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92 lines
3.8 KiB
C++
92 lines
3.8 KiB
C++
/*****************************************************************************************
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* *
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* OpenSpace *
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* *
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* Copyright (c) 2014 - 2016 *
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* *
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this *
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* software and associated documentation files (the "Software"), to deal in the Software *
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* without restriction, including without limitation the rights to use, copy, modify, *
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* merge, publish, distribute, sublicense, and/or sell copies of the Software, and to *
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* permit persons to whom the Software is furnished to do so, subject to the following *
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* conditions: *
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* *
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* The above copyright notice and this permission notice shall be included in all copies *
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* or substantial portions of the Software. *
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* *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, *
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* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A *
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* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT *
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF *
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE *
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* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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****************************************************************************************/
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#ifndef __LRUCACHE_H__
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#define __LRUCACHE_H__
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#include <glm/glm.hpp>
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#include <list>
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#include <iterator>
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namespace openspace {
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template <typename ValueType>
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class LinearLruCache {
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public:
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LinearLruCache(size_t capacity, size_t nIndices)
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: _tracker()
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, _cache(nIndices, std::make_pair(nullptr, _tracker.end()))
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, _capacity(capacity) {};
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bool has(size_t key) {
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return _cache[key].first != nullptr;
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};
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void set(size_t key, ValueType value) {
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auto prev = _cache[key];
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if (prev.first != nullptr) {
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prev.first = value;
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std::list<size_t>::iterator trackerIter = prev.second;
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_tracker.splice(_tracker.end(),
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_tracker,
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trackerIter);
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}
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else {
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insert(key, value);
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}
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};
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ValueType& use(size_t key) {
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auto pair = _cache[key];
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std::list<size_t>::iterator trackerIter = pair.second;
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_tracker.splice(_tracker.end(),
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_tracker,
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trackerIter);
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return pair.first;
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};
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ValueType& get(size_t key) {
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return _cache[key].first;
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};
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void evict() {
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_cache[_tracker.front()] = make_pair(nullptr, _tracker.end());
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_tracker.pop_front();
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};
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size_t capacity() {
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return _capacity;
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};
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private:
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void insert(size_t key, const ValueType& value) {
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if (_tracker.size() == _capacity) {
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evict();
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}
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auto iter = _tracker.insert(_tracker.end(), key);
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_cache[key] = std::make_pair(value, iter);
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};
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std::list<size_t> _tracker;
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std::vector<std::pair<ValueType, typename std::list<size_t>::iterator>> _cache;
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size_t _capacity;
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};
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}
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#endif
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