. /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   817 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int) 157   825 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int)
HITCBC 158   817 : epoll_fd_(-1) 158   825 : epoll_fd_(-1)
HITCBC 159   817 , event_fd_(-1) 159   825 , event_fd_(-1)
HITCBC 160   817 , timer_fd_(-1) 160   825 , timer_fd_(-1)
HITCBC 161   1634 , event_buffer_(max_events_per_poll_) 161   1650 , event_buffer_(max_events_per_poll_)
162   { 162   {
HITCBC 163   817 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC); 163   825 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC);
HITCBC 164   817 if (epoll_fd_ < 0) 164   825 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   817 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); 167   825 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
HITCBC 168   817 if (event_fd_ < 0) 168   825 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   817 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC); 175   825 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
HITCBC 176   817 if (timer_fd_ < 0) 176   825 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   817 epoll_event ev{}; 184   825 epoll_event ev{};
HITCBC 185   817 ev.events = EPOLLIN | EPOLLET; 185   825 ev.events = EPOLLIN | EPOLLET;
HITCBC 186   817 ev.data.ptr = nullptr; 186   825 ev.data.ptr = nullptr;
HITCBC 187   817 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0) 187   825 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   817 epoll_event timer_ev{}; 196   825 epoll_event timer_ev{};
HITCBC 197   817 timer_ev.events = EPOLLIN | EPOLLERR; 197   825 timer_ev.events = EPOLLIN | EPOLLERR;
HITCBC 198   817 timer_ev.data.ptr = &timer_fd_; 198   825 timer_ev.data.ptr = &timer_fd_;
HITCBC 199   817 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0) 199   825 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   817 timer_svc_ = &get_timer_service(ctx, *this); 208   825 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 209   817 timer_svc_->set_on_earliest_changed( 209   825 timer_svc_->set_on_earliest_changed(
HITCBC 210   6540 timer_service::callback(this, [](void* p) { 210   6366 timer_service::callback(this, [](void* p) {
HITCBC 211   5723 auto* self = static_cast<epoll_scheduler*>(p); 211   5541 auto* self = static_cast<epoll_scheduler*>(p);
HITCBC 212   5723 self->timerfd_stale_.store(true, std::memory_order_release); 212   5541 self->timerfd_stale_.store(true, std::memory_order_release);
HITCBC 213   5723 self->interrupt_reactor(); 213   5541 self->interrupt_reactor();
HITCBC 214   5723 })); 214   5541 }));
215   215  
HITCBC 216   817 get_resolver_service(ctx, *this); 216   825 get_resolver_service(ctx, *this);
HITCBC 217   817 get_signal_service(ctx, *this); 217   825 get_signal_service(ctx, *this);
HITCBC 218   817 get_stream_file_service(ctx, *this); 218   825 get_stream_file_service(ctx, *this);
HITCBC 219   817 get_random_access_file_service(ctx, *this); 219   825 get_random_access_file_service(ctx, *this);
220   220  
HITCBC 221   817 completed_ops_.push(&task_op_); 221   825 completed_ops_.push(&task_op_);
HITCBC 222   817 } 222   825 }
223   223  
HITCBC 224   1634 inline epoll_scheduler::~epoll_scheduler() 224   1650 inline epoll_scheduler::~epoll_scheduler()
225   { 225   {
HITCBC 226   817 if (timer_fd_ >= 0) 226   825 if (timer_fd_ >= 0)
HITCBC 227   817 ::close(timer_fd_); 227   825 ::close(timer_fd_);
HITCBC 228   817 if (event_fd_ >= 0) 228   825 if (event_fd_ >= 0)
HITCBC 229   817 ::close(event_fd_); 229   825 ::close(event_fd_);
HITCBC 230   817 if (epoll_fd_ >= 0) 230   825 if (epoll_fd_ >= 0)
HITCBC 231   817 ::close(epoll_fd_); 231   825 ::close(epoll_fd_);
HITCBC 232   1634 } 232   1650 }
233   233  
234   inline void 234   inline void
HITCBC 235   817 epoll_scheduler::shutdown() 235   825 epoll_scheduler::shutdown()
236   { 236   {
HITCBC 237   817 shutdown_drain(); 237   825 shutdown_drain();
238   238  
HITCBC 239   817 if (event_fd_ >= 0) 239   825 if (event_fd_ >= 0)
