. /include/boost/corosio /detail /timer_service.hpp
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1   // 1   //
2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com) 2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3   // Copyright (c) 2026 Steve Gerbino 3   // Copyright (c) 2026 Steve Gerbino
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_DETAIL_TIMER_SERVICE_HPP 11   #ifndef BOOST_COROSIO_DETAIL_TIMER_SERVICE_HPP
12   #define BOOST_COROSIO_DETAIL_TIMER_SERVICE_HPP 12   #define BOOST_COROSIO_DETAIL_TIMER_SERVICE_HPP
13   13  
14   #include <boost/corosio/detail/timer.hpp> 14   #include <boost/corosio/detail/timer.hpp>
15   #include <boost/corosio/detail/scheduler.hpp> 15   #include <boost/corosio/detail/scheduler.hpp>
16   #include <boost/corosio/detail/scheduler_op.hpp> 16   #include <boost/corosio/detail/scheduler_op.hpp>
17   #include <boost/corosio/detail/intrusive.hpp> 17   #include <boost/corosio/detail/intrusive.hpp>
18   #include <boost/corosio/detail/thread_local_ptr.hpp> 18   #include <boost/corosio/detail/thread_local_ptr.hpp>
19   #include <boost/capy/error.hpp> 19   #include <boost/capy/error.hpp>
20   #include <boost/capy/ex/execution_context.hpp> 20   #include <boost/capy/ex/execution_context.hpp>
21   #include <boost/capy/ex/executor_ref.hpp> 21   #include <boost/capy/ex/executor_ref.hpp>
22   #include <system_error> 22   #include <system_error>
23   23  
24   #include <atomic> 24   #include <atomic>
25   #include <chrono> 25   #include <chrono>
26   #include <coroutine> 26   #include <coroutine>
27   #include <cstddef> 27   #include <cstddef>
28   #include <limits> 28   #include <limits>
29   #include <mutex> 29   #include <mutex>
30   #include <stop_token> 30   #include <stop_token>
31   #include <utility> 31   #include <utility>
32   #include <vector> 32   #include <vector>
33   33  
34   namespace boost::corosio::detail { 34   namespace boost::corosio::detail {
35   35  
36   struct scheduler; 36   struct scheduler;
37   37  
38   /* 38   /*
39   Timer Service 39   Timer Service
40   ============= 40   =============
41   41  
42   Data Structures 42   Data Structures
43   --------------- 43   ---------------
44   waiter_node (defined in timer.hpp) holds per-waiter state: 44   waiter_node (defined in timer.hpp) holds per-waiter state:
45   coroutine handle, executor, error output, embedded 45   coroutine handle, executor, error output, embedded
46   completion_op. Each concurrent co_await t.wait() embeds one 46   completion_op. Each concurrent co_await t.wait() embeds one
47   waiter_node in the awaitable on the suspended coroutine's 47   waiter_node in the awaitable on the suspended coroutine's
48   frame — waits perform no allocation. 48   frame — waits perform no allocation.
49   49  
50   timer::implementation holds per-timer state: expiry, heap 50   timer::implementation holds per-timer state: expiry, heap
51   index, and the single published waiter. Each timer holds 51   index, and the single published waiter. Each timer holds
52   at most one waiter; process_expired's local cross-timer drain 52   at most one waiter; process_expired's local cross-timer drain
53   list still threads waiters through their intrusive hooks when 53   list still threads waiters through their intrusive hooks when
54   collecting several timers' waiters past the lock. 54   collecting several timers' waiters past the lock.
55   55  
56   timer_service owns a min-heap of active timers and a free list 56   timer_service owns a min-heap of active timers and a free list
57   of recycled impls. The heap is ordered by expiry time; the 57   of recycled impls. The heap is ordered by expiry time; the
58   scheduler queries nearest_expiry() to set the epoll/timerfd 58   scheduler queries nearest_expiry() to set the epoll/timerfd
59   timeout. 59   timeout.
60   60  
61   Optimization Strategy 61   Optimization Strategy
62   --------------------- 62   ---------------------
63   1. Deferred heap insertion — expires_after() stores the expiry 63   1. Deferred heap insertion — expires_after() stores the expiry
64   but does not insert into the heap. Insertion happens in wait(). 64   but does not insert into the heap. Insertion happens in wait().
65   2. Thread-local impl cache — single-slot per-thread cache. 65   2. Thread-local impl cache — single-slot per-thread cache.
66   3. Frame-resident waiter_node with embedded completion_op — 66   3. Frame-resident waiter_node with embedded completion_op —
67   eliminates heap allocation per wait/fire/cancel. 67   eliminates heap allocation per wait/fire/cancel.
68   4. Cached nearest expiry — atomic avoids mutex in nearest_expiry(). 68   4. Cached nearest expiry — atomic avoids mutex in nearest_expiry().
69   5. might_have_pending_waits_ flag — skips lock when no wait issued. 69   5. might_have_pending_waits_ flag — skips lock when no wait issued.
70   70  
71   Concurrency 71   Concurrency
72   ----------- 72   -----------
73   stop_token callbacks can fire from any thread. The impl_ 73   stop_token callbacks can fire from any thread. The impl_
74   pointer on waiter_node is used as a "still in list" marker. 74   pointer on waiter_node is used as a "still in list" marker.
75   A waiter_node's storage is the suspended coroutine's frame: 75   A waiter_node's storage is the suspended coroutine's frame:
76   every completion path must finish touching the node before 76   every completion path must finish touching the node before
77   posting the continuation or destroying the handle. 77   posting the continuation or destroying the handle.
78   */ 78   */
79   79  
80   inline void timer_service_invalidate_cache() noexcept; 80   inline void timer_service_invalidate_cache() noexcept;
81   81  
82   // timer_service class body — member function definitions are 82   // timer_service class body — member function definitions are
83   // out-of-class (after implementation and waiter_node are complete) 83   // out-of-class (after implementation and waiter_node are complete)
84   class BOOST_COROSIO_DECL timer_service final 84   class BOOST_COROSIO_DECL timer_service final
85   : public capy::execution_context::service 85   : public capy::execution_context::service
86   , public io_object::io_service 86   , public io_object::io_service
87   { 87   {
88   public: 88   public:
89   using clock_type = std::chrono::steady_clock; 89   using clock_type = std::chrono::steady_clock;
90   using time_point = clock_type::time_point; 90   using time_point = clock_type::time_point;
91   91  
92   /// Type-erased callback for earliest-expiry-changed notifications. 92   /// Type-erased callback for earliest-expiry-changed notifications.
