HITCBC 235   791 epoll_scheduler::shutdown() 235   791 epoll_scheduler::shutdown()
236   { 236   {
HITCBC 237   791 shutdown_drain(); 237   791 shutdown_drain();
238   238  
HITCBC 239   791 if (event_fd_ >= 0) 239   791 if (event_fd_ >= 0)
HITCBC 240   791 interrupt_reactor(); 240   791 interrupt_reactor();
HITCBC 241   791 } 241   791 }
242   242  
243   inline void 243   inline void
HITCBC 244   19 epoll_scheduler::configure_reactor( 244   19 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   19 reactor_scheduler::configure_reactor( 250   19 reactor_scheduler::configure_reactor(
251   max_events, budget_init, budget_max, unassisted); 251   max_events, budget_init, budget_max, unassisted);
HITCBC 252   18 event_buffer_.resize(max_events_per_poll_); 252   18 event_buffer_.resize(max_events_per_poll_);
HITCBC 253   18 } 253   18 }
254   254  
255   inline void 255   inline void
HITCBC 256   5224 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const 256   5157 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const
257   { 257   {
HITCBC 258   5224 epoll_event ev{}; 258   5157 epoll_event ev{};
HITCBC 259   5224 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP; 259   5157 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP;
HITCBC 260   5224 ev.data.ptr = desc; 260   5157 ev.data.ptr = desc;
261   261  
HITCBC 262   5224 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0) 262   5157 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   5224 desc->registered_events = ev.events; 265   5157 desc->registered_events = ev.events;
HITCBC 266   5224 desc->fd = fd; 266   5157 desc->fd = fd;
HITCBC 267   5224 desc->scheduler_ = this; 267   5157 desc->scheduler_ = this;
HITCBC 268   5224 desc->mutex.set_enabled(reactor_io_locking_); 268   5157 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 269   5224 desc->ready_events_.store(0, std::memory_order_relaxed); 269   5157 desc->ready_events_.store(0, std::memory_order_relaxed);
270   270  
HITCBC 271   5224 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 271   5157 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 272   5224 desc->impl_ref_.reset(); 272   5157 desc->impl_ref_.reset();
HITCBC 273   5224 desc->read_ready = false; 273   5157 desc->read_ready = false;
HITCBC 274   5224 desc->write_ready = false; 274   5157 desc->write_ready = false;
HITCBC 275   5224 } 275   5157 }
276   276  
277   inline void 277   inline void
HITCBC 278   5173 epoll_scheduler::deregister_descriptor(int fd) const 278   5106 epoll_scheduler::deregister_descriptor(int fd) const
279   { 279   {
HITCBC 280   5173 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr); 280   5106 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr);
HITCBC 281   5173 } 281   5106 }
282   282  
283   inline void 283   inline void
HITCBC 284   4690 epoll_scheduler::interrupt_reactor() const 284   4614 epoll_scheduler::interrupt_reactor() const
285   { 285   {
HITCBC 286   4690 bool expected = false; 286   4614 bool expected = false;
HITCBC 287   4690 if (eventfd_armed_.compare_exchange_strong( 287   4614 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   3524 std::uint64_t val = 1; 291   3498 std::uint64_t val = 1;
HITCBC 292   3524 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val)); 292   3498 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val));
293   } 293   }
HITCBC 294   4690 } 294   4614 }
295   295  
296   inline void 296   inline void
HITCBC 297   5029 epoll_scheduler::update_timerfd() const 297   4963 epoll_scheduler::update_timerfd() const
298   { 298   {
HITCBC 299   5029 auto nearest = timer_svc_->nearest_expiry(); 299   4963 auto nearest = timer_svc_->nearest_expiry();
300   300  
HITCBC 301   5029 itimerspec ts{}; 301   4963 itimerspec ts{};
HITCBC 302   5029 int flags = 0; 302   4963 int flags = 0;
303   303  
HITCBC 304   5029 if (nearest == timer_service::time_point::max()) 304   4963 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   4878 auto now = std::chrono::steady_clock::now(); 310   4810 auto now = std::chrono::steady_clock::now();
HITCBC 311   4878 if (nearest <= now) 311   4810 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   172 ts.it_value.tv_nsec = 1; 314   253 ts.it_value.tv_nsec = 1;
315   } 315   }
316   else 316   else
317   { 317   {
HITCBC 318   4706 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>( 318   4557 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(
