. /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   41 void register_signal_reader(int read_fd) override
127   { 127   {
HITCBC 128   51 register_descriptor(read_fd, signal_pipe_reader_.arm()); 128   41 register_descriptor(read_fd, signal_pipe_reader_.arm());
HITCBC 129   51 } 129   41 }
130   130  
131   private: 131   private:
132   void 132   void
133   run_task(lock_type& lock, context_type* ctx, 133   run_task(lock_type& lock, context_type* ctx,
134   long timeout_us) override; 134   long timeout_us) override;
135   void interrupt_reactor() const override; 135   void interrupt_reactor() const override;
136   void update_timerfd() const; 136   void update_timerfd() const;
137   137  
138   int epoll_fd_; 138   int epoll_fd_;
139   int event_fd_; 139   int event_fd_;
140   int timer_fd_; 140   int timer_fd_;
141   141  
142   // Watches the global signal self-pipe's read end (armed lazily by 142   // Watches the global signal self-pipe's read end (armed lazily by
143   // register_signal_reader on the first signal registration). 143   // register_signal_reader on the first signal registration).
144   reactor_signal_pipe_reader signal_pipe_reader_; 144   reactor_signal_pipe_reader signal_pipe_reader_;
145   145  
146   // Edge-triggered eventfd state 146   // Edge-triggered eventfd state
147   mutable std::atomic<bool> eventfd_armed_{false}; 147   mutable std::atomic<bool> eventfd_armed_{false};
148   148  
149   // Set when the earliest timer changes; flushed before epoll_wait 149   // Set when the earliest timer changes; flushed before epoll_wait
150   mutable std::atomic<bool> timerfd_stale_{false}; 150   mutable std::atomic<bool> timerfd_stale_{false};
151   151  
152   // Event buffer sized from max_events_per_poll_ (set at construction, 152   // Event buffer sized from max_events_per_poll_ (set at construction,
153   // resized by configure_reactor via io_context_options). 153   // resized by configure_reactor via io_context_options).
154   std::vector<epoll_event> event_buffer_; 154   std::vector<epoll_event> event_buffer_;
155   }; 155   };
156   156  
HITCBC 157   785 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int) 157   648 inline epoll_scheduler::epoll_scheduler(capy::execution_context& ctx, int)
HITCBC 158   785 : epoll_fd_(-1) 158   648 : epoll_fd_(-1)
HITCBC 159   785 , event_fd_(-1) 159   648 , event_fd_(-1)
HITCBC 160   785 , timer_fd_(-1) 160   648 , timer_fd_(-1)
HITCBC 161   1570 , event_buffer_(max_events_per_poll_) 161   1296 , event_buffer_(max_events_per_poll_)
162   { 162   {
HITCBC 163   785 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC); 163   648 epoll_fd_ = ::epoll_create1(EPOLL_CLOEXEC);
HITCBC 164   785 if (epoll_fd_ < 0) 164   648 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   785 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); 167   648 event_fd_ = ::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
HITCBC 168   785 if (event_fd_ < 0) 168   648 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   785 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC); 175   648 timer_fd_ = ::timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
HITCBC 176   785 if (timer_fd_ < 0) 176   648 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   785 epoll_event ev{}; 184   648 epoll_event ev{};
HITCBC 185   785 ev.events = EPOLLIN | EPOLLET; 185   648 ev.events = EPOLLIN | EPOLLET;
HITCBC 186   785 ev.data.ptr = nullptr; 186   648 ev.data.ptr = nullptr;
HITCBC 187   785 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, event_fd_, &ev) < 0) 187   648 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   785 epoll_event timer_ev{}; 196   648 epoll_event timer_ev{};
HITCBC 197   785 timer_ev.events = EPOLLIN | EPOLLERR; 197   648 timer_ev.events = EPOLLIN | EPOLLERR;