93   class callback 93   class callback
94   { 94   {
95   void* ctx_ = nullptr; 95   void* ctx_ = nullptr;
96   void (*fn_)(void*) = nullptr; 96   void (*fn_)(void*) = nullptr;
97   97  
98   public: 98   public:
99   /// Construct an empty callback. 99   /// Construct an empty callback.
HITCBC 100   2106 callback() = default; 100   2106 callback() = default;
101   101  
102   /// Construct a callback with the given context and function. 102   /// Construct a callback with the given context and function.
HITCBC 103   2106 callback(void* ctx, void (*fn)(void*)) noexcept : ctx_(ctx), fn_(fn) {} 103   2106 callback(void* ctx, void (*fn)(void*)) noexcept : ctx_(ctx), fn_(fn) {}
104   104  
105   /// Return true if the callback is non-empty. 105   /// Return true if the callback is non-empty.
106   explicit operator bool() const noexcept 106   explicit operator bool() const noexcept
107   { 107   {
108   return fn_ != nullptr; 108   return fn_ != nullptr;
109   } 109   }
110   110  
111   /// Invoke the callback. 111   /// Invoke the callback.
HITCBC 112   7263 void operator()() const 112   6893 void operator()() const
113   { 113   {
HITCBC 114   7263 if (fn_) 114   6893 if (fn_)
HITCBC 115   7263 fn_(ctx_); 115   6893 fn_(ctx_);
HITCBC 116   7263 } 116   6893 }
117   }; 117   };
118   118  
119   private: 119   private:
120   struct heap_entry 120   struct heap_entry
121   { 121   {
122   time_point time_; 122   time_point time_;
123   timer::implementation* timer_; 123   timer::implementation* timer_;
124   }; 124   };
125   125  
126   scheduler* sched_ = nullptr; 126   scheduler* sched_ = nullptr;
127   BOOST_COROSIO_MSVC_WARNING_PUSH 127   BOOST_COROSIO_MSVC_WARNING_PUSH
128   BOOST_COROSIO_MSVC_WARNING_DISABLE(4251) // std:: members, dll-interface 128   BOOST_COROSIO_MSVC_WARNING_DISABLE(4251) // std:: members, dll-interface
129   mutable std::mutex mutex_; 129   mutable std::mutex mutex_;
130   std::vector<heap_entry> heap_; 130   std::vector<heap_entry> heap_;
131   timer::implementation* free_list_ = nullptr; 131   timer::implementation* free_list_ = nullptr;
132   callback on_earliest_changed_; 132   callback on_earliest_changed_;
133   bool shutting_down_ = false; 133   bool shutting_down_ = false;
134   // Avoids mutex in nearest_expiry() and empty() 134   // Avoids mutex in nearest_expiry() and empty()
135   mutable std::atomic<std::int64_t> cached_nearest_ns_{ 135   mutable std::atomic<std::int64_t> cached_nearest_ns_{
136   (std::numeric_limits<std::int64_t>::max)()}; 136   (std::numeric_limits<std::int64_t>::max)()};
137   BOOST_COROSIO_MSVC_WARNING_POP 137   BOOST_COROSIO_MSVC_WARNING_POP
138   138  
139   public: 139   public:
140   /// Construct the timer service bound to a scheduler. 140   /// Construct the timer service bound to a scheduler.
HITCBC 141   2106 inline timer_service(capy::execution_context&, scheduler& sched) 141   2106 inline timer_service(capy::execution_context&, scheduler& sched)
HITCBC 142   2106 : sched_(&sched) 142   2106 : sched_(&sched)
143   { 143   {
HITCBC 144   2106 } 144   2106 }
145   145  
146   /// Return the associated scheduler. 146   /// Return the associated scheduler.
HITCBC 147   28263 inline scheduler& get_scheduler() noexcept 147   27925 inline scheduler& get_scheduler() noexcept
148   { 148   {
HITCBC 149   28263 return *sched_; 149   27925 return *sched_;
150   } 150   }
151   151  
152   /// Destroy the timer service. 152   /// Destroy the timer service.
HITCBC 153   4212 ~timer_service() override = default; 153   4212 ~timer_service() override = default;
154   154  
155   timer_service(timer_service const&) = delete; 155   timer_service(timer_service const&) = delete;
156   timer_service& operator=(timer_service const&) = delete; 156   timer_service& operator=(timer_service const&) = delete;
157   157  
158   /// Register a callback invoked when the earliest expiry changes. 158   /// Register a callback invoked when the earliest expiry changes.
HITCBC 159   2106 inline void set_on_earliest_changed(callback cb) 159   2106 inline void set_on_earliest_changed(callback cb)
160   { 160   {
HITCBC 161   2106 on_earliest_changed_ = cb; 161   2106 on_earliest_changed_ = cb;
HITCBC 162   2106 } 162   2106 }
163   163  
164   /// Return true if no timers are in the heap. 164   /// Return true if no timers are in the heap.
165   inline bool empty() const noexcept 165   inline bool empty() const noexcept
166   { 166   {
167   return cached_nearest_ns_.load(std::memory_order_acquire) == 167   return cached_nearest_ns_.load(std::memory_order_acquire) ==
168   (std::numeric_limits<std::int64_t>::max)(); 168   (std::numeric_limits<std::int64_t>::max)();
169   } 169   }
170   170  
171   /// Return the nearest timer expiry without acquiring the mutex. 171   /// Return the nearest timer expiry without acquiring the mutex.
HITCBC 172   278762 inline time_point nearest_expiry() const noexcept 172   264506 inline time_point nearest_expiry() const noexcept
173   { 173   {
HITCBC 174   278762 auto ns = cached_nearest_ns_.load(std::memory_order_acquire); 174   264506 auto ns = cached_nearest_ns_.load(std::memory_order_acquire);
HITCBC 175   278762 return time_point(time_point::duration(ns)); 175   264506 return time_point(time_point::duration(ns));
176   } 176   }
177   177  
178   /// Cancel all pending timers and free cached resources. 178   /// Cancel all pending timers and free cached resources.
179   inline void shutdown() override; 179   inline void shutdown() override;
180   180  
181   /// Construct a new timer implementation. 181   /// Construct a new timer implementation.
