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de2a447576
Default constructed extremum_tracker has uninitialised _default_value which basically makes it never correct to do that. Since this class is a mechanism and not a value it doesn't really need to be a regular type, so let's drop the default constructor. Message-Id: <20190207162430.7460-1-pdziepak@scylladb.com>
104 lines
2.4 KiB
C++
104 lines
2.4 KiB
C++
/*
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* Copyright (C) 2018 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <functional>
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namespace detail {
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template<typename T, typename Comparator>
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class extremum_tracker {
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T _default_value;
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bool _is_set = false;
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T _value;
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public:
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explicit extremum_tracker(T default_value) {
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_default_value = default_value;
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}
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void update(T value) {
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if (!_is_set) {
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_value = value;
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_is_set = true;
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} else {
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if (Comparator{}(value,_value)) {
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_value = value;
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}
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}
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}
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void update(const extremum_tracker& other) {
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if (other._is_set) {
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update(other._value);
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}
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}
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T get() const {
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if (_is_set) {
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return _value;
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}
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return _default_value;
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}
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};
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} // namespace detail
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template <typename T>
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using min_tracker = detail::extremum_tracker<T, std::less<T>>;
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template <typename T>
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using max_tracker = detail::extremum_tracker<T, std::greater<T>>;
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template <typename T>
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class min_max_tracker {
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min_tracker<T> _min_tracker;
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max_tracker<T> _max_tracker;
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public:
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min_max_tracker()
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: _min_tracker(std::numeric_limits<T>::min())
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, _max_tracker(std::numeric_limits<T>::max())
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{}
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min_max_tracker(T default_min, T default_max)
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: _min_tracker(default_min)
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, _max_tracker(default_max)
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{}
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void update(T value) {
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_min_tracker.update(value);
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_max_tracker.update(value);
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}
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void update(const min_max_tracker<T>& other) {
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_min_tracker.update(other._min_tracker);
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_max_tracker.update(other._max_tracker);
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}
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T min() const {
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return _min_tracker.get();
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}
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T max() const {
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return _max_tracker.get();
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}
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};
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