#ifndef _LIBCPP_BARRIER
#define _LIBCPP_BARRIER
#include <__config>
#if !defined(_LIBCPP_HAS_NO_THREADS)
# include <__assert>
# include <__atomic/atomic_base.h>
# include <__atomic/memory_order.h>
# include <__memory/unique_ptr.h>
# include <__thread/poll_with_backoff.h>
# include <__thread/timed_backoff_policy.h>
# include <__utility/move.h>
# include <cstddef>
# include <cstdint>
# include <limits>
# include <version>
# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
# endif
_LIBCPP_PUSH_MACROS
# include <__undef_macros>
# if _LIBCPP_STD_VER >= 20
_LIBCPP_BEGIN_NAMESPACE_STD
struct __empty_completion { … };
# ifndef _LIBCPP_HAS_NO_TREE_BARRIER
__barrier_phase_t;
class __barrier_algorithm_base;
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __barrier_algorithm_base*
__construct_barrier_algorithm_base(ptrdiff_t& __expected);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI bool
__arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier, __barrier_phase_t __old_phase) noexcept;
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void
__destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier) noexcept;
template <class _CompletionF>
class __barrier_base { … };
# else
template <class _CompletionF>
class __barrier_base {
__atomic_base<ptrdiff_t> __expected;
__atomic_base<ptrdiff_t> __arrived;
_CompletionF __completion;
__atomic_base<bool> __phase;
public:
using arrival_token = bool;
static constexpr ptrdiff_t max() noexcept { return numeric_limits<ptrdiff_t>::max(); }
_LIBCPP_HIDE_FROM_ABI __barrier_base(ptrdiff_t __expected, _CompletionF __completion = _CompletionF())
: __expected(__expected), __arrived(__expected), __completion(std::move(__completion)), __phase(false) {}
[[nodiscard]] _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI arrival_token arrive(ptrdiff_t update) {
auto const __old_phase = __phase.load(memory_order_relaxed);
auto const __result = __arrived.fetch_sub(update, memory_order_acq_rel) - update;
auto const new_expected = __expected.load(memory_order_relaxed);
_LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
update <= new_expected, "update is greater than the expected count for the current barrier phase");
if (0 == __result) {
__completion();
__arrived.store(new_expected, memory_order_relaxed);
__phase.store(!__old_phase, memory_order_release);
__phase.notify_all();
}
return __old_phase;
}
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(arrival_token&& __old_phase) const {
__phase.wait(__old_phase, memory_order_acquire);
}
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_drop() {
__expected.fetch_sub(1, memory_order_relaxed);
(void)arrive(1);
}
};
template <>
class __barrier_base<__empty_completion> {
static constexpr uint64_t __expected_unit = 1ull;
static constexpr uint64_t __arrived_unit = 1ull << 32;
static constexpr uint64_t __expected_mask = __arrived_unit - 1;
static constexpr uint64_t __phase_bit = 1ull << 63;
static constexpr uint64_t __arrived_mask = (__phase_bit - 1) & ~__expected_mask;
__atomic_base<uint64_t> __phase_arrived_expected;
static _LIBCPP_HIDE_FROM_ABI constexpr uint64_t __init(ptrdiff_t __count) _NOEXCEPT {
return ((uint64_t(1u << 31) - __count) << 32) | (uint64_t(1u << 31) - __count);
}
public:
using arrival_token = uint64_t;
static constexpr ptrdiff_t max() noexcept { return ptrdiff_t(1u << 31) - 1; }
_LIBCPP_HIDE_FROM_ABI explicit inline __barrier_base(ptrdiff_t __count, __empty_completion = __empty_completion())
: __phase_arrived_expected(__init(__count)) {}
[[nodiscard]] inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI arrival_token arrive(ptrdiff_t update) {
auto const __inc = __arrived_unit * update;
auto const __old = __phase_arrived_expected.fetch_add(__inc, memory_order_acq_rel);
_LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
update <= __old, "update is greater than the expected count for the current barrier phase");
if ((__old ^ (__old + __inc)) & __phase_bit) {
__phase_arrived_expected.fetch_add((__old & __expected_mask) << 32, memory_order_relaxed);
__phase_arrived_expected.notify_all();
}
return __old & __phase_bit;
}
inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(arrival_token&& __phase) const {
auto const __test_fn = [=]() -> bool {
uint64_t const __current = __phase_arrived_expected.load(memory_order_acquire);
return ((__current & __phase_bit) != __phase);
};
__libcpp_thread_poll_with_backoff(__test_fn, __libcpp_timed_backoff_policy());
}
inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_drop() {
__phase_arrived_expected.fetch_add(__expected_unit, memory_order_relaxed);
(void)arrive(1);
}
};
# endif
template <class _CompletionF = __empty_completion>
class barrier { … };
_LIBCPP_END_NAMESPACE_STD
# endif
_LIBCPP_POP_MACROS
#endif
#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <atomic>
# include <concepts>
# include <iterator>
# include <memory>
# include <stdexcept>
# include <variant>
#endif
#endif