182   inline io_object::implementation* construct() override; 182   inline io_object::implementation* construct() override;
183   183  
184   /// Destroy a timer implementation, cancelling pending waiters. 184   /// Destroy a timer implementation, cancelling pending waiters.
185   inline void destroy(io_object::implementation* p) override; 185   inline void destroy(io_object::implementation* p) override;
186   186  
187   /// Cancel and recycle a timer implementation. 187   /// Cancel and recycle a timer implementation.
188   inline void destroy_impl(timer::implementation& impl); 188   inline void destroy_impl(timer::implementation& impl);
189   189  
190   /// Publish the timer's waiter and insert the timer into the heap. 190   /// Publish the timer's waiter and insert the timer into the heap.
191   inline void insert_waiter(timer::implementation& impl, waiter_node* w); 191   inline void insert_waiter(timer::implementation& impl, waiter_node* w);
192   192  
193   /// Cancel the timer's published waiter, if any. 193   /// Cancel the timer's published waiter, if any.
194   inline void cancel_timer(timer::implementation& impl); 194   inline void cancel_timer(timer::implementation& impl);
195   195  
196   /// Cancel one specific waiter ( stop_token callback path ). 196   /// Cancel one specific waiter ( stop_token callback path ).
197   inline void cancel_waiter(waiter_node* w); 197   inline void cancel_waiter(waiter_node* w);
198   198  
199   /// Complete all waiters whose timers have expired. 199   /// Complete all waiters whose timers have expired.
200   inline std::size_t process_expired(); 200   inline std::size_t process_expired();
201   201  
202   private: 202   private:
HITCBC 203   318718 inline void refresh_cached_nearest() noexcept 203   305443 inline void refresh_cached_nearest() noexcept
204   { 204   {
HITCBC 205   318718 auto ns = heap_.empty() ? (std::numeric_limits<std::int64_t>::max)() 205   305443 auto ns = heap_.empty() ? (std::numeric_limits<std::int64_t>::max)()
HITCBC 206   313735 : heap_[0].time_.time_since_epoch().count(); 206   300595 : heap_[0].time_.time_since_epoch().count();
HITCBC 207   318718 cached_nearest_ns_.store(ns, std::memory_order_release); 207   305443 cached_nearest_ns_.store(ns, std::memory_order_release);
HITCBC 208   318718 } 208   305443 }
209   209  
210   inline void remove_timer_impl(timer::implementation& impl); 210   inline void remove_timer_impl(timer::implementation& impl);
211   inline void up_heap(std::size_t index); 211   inline void up_heap(std::size_t index);
212   inline void down_heap(std::size_t index); 212   inline void down_heap(std::size_t index);
213   inline void swap_heap(std::size_t i1, std::size_t i2); 213   inline void swap_heap(std::size_t i1, std::size_t i2);
214   }; 214   };
215   215  
216   // Thread-local cache avoids hot-path mutex acquisitions: 216   // Thread-local cache avoids hot-path mutex acquisitions:
217   // single-slot impl cache, validated by comparing svc_. Cleared by 217   // single-slot impl cache, validated by comparing svc_. Cleared by
218   // timer_service_invalidate_cache() during shutdown. 218   // timer_service_invalidate_cache() during shutdown.
219   219  
220   inline thread_local_ptr<timer::implementation> tl_cached_impl; 220   inline thread_local_ptr<timer::implementation> tl_cached_impl;
221   221  
222   // The POD TLS slot above never runs destructors, so a short-lived 222   // The POD TLS slot above never runs destructors, so a short-lived
223   // run() thread would leak its cached impl. Each push arms this 223   // run() thread would leak its cached impl. Each push arms this
224   // owner, whose destructor frees the slot at thread exit. A cached 224   // owner, whose destructor frees the slot at thread exit. A cached
225   // entry is a quiescent heap object (nothing in the heap or free 225   // entry is a quiescent heap object (nothing in the heap or free
226   // list) and deletion touches no service state, so it is safe after 226   // list) and deletion touches no service state, so it is safe after
227   // the owning service is gone (the stale-entry path in 227   // the owning service is gone (the stale-entry path in
228   // try_pop_tl_cache deletes the same way). 228   // try_pop_tl_cache deletes the same way).
229   struct tl_cache_owner 229   struct tl_cache_owner
230   { 230   {
HITCBC 231   42 ~tl_cache_owner() 231   42 ~tl_cache_owner()
232   { 232   {
HITCBC 233   42 delete tl_cached_impl.get(); 233   42 delete tl_cached_impl.get();
HITCBC 234   42 tl_cached_impl.set(nullptr); 234   42 tl_cached_impl.set(nullptr);
HITCBC 235   42 } 235   42 }
236   }; 236   };
237   237  
238   inline void 238   inline void
HITCBC 239   14186 arm_tl_cache_cleanup() noexcept 239   13845 arm_tl_cache_cleanup() noexcept
240   { 240   {
HITCBC 241   14186 [[maybe_unused]] thread_local tl_cache_owner owner; 241   13845 [[maybe_unused]] thread_local tl_cache_owner owner;
HITCBC 242   14186 } 242   13845 }
243   243  
244   inline timer::implementation* 244   inline timer::implementation*
HITCBC 245   14999 try_pop_tl_cache(timer_service* svc) noexcept 245   14828 try_pop_tl_cache(timer_service* svc) noexcept
246   { 246   {
HITCBC 247   14999 auto* impl = tl_cached_impl.get(); 247   14828 auto* impl = tl_cached_impl.get();
HITCBC 248   14999 if (impl) 248   14828 if (impl)
249   { 249   {
HITCBC 250   13783 tl_cached_impl.set(nullptr); 250   13442 tl_cached_impl.set(nullptr);
HITCBC 251   13783 if (impl->svc_ == svc) 251   13442 if (impl->svc_ == svc)
HITCBC 252   13783 return impl; 252   13442 return impl;
253   // Stale impl from a destroyed service 253   // Stale impl from a destroyed service
MISUBC 254   ✗ delete impl; 254   ✗ delete impl;
255   } 255   }
HITCBC 256   1216 return nullptr; 256   1386 return nullptr;
257   } 257   }
258   258  
259   inline bool 259   inline bool
HITCBC 260   14970 try_push_tl_cache(timer::implementation* impl) noexcept 260   14799 try_push_tl_cache(timer::implementation* impl) noexcept
261   { 261   {
HITCBC 262   14970 if (!tl_cached_impl.get()) 262   14799 if (!tl_cached_impl.get())
263   { 263   {
HITCBC 264   14186 arm_tl_cache_cleanup(); 264   13845 arm_tl_cache_cleanup();
HITCBC 265   14186 tl_cached_impl.set(impl); 265   13845 tl_cached_impl.set(impl);
HITCBC 266   14186 return true; 266   13845 return true;
267   } 267   }
HITCBC 268   784 return false; 268   954 return false;
269   } 269   }
270   270  
271   inline void 271   inline void
HITCBC 272   2106 timer_service_invalidate_cache() noexcept 272   2106 timer_service_invalidate_cache() noexcept
273   { 273   {
HITCBC 274   2106 delete tl_cached_impl.get(); 274   2106 delete tl_cached_impl.get();
HITCBC 275   2106 tl_cached_impl.set(nullptr); 275   2106 tl_cached_impl.set(nullptr);
HITCBC 276   2106 } 276   2106 }
277   277  
278   // timer_service out-of-class member function definitions 278   // timer_service out-of-class member function definitions
279   279  
280   inline void 280   inline void
HITCBC 281   2106 timer_service::shutdown() 281   2106 timer_service::shutdown()
282   { 282   {
HITCBC 283   2106 timer_service_invalidate_cache(); 283   2106 timer_service_invalidate_cache();
HITCBC 284   2106 shutting_down_ = true; 284   2106 shutting_down_ = true;
285   285  
286   // Snapshot impls and detach them from the heap so that 286   // Snapshot impls and detach them from the heap so that
287   // coroutine-owned timer destructors (triggered by h.destroy() 287   // coroutine-owned timer destructors (triggered by h.destroy()
288   // below) cannot re-enter remove_timer_impl() and mutate the 288   // below) cannot re-enter remove_timer_impl() and mutate the
289   // vector during iteration. 289   // vector during iteration.
