| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| #pragma once |
| |
| #include <deque> |
| #include <functional> |
| #include <unordered_map> |
| #include <vector> |
| |
| namespace pulsar { |
| |
| // A map cache that supports removing the first N oldest entries from the map. |
| // Value must be moveable and have the default constructor. |
| template <typename Key, typename Value> |
| class MapCache { |
| std::unordered_map<Key, Value> map_; |
| std::deque<Key> keys_; |
| |
| public: |
| using const_iterator = typename decltype(map_)::const_iterator; |
| using iterator = typename decltype(map_)::iterator; |
| |
| MapCache() = default; |
| // Here we don't use =default to be compatible with GCC 4.8 |
| MapCache(MapCache&& rhs) noexcept : map_(std::move(rhs.map_)), keys_(std::move(rhs.keys_)) {} |
| |
| size_t size() const noexcept { return map_.size(); } |
| |
| const_iterator find(const Key& key) const { return map_.find(key); } |
| iterator find(const Key& key) { return map_.find(key); } |
| |
| const_iterator end() const noexcept { return map_.end(); } |
| iterator end() noexcept { return map_.end(); } |
| |
| iterator putIfAbsent(const Key& key, Value&& value) { |
| auto it = map_.find(key); |
| if (it == map_.end()) { |
| keys_.push_back(key); |
| return map_.emplace(key, std::move(value)).first; |
| } else { |
| return end(); |
| } |
| } |
| |
| void removeOldestValues(size_t numToRemove, |
| const std::function<void(const Key&, const Value&)>& callback) { |
| for (size_t i = 0; !keys_.empty() && i < numToRemove; i++) { |
| const auto key = keys_.front(); |
| auto it = map_.find(key); |
| if (it != map_.end()) { |
| if (callback) { |
| callback(it->first, it->second); |
| } |
| map_.erase(it); |
| } |
| keys_.pop_front(); |
| } |
| } |
| |
| void removeOldestValuesIf(const std::function<bool(const Key&, const Value&)>& condition) { |
| if (!condition) return; |
| while (!keys_.empty()) { |
| const auto key = keys_.front(); |
| auto it = map_.find(key); |
| if (it == map_.end()) { |
| continue; |
| } |
| if (condition(it->first, it->second)) { |
| map_.erase(it); |
| keys_.pop_front(); |
| } else { |
| return; |
| } |
| } |
| } |
| |
| void remove(const Key& key) { |
| auto it = map_.find(key); |
| if (it != map_.end()) { |
| removeKeyFromKeys(key); |
| map_.erase(it); |
| } |
| } |
| |
| // Following methods are only used for tests |
| std::vector<Key> getKeys() const { |
| std::vector<Key> keys; |
| for (auto key : keys_) { |
| keys.emplace_back(key); |
| } |
| return keys; |
| } |
| |
| private: |
| void removeKeyFromKeys(const Key& key) { |
| for (auto it = keys_.begin(); it != keys_.end(); ++it) { |
| if (*it == key) { |
| keys_.erase(it); |
| break; |
| } |
| } |
| } |
| }; |
| |
| } // namespace pulsar |