HITCBC 240   817 interrupt_reactor(); 240   825 interrupt_reactor();
HITCBC 241   817 } 241   825 }
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   10424 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const 256   10003 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const
257   { 257   {
HITCBC 258   10424 epoll_event ev{}; 258   10003 epoll_event ev{};
HITCBC 259   10424 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP; 259   10003 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP;
HITCBC 260   10424 ev.data.ptr = desc; 260   10003 ev.data.ptr = desc;
261   261  
HITCBC 262   10424 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0) 262   10003 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   10424 desc->registered_events = ev.events; 265   10003 desc->registered_events = ev.events;
HITCBC 266   10424 desc->fd = fd; 266   10003 desc->fd = fd;
HITCBC 267   10424 desc->scheduler_ = this; 267   10003 desc->scheduler_ = this;
HITCBC 268   10424 desc->mutex.set_enabled(reactor_io_locking_); 268   10003 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 269   10424 desc->ready_events_.store(0, std::memory_order_relaxed); 269   10003 desc->ready_events_.store(0, std::memory_order_relaxed);
270   270  
HITCBC 271   10424 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 271   10003 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 272   10424 desc->impl_ref_.reset(); 272   10003 desc->impl_ref_.reset();
HITCBC 273   10424 desc->read_ready = false; 273   10003 desc->read_ready = false;
HITCBC 274   10424 desc->write_ready = false; 274   10003 desc->write_ready = false;
HITCBC 275   10424 } 275   10003 }
276   276  
277   inline void 277   inline void
HITCBC 278   10373 epoll_scheduler::deregister_descriptor(int fd) const 278   9952 epoll_scheduler::deregister_descriptor(int fd) const
279   { 279   {
HITCBC 280   10373 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr); 280   9952 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr);
HITCBC 281   10373 } 281   9952 }
282   282  
283   inline void 283   inline void
HITCBC 284   7271 epoll_scheduler::interrupt_reactor() const 284   7112 epoll_scheduler::interrupt_reactor() const
285   { 285   {
HITCBC 286   7271 bool expected = false; 286   7112 bool expected = false;
HITCBC 287   7271 if (eventfd_armed_.compare_exchange_strong( 287   7112 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   6174 std::uint64_t val = 1; 291   5968 std::uint64_t val = 1;
HITCBC 292   6174 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val)); 292   5968 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val));
293   } 293   }
HITCBC 294   7271 } 294   7112 }
295   295  
296   inline void 296   inline void
HITCBC 297   10255 epoll_scheduler::update_timerfd() const 297   9811 epoll_scheduler::update_timerfd() const
298   { 298   {
HITCBC 299   10255 auto nearest = timer_svc_->nearest_expiry(); 299   9811 auto nearest = timer_svc_->nearest_expiry();
300   300  
HITCBC 301   10255 itimerspec ts{}; 301   9811 itimerspec ts{};
HITCBC 302   10255 int flags = 0; 302   9811 int flags = 0;
303   303  
HITCBC 304   10255 if (nearest == timer_service::time_point::max()) 304   9811 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   10084 auto now = std::chrono::steady_clock::now(); 310   9639 auto now = std::chrono::steady_clock::now();
HITCBC 311   10084 if (nearest <= now) 311   9639 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   523 ts.it_value.tv_nsec = 1; 314   860 ts.it_value.tv_nsec = 1;
315   } 315   }
316   else 316   else
317   { 317   {
HITCBC 318   9561 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>( 318   8779 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(
HITCBC 319   9561 nearest - now) 319   8779 nearest - now)
HITCBC 320   9561 .count(); 320   8779 .count();
HITCBC 321   9561 ts.it_value.tv_sec = nsec / 1000000000; 321   8779 ts.it_value.tv_sec = nsec / 1000000000;
HITCBC 322   9561 ts.it_value.tv_nsec = nsec % 1000000000; 322   8779 ts.it_value.tv_nsec = nsec % 1000000000;