HITCBC 290   2106 std::vector<timer::implementation*> impls; 290   2106 std::vector<timer::implementation*> impls;
HITCBC 291   2106 impls.reserve(heap_.size()); 291   2106 impls.reserve(heap_.size());
HITCBC 292   2135 for (auto& entry : heap_) 292   2135 for (auto& entry : heap_)
293   { 293   {
HITCBC 294   29 entry.timer_->heap_index_.store( 294   29 entry.timer_->heap_index_.store(
295   (std::numeric_limits<std::size_t>::max)(), 295   (std::numeric_limits<std::size_t>::max)(),
296   std::memory_order_relaxed); 296   std::memory_order_relaxed);
HITCBC 297   29 impls.push_back(entry.timer_); 297   29 impls.push_back(entry.timer_);
298   } 298   }
HITCBC 299   2106 heap_.clear(); 299   2106 heap_.clear();
HITCBC 300   2106 cached_nearest_ns_.store( 300   2106 cached_nearest_ns_.store(
301   (std::numeric_limits<std::int64_t>::max)(), std::memory_order_release); 301   (std::numeric_limits<std::int64_t>::max)(), std::memory_order_release);
302   302  
303   // Cancel waiting timers. Each waiter called work_started() 303   // Cancel waiting timers. Each waiter called work_started()
304   // in implementation::wait(). On IOCP the scheduler shutdown 304   // in implementation::wait(). On IOCP the scheduler shutdown
305   // loop exits when outstanding_work_ reaches zero, so we must 305   // loop exits when outstanding_work_ reaches zero, so we must
306   // call work_finished() here to balance it. On other backends 306   // call work_finished() here to balance it. On other backends
307   // this is harmless. 307   // this is harmless.
HITCBC 308   2135 for (auto* impl : impls) 308   2135 for (auto* impl : impls)
309   { 309   {
HITCBC 310   29 if (auto* w = std::exchange(impl->waiter_, nullptr)) 310   29 if (auto* w = std::exchange(impl->waiter_, nullptr))
311   { 311   {
HITCBC 312   29 w->reset_stop_cb(); 312   29 w->reset_stop_cb();
HITCBC 313   29 auto h = std::exchange(w->h_, {}); 313   29 auto h = std::exchange(w->h_, {});
HITCBC 314   29 sched_->work_finished(); 314   29 sched_->work_finished();
315   // Destroying the frame also ends the node's storage 315   // Destroying the frame also ends the node's storage
HITCBC 316   29 if (h) 316   29 if (h)
HITCBC 317   29 h.destroy(); 317   29 h.destroy();
318   } 318   }
HITCBC 319   29 delete impl; 319   29 delete impl;
320   } 320   }
321   321  
322   // Delete free-listed impls 322   // Delete free-listed impls
HITCBC 323   2888 while (free_list_) 323   3058 while (free_list_)
324   { 324   {
HITCBC 325   782 auto* next = free_list_->next_free_; 325   952 auto* next = free_list_->next_free_;
HITCBC 326   782 delete free_list_; 326   952 delete free_list_;
HITCBC 327   782 free_list_ = next; 327   952 free_list_ = next;
328   } 328   }
HITCBC 329   2106 } 329   2106 }
330   330  
331   inline io_object::implementation* 331   inline io_object::implementation*
HITCBC 332   14999 timer_service::construct() 332   14828 timer_service::construct()
333   { 333   {
HITCBC 334   14999 timer::implementation* impl = try_pop_tl_cache(this); 334   14828 timer::implementation* impl = try_pop_tl_cache(this);
HITCBC 335   14999 if (impl) 335   14828 if (impl)
336   { 336   {
HITCBC 337 - 13783 impl->svc_ = this; 337 + 13442 impl->svc_ = this;
338   // Reset expiry_ too: a recycled impl must behave like a fresh 338   // Reset expiry_ too: a recycled impl must behave like a fresh
339   // one, whose default expiry reads as already elapsed 339   // one, whose default expiry reads as already elapsed
HITCBC 340   13783 impl->expiry_ = {}; 340   13442 impl->expiry_ = {};
HITCBC 341   13783 impl->heap_index_.store( 341   13442 impl->heap_index_.store(
342   (std::numeric_limits<std::size_t>::max)(), 342   (std::numeric_limits<std::size_t>::max)(),
343   std::memory_order_relaxed); 343   std::memory_order_relaxed);
HITCBC 344   13783 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed); 344   13442 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed);
HITCBC 345   13783 BOOST_COROSIO_ASSERT(impl->waiter_ == nullptr); 345   13442 BOOST_COROSIO_ASSERT(impl->waiter_ == nullptr);
HITCBC 346   13783 return impl; 346   13442 return impl;
347   } 347   }
348   348  
HITCBC 349   1216 std::lock_guard lock(mutex_); 349   1386 std::lock_guard lock(mutex_);
HITCBC 350   1216 if (free_list_) 350   1386 if (free_list_)
351   { 351   {
HITCBC 352 - 2 impl = free_list_; 352 + 2 impl = free_list_;
HITCBC 353 - 2 free_list_ = impl->next_free_; 353 + 2 free_list_ = impl->next_free_;
HITCBC 354 - 2 impl->next_free_ = nullptr; 354 + 2 impl->next_free_ = nullptr;
HITCBC 355 - 2 impl->svc_ = this; 355 + 2 impl->svc_ = this;
HITCBC 356 - 2 impl->expiry_ = {}; 356 + 2 impl->expiry_ = {};
HITCBC 357   2 impl->heap_index_.store( 357   2 impl->heap_index_.store(
