3ae45e0d19
Reviewers: dgleich, mislav.bradac, buda Reviewed By: mislav.bradac Subscribers: pullbot Differential Revision: https://phabricator.memgraph.io/D1060
50 lines
1.8 KiB
C++
50 lines
1.8 KiB
C++
#pragma once
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#include "data_structures/concurrent/concurrent_map.hpp"
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#include "storage/concurrent_id_mapper.hpp"
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namespace storage {
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/** SingleNode implementation of ConcurrentIdMapper. */
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template <typename TId>
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class SingleNodeConcurrentIdMapper : public ConcurrentIdMapper<TId> {
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using StorageT = typename TId::StorageT;
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public:
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TId value_to_id(const std::string &value) override {
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auto value_to_id_acc = value_to_id_.access();
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auto found = value_to_id_acc.find(value);
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TId inserted_id(0);
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if (found == value_to_id_acc.end()) {
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StorageT new_id = id_.fetch_add(1);
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DCHECK(new_id < std::numeric_limits<StorageT>::max())
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<< "Number of used ids overflowed our container";
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auto insert_result = value_to_id_acc.insert(value, TId(new_id));
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// After we tried to insert value with our id we either got our id, or the
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// id created by the thread which succesfully inserted (value, id) pair
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inserted_id = insert_result.first->second;
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} else {
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inserted_id = found->second;
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}
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auto id_to_value_acc = id_to_value_.access();
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// We have to try to insert the inserted_id and value even if we are not the
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// one who assigned id because we have to make sure that after this method
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// returns that both mappings between id->value and value->id exist.
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id_to_value_acc.insert(inserted_id, value);
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return inserted_id;
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}
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const std::string &id_to_value(const TId &id) override {
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const auto id_to_value_acc = id_to_value_.access();
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auto result = id_to_value_acc.find(id);
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DCHECK(result != id_to_value_acc.end());
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return result->second;
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}
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private:
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ConcurrentMap<std::string, TId> value_to_id_;
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ConcurrentMap<TId, std::string> id_to_value_;
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std::atomic<StorageT> id_{0};
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};
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} // namespace storage
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