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Исправление: Налитов Денис. Технология STL. Поиск кратчайших путей из одной вершины (алгоритм Дейкстры). Вариант 21 #1558

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Merged
allnes merged 2 commits into from
Jun 4, 2026
Merged

Исправление: Налитов Денис. Технология STL. Поиск кратчайших путей из одной вершины (алгоритм Дейкстры). Вариант 21 #1558

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a8e5cfe
fix: prevent pivot race condition
lotva Jun 4, 2026
c4a6166
style: fix warnings
lotva Jun 4, 2026
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3 changes: 2 additions & 1 deletion tasks/nalitov_d_dijkstras_algorithm/stl/include/ops_stl.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,8 @@ class NalitovDDijkstrasAlgorithmSTL : public BaseTask {
int worker_slots_{};
std::vector<std::thread> pool_;
std::vector<ShardResult> shard_results_;
NodeId pivot_{};

std::atomic<NodeId> pivot_;

std::atomic<WorkMode> mode_{WorkMode::kParked};
std::atomic<bool> shutdown_{false};
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7 changes: 5 additions & 2 deletions tasks/nalitov_d_dijkstras_algorithm/stl/src/ops_stl.cpp
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Expand Up @@ -124,7 +124,7 @@ void NalitovDDijkstrasAlgorithmSTL::PartitionScanBest(int slot) {
}

void NalitovDDijkstrasAlgorithmSTL::PartitionPushDist(int slot) {
const auto hub = static_cast<std::size_t>(pivot_);
const auto hub = static_cast<std::size_t>(pivot_.load(std::memory_order_acquire));
const auto &bundle = graph_[hub];
const std::size_t m = bundle.size();
if (m == 0) {
Expand Down Expand Up @@ -218,6 +218,7 @@ bool NalitovDDijkstrasAlgorithmSTL::PreProcessingImpl() {

shutdown_.store(false, std::memory_order_relaxed);
mode_.store(WorkMode::kParked, std::memory_order_relaxed);
pivot_.store(-1, std::memory_order_relaxed);

const int total_parties = worker_slots_ + 1;
bar_start_ = std::make_unique<std::barrier<>>(total_parties);
Expand Down Expand Up @@ -252,8 +253,10 @@ bool NalitovDDijkstrasAlgorithmSTL::RunImpl() {
if (!ReduceShardResults(shard_results_, worker_slots_, &pick_c, &pick_v)) {
break;
}

visited_[static_cast<std::size_t>(pick_v)] = 1;
pivot_ = pick_v;
pivot_.store(pick_v, std::memory_order_release);
std::atomic_thread_fence(std::memory_order_release);

mode_.store(WorkMode::kPushDist, std::memory_order_release);
bar_start_->arrive_and_wait();
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