39 lines
894 B
C++
39 lines
894 B
C++
#pragma once
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#include <atomic>
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namespace mvcc {
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template <class T>
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class Version {
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public:
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Version() = default;
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Version(T *older) : older(older) {}
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~Version() { delete older.load(std::memory_order_seq_cst); }
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// return a pointer to an older version stored in this record
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T *next(std::memory_order order = std::memory_order_seq_cst) {
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return older.load(order);
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}
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const T *next(std::memory_order order = std::memory_order_seq_cst) const {
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return older.load(order);
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}
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// set the older version of this record
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void next(T *value, std::memory_order order = std::memory_order_seq_cst) {
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older.store(value, order);
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}
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// sets if as expected
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bool cas(T *expected, T *set,
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std::memory_order order = std::memory_order_seq_cst) {
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return older.compare_exchange_strong(expected, set, order);
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}
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private:
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std::atomic<T *> older{nullptr};
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};
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}
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