358   (std::numeric_limits<std::size_t>::max)(), 358   (std::numeric_limits<std::size_t>::max)(),
359   std::memory_order_relaxed); 359   std::memory_order_relaxed);
HITCBC 360   2 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed); 360   2 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed);
HITCBC 361   2 BOOST_COROSIO_ASSERT(impl->waiter_ == nullptr); 361   2 BOOST_COROSIO_ASSERT(impl->waiter_ == nullptr);
362   } 362   }
363   else 363   else
364   { 364   {
HITCBC 365   1214 impl = new timer::implementation(*this); 365   1384 impl = new timer::implementation(*this);
366   } 366   }
HITCBC 367   1216 return impl; 367   1386 return impl;
HITCBC 368   1216 } 368   1386 }
369   369  
370   inline void 370   inline void
HITCBC 371   14999 timer_service::destroy(io_object::implementation* p) 371   14828 timer_service::destroy(io_object::implementation* p)
372   { 372   {
373   // During shutdown the drain loop owns every impl and deletes 373   // During shutdown the drain loop owns every impl and deletes
374   // them directly. A frame destroyed by that loop can unwind a 374   // them directly. A frame destroyed by that loop can unwind a
375   // handle whose impl was freed in an earlier iteration (a 375   // handle whose impl was freed in an earlier iteration (a
376   // timeout's parent frame owns the timeout timer while 376   // timeout's parent frame owns the timeout timer while
377   // suspended on the inner delay's timer), so bail out before 377   // suspended on the inner delay's timer), so bail out before
378   // even downcasting the pointer. 378   // even downcasting the pointer.
HITCBC 379   14999 if (shutting_down_) 379   14828 if (shutting_down_)
HITCBC 380   29 return; 380   29 return;
HITCBC 381   14970 destroy_impl(static_cast<timer::implementation&>(*p)); 381   14799 destroy_impl(static_cast<timer::implementation&>(*p));
382   } 382   }
383   383  
384   inline void 384   inline void
HITCBC 385   14970 timer_service::destroy_impl(timer::implementation& impl) 385   14799 timer_service::destroy_impl(timer::implementation& impl)
386   { 386   {
387   // During shutdown the impl is owned by the shutdown loop. 387   // During shutdown the impl is owned by the shutdown loop.
388   // Re-entering here (from a coroutine-owned timer destructor 388   // Re-entering here (from a coroutine-owned timer destructor
389   // triggered by h.destroy()) must not modify the heap or 389   // triggered by h.destroy()) must not modify the heap or
390   // recycle the impl — shutdown deletes it directly. 390   // recycle the impl — shutdown deletes it directly.
HITCBC 391   14970 if (shutting_down_) 391   14799 if (shutting_down_)
HITCBC 392   14186 return; 392   13845 return;
393   393  
HITCBC 394   14970 cancel_timer(impl); 394   14799 cancel_timer(impl);
395   395  
HITCBC 396   29940 if (impl.heap_index_.load(std::memory_order_relaxed) != 396   29598 if (impl.heap_index_.load(std::memory_order_relaxed) !=
HITCBC 397   14970 (std::numeric_limits<std::size_t>::max)()) 397   14799 (std::numeric_limits<std::size_t>::max)())
398   { 398   {
MISUBC 399   ✗ std::lock_guard lock(mutex_); 399   ✗ std::lock_guard lock(mutex_);
MISUBC 400   ✗ remove_timer_impl(impl); 400   ✗ remove_timer_impl(impl);
MISUBC 401   ✗ refresh_cached_nearest(); 401   ✗ refresh_cached_nearest();
MISUBC 402   ✗ } 402   ✗ }
403   403  
HITCBC 404   14970 if (try_push_tl_cache(&impl)) 404   14799 if (try_push_tl_cache(&impl))
HITCBC 405   14186 return; 405   13845 return;
406   406  
HITCBC 407   784 std::lock_guard lock(mutex_); 407   954 std::lock_guard lock(mutex_);
HITCBC 408   784 impl.next_free_ = free_list_; 408   954 impl.next_free_ = free_list_;
HITCBC 409   784 free_list_ = &impl; 409   954 free_list_ = &impl;
HITCBC 410   784 } 410   954 }
411   411  
412   inline void 412   inline void
HITCBC 413   18239 timer_service::insert_waiter(timer::implementation& impl, waiter_node* w) 413   18038 timer_service::insert_waiter(timer::implementation& impl, waiter_node* w)
414   { 414   {
HITCBC 415   18239 bool notify = false; 415   18038 bool notify = false;
HITCBC 416   18239 bool lost_cancel = false; 416   18038 bool lost_cancel = false;
417   { 417   {
HITCBC 418   18239 std::lock_guard lock(mutex_); 418   18038 std::lock_guard lock(mutex_);
419   // Grow before publishing anything, so the push_back below 419   // Grow before publishing anything, so the push_back below
420   // cannot throw: a failure here leaves the waiter untouched, 420   // cannot throw: a failure here leaves the waiter untouched,
421   // the strong guarantee rearm_wait's recovery relies on. 421   // the strong guarantee rearm_wait's recovery relies on.
