67 lines
1.4 KiB
C++
67 lines
1.4 KiB
C++
#pragma once
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#include <algorithm>
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#include <vector>
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#include "mvcc/id.hpp"
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#include "utils/option.hpp"
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namespace tx {
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class Engine;
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template <class id_t>
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class Snapshot {
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public:
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Snapshot() = default;
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Snapshot(std::vector<id_t> active) : active(std::move(active)) {}
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Snapshot(const Snapshot &other) { active = other.active; }
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Snapshot(Snapshot &&other) { active = std::move(other.active); }
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// True if all transaction from snapshot have finished.
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bool all_finished(Engine &engine);
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bool is_active(id_t xid) const {
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return std::binary_search(active.begin(), active.end(), xid);
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}
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// Return id of oldest transaction. None if there is no transactions in
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// snapshot.
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Option<Id> oldest_active() {
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auto n = active.size();
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if (n > 0) {
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Id min = active[0];
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for (auto i = 1; i < n; i++) {
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if (active[i] < min) {
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min = active[i];
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}
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}
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return Option<Id>(min);
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} else {
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return Option<Id>();
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}
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}
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void insert(const id_t &id) { active.push_back(id); }
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void remove(const id_t &id) {
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// remove transaction from the active transactions list
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auto last = std::remove(active.begin(), active.end(), id);
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active.erase(last, active.end());
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}
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const id_t &front() { return active.front(); }
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const id_t &back() { return active.back(); }
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size_t size() { return active.size(); }
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private:
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std::vector<id_t> active;
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};
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}
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