30#define _GLIBCXX_LATCH 1
33#pragma GCC system_header
38#define __glibcxx_want_latch
46namespace std _GLIBCXX_VISIBILITY(default)
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
53 static constexpr ptrdiff_t
57 constexpr auto __max = __int_traits<__detail::__platform_wait_t>::__max;
58 if constexpr (std::cmp_less(__max, __PTRDIFF_MAX__))
60 return __PTRDIFF_MAX__;
64 latch(ptrdiff_t __expected) noexcept
66 { __glibcxx_assert(__expected >= 0 && __expected <= max()); }
70 latch(
const latch&) =
delete;
71 latch& operator=(
const latch&) =
delete;
73 _GLIBCXX_ALWAYS_INLINE
void
74 count_down(ptrdiff_t __update = 1)
76 __glibcxx_assert(__update >= 0 && __update <= max());
77 auto const __old = __atomic_impl::fetch_sub(&_M_a, __update,
78 memory_order::release);
79 if (std::cmp_equal(__old, __update))
80 __atomic_impl::notify_all(&_M_a);
82 __glibcxx_assert(std::cmp_less(__update, __old));
85 _GLIBCXX_ALWAYS_INLINE
bool
86 try_wait() const noexcept
87 {
return __atomic_impl::load(&_M_a, memory_order::acquire) == 0; }
89 _GLIBCXX_ALWAYS_INLINE
void
92 auto const __pred = [
this] {
return this->try_wait(); };
93 std::__atomic_wait_address(&_M_a, __pred);
96 _GLIBCXX_ALWAYS_INLINE
void
97 arrive_and_wait(ptrdiff_t __update = 1) noexcept
104 alignas(__detail::__platform_wait_alignment)
105 __detail::__platform_wait_t _M_a;
107_GLIBCXX_END_NAMESPACE_VERSION
ISO C++ entities toplevel namespace is std.
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.