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89 lines
3.8 KiB
C++
89 lines
3.8 KiB
C++
/*****************************************************************************************
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* *
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* OpenSpace *
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* *
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* Copyright (c) 2014-2017 *
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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 __OPENSPACE_MODULE_GLOBEBROWSING___LRU_CACHE___H__
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#define __OPENSPACE_MODULE_GLOBEBROWSING___LRU_CACHE___H__
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#include <list>
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#include <unordered_map>
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#include <vector>
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namespace openspace::globebrowsing::cache {
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/**
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* Templated class implementing a Least-Recently-Used Cache.
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* <code>KeyType</code> needs to be an enumerable type.
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*/
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template<typename KeyType, typename ValueType, typename HasherType>
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class LRUCache {
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public:
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using Item = std::pair<KeyType, ValueType>;
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using Items = std::list<Item>;
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/**
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* \param size is the maximum size of the cache given in number of cached items.
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*/
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LRUCache(size_t size);
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void put(const KeyType& key, const ValueType& value);
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std::vector<Item> putAndFetchPopped(const KeyType& key, const ValueType& value);
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void clear();
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bool exist(const KeyType& key) const;
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/**
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* If value exists, the value is bumped to the front of the queue.
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* \returns true if value of this key exists.
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*/
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bool touch(const KeyType& key);
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bool isEmpty() const;
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ValueType get(const KeyType& key);
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/**
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* Pops the front of the queue.
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*/
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Item popMRU();
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/**
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* Pops the back of the queue.
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*/
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Item popLRU();
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size_t size() const;
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size_t maximumCacheSize() const;
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private:
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void putWithoutCleaning(const KeyType& key, const ValueType& value);
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void clean();
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std::vector<Item> cleanAndFetchPopped();
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Items _itemList;
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std::unordered_map<KeyType, typename Items::const_iterator, HasherType> _itemMap;
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size_t _maximumCacheSize;
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};
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} // namespace openspace::globebrowsing::cache
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#include <modules/globebrowsing/cache/lrucache.inl>
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#endif // __OPENSPACE_MODULE_GLOBEBROWSING___LRU_CACHE___H__
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