. /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   7110 void operator()() const 112   7108 void operator()() const
113   { 113   {
HITCBC 114   7110 if (fn_) 114   7108 if (fn_)
HITCBC 115   7110 fn_(ctx_); 115   7108 fn_(ctx_);
HITCBC 116   7110 } 116   7108 }
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   28317 inline scheduler& get_scheduler() noexcept 147   28377 inline scheduler& get_scheduler() noexcept
148   { 148   {
HITCBC 149   28317 return *sched_; 149   28377 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   298131 inline time_point nearest_expiry() const noexcept 172   302870 inline time_point nearest_expiry() const noexcept
173   { 173   {
HITCBC 174   298131 auto ns = cached_nearest_ns_.load(std::memory_order_acquire); 174   302870 auto ns = cached_nearest_ns_.load(std::memory_order_acquire);
HITCBC 175   298131 return time_point(time_point::duration(ns)); 175   302870 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   338392 inline void refresh_cached_nearest() noexcept 203   342908 inline void refresh_cached_nearest() noexcept
204   { 204   {
HITCBC 205   338392 auto ns = heap_.empty() ? (std::numeric_limits<std::int64_t>::max)() 205   342908 auto ns = heap_.empty() ? (std::numeric_limits<std::int64_t>::max)()
HITCBC 206   333510 : heap_[0].time_.time_since_epoch().count(); 206   337985 : heap_[0].time_.time_since_epoch().count();
HITCBC 207   338392 cached_nearest_ns_.store(ns, std::memory_order_release); 207   342908 cached_nearest_ns_.store(ns, std::memory_order_release);
HITCBC 208   338392 } 208   342908 }
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   43 ~tl_cache_owner()
232   { 232   {
HITCBC 233   42 delete tl_cached_impl.get(); 233   43 delete tl_cached_impl.get();
HITCBC 234   42 tl_cached_impl.set(nullptr); 234   43 tl_cached_impl.set(nullptr);
HITCBC 235   42 } 235   43 }
236   }; 236   };
237   237  
238   inline void 238   inline void
HITCBC 239   14044 arm_tl_cache_cleanup() noexcept 239   14059 arm_tl_cache_cleanup() noexcept
240   { 240   {
HITCBC 241   14044 [[maybe_unused]] thread_local tl_cache_owner owner; 241   14059 [[maybe_unused]] thread_local tl_cache_owner owner;
HITCBC 242   14044 } 242   14059 }
243   243  
244   inline timer::implementation* 244   inline timer::implementation*
HITCBC 245   15025 try_pop_tl_cache(timer_service* svc) noexcept 245   15056 try_pop_tl_cache(timer_service* svc) noexcept
246   { 246   {
HITCBC 247   15025 auto* impl = tl_cached_impl.get(); 247   15056 auto* impl = tl_cached_impl.get();
HITCBC 248   15025 if (impl) 248   15056 if (impl)
249   { 249   {
HITCBC 250   13641 tl_cached_impl.set(nullptr); 250   13655 tl_cached_impl.set(nullptr);
HITCBC 251   13641 if (impl->svc_ == svc) 251   13655 if (impl->svc_ == svc)
HITCBC 252   13641 return impl; 252   13655 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   1384 return nullptr; 256   1401 return nullptr;
257   } 257   }
258   258  
259   inline bool 259   inline bool
HITCBC 260   14996 try_push_tl_cache(timer::implementation* impl) noexcept 260   15027 try_push_tl_cache(timer::implementation* impl) noexcept
261   { 261   {
HITCBC 262   14996 if (!tl_cached_impl.get()) 262   15027 if (!tl_cached_impl.get())
263   { 263   {
HITCBC 264   14044 arm_tl_cache_cleanup(); 264   14059 arm_tl_cache_cleanup();
HITCBC 265   14044 tl_cached_impl.set(impl); 265   14059 tl_cached_impl.set(impl);
HITCBC 266   14044 return true; 266   14059 return true;
267   } 267   }
HITCBC 268   952 return false; 268   968 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   3056 while (free_list_) 323   3072 while (free_list_)
324   { 324   {
HITCBC 325   950 auto* next = free_list_->next_free_; 325   966 auto* next = free_list_->next_free_;
HITCBC 326   950 delete free_list_; 326   966 delete free_list_;
HITCBC 327   950 free_list_ = next; 327   966 free_list_ = next;
328   } 328   }
HITCBC 329   2106 } 329   2106 }
330   330  
331   inline io_object::implementation* 331   inline io_object::implementation*
HITCBC 332   15025 timer_service::construct() 332   15056 timer_service::construct()
