29 #ifndef _GLIBCXX_STOP_TOKEN
30 #define _GLIBCXX_STOP_TOKEN
32 #if __cplusplus > 201703L
39 #define __cpp_lib_jthread 201911L
41 namespace std _GLIBCXX_VISIBILITY(default)
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46 struct nostopstate_t {
explicit nostopstate_t() =
default; };
47 inline constexpr nostopstate_t nostopstate{};
55 stop_token() noexcept = default;
57 stop_token(const stop_token&) noexcept = default;
58 stop_token(stop_token&&) noexcept = default;
60 ~stop_token() = default;
63 operator=(const stop_token&) noexcept = default;
66 operator=(stop_token&&) noexcept = default;
70 stop_possible() const noexcept
72 return static_cast<bool>(_M_state) && _M_state->_M_stop_possible();
77 stop_requested() const noexcept
79 return static_cast<bool>(_M_state) && _M_state->_M_stop_requested();
83 swap(stop_token& __rhs) noexcept
84 { _M_state.swap(__rhs._M_state); }
88 operator==(
const stop_token& __a,
const stop_token& __b)
89 {
return __a._M_state == __b._M_state; }
92 swap(stop_token& __lhs, stop_token& __rhs) noexcept
93 { __lhs.swap(__rhs); }
96 friend class stop_source;
97 template<
typename _Callback>
98 friend class stop_callback;
103 #if defined __i386__ || defined __x86_64__
104 __builtin_ia32_pause();
109 #ifndef __cpp_lib_semaphore
110 struct binary_semaphore
112 explicit binary_semaphore(
int __d) : _M_counter(__d > 0) { }
119 while (!_M_counter.compare_exchange_weak(__old, 0,
120 memory_order::acquire,
121 memory_order::relaxed))
128 atomic<int> _M_counter;
134 using __cb_type = void(_Stop_cb*) noexcept;
135 __cb_type* _M_callback;
136 _Stop_cb* _M_prev =
nullptr;
137 _Stop_cb* _M_next =
nullptr;
138 bool* _M_destroyed =
nullptr;
139 binary_semaphore _M_done{0};
141 [[__gnu__::__nonnull__]]
143 _Stop_cb(__cb_type* __cb)
147 void _M_run() noexcept { _M_callback(
this); }
152 using value_type = uint32_t;
153 static constexpr value_type _S_stop_requested_bit = 1;
154 static constexpr value_type _S_locked_bit = 2;
155 static constexpr value_type _S_ssrc_counter_inc = 4;
159 _Stop_cb* _M_head =
nullptr;
162 _Stop_state_t() =
default;
165 _M_stop_possible() noexcept
169 return _M_value.load(memory_order::acquire) & ~_S_locked_bit;
173 _M_stop_requested() noexcept
175 return _M_value.load(memory_order::acquire) & _S_stop_requested_bit;
179 _M_add_owner() noexcept
181 _M_owners.fetch_add(1, memory_order::relaxed);
185 _M_release_ownership() noexcept
187 if (_M_owners.fetch_sub(1, memory_order::acq_rel) == 1)
192 _M_add_ssrc() noexcept
194 _M_value.fetch_add(_S_ssrc_counter_inc, memory_order::relaxed);
198 _M_sub_ssrc() noexcept
209 auto __old = _M_value.load(memory_order::relaxed);
210 while (!_M_try_lock(__old, memory_order::relaxed))
222 _M_request_stop() noexcept
225 auto __old = _M_value.load(memory_order::acquire);
228 if (__old & _S_stop_requested_bit)
231 while (!_M_try_lock_and_stop(__old));
238 _Stop_cb* __cb = _M_head;
239 _M_head = _M_head->_M_next;
242 _M_head->_M_prev =
nullptr;
251 bool __destroyed =
false;
252 __cb->_M_destroyed = &__destroyed;
259 __cb->_M_destroyed =
nullptr;
262 if (!__gnu_cxx::__is_single_threaded())
263 __cb->_M_done.release();
277 [[__gnu__::__nonnull__]]
279 _M_register_callback(_Stop_cb* __cb) noexcept
281 auto __old = _M_value.load(memory_order::acquire);
284 if (__old & _S_stop_requested_bit)
290 if (__old < _S_ssrc_counter_inc)
296 while (!_M_try_lock(__old));
298 __cb->_M_next = _M_head;
301 _M_head->_M_prev = __cb;
309 [[__gnu__::__nonnull__]]
311 _M_remove_callback(_Stop_cb* __cb)
317 _M_head = _M_head->_M_next;
319 _M_head->_M_prev =
nullptr;
323 else if (__cb->_M_prev)
325 __cb->_M_prev->_M_next = __cb->_M_next;
327 __cb->_M_next->_M_prev = __cb->_M_prev;
343 __cb->_M_done.acquire();
348 if (__cb->_M_destroyed)
349 *__cb->_M_destroyed =
true;
357 _M_try_lock(value_type& __curval,
358 memory_order __failure = memory_order::acquire) noexcept
360 return _M_do_try_lock(__curval, 0, memory_order::acquire, __failure);
370 _M_try_lock_and_stop(value_type& __curval) noexcept
372 return _M_do_try_lock(__curval, _S_stop_requested_bit,
373 memory_order::acq_rel, memory_order::acquire);
377 _M_do_try_lock(value_type& __curval, value_type __newbits,
380 if (__curval & _S_locked_bit)
383 __curval = _M_value.load(__failure);
386 __newbits |= _S_locked_bit;
387 return _M_value.compare_exchange_weak(__curval, __curval | __newbits,
388 __success, __failure);
392 struct _Stop_state_ref
394 _Stop_state_ref() =
default;
397 _Stop_state_ref(
const stop_source&)
398 : _M_ptr(new _Stop_state_t())
401 _Stop_state_ref(