HITCBC 422   18239 if (impl.heap_index_.load(std::memory_order_relaxed) == 422   18038 if (impl.heap_index_.load(std::memory_order_relaxed) ==
HITCBC 423   36478 (std::numeric_limits<std::size_t>::max)() && 423   36076 (std::numeric_limits<std::size_t>::max)() &&
HITCBC 424   18239 heap_.size() == heap_.capacity()) 424   18038 heap_.size() == heap_.capacity())
HITCBC 425 - 409 heap_.reserve(heap_.capacity() == 0 ? 16 : 2 * heap_.capacity()); 425 + 420 heap_.reserve(
HITGNC   426 + 420 heap_.capacity() == 0 ? 16 : 2 * heap_.capacity());
426   // Publish: from here the waiter is visible to the fire path and 427   // Publish: from here the waiter is visible to the fire path and
427   // to its own stop callback (impl_ non-null enables cancel_waiter). 428   // to its own stop callback (impl_ non-null enables cancel_waiter).
HITCBC 428   18239 w->impl_ = &impl; 429   18038 w->impl_ = &impl;
HITCBC 429   36478 if (impl.heap_index_.load(std::memory_order_relaxed) == 430   36076 if (impl.heap_index_.load(std::memory_order_relaxed) ==
HITCBC 430   18239 (std::numeric_limits<std::size_t>::max)()) 431   18038 (std::numeric_limits<std::size_t>::max)())
431   { 432   {
HITCBC 432   18239 impl.heap_index_.store(heap_.size(), std::memory_order_relaxed); 433   18038 impl.heap_index_.store(heap_.size(), std::memory_order_relaxed);
HITCBC 433   18239 heap_.push_back({impl.expiry_, &impl}); 434   18038 heap_.push_back({impl.expiry_, &impl});
HITCBC 434   18239 up_heap(heap_.size() - 1); 435   18038 up_heap(heap_.size() - 1);
HITCBC 435 - 18239 notify = (impl.heap_index_.load(std::memory_order_relaxed) == 0); 436 + 18038 notify =
HITGNC   437 + 18038 (impl.heap_index_.load(std::memory_order_relaxed) == 0);
HITCBC 436   18239 refresh_cached_nearest(); 438   18038 refresh_cached_nearest();
437   } 439   }
HITCBC 438   18239 BOOST_COROSIO_ASSERT(impl.waiter_ == nullptr); 440   18038 BOOST_COROSIO_ASSERT(impl.waiter_ == nullptr);
HITCBC 439   18239 impl.waiter_ = w; 441   18038 impl.waiter_ = w;
440   442  
441   // Lost-cancel re-check: a stop requested after the canceller was 443   // Lost-cancel re-check: a stop requested after the canceller was
442   // armed in wait() but before this publication found impl_ null 444   // armed in wait() but before this publication found impl_ null
443   // and returned a no-op. Observe it now and undo the insertion. 445   // and returned a no-op. Observe it now and undo the insertion.
HITCBC 444   18239 if (w->token_->stop_requested()) 446   18038 if (w->token_->stop_requested())
445   { 447   {
HITGBC 446   ✗ w->impl_ = nullptr; 448   3 w->impl_ = nullptr;
HITGBC 447   ✗ impl.waiter_ = nullptr; 449   3 impl.waiter_ = nullptr;
HITGBC 448   ✗ remove_timer_impl(impl); 450   3 remove_timer_impl(impl);
HITGBC 449   ✗ impl.might_have_pending_waits_.store( 451   3 impl.might_have_pending_waits_.store(
450   false, std::memory_order_relaxed); 452   false, std::memory_order_relaxed);
HITGBC 451   ✗ refresh_cached_nearest(); 453   3 refresh_cached_nearest();
HITGBC 452   ✗ lost_cancel = true; 454   3 lost_cancel = true;
HITGBC 453   ✗ notify = false; // insertion undone; nearest unchanged 455   3 notify = false; // insertion undone; nearest unchanged
454   } 456   }
HITCBC 455   18239 } 457   18038 }
HITCBC 456   18239 if (notify) 458   18038 if (notify)
HITCBC 457   7263 on_earliest_changed_(); 459   6893 on_earliest_changed_();
HITCBC 458   18239 if (lost_cancel) 460   18038 if (lost_cancel)
459   { 461   {
HITGBC 460   ✗ w->ec_ = make_error_code(capy::error::canceled); 462   3 w->ec_ = make_error_code(capy::error::canceled);
HITGBC 461   ✗ sched_->post(&w->op_); 463   3 sched_->post(&w->op_);
462   } 464   }
HITCBC 463   18239 } 465   18038 }
464   466  
465   inline void 467   inline void
HITCBC 466   14970 timer_service::cancel_timer(timer::implementation& impl) 468   14799 timer_service::cancel_timer(timer::implementation& impl)
467   { 469   {
HITCBC 468   14970 if (!impl.might_have_pending_waits_.load(std::memory_order_relaxed)) 470   14799 if (!impl.might_have_pending_waits_.load(std::memory_order_relaxed))
HITCBC 469   14968 return; 471   14797 return;
470   472  
471   // No unlocked already-done fast-out here: it would need the 473   // No unlocked already-done fast-out here: it would need the
472   // non-atomic waiter_ (a race with concurrent drains), and an 474   // non-atomic waiter_ (a race with concurrent drains), and an
473   // index-only check is lifetime-unsafe because npos is stored 475   // index-only check is lifetime-unsafe because npos is stored
474   // before the drain finishes touching the impl. A stale-true 476   // before the drain finishes touching the impl. A stale-true
475   // flag is rare with the stateless API; the locked path below 477   // flag is rare with the stateless API; the locked path below
476   // re-validates. 478   // re-validates.
477   479  
HITCBC 478   2 waiter_node* canceled = nullptr; 480   2 waiter_node* canceled = nullptr;
479   481  
480   { 482   {
HITCBC 481   2 std::lock_guard lock(mutex_); 483   2 std::lock_guard lock(mutex_);
HITCBC 482   2 remove_timer_impl(impl); 484   2 remove_timer_impl(impl);
HITCBC 483   2 canceled = std::exchange(impl.waiter_, nullptr); 485   2 canceled = std::exchange(impl.waiter_, nullptr);
HITCBC 484   2 if (canceled) 486   2 if (canceled)
HITCBC 485   2 canceled->impl_ = nullptr; 487   2 canceled->impl_ = nullptr;
486   // Store false as the final touch of the impl under the lock so 488   // Store false as the final touch of the impl under the lock so
487   // a pre-lock false-flag check trusts it unqualified. 489   // a pre-lock false-flag check trusts it unqualified.
