diff --git a/include/util/packed_vector.hpp b/include/util/packed_vector.hpp index 18b1e7bb8..8d4672f1e 100644 --- a/include/util/packed_vector.hpp +++ b/include/util/packed_vector.hpp @@ -10,6 +10,7 @@ #include #include +#include #include #include @@ -348,7 +349,7 @@ template class Pack fill(initial_value); } - PackedVector(util::ViewOrVector vec_, std::size_t num_elements) + PackedVector(util::ViewOrVector vec_, std::size_t num_elements) : vec(std::move(vec_)), num_elements(num_elements) { initialize(); @@ -497,20 +498,39 @@ template class Pack inline void set_value(const InternalIndex internal_index, const T value) { + // ⚠ The method uses CAS spinlocks to prevent data races in parallel calls + // TBB internal atomic's are used for CAS on non-atomic data + // Parallel read and write access is not allowed + auto &lower_word = vec[internal_index.lower_word]; auto &upper_word = vec[internal_index.lower_word + 1]; - lower_word = set_lower_value(lower_word, - lower_mask[internal_index.element], - lower_offset[internal_index.element], - value); - upper_word = set_upper_value(upper_word, - upper_mask[internal_index.element], - upper_offset[internal_index.element], - value); + // Lock-free update of the lower word + WordT local_lower_word, new_lower_word; + do + { + local_lower_word = lower_word; + new_lower_word = set_lower_value(local_lower_word, + lower_mask[internal_index.element], + lower_offset[internal_index.element], + value); + } while (tbb::internal::as_atomic(lower_word) + .compare_and_swap(new_lower_word, local_lower_word) != local_lower_word); + + // Lock-free update of the upper word + WordT local_upper_word, new_upper_word; + do + { + local_upper_word = upper_word; + new_upper_word = set_upper_value(local_upper_word, + upper_mask[internal_index.element], + upper_offset[internal_index.element], + value); + } while (tbb::internal::as_atomic(upper_word) + .compare_and_swap(new_upper_word, local_upper_word) != local_upper_word); } - util::ViewOrVector vec; + util::ViewOrVector vec; std::uint64_t num_elements = 0; }; }