dfa600fb8f
Add a `simple_value_with_expiry` utility class, which functions like a `std::optional` with added timeout. When emplacing a value, user needs to provide timeout, after which value expires (in which case the `simple_value_with_expiry` object behaves as if was never set at all). Add boost tests for the new class.
45 lines
1.2 KiB
C++
45 lines
1.2 KiB
C++
/*
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* Copyright (C) 2025-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#pragma once
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#include <optional>
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#include <chrono>
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namespace utils {
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// simple value with attached expiry timeout
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// the value might be not set or expired, in which case get() returns std::nullopt
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// set_if_longer_expiry() sets the value and expiry time to the given values, only if
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// either value is not set, is expired or passed expiry timeout is further into the future
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template <typename T> class simple_value_with_expiry {
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public:
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using time_point = std::chrono::high_resolution_clock::time_point;
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private:
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time_point expire_when;
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std::optional<T> value;
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public:
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simple_value_with_expiry() = default;
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std::optional<T> get(time_point now_moment = std::chrono::high_resolution_clock::now()) const {
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if (now_moment <= expire_when) {
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return value;
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}
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return std::nullopt;
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}
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void set_if_longer_expiry(T v, time_point expiry) {
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if (expiry > expire_when) {
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expire_when = expiry;
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value = std::move(v);
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}
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}
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};
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}
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