| // Copyright (C) 2020 The Android Open Source Project |
| // |