HITCBC 323   9561 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0) 323   8779 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   10255 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0) 328   9811 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   10255 } 330   9811 }
331   331  
332   inline void 332   inline void
HITCBC 333   56244 epoll_scheduler::run_task( 333   55110 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   56244 if (task_interrupted_) 337   55110 if (task_interrupted_)
HITCBC 338   41497 timeout_ms = 0; 338   41568 timeout_ms = 0;
HITCBC 339   14747 else if (timeout_us < 0) 339   13542 else if (timeout_us < 0)
HITCBC 340   14743 timeout_ms = -1; 340   13538 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   56244 if (lock.owns_lock()) 344   55110 if (lock.owns_lock())
HITCBC 345   14749 lock.unlock(); 345   13544 lock.unlock();
346   346  
HITCBC 347   56244 task_cleanup on_exit{this, &lock, ctx}; 347   55110 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   56244 if (timerfd_stale_.exchange(false, std::memory_order_acquire)) 350   55110 if (timerfd_stale_.exchange(false, std::memory_order_acquire))
HITCBC 351   5135 update_timerfd(); 351   4913 update_timerfd();
352   352  
HITCBC 353   56244 int nfds = ::epoll_wait( 353   55110 int nfds = ::epoll_wait(
354   epoll_fd_, event_buffer_.data(), 354   epoll_fd_, event_buffer_.data(),
HITCBC 355   56244 static_cast<int>(event_buffer_.size()), timeout_ms); 355   55110 static_cast<int>(event_buffer_.size()), timeout_ms);
356   356  
HITCBC 357   56244 if (nfds < 0 && errno != EINTR) 357   55110 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   56244 bool check_timers = false; 360   55110 bool check_timers = false;
HITCBC 361   56244 ready_queue local_ops; 361   55110 ready_queue local_ops;
362   362  
HITCBC 363   126675 for (int i = 0; i < nfds; ++i) 363   125755 for (int i = 0; i < nfds; ++i)
364   { 364   {
HITCBC 365   70431 if (event_buffer_[i].data.ptr == nullptr) 365   70645 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   5357 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val)); 369   5143 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val));
HITCBC 370   5357 eventfd_armed_.store(false, std::memory_order_relaxed); 370   5143 eventfd_armed_.store(false, std::memory_order_relaxed);
HITCBC 371   5357 continue; 371   5143 continue;
HITCBC 372   5357 } 372   5143 }
373   373  
HITCBC 374   65074 if (event_buffer_[i].data.ptr == &timer_fd_) 374   65502 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   5120 ::read(timer_fd_, &expirations, sizeof(expirations)); 379   4898 ::read(timer_fd_, &expirations, sizeof(expirations));
HITCBC 380   5120 check_timers = true; 380   4898 check_timers = true;
HITCBC 381   5120 continue; 381   4898 continue;
HITCBC 382   5120 } 382   4898 }
383   383  
384   auto* desc = 384   auto* desc =
HITCBC 385   59954 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr); 385   60604 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr);
HITCBC 386   59954 desc->add_ready_events(event_buffer_[i].events); 386   60604 desc->add_ready_events(event_buffer_[i].events);
387   387  
HITCBC 388   59954 bool expected = false; 388   60604 bool expected = false;
HITCBC 389   59954 if (desc->is_enqueued_.compare_exchange_strong( 389   60604 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   59954 local_ops.push(desc); 393   60604 local_ops.push(desc);
394   } 394   }
395   } 395   }
396   396  
HITCBC 397   56244 if (check_timers) 397   55110 if (check_timers)
398   { 398   {
HITCBC 399   5120 timer_svc_->process_expired(); 399   4898 timer_svc_->process_expired();
HITCBC 400   5120 update_timerfd(); 400   4898 update_timerfd();
401   } 401   }
402   402  
HITCBC 403   56244 lock.lock(); 403   55110 lock.lock();
404   404  
HITCBC 405   56244 completed_ops_.splice(local_ops); 405   55110 completed_ops_.splice(local_ops);
HITCBC 406   56244 } 406   55110 }
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