50 lines
947 B
C++
50 lines
947 B
C++
#ifndef RFL_INTERNAL_MEMOIZATION_HPP_
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#define RFL_INTERNAL_MEMOIZATION_HPP_
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#include <atomic>
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#include <mutex>
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namespace rfl {
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namespace internal {
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/// For a thread-safe memoization pattern.
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template <class T>
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class Memoization {
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public:
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Memoization() { flag_.clear(); }
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~Memoization() = default;
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public:
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/// Returns the underlying value.
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template <class F>
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const T& value(const F& _f) {
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if (flag_.test()) { return value_; }
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std::lock_guard<std::mutex> guard(mtx_);
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if (flag_.test()) { return value_; }
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_f(&value_);
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flag_.test_and_set();
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return value_;
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}
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private:
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/// Signifies whether t_ has been set.
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std::atomic_flag flag_;
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/// A mutex, only needed for writing.
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std::mutex mtx_;
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/// The type to be initialized.
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T value_;
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};
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} // namespace internal
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} // namespace rfl
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#endif
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