333   { 333   {
HITCBC 334   15025 timer::implementation* impl = try_pop_tl_cache(this); 334   15056 timer::implementation* impl = try_pop_tl_cache(this);
HITCBC 335   15025 if (impl) 335   15056 if (impl)
336   { 336   {
HITCBC 337 - 13641 impl->svc_ = this; 337 + 13655 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   13641 impl->expiry_ = {}; 340   13655 impl->expiry_ = {};
HITCBC 341   13641 impl->heap_index_.store( 341   13655 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   13641 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed); 344   13655 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed);
HITCBC 345   13641 BOOST_COROSIO_ASSERT(impl->waiter_ == nullptr); 345   13655 BOOST_COROSIO_ASSERT(impl->waiter_ == nullptr);
HITCBC 346   13641 return impl; 346   13655 return impl;
347   } 347   }
348   348  
HITCBC 349   1384 std::lock_guard lock(mutex_); 349   1401 std::lock_guard lock(mutex_);
HITCBC 350   1384 if (free_list_) 350   1401 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   1382 impl = new timer::implementation(*this); 365   1399 impl = new timer::implementation(*this);
366   } 366   }
HITCBC 367   1384 return impl; 367   1401 return impl;
HITCBC 368   1384 } 368   1401 }
369   369  
370   inline void 370   inline void
HITCBC 371   15025 timer_service::destroy(io_object::implementation* p) 371   15056 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   15025 if (shutting_down_) 379   15056 if (shutting_down_)
HITCBC 380   29 return; 380   29 return;
HITCBC 381   14996 destroy_impl(static_cast<timer::implementation&>(*p)); 381   15027 destroy_impl(static_cast<timer::implementation&>(*p));
382   } 382   }
383   383  
384   inline void 384   inline void
HITCBC 385   14996 timer_service::destroy_impl(timer::implementation& impl) 385   15027 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   14996 if (shutting_down_) 391   15027 if (shutting_down_)
HITCBC 392   14044 return; 392   14059 return;
393   393  
HITCBC 394   14996 cancel_timer(impl); 394   15027 cancel_timer(impl);
395   395  
HITCBC 396   29992 if (impl.heap_index_.load(std::memory_order_relaxed) != 396   30054 if (impl.heap_index_.load(std::memory_order_relaxed) !=
HITCBC 397   14996 (std::numeric_limits<std::size_t>::max)()) 397   15027 (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   14996 if (try_push_tl_cache(&impl)) 404   15027 if (try_push_tl_cache(&impl))
HITCBC 405   14044 return; 405   14059 return;
406   406  
HITCBC 407   952 std::lock_guard lock(mutex_); 407   968 std::lock_guard lock(mutex_);
HITCBC 408   952 impl.next_free_ = free_list_; 408   968 impl.next_free_ = free_list_;
HITCBC 409   952 free_list_ = &impl; 409   968 free_list_ = &impl;
HITCBC 410   952 } 410   968 }
411   411  
412   inline void 412   inline void
HITCBC 413   18247 timer_service::insert_waiter(timer::implementation& impl, waiter_node* w) 413   18444 timer_service::insert_waiter(timer::implementation& impl, waiter_node* w)
414   { 414   {
HITCBC 415   18247 bool notify = false; 415   18444 bool notify = false;
HITCBC 416   18247 bool lost_cancel = false; 416   18444 bool lost_cancel = false;
417   { 417   {
HITCBC 418   18247 std::lock_guard lock(mutex_); 418   18444 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   18247 if (impl.heap_index_.load(std::memory_order_relaxed) == 422   18444 if (impl.heap_index_.load(std::memory_order_relaxed) ==
HITCBC 423   36494 (std::numeric_limits<std::size_t>::max)() && 423   36888 (std::numeric_limits<std::size_t>::max)() &&
HITCBC 424   18247 heap_.size() == heap_.capacity()) 424   18444 heap_.size() == heap_.capacity())
HITCBC 425 - 422 heap_.reserve( 425 + 414 heap_.reserve(heap_.capacity() == 0 ? 16 : 2 * heap_.capacity());
DCB 426 - 422 heap_.capacity() == 0 ? 16 : 2 * heap_.capacity());  
427   // Publish: from here the waiter is visible to the fire path and 426   // Publish: from here the waiter is visible to the fire path and
428   // to its own stop callback (impl_ non-null enables cancel_waiter). 427   // to its own stop callback (impl_ non-null enables cancel_waiter).
