LRUEvictionAlgorithm.h

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/*
 * Copyright 2022 HEAVY.AI, Inc.
 *
 * Licensed 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 <cstddef>
#include <list>
#include "CacheEvictionAlgorithm.h"
#include "Shared/heavyai_shared_mutex.h"

class LRUEvictionAlgorithm : public CacheEvictionAlgorithm {
 public:
  ~LRUEvictionAlgorithm() override {}
  // Returns the next chunk to evict and evicts.
  const ChunkKey evictNextChunk() override;
  // Update the algorithm knowing that this chunk was recently touched by the system.
  void touchChunk(const ChunkKey&) override;
  // Removes a chunk from the eviction queue if present.
  void removeChunk(const ChunkKey&) override;
  // Used for debugging.
  std::string dumpEvictionQueue();

 private:
  std::list<ChunkKey> cache_items_list_;
  std::map<const ChunkKey, std::list<ChunkKey>::iterator> cache_items_map_;
  mutable heavyai::shared_mutex cache_mutex_;
};