const _Stop_state_ref& __other) noexcept
402 : _M_ptr(__other._M_ptr)
405 _M_ptr->_M_add_owner();
408 _Stop_state_ref(_Stop_state_ref&& __other) noexcept
409 : _M_ptr(__other._M_ptr)
411 __other._M_ptr =
nullptr;
415 operator=(
const _Stop_state_ref& __other) noexcept
417 if (
auto __ptr = __other._M_ptr; __ptr != _M_ptr)
420 __ptr->_M_add_owner();
422 _M_ptr->_M_release_ownership();
429 operator=(_Stop_state_ref&& __other) noexcept
431 _Stop_state_ref(
std::move(__other)).swap(*
this);
438 _M_ptr->_M_release_ownership();
442 swap(_Stop_state_ref& __other) noexcept
443 { std::swap(_M_ptr, __other._M_ptr); }
445 explicit operator bool() const noexcept {
return _M_ptr !=
nullptr; }
447 _Stop_state_t*
operator->() const noexcept {
return _M_ptr; }
449 #if __cpp_impl_three_way_comparison >= 201907L
451 operator==(
const _Stop_state_ref&,
const _Stop_state_ref&) =
default;
454 operator==(
const _Stop_state_ref& __lhs,
const _Stop_state_ref& __rhs)
456 {
return __lhs._M_ptr == __rhs._M_ptr; }
459 operator!=(
const _Stop_state_ref& __lhs,
const _Stop_state_ref& __rhs)
461 {
return __lhs._M_ptr != __rhs._M_ptr; }
465 _Stop_state_t* _M_ptr =
nullptr;
468 _Stop_state_ref _M_state;
471 stop_token(
const _Stop_state_ref& __state) noexcept
480 stop_source() : _M_state(*this)
483 explicit stop_source(std::nostopstate_t) noexcept
486 stop_source(
const stop_source& __other) noexcept
487 : _M_state(__other._M_state)
490 _M_state->_M_add_ssrc();
493 stop_source(stop_source&&) noexcept = default;
496 operator=(const stop_source& __other) noexcept
498 if (_M_state != __other._M_state)
501 _M_state = __other._M_state;
503 _M_state->_M_add_ssrc();
509 operator=(stop_source&&) noexcept = default;
514 _M_state->_M_sub_ssrc();
519 stop_possible() const noexcept
521 return static_cast<bool>(_M_state);
526 stop_requested() const noexcept
528 return static_cast<bool>(_M_state) && _M_state->_M_stop_requested();
532 request_stop() const noexcept
535 return _M_state->_M_request_stop();
541 get_token() const noexcept
543 return stop_token{_M_state};
547 swap(stop_source& __other) noexcept
549 _M_state.swap(__other._M_state);
554 operator==(
const stop_source& __a,
const stop_source& __b) noexcept
556 return __a._M_state == __b._M_state;
560 swap(stop_source& __lhs, stop_source& __rhs) noexcept
566 stop_token::_Stop_state_ref _M_state;
570 template<
typename _Callback>
571 class [[nodiscard]] stop_callback
573 static_assert(is_nothrow_destructible_v<_Callback>);
574 static_assert(is_invocable_v<_Callback>);
577 using callback_type = _Callback;
579 template<
typename _Cb,
580 enable_if_t<is_constructible_v<_Callback, _Cb>,
int> = 0>
582 stop_callback(
const stop_token& __token, _Cb&& __cb)
583 noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
584 : _M_cb(std::
forward<_Cb>(__cb))
586 if (
auto __state = __token._M_state)
588 if (__state->_M_register_callback(&_M_cb))
589 _M_state.swap(__state);
593 template<
typename _Cb,
594 enable_if_t<is_constructible_v<_Callback, _Cb>,
int> = 0>
596 stop_callback(stop_token&& __token, _Cb&& __cb)
597 noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
598 : _M_cb(std::
forward<_Cb>(__cb))
600 if (
auto& __state = __token._M_state)
602 if (__state->_M_register_callback(&_M_cb))
603 _M_state.swap(__state);
611 _M_state->_M_remove_callback(&_M_cb);
615 stop_callback(
const stop_callback&) =
delete;
616 stop_callback&
operator=(
const stop_callback&) =
delete;
617 stop_callback(stop_callback&&) =
delete;
618 stop_callback&
operator=(stop_callback&&) =
delete;
621 struct _Cb_impl : stop_token::_Stop_cb
623 template<
typename _Cb>
626 : _Stop_cb(&_S_execute),
632 [[__gnu__::__nonnull__]]
634 _S_execute(_Stop_cb* __that) noexcept
636 _Callback& __cb =
static_cast<_Cb_impl*
>(__that)->_M_cb;
637 std::forward<_Callback>(__cb)();
642 stop_token::_Stop_state_ref _M_state;
645 template<
typename _Callback>
646 stop_callback(stop_token, _Callback) -> stop_callback<_Callback>;
648 _GLIBCXX_END_NAMESPACE_VERSION
650 #endif // __cplusplus > 201703L
651 #endif // _GLIBCXX_STOP_TOKEN
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
void yield() noexcept
this_thread::yield
element_type * release()
Bypassing the smart pointer.
Generic atomic type, primary class template.
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
thread::id get_id() noexcept
this_thread::get_id
element_type * operator->() const
Smart pointer dereferencing.
memory_order
Enumeration for memory_order.
auto_ptr & operator=(auto_ptr &__a)
auto_ptr assignment operator.