HITCBC 429   18247 w->impl_ = &impl; 428   18444 w->impl_ = &impl;
HITCBC 430   36494 if (impl.heap_index_.load(std::memory_order_relaxed) == 429   36888 if (impl.heap_index_.load(std::memory_order_relaxed) ==
HITCBC 431   18247 (std::numeric_limits<std::size_t>::max)()) 430   18444 (std::numeric_limits<std::size_t>::max)())
432   { 431   {
HITCBC 433   18247 impl.heap_index_.store(heap_.size(), std::memory_order_relaxed); 432   18444 impl.heap_index_.store(heap_.size(), std::memory_order_relaxed);
HITCBC 434   18247 heap_.push_back({impl.expiry_, &impl}); 433   18444 heap_.push_back({impl.expiry_, &impl});
HITCBC 435   18247 up_heap(heap_.size() - 1); 434   18444 up_heap(heap_.size() - 1);
HITCBC 436 - 18247 notify = 435 + 18444 notify = (impl.heap_index_.load(std::memory_order_relaxed) == 0);
DCB 437 - 18247 (impl.heap_index_.load(std::memory_order_relaxed) == 0);  
HITCBC 438   18247 refresh_cached_nearest(); 436   18444 refresh_cached_nearest();
439   } 437   }
HITCBC 440   18247 BOOST_COROSIO_ASSERT(impl.waiter_ == nullptr); 438   18444 BOOST_COROSIO_ASSERT(impl.waiter_ == nullptr);
HITCBC 441   18247 impl.waiter_ = w; 439   18444 impl.waiter_ = w;
442   440  
443   // Lost-cancel re-check: a stop requested after the canceller was 441   // Lost-cancel re-check: a stop requested after the canceller was
444   // armed in wait() but before this publication found impl_ null 442   // armed in wait() but before this publication found impl_ null
445   // and returned a no-op. Observe it now and undo the insertion. 443   // and returned a no-op. Observe it now and undo the insertion.