HITCBC 488   2 impl.might_have_pending_waits_.store(false, std::memory_order_relaxed); 490   2 impl.might_have_pending_waits_.store(false, std::memory_order_relaxed);
HITCBC 489   2 refresh_cached_nearest(); 491   2 refresh_cached_nearest();
HITCBC 490   2 } 492   2 }
491   493  
HITCBC 492   2 if (canceled) 494   2 if (canceled)
493   { 495   {
HITCBC 494   2 canceled->ec_ = make_error_code(capy::error::canceled); 496   2 canceled->ec_ = make_error_code(capy::error::canceled);
HITCBC 495   2 sched_->post(&canceled->op_); 497   2 sched_->post(&canceled->op_);
496   } 498   }
497   } 499   }
498   500  
499   inline void 501   inline void
HITCBC 500   1456 timer_service::cancel_waiter(waiter_node* w) 502   1538 timer_service::cancel_waiter(waiter_node* w)
501   { 503   {
502   { 504   {
HITCBC 503   1456 std::lock_guard lock(mutex_); 505   1538 std::lock_guard lock(mutex_);
504   // Already removed by another drain: cancel_timer, 506   // Already removed by another drain: cancel_timer,
505   // process_expired, or insert_waiter's lost-cancel recheck 507   // process_expired, or insert_waiter's lost-cancel recheck
HITCBC 506   1456 if (!w->impl_) 508   1538 if (!w->impl_)
HITGBC 507   ✗ return; 509   5 return;
HITCBC 508   1456 auto* impl = w->impl_; 510   1533 auto* impl = w->impl_;
HITCBC 509   1456 w->impl_ = nullptr; 511   1533 w->impl_ = nullptr;
HITCBC 510   1456 impl->waiter_ = nullptr; 512   1533 impl->waiter_ = nullptr;
HITCBC 511   1456 remove_timer_impl(*impl); 513   1533 remove_timer_impl(*impl);
HITCBC 512 - 1456 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed); 514 + 1533 impl->might_have_pending_waits_.store(
  515 + false, std::memory_order_relaxed);
HITCBC 513   1456 refresh_cached_nearest(); 516   1533 refresh_cached_nearest();
HITCBC 514   1456 } 517   1538 }
515   518  
HITCBC 516   1456 w->ec_ = make_error_code(capy::error::canceled); 519   1533 w->ec_ = make_error_code(capy::error::canceled);
HITCBC 517   1456 sched_->post(&w->op_); 520   1533 sched_->post(&w->op_);
518   } 521   }
519   522  
520   inline std::size_t 523   inline std::size_t
HITCBC 521   299021 timer_service::process_expired() 524   285867 timer_service::process_expired()
522   { 525   {
HITCBC 523   299021 intrusive_list<waiter_node> expired; 526   285867 intrusive_list<waiter_node> expired;
524   527  
525   { 528   {
HITCBC 526   299021 std::lock_guard lock(mutex_); 529   285867 std::lock_guard lock(mutex_);
HITCBC 527   299021 auto now = clock_type::now(); 530   285867 auto now = clock_type::now();
528   531  
HITCBC 529   315773 while (!heap_.empty() && heap_[0].time_ <= now) 532   302338 while (!heap_.empty() && heap_[0].time_ <= now)
530   { 533   {
HITCBC 531   16752 timer::implementation* t = heap_[0].timer_; 534   16471 timer::implementation* t = heap_[0].timer_;
HITCBC 532   16752 remove_timer_impl(*t); 535   16471 remove_timer_impl(*t);
HITCBC 533   16752 if (auto* w = std::exchange(t->waiter_, nullptr)) 536   16471 if (auto* w = std::exchange(t->waiter_, nullptr))
534   { 537   {
HITCBC 535   16752 w->impl_ = nullptr; 538   16471 w->impl_ = nullptr;
HITCBC 536   16752 w->ec_ = {}; 539   16471 w->ec_ = {};
HITCBC 537   16752 expired.push_back(w); 540   16471 expired.push_back(w);
538   } 541   }
HITCBC 539   16752 t->might_have_pending_waits_.store( 542   16471 t->might_have_pending_waits_.store(
540   false, std::memory_order_relaxed); 543   false, std::memory_order_relaxed);
541   } 544   }
542   545  
HITCBC 543   299021 refresh_cached_nearest(); 546   285867 refresh_cached_nearest();
HITCBC 544   299021 } 547   285867 }
545   548  
HITCBC 546   299021 std::size_t count = 0; 549   285867 std::size_t count = 0;
HITCBC 547   315773 while (auto* w = expired.pop_front()) 550   302338 while (auto* w = expired.pop_front())
548   { 551   {
HITCBC 549   16752 sched_->post(&w->op_); 552   16471 sched_->post(&w->op_);
HITCBC 550   16752 ++count; 553   16471 ++count;
HITCBC 551   16752 } 554   16471 }
552   555  
HITCBC 553   299021 return count; 556   285867 return count;
554   } 557   }
555   558  
556   inline void 559   inline void
HITCBC 557   18210 timer_service::remove_timer_impl(timer::implementation& impl) 560   18009 timer_service::remove_timer_impl(timer::implementation& impl)
558   { 561   {
HITCBC 559   18210 std::size_t index = impl.heap_index_.load(std::memory_order_relaxed); 562   18009 std::size_t index = impl.heap_index_.load(std::memory_order_relaxed);
HITCBC 560   18210 if (index >= heap_.size()) 563   18009 if (index >= heap_.size())
MISUBC 561   ✗ return; // Not in heap 564   ✗ return; // Not in heap
562   565  
HITCBC 563   18210 if (index == heap_.size() - 1) 566   18009 if (index == heap_.size() - 1)
564   { 567   {
565   // Last element, just pop 568   // Last element, just pop
HITCBC 566   2653 impl.heap_index_.store( 569   2612 impl.heap_index_.store(
567   (std::numeric_limits<std::size_t>::max)(), 570   (std::numeric_limits<std::size_t>::max)(),
568   std::memory_order_relaxed); 571   std::memory_order_relaxed);
HITCBC 569   2653 heap_.pop_back(); 572   2612 heap_.pop_back();
570   } 573   }
571   else 574   else
572   { 575   {
573   // Swap with last and reheapify 576   // Swap with last and reheapify
HITCBC 574   15557 swap_heap(index, heap_.size() - 1); 577   15397 swap_heap(index, heap_.size() - 1);
HITCBC 575   15557 impl.heap_index_.store( 578   15397 impl.heap_index_.store(
576   (std::numeric_limits<std::size_t>::max)(), 579   (std::numeric_limits<std::size_t>::max)(),