HITCBC 198   785 timer_ev.data.ptr = &timer_fd_; 198   648 timer_ev.data.ptr = &timer_fd_;
HITCBC 199   785 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &timer_ev) < 0) 199   648 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   785 timer_svc_ = &get_timer_service(ctx, *this); 208   648 timer_svc_ = &get_timer_service(ctx, *this);
HITCBC 209   785 timer_svc_->set_on_earliest_changed( 209   648 timer_svc_->set_on_earliest_changed(
HITCBC 210   3990 timer_service::callback(this, [](void* p) { 210   5733 timer_service::callback(this, [](void* p) {
HITCBC 211   3205 auto* self = static_cast<epoll_scheduler*>(p); 211   5085 auto* self = static_cast<epoll_scheduler*>(p);
HITCBC 212   3205 self->timerfd_stale_.store(true, std::memory_order_release); 212   5085 self->timerfd_stale_.store(true, std::memory_order_release);
HITCBC 213   3205 self->interrupt_reactor(); 213   5085 self->interrupt_reactor();
HITCBC 214   3205 })); 214   5085 }));
215   215  
HITCBC 216   785 get_resolver_service(ctx, *this); 216   648 get_resolver_service(ctx, *this);
HITCBC 217   785 get_signal_service(ctx, *this); 217   648 get_signal_service(ctx, *this);
HITCBC 218   785 get_stream_file_service(ctx, *this); 218   648 get_stream_file_service(ctx, *this);
HITCBC 219   785 get_random_access_file_service(ctx, *this); 219   648 get_random_access_file_service(ctx, *this);
220   220  
HITCBC 221   785 completed_ops_.push(&task_op_); 221   648 completed_ops_.push(&task_op_);
HITCBC 222   785 } 222   648 }
223   223  
HITCBC 224   1570 inline epoll_scheduler::~epoll_scheduler() 224   1296 inline epoll_scheduler::~epoll_scheduler()
225   { 225   {
HITCBC 226   785 if (timer_fd_ >= 0) 226   648 if (timer_fd_ >= 0)
HITCBC 227   785 ::close(timer_fd_); 227   648 ::close(timer_fd_);
HITCBC 228   785 if (event_fd_ >= 0) 228   648 if (event_fd_ >= 0)
HITCBC 229   785 ::close(event_fd_); 229   648 ::close(event_fd_);
HITCBC 230   785 if (epoll_fd_ >= 0) 230   648 if (epoll_fd_ >= 0)
HITCBC 231   785 ::close(epoll_fd_); 231   648 ::close(epoll_fd_);
HITCBC 232   1570 } 232   1296 }
233   233  
234   inline void 234   inline void
HITCBC 235   785 epoll_scheduler::shutdown() 235   648 epoll_scheduler::shutdown()
236   { 236   {
HITCBC 237   785 shutdown_drain(); 237   648 shutdown_drain();
238   238  
HITCBC 239   785 if (event_fd_ >= 0) 239   648 if (event_fd_ >= 0)
HITCBC 240   785 interrupt_reactor(); 240   648 interrupt_reactor();
HITCBC 241   785 } 241   648 }
242   242  
243   inline void 243   inline void
HITCBC 244   19 epoll_scheduler::configure_reactor( 244   16 epoll_scheduler::configure_reactor(
245   unsigned max_events, 245   unsigned max_events,
246   unsigned budget_init, 246   unsigned budget_init,
247   unsigned budget_max, 247   unsigned budget_max,
248   unsigned unassisted) 248   unsigned unassisted)
249   { 249   {
HITCBC 250   19 reactor_scheduler::configure_reactor( 250   16 reactor_scheduler::configure_reactor(
251   max_events, budget_init, budget_max, unassisted); 251   max_events, budget_init, budget_max, unassisted);
HITCBC 252   18 event_buffer_.resize(max_events_per_poll_); 252   15 event_buffer_.resize(max_events_per_poll_);
HITCBC 253   18 } 253   15 }
254   254  
255   inline void 255   inline void
HITCBC 256   5253 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const 256   9067 epoll_scheduler::register_descriptor(int fd, reactor_descriptor_state* desc) const
257   { 257   {
HITCBC 258   5253 epoll_event ev{}; 258   9067 epoll_event ev{};
HITCBC 259   5253 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP; 259   9067 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLERR | EPOLLHUP;
HITCBC 260   5253 ev.data.ptr = desc; 260   9067 ev.data.ptr = desc;
