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115 lines
3.3 KiB
C++
115 lines
3.3 KiB
C++
// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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#pragma once
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#include <unordered_map>
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#include <list>
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#include <cstddef>
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#include <stdexcept>
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namespace zilliz {
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namespace milvus {
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namespace cache {
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template<typename key_t, typename value_t>
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class LRU {
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public:
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typedef typename std::pair<key_t, value_t> key_value_pair_t;
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typedef typename std::list<key_value_pair_t>::iterator list_iterator_t;
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typedef typename std::list<key_value_pair_t>::reverse_iterator reverse_list_iterator_t;
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LRU(size_t max_size) : _max_size(max_size) {}
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void put(const key_t& key, const value_t& value) {
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auto it = _cache_items_map.find(key);
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_cache_items_list.push_front(key_value_pair_t(key, value));
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if (it != _cache_items_map.end()) {
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_cache_items_list.erase(it->second);
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_cache_items_map.erase(it);
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}
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_cache_items_map[key] = _cache_items_list.begin();
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if (_cache_items_map.size() > _max_size) {
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auto last = _cache_items_list.end();
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last--;
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_cache_items_map.erase(last->first);
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_cache_items_list.pop_back();
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}
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}
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const value_t& get(const key_t& key) {
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auto it = _cache_items_map.find(key);
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if (it == _cache_items_map.end()) {
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throw std::range_error("There is no such key in cache");
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} else {
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_cache_items_list.splice(_cache_items_list.begin(), _cache_items_list, it->second);
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return it->second->second;
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}
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}
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void erase(const key_t& key) {
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auto it = _cache_items_map.find(key);
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if (it != _cache_items_map.end()) {
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_cache_items_list.erase(it->second);
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_cache_items_map.erase(it);
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}
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}
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bool exists(const key_t& key) const {
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return _cache_items_map.find(key) != _cache_items_map.end();
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}
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size_t size() const {
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return _cache_items_map.size();
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}
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list_iterator_t begin() {
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_iter = _cache_items_list.begin();
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return _iter;
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}
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list_iterator_t end() {
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return _cache_items_list.end();
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}
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reverse_list_iterator_t rbegin() {
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return _cache_items_list.rbegin();
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}
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reverse_list_iterator_t rend() {
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return _cache_items_list.rend();
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}
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void clear() {
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_cache_items_list.clear();
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_cache_items_map.clear();
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}
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private:
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std::list<key_value_pair_t> _cache_items_list;
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std::unordered_map<key_t, list_iterator_t> _cache_items_map;
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size_t _max_size;
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list_iterator_t _iter;
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};
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} // cache
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} // milvus
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} // zilliz
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