HITCBC 446   18247 if (w->token_->stop_requested()) 444   18444 if (w->token_->stop_requested())
447   { 445   {
HITCBC 448   2 w->impl_ = nullptr; 446   4 w->impl_ = nullptr;
HITCBC 449   2 impl.waiter_ = nullptr; 447   4 impl.waiter_ = nullptr;
HITCBC 450   2 remove_timer_impl(impl); 448   4 remove_timer_impl(impl);
HITCBC 451   2 impl.might_have_pending_waits_.store( 449   4 impl.might_have_pending_waits_.store(
452   false, std::memory_order_relaxed); 450   false, std::memory_order_relaxed);
HITCBC 453   2 refresh_cached_nearest(); 451   4 refresh_cached_nearest();
HITCBC 454   2 lost_cancel = true; 452   4 lost_cancel = true;
HITCBC 455   2 notify = false; // insertion undone; nearest unchanged 453   4 notify = false; // insertion undone; nearest unchanged
456   } 454   }
HITCBC 457   18247 } 455   18444 }
HITCBC 458   18247 if (notify) 456   18444 if (notify)
HITCBC 459   7110 on_earliest_changed_(); 457   7108 on_earliest_changed_();
HITCBC 460   18247 if (lost_cancel) 458   18444 if (lost_cancel)
461   { 459   {
HITCBC 462   2 w->ec_ = make_error_code(capy::error::canceled); 460   4 w->ec_ = make_error_code(capy::error::canceled);
HITCBC 463   2 sched_->post(&w->op_); 461   4 sched_->post(&w->op_);
464   } 462   }
HITCBC 465   18247 } 463   18444 }
466   464  
467   inline void 465   inline void
HITCBC 468   14996 timer_service::cancel_timer(timer::implementation& impl) 466   15027 timer_service::cancel_timer(timer::implementation& impl)
469   { 467   {
HITCBC 470   14996 if (!impl.might_have_pending_waits_.load(std::memory_order_relaxed)) 468   15027 if (!impl.might_have_pending_waits_.load(std::memory_order_relaxed))
HITCBC 471   14994 return; 469   15025 return;
472   470  
473   // No unlocked already-done fast-out here: it would need the 471   // No unlocked already-done fast-out here: it would need the
474   // non-atomic waiter_ (a race with concurrent drains), and an 472   // non-atomic waiter_ (a race with concurrent drains), and an
475   // index-only check is lifetime-unsafe because npos is stored 473   // index-only check is lifetime-unsafe because npos is stored
476   // before the drain finishes touching the impl. A stale-true 474   // before the drain finishes touching the impl. A stale-true
477   // flag is rare with the stateless API; the locked path below 475   // flag is rare with the stateless API; the locked path below
478   // re-validates. 476   // re-validates.
479   477  
HITCBC 480   2 waiter_node* canceled = nullptr; 478   2 waiter_node* canceled = nullptr;
481   479  
482   { 480   {
HITCBC 483   2 std::lock_guard lock(mutex_); 481   2 std::lock_guard lock(mutex_);
HITCBC 484   2 remove_timer_impl(impl); 482   2 remove_timer_impl(impl);
HITCBC 485   2 canceled = std::exchange(impl.waiter_, nullptr); 483   2 canceled = std::exchange(impl.waiter_, nullptr);
HITCBC 486   2 if (canceled) 484   2 if (canceled)
HITCBC 487   2 canceled->impl_ = nullptr; 485   2 canceled->impl_ = nullptr;
488   // Store false as the final touch of the impl under the lock so 486   // Store false as the final touch of the impl under the lock so
489   // a pre-lock false-flag check trusts it unqualified. 487   // a pre-lock false-flag check trusts it unqualified.