HITCBC 319   4706 nearest - now) 319   4557 nearest - now)
HITCBC 320   4706 .count(); 320   4557 .count();
HITCBC 321   4706 ts.it_value.tv_sec = nsec / 1000000000; 321   4557 ts.it_value.tv_sec = nsec / 1000000000;
HITCBC 322   4706 ts.it_value.tv_nsec = nsec % 1000000000; 322   4557 ts.it_value.tv_nsec = nsec % 1000000000;
HITCBC 323   4706 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0) 323   4557 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   5029 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0) 328   4963 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   5029 } 330   4963 }
331   331  
332   inline void 332   inline void
HITCBC 333   33191 epoll_scheduler::run_task( 333   31513 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   33191 if (task_interrupted_) 337   31513 if (task_interrupted_)
HITCBC 338   25893 timeout_ms = 0; 338   24389 timeout_ms = 0;
HITCBC 339   7298 else if (timeout_us < 0) 339   7124 else if (timeout_us < 0)
HITCBC 340   7294 timeout_ms = -1; 340   7120 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   33191 if (lock.owns_lock()) 344   31513 if (lock.owns_lock())
HITCBC 345   7300 lock.unlock(); 345   7126 lock.unlock();
346   346  
HITCBC 347   33191 task_cleanup on_exit{this, &lock, ctx}; 347   31513 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   33191 if (timerfd_stale_.exchange(false, std::memory_order_acquire)) 350   31513 if (timerfd_stale_.exchange(false, std::memory_order_acquire))
HITCBC 351   2523 update_timerfd(); 351   2489 update_timerfd();
352   352  
HITCBC 353   33191 int nfds = ::epoll_wait( 353   31513 int nfds = ::epoll_wait(
354   epoll_fd_, event_buffer_.data(), 354   epoll_fd_, event_buffer_.data(),
HITCBC 355   33191 static_cast<int>(event_buffer_.size()), timeout_ms); 355   31513 static_cast<int>(event_buffer_.size()), timeout_ms);
356   356  
HITCBC 357   33191 if (nfds < 0 && errno != EINTR) 357   31513 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   33191 bool check_timers = false; 360   31513 bool check_timers = false;
HITCBC 361   33191 ready_queue local_ops; 361   31513 ready_queue local_ops;
362   362  
HITCBC 363   75884 for (int i = 0; i < nfds; ++i) 363   73265 for (int i = 0; i < nfds; ++i)
364   { 364   {
HITCBC 365   42693 if (event_buffer_[i].data.ptr == nullptr) 365   41752 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   2733 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val)); 369   2707 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val));
HITCBC 370   2733 eventfd_armed_.store(false, std::memory_order_relaxed); 370   2707 eventfd_armed_.store(false, std::memory_order_relaxed);
HITCBC 371   2733 continue; 371   2707 continue;
HITCBC 372   2733 } 372   2707 }
373   373  
HITCBC 374   39960 if (event_buffer_[i].data.ptr == &timer_fd_) 374   39045 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   2506 ::read(timer_fd_, &expirations, sizeof(expirations)); 379   2474 ::read(timer_fd_, &expirations, sizeof(expirations));
HITCBC 380   2506 check_timers = true; 380   2474 check_timers = true;
HITCBC 381   2506 continue; 381   2474 continue;
HITCBC 382   2506 } 382   2474 }
383   383  
384   auto* desc = 384   auto* desc =
HITCBC 385   37454 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr); 385   36571 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr);
HITCBC 386   37454 desc->add_ready_events(event_buffer_[i].events); 386   36571 desc->add_ready_events(event_buffer_[i].events);
387   387  
HITCBC 388   37454 bool expected = false; 388   36571 bool expected = false;
HITCBC 389   37454 if (desc->is_enqueued_.compare_exchange_strong( 389   36571 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   37454 local_ops.push(desc); 393   36571 local_ops.push(desc);
394   } 394   }
395   } 395   }
396   396  
HITCBC 397   33191 if (check_timers) 397   31513 if (check_timers)
398   { 398   {
HITCBC 399   2506 timer_svc_->process_expired(); 399   2474 timer_svc_->process_expired();
HITCBC 400   2506 update_timerfd(); 400   2474 update_timerfd();
401   } 401   }
402   402  
HITCBC 403   33191 lock.lock(); 403   31513 lock.lock();
404   404  
HITCBC 405   33191 completed_ops_.splice(local_ops); 405   31513 completed_ops_.splice(local_ops);
HITCBC 406   33191 } 406   31513 }
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