261   261  
HITCBC 262   5253 if (::epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) < 0) 262   9067 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   5253 desc->registered_events = ev.events; 265   9067 desc->registered_events = ev.events;
HITCBC 266   5253 desc->fd = fd; 266   9067 desc->fd = fd;
HITCBC 267   5253 desc->scheduler_ = this; 267   9067 desc->scheduler_ = this;
HITCBC 268   5253 desc->mutex.set_enabled(reactor_io_locking_); 268   9067 desc->mutex.set_enabled(reactor_io_locking_);
HITCBC 269   5253 desc->ready_events_.store(0, std::memory_order_relaxed); 269   9067 desc->ready_events_.store(0, std::memory_order_relaxed);
270   270  
HITCBC 271   5253 conditionally_enabled_mutex::scoped_lock lock(desc->mutex); 271   9067 conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
HITCBC 272   5253 desc->impl_ref_.reset(); 272   9067 desc->impl_ref_.reset();
HITCBC 273   5253 desc->read_ready = false; 273   9067 desc->read_ready = false;
HITCBC 274   5253 desc->write_ready = false; 274   9067 desc->write_ready = false;
HITCBC 275   5253 } 275   9067 }
276   276  
277   inline void 277   inline void
HITCBC 278   5202 epoll_scheduler::deregister_descriptor(int fd) const 278   9026 epoll_scheduler::deregister_descriptor(int fd) const
279   { 279   {
HITCBC 280   5202 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr); 280   9026 ::epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr);
HITCBC 281   5202 } 281   9026 }
282   282  
283   inline void 283   inline void
HITCBC 284   4689 epoll_scheduler::interrupt_reactor() const 284   6265 epoll_scheduler::interrupt_reactor() const
285   { 285   {
HITCBC 286   4689 bool expected = false; 286   6265 bool expected = false;
HITCBC 287   4689 if (eventfd_armed_.compare_exchange_strong( 287   6265 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   3529 std::uint64_t val = 1; 291   5346 std::uint64_t val = 1;
HITCBC 292   3529 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val)); 292   5346 [[maybe_unused]] auto r = ::write(event_fd_, &val, sizeof(val));
293   } 293   }
HITCBC 294   4689 } 294   6265 }
295   295  
296   inline void 296   inline void
HITCBC 297   5057 epoll_scheduler::update_timerfd() const 297   9071 epoll_scheduler::update_timerfd() const
298   { 298   {
HITCBC 299   5057 auto nearest = timer_svc_->nearest_expiry(); 299   9071 auto nearest = timer_svc_->nearest_expiry();
300   300  
HITCBC 301   5057 itimerspec ts{}; 301   9071 itimerspec ts{};
HITCBC 302   5057 int flags = 0; 302   9071 int flags = 0;
303   303  
HITCBC 304   5057 if (nearest == timer_service::time_point::max()) 304   9071 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   4906 auto now = std::chrono::steady_clock::now(); 310   8933 auto now = std::chrono::steady_clock::now();
HITCBC 311   4906 if (nearest <= now) 311   8933 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   218 ts.it_value.tv_nsec = 1; 314   566 ts.it_value.tv_nsec = 1;
315   } 315   }
316   else 316   else
317   { 317   {
HITCBC 318   4688 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>( 318   8367 auto nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(
HITCBC 319   4688 nearest - now) 319   8367 nearest - now)
HITCBC 320   4688 .count(); 320   8367 .count();
HITCBC 321   4688 ts.it_value.tv_sec = nsec / 1000000000; 321   8367 ts.it_value.tv_sec = nsec / 1000000000;
HITCBC 322   4688 ts.it_value.tv_nsec = nsec % 1000000000; 322   8367 ts.it_value.tv_nsec = nsec % 1000000000;
HITCBC 323   4688 if (ts.it_value.tv_sec == 0 && ts.it_value.tv_nsec == 0) 323   8367 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   5057 if (::timerfd_settime(timer_fd_, flags, &ts, nullptr) < 0) 328   9071 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   5057 } 330   9071 }