HITCBC 490   2 impl.might_have_pending_waits_.store(false, std::memory_order_relaxed); 488   2 impl.might_have_pending_waits_.store(false, std::memory_order_relaxed);
HITCBC 491   2 refresh_cached_nearest(); 489   2 refresh_cached_nearest();
HITCBC 492   2 } 490   2 }
493   491  
HITCBC 494   2 if (canceled) 492   2 if (canceled)
495   { 493   {
HITCBC 496   2 canceled->ec_ = make_error_code(capy::error::canceled); 494   2 canceled->ec_ = make_error_code(capy::error::canceled);
HITCBC 497   2 sched_->post(&canceled->op_); 495   2 sched_->post(&canceled->op_);
498   } 496   }
499   } 497   }
500   498  
501   inline void 499   inline void
HITCBC 502   1540 timer_service::cancel_waiter(waiter_node* w) 500   1548 timer_service::cancel_waiter(waiter_node* w)
503   { 501   {
504   { 502   {
HITCBC 505   1540 std::lock_guard lock(mutex_); 503   1548 std::lock_guard lock(mutex_);
506   // Already removed by another drain: cancel_timer, 504   // Already removed by another drain: cancel_timer,
507   // process_expired, or insert_waiter's lost-cancel recheck 505   // process_expired, or insert_waiter's lost-cancel recheck
HITCBC 508   1540 if (!w->impl_) 506   1548 if (!w->impl_)
HITCBC 509   3 return; 507   5 return;
HITCBC 510   1537 auto* impl = w->impl_; 508   1543 auto* impl = w->impl_;
HITCBC 511   1537 w->impl_ = nullptr; 509   1543 w->impl_ = nullptr;
HITCBC 512   1537 impl->waiter_ = nullptr; 510   1543 impl->waiter_ = nullptr;
HITCBC 513   1537 remove_timer_impl(*impl); 511   1543 remove_timer_impl(*impl);
HITCBC 514 - 1537 impl->might_have_pending_waits_.store( 512 + 1543 impl->might_have_pending_waits_.store(false, std::memory_order_relaxed);
515 - false, std::memory_order_relaxed);  
HITCBC 516   1537 refresh_cached_nearest(); 513   1543 refresh_cached_nearest();
HITCBC 517   1540 } 514   1548 }
518   515  
HITCBC 519   1537 w->ec_ = make_error_code(capy::error::canceled); 516   1543 w->ec_ = make_error_code(capy::error::canceled);
HITCBC 520   1537 sched_->post(&w->op_); 517   1543 sched_->post(&w->op_);
521   } 518   }
522   519  
523   inline std::size_t 520   inline std::size_t
HITCBC 524   318604 timer_service::process_expired() 521   322915 timer_service::process_expired()
525   { 522   {
HITCBC 526   318604 intrusive_list<waiter_node> expired; 523   322915 intrusive_list<waiter_node> expired;
527   524  
528   { 525   {
HITCBC 529   318604 std::lock_guard lock(mutex_); 526   322915 std::lock_guard lock(mutex_);
HITCBC 530   318604 auto now = clock_type::now(); 527   322915 auto now = clock_type::now();
531   528  
HITCBC 532   335281 while (!heap_.empty() && heap_[0].time_ <= now) 529   339781 while (!heap_.empty() && heap_[0].time_ <= now)
533   { 530   {
HITCBC 534   16677 timer::implementation* t = heap_[0].timer_; 531   16866 timer::implementation* t = heap_[0].timer_;
HITCBC 535   16677 remove_timer_impl(*t); 532   16866 remove_timer_impl(*t);
HITCBC 536   16677 if (auto* w = std::exchange(t->waiter_, nullptr)) 533   16866 if (auto* w = std::exchange(t->waiter_, nullptr))
537   { 534   {
HITCBC 538   16677 w->impl_ = nullptr; 535   16866 w->impl_ = nullptr;
HITCBC 539   16677 w->ec_ = {}; 536   16866 w->ec_ = {};
HITCBC 540   16677 expired.push_back(w); 537   16866 expired.push_back(w);
541   } 538   }
HITCBC 542   16677 t->might_have_pending_waits_.store( 539   16866 t->might_have_pending_waits_.store(
543   false, std::memory_order_relaxed); 540   false, std::memory_order_relaxed);
544   } 541   }
545   542  
HITCBC 546   318604 refresh_cached_nearest(); 543   322915 refresh_cached_nearest();
HITCBC 547   318604 } 544   322915 }
548   545  
HITCBC 549   318604 std::size_t count = 0; 546   322915 std::size_t count = 0;