577   std::memory_order_relaxed); 580   std::memory_order_relaxed);
HITCBC 578   15557 heap_.pop_back(); 581   15397 heap_.pop_back();
579   582  
HITCBC 580   15557 if (index > 0 && heap_[index].time_ < heap_[(index - 1) / 2].time_) 583   15397 if (index > 0 && heap_[index].time_ < heap_[(index - 1) / 2].time_)
MISUBC 581   ✗ up_heap(index); 584   ✗ up_heap(index);
582   else 585   else
HITCBC 583   15557 down_heap(index); 586   15397 down_heap(index);
584   } 587   }
585   } 588   }
586   589  
587   inline void 590   inline void
HITCBC 588   18239 timer_service::up_heap(std::size_t index) 591   18038 timer_service::up_heap(std::size_t index)
589   { 592   {
HITCBC 590   25255 while (index > 0) 593   24756 while (index > 0)
591   { 594   {
HITCBC 592   17992 std::size_t parent = (index - 1) / 2; 595   17861 std::size_t parent = (index - 1) / 2;
HITCBC 593   17992 if (!(heap_[index].time_ < heap_[parent].time_)) 596   17861 if (!(heap_[index].time_ < heap_[parent].time_))
HITCBC 594   10976 break; 597   11143 break;
HITCBC 595   7016 swap_heap(index, parent); 598   6718 swap_heap(index, parent);
HITCBC 596   7016 index = parent; 599   6718 index = parent;
597   } 600   }
HITCBC 598   18239 } 601   18038 }
599   602  
600   inline void 603   inline void
HITCBC 601   15557 timer_service::down_heap(std::size_t index) 604   15397 timer_service::down_heap(std::size_t index)
602   { 605   {
HITCBC 603   15557 std::size_t child = index * 2 + 1; 606   15397 std::size_t child = index * 2 + 1;
HITCBC 604   32923 while (child < heap_.size()) 607   33007 while (child < heap_.size())
605   { 608   {
HITCBC 606   19329 std::size_t min_child = (child + 1 == heap_.size() || 609   19420 std::size_t min_child = (child + 1 == heap_.size() ||
HITCBC 607   15547 heap_[child].time_ < heap_[child + 1].time_) 610   16170 heap_[child].time_ < heap_[child + 1].time_)
HITCBC 608   34876 ? child 611   35590 ? child
HITCBC 609   19329 : child + 1; 612   19420 : child + 1;
610   613  
HITCBC 611   19329 if (heap_[index].time_ < heap_[min_child].time_) 614   19420 if (heap_[index].time_ < heap_[min_child].time_)
HITCBC 612   1963 break; 615   1810 break;
613   616  
HITCBC 614   17366 swap_heap(index, min_child); 617   17610 swap_heap(index, min_child);
HITCBC 615   17366 index = min_child; 618   17610 index = min_child;
HITCBC 616   17366 child = index * 2 + 1; 619   17610 child = index * 2 + 1;
617   } 620   }
HITCBC 618   15557 } 621   15397 }
619   622  
620   inline void 623   inline void
HITCBC 621   39939 timer_service::swap_heap(std::size_t i1, std::size_t i2) 624   39725 timer_service::swap_heap(std::size_t i1, std::size_t i2)
622   { 625   {
HITCBC 623 - 39939 heap_entry tmp = heap_[i1]; 626 + 39725 heap_entry tmp = heap_[i1];
HITCBC 624 - 39939 heap_[i1] = heap_[i2]; 627 + 39725 heap_[i1] = heap_[i2];
HITCBC 625 - 39939 heap_[i2] = tmp; 628 + 39725 heap_[i2] = tmp;
HITCBC 626   39939 heap_[i1].timer_->heap_index_.store(i1, std::memory_order_relaxed); 629   39725 heap_[i1].timer_->heap_index_.store(i1, std::memory_order_relaxed);
HITCBC 627   39939 heap_[i2].timer_->heap_index_.store(i2, std::memory_order_relaxed); 630   39725 heap_[i2].timer_->heap_index_.store(i2, std::memory_order_relaxed);
HITCBC 628   39939 } 631   39725 }
629   632  
630   // waiter_node's completion_op and canceller members are defined in 633   // waiter_node's completion_op and canceller members are defined in
631   // timer.cpp alongside implementation::wait(), for the same reason 634   // timer.cpp alongside implementation::wait(), for the same reason
632   // wait() lives there (see below). 635   // wait() lives there (see below).
633   636  
634   // timer::implementation::wait() is defined in timer.cpp, not here. 637   // timer::implementation::wait() is defined in timer.cpp, not here.
635   // It must be a non-inline definition in a translation unit that is 638   // It must be a non-inline definition in a translation unit that is
636   // always pulled into the link whenever detail::timer is used (every 639   // always pulled into the link whenever detail::timer is used (every
637   // consumer needs timer's constructors from that same object file). 640   // consumer needs timer's constructors from that same object file).
638   // An inline definition in this header would only be emitted in 641   // An inline definition in this header would only be emitted in
639   // translation units that happen to also include this header, which 642   // translation units that happen to also include this header, which
640   // is not guaranteed for every caller of wait_awaitable::await_suspend 643   // is not guaranteed for every caller of wait_awaitable::await_suspend
641   // in timer.hpp (e.g. code that only reaches timer.hpp through 644   // in timer.hpp (e.g. code that only reaches timer.hpp through
642   // delay.hpp, without transitively including a scheduler header). 645   // delay.hpp, without transitively including a scheduler header).
643   646  
644   // Free functions 647   // Free functions
645   648  
646   inline timer_service& 649   inline timer_service&
HITCBC 647   2106 get_timer_service(capy::execution_context& ctx, scheduler& sched) 650   2106 get_timer_service(capy::execution_context& ctx, scheduler& sched)
648   { 651   {
HITCBC 649   2106 return ctx.make_service<timer_service>(sched); 652   2106 return ctx.make_service<timer_service>(sched);
650   } 653   }
651   654  
652   } // namespace boost::corosio::detail 655   } // namespace boost::corosio::detail
653   656  
654   #endif 657   #endif