331   331  
332   inline void 332   inline void
HITCBC 333   31536 epoll_scheduler::run_task( 333   38537 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   31536 if (task_interrupted_) 337   38537 if (task_interrupted_)
HITCBC 338   24232 timeout_ms = 0; 338   25640 timeout_ms = 0;
HITCBC 339   7304 else if (timeout_us < 0) 339   12897 else if (timeout_us < 0)
HITCBC 340   7300 timeout_ms = -1; 340   12893 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   31536 if (lock.owns_lock()) 344   38537 if (lock.owns_lock())
HITCBC 345   7306 lock.unlock(); 345   12899 lock.unlock();
346   346  
HITCBC 347   31536 task_cleanup on_exit{this, &lock, ctx}; 347   38537 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   31536 if (timerfd_stale_.exchange(false, std::memory_order_acquire)) 350   38537 if (timerfd_stale_.exchange(false, std::memory_order_acquire))
HITCBC 351   2536 update_timerfd(); 351   4541 update_timerfd();
352   352  
HITCBC 353   31536 int nfds = ::epoll_wait( 353   38537 int nfds = ::epoll_wait(
354   epoll_fd_, event_buffer_.data(), 354   epoll_fd_, event_buffer_.data(),
HITCBC 355   31536 static_cast<int>(event_buffer_.size()), timeout_ms); 355   38537 static_cast<int>(event_buffer_.size()), timeout_ms);
356   356  
HITCBC 357   31536 if (nfds < 0 && errno != EINTR) 357   38537 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   31536 bool check_timers = false; 360   38537 bool check_timers = false;
HITCBC 361   31536 ready_queue local_ops; 361   38537 ready_queue local_ops;
362   362  
HITCBC 363   73172 for (int i = 0; i < nfds; ++i) 363   87336 for (int i = 0; i < nfds; ++i)
364   { 364   {
HITCBC 365   41636 if (event_buffer_[i].data.ptr == nullptr) 365   48799 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   2744 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val)); 369   4698 [[maybe_unused]] auto r = ::read(event_fd_, &val, sizeof(val));
HITCBC 370   2744 eventfd_armed_.store(false, std::memory_order_relaxed); 370   4698 eventfd_armed_.store(false, std::memory_order_relaxed);
HITCBC 371   2744 continue; 371   4698 continue;
HITCBC 372   2744 } 372   4698 }
373   373  
HITCBC 374   38892 if (event_buffer_[i].data.ptr == &timer_fd_) 374   44101 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   2521 ::read(timer_fd_, &expirations, sizeof(expirations)); 379   4530 ::read(timer_fd_, &expirations, sizeof(expirations));
HITCBC 380   2521 check_timers = true; 380   4530 check_timers = true;
HITCBC 381   2521 continue; 381   4530 continue;
HITCBC 382   2521 } 382   4530 }
383   383  
384   auto* desc = 384   auto* desc =
HITCBC 385   36371 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr); 385   39571 static_cast<reactor_descriptor_state*>(event_buffer_[i].data.ptr);
HITCBC 386   36371 desc->add_ready_events(event_buffer_[i].events); 386   39571 desc->add_ready_events(event_buffer_[i].events);
387   387  
HITCBC 388   36371 bool expected = false; 388   39571 bool expected = false;
HITCBC 389   36371 if (desc->is_enqueued_.compare_exchange_strong( 389   39571 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   36371 local_ops.push(desc); 393   39571 local_ops.push(desc);
394   } 394   }
395   } 395   }
396   396  
HITCBC 397   31536 if (check_timers) 397   38537 if (check_timers)
398   { 398   {
HITCBC 399   2521 timer_svc_->process_expired(); 399   4530 timer_svc_->process_expired();
HITCBC 400   2521 update_timerfd(); 400   4530 update_timerfd();
401   } 401   }
402   402  
HITCBC 403   31536 lock.lock(); 403   38537 lock.lock();
404   404  
HITCBC 405   31536 completed_ops_.splice(local_ops); 405   38537 completed_ops_.splice(local_ops);
HITCBC 406   31536 } 406   38537 }
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