HITCBC 550   335281 while (auto* w = expired.pop_front()) 547   339781 while (auto* w = expired.pop_front())
551   { 548   {
HITCBC 552   16677 sched_->post(&w->op_); 549   16866 sched_->post(&w->op_);
HITCBC 553   16677 ++count; 550   16866 ++count;
HITCBC 554   16677 } 551   16866 }
555   552  
HITCBC 556   318604 return count; 553   322915 return count;
557   } 554   }
558   555  
559   inline void 556   inline void
HITCBC 560   18218 timer_service::remove_timer_impl(timer::implementation& impl) 557   18415 timer_service::remove_timer_impl(timer::implementation& impl)
561   { 558   {
HITCBC 562   18218 std::size_t index = impl.heap_index_.load(std::memory_order_relaxed); 559   18415 std::size_t index = impl.heap_index_.load(std::memory_order_relaxed);
HITCBC 563   18218 if (index >= heap_.size()) 560   18415 if (index >= heap_.size())
MISUBC 564   ✗ return; // Not in heap 561   ✗ return; // Not in heap
565   562  
HITCBC 566   18218 if (index == heap_.size() - 1) 563   18415 if (index == heap_.size() - 1)
567   { 564   {
568   // Last element, just pop 565   // Last element, just pop
HITCBC 569   2626 impl.heap_index_.store( 566   2639 impl.heap_index_.store(
570   (std::numeric_limits<std::size_t>::max)(), 567   (std::numeric_limits<std::size_t>::max)(),
571   std::memory_order_relaxed); 568   std::memory_order_relaxed);
HITCBC 572   2626 heap_.pop_back(); 569   2639 heap_.pop_back();
573   } 570   }
574   else 571   else
575   { 572   {
576   // Swap with last and reheapify 573   // Swap with last and reheapify
HITCBC 577   15592 swap_heap(index, heap_.size() - 1); 574   15776 swap_heap(index, heap_.size() - 1);
HITCBC 578   15592 impl.heap_index_.store( 575   15776 impl.heap_index_.store(
579   (std::numeric_limits<std::size_t>::max)(), 576   (std::numeric_limits<std::size_t>::max)(),
580   std::memory_order_relaxed); 577   std::memory_order_relaxed);
HITCBC 581   15592 heap_.pop_back(); 578   15776 heap_.pop_back();
582   579  
HITCBC 583   15592 if (index > 0 && heap_[index].time_ < heap_[(index - 1) / 2].time_) 580   15776 if (index > 0 && heap_[index].time_ < heap_[(index - 1) / 2].time_)
MISLBC 584   1 up_heap(index); 581   ✗ up_heap(index);
585   else 582   else
HITCBC 586   15591 down_heap(index); 583   15776 down_heap(index);
587   } 584   }
588   } 585   }
589   586  
590   inline void 587   inline void
HITCBC 591   18248 timer_service::up_heap(std::size_t index) 588   18444 timer_service::up_heap(std::size_t index)
592   { 589   {
HITCBC 593   25426 while (index > 0) 590   25281 while (index > 0)
594   { 591   {
HITCBC 595   18314 std::size_t parent = (index - 1) / 2; 592   18169 std::size_t parent = (index - 1) / 2;
HITCBC 596   18314 if (!(heap_[index].time_ < heap_[parent].time_)) 593   18169 if (!(heap_[index].time_ < heap_[parent].time_))
HITCBC 597   11136 break; 594   11332 break;
HITCBC 598   7178 swap_heap(index, parent); 595   6837 swap_heap(index, parent);
HITCBC 599   7178 index = parent; 596   6837 index = parent;
600   } 597   }
HITCBC 601   18248 } 598   18444 }
602   599  
603   inline void 600   inline void
HITCBC 604   15591 timer_service::down_heap(std::size_t index) 601   15776 timer_service::down_heap(std::size_t index)
605   { 602   {
HITCBC 606   15591 std::size_t child = index * 2 + 1; 603   15776 std::size_t child = index * 2 + 1;
HITCBC 607   33257 while (child < heap_.size()) 604   33443 while (child < heap_.size())
608   { 605   {
HITCBC 609   19269 std::size_t min_child = (child + 1 == heap_.size() || 606   19633 std::size_t min_child = (child + 1 == heap_.size() ||
HITCBC 610   16546 heap_[child].time_ < heap_[child + 1].time_) 607   16399 heap_[child].time_ < heap_[child + 1].time_)
