diff options
Diffstat (limited to 'libcxx/src/barrier.cpp')
| -rw-r--r-- | libcxx/src/barrier.cpp | 106 |
1 files changed, 45 insertions, 61 deletions
diff --git a/libcxx/src/barrier.cpp b/libcxx/src/barrier.cpp index 3242e08..baa2610 100644 --- a/libcxx/src/barrier.cpp +++ b/libcxx/src/barrier.cpp @@ -15,75 +15,59 @@ _LIBCPP_BEGIN_NAMESPACE_STD class __barrier_algorithm_base { public: - struct alignas(64) /* naturally-align the heap state */ __state_t - { - struct { - __atomic_base<__barrier_phase_t> __phase{0}; - } __tickets[64]; - }; + struct alignas(64) /* naturally-align the heap state */ __state_t { + struct { + __atomic_base<__barrier_phase_t> __phase{0}; + } __tickets[64]; + }; - ptrdiff_t& __expected; - unique_ptr<__state_t[]> __state; + ptrdiff_t& __expected; + unique_ptr<__state_t[]> __state; - _LIBCPP_HIDDEN - __barrier_algorithm_base(ptrdiff_t& __expected) - : __expected(__expected) - { - size_t const __count = (__expected + 1) >> 1; - __state = unique_ptr<__state_t[]>(new __state_t[__count]); - } - _LIBCPP_HIDDEN - bool __arrive(__barrier_phase_t __old_phase) - { - __barrier_phase_t const __half_step = __old_phase + 1, - __full_step = __old_phase + 2; - size_t __current_expected = __expected, - __current = hash<thread::id>()(this_thread::get_id()) % ((__expected + 1) >> 1); - for(int __round = 0;; ++__round) { - if(__current_expected <= 1) - return true; - size_t const __end_node = ((__current_expected + 1) >> 1), - __last_node = __end_node - 1; - for(;;++__current) { - if(__current == __end_node) - __current = 0; - __barrier_phase_t expect = __old_phase; - if(__current == __last_node && (__current_expected & 1)) - { - if(__state[__current].__tickets[__round].__phase.compare_exchange_strong(expect, __full_step, memory_order_acq_rel)) - break; // I'm 1 in 1, go to next __round - } - else if(__state[__current].__tickets[__round].__phase.compare_exchange_strong(expect, __half_step, memory_order_acq_rel)) - { - return false; // I'm 1 in 2, done with arrival - } - else if(expect == __half_step) - { - if(__state[__current].__tickets[__round].__phase.compare_exchange_strong(expect, __full_step, memory_order_acq_rel)) - break; // I'm 2 in 2, go to next __round - } - } - __current_expected = __last_node + 1; - __current >>= 1; + _LIBCPP_HIDDEN __barrier_algorithm_base(ptrdiff_t& __expected) : __expected(__expected) { + size_t const __count = (__expected + 1) >> 1; + __state = unique_ptr<__state_t[]>(new __state_t[__count]); + } + _LIBCPP_HIDDEN bool __arrive(__barrier_phase_t __old_phase) { + __barrier_phase_t const __half_step = __old_phase + 1, __full_step = __old_phase + 2; + size_t __current_expected = __expected, + __current = hash<thread::id>()(this_thread::get_id()) % ((__expected + 1) >> 1); + for (int __round = 0;; ++__round) { + if (__current_expected <= 1) + return true; + size_t const __end_node = ((__current_expected + 1) >> 1), __last_node = __end_node - 1; + for (;; ++__current) { + if (__current == __end_node) + __current = 0; + __barrier_phase_t expect = __old_phase; + if (__current == __last_node && (__current_expected & 1)) { + if (__state[__current].__tickets[__round].__phase.compare_exchange_strong( + expect, __full_step, memory_order_acq_rel)) + break; // I'm 1 in 1, go to next __round + } else if (__state[__current].__tickets[__round].__phase.compare_exchange_strong( + expect, __half_step, memory_order_acq_rel)) { + return false; // I'm 1 in 2, done with arrival + } else if (expect == __half_step) { + if (__state[__current].__tickets[__round].__phase.compare_exchange_strong( + expect, __full_step, memory_order_acq_rel)) + break; // I'm 2 in 2, go to next __round } + } + __current_expected = __last_node + 1; + __current >>= 1; } + } }; -_LIBCPP_EXPORTED_FROM_ABI -__barrier_algorithm_base * __construct_barrier_algorithm_base(ptrdiff_t& __expected) -{ - return new __barrier_algorithm_base(__expected); +_LIBCPP_EXPORTED_FROM_ABI __barrier_algorithm_base* __construct_barrier_algorithm_base(ptrdiff_t& __expected) { + return new __barrier_algorithm_base(__expected); } -_LIBCPP_EXPORTED_FROM_ABI -bool __arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier, - __barrier_phase_t __old_phase) -{ - return __barrier->__arrive(__old_phase); +_LIBCPP_EXPORTED_FROM_ABI bool +__arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier, __barrier_phase_t __old_phase) { + return __barrier->__arrive(__old_phase); } -_LIBCPP_EXPORTED_FROM_ABI -void __destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier) -{ - delete __barrier; +_LIBCPP_EXPORTED_FROM_ABI void __destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier) { + delete __barrier; } #endif // !defined(_LIBCPP_HAS_NO_TREE_BARRIER) |