HITCBC 611   35815 ? child 608   36032 ? child
HITCBC 612   19269 : child + 1; 609   19633 : child + 1;
613   610  
HITCBC 614   19269 if (heap_[index].time_ < heap_[min_child].time_) 611   19633 if (heap_[index].time_ < heap_[min_child].time_)
HITCBC 615   1603 break; 612   1966 break;
616   613  
HITCBC 617   17666 swap_heap(index, min_child); 614   17667 swap_heap(index, min_child);
HITCBC 618   17666 index = min_child; 615   17667 index = min_child;
HITCBC 619   17666 child = index * 2 + 1; 616   17667 child = index * 2 + 1;
620   } 617   }
HITCBC 621   15591 } 618   15776 }
622   619  
623   inline void 620   inline void
HITCBC 624   40436 timer_service::swap_heap(std::size_t i1, std::size_t i2) 621   40280 timer_service::swap_heap(std::size_t i1, std::size_t i2)
625   { 622   {
HITCBC 626 - 40436 heap_entry tmp = heap_[i1]; 623 + 40280 heap_entry tmp = heap_[i1];
HITCBC 627 - 40436 heap_[i1] = heap_[i2]; 624 + 40280 heap_[i1] = heap_[i2];
HITCBC 628 - 40436 heap_[i2] = tmp; 625 + 40280 heap_[i2] = tmp;
HITCBC 629   40436 heap_[i1].timer_->heap_index_.store(i1, std::memory_order_relaxed); 626   40280 heap_[i1].timer_->heap_index_.store(i1, std::memory_order_relaxed);
HITCBC 630   40436 heap_[i2].timer_->heap_index_.store(i2, std::memory_order_relaxed); 627   40280 heap_[i2].timer_->heap_index_.store(i2, std::memory_order_relaxed);
HITCBC 631   40436 } 628   40280 }
632   629  
633   // waiter_node's completion_op and canceller members are defined in 630   // waiter_node's completion_op and canceller members are defined in
634   // timer.cpp alongside implementation::wait(), for the same reason 631   // timer.cpp alongside implementation::wait(), for the same reason
635   // wait() lives there (see below). 632   // wait() lives there (see below).
636   633  
637   // timer::implementation::wait() is defined in timer.cpp, not here. 634   // timer::implementation::wait() is defined in timer.cpp, not here.
638   // It must be a non-inline definition in a translation unit that is 635   // It must be a non-inline definition in a translation unit that is
639   // always pulled into the link whenever detail::timer is used (every 636   // always pulled into the link whenever detail::timer is used (every
640   // consumer needs timer's constructors from that same object file). 637   // consumer needs timer's constructors from that same object file).
641   // An inline definition in this header would only be emitted in 638   // An inline definition in this header would only be emitted in
642   // translation units that happen to also include this header, which 639   // translation units that happen to also include this header, which
643   // is not guaranteed for every caller of wait_awaitable::await_suspend 640   // is not guaranteed for every caller of wait_awaitable::await_suspend
644   // in timer.hpp (e.g. code that only reaches timer.hpp through 641   // in timer.hpp (e.g. code that only reaches timer.hpp through
645   // delay.hpp, without transitively including a scheduler header). 642   // delay.hpp, without transitively including a scheduler header).
646   643  
647   // Free functions 644   // Free functions
648   645  
649   inline timer_service& 646   inline timer_service&
HITCBC 650   2106 get_timer_service(capy::execution_context& ctx, scheduler& sched) 647   2106 get_timer_service(capy::execution_context& ctx, scheduler& sched)
651   { 648   {
HITCBC 652   2106 return ctx.make_service<timer_service>(sched); 649   2106 return ctx.make_service<timer_service>(sched);
653   } 650   }
654   651  
655   } // namespace boost::corosio::detail 652   } // namespace boost::corosio::detail
656   653  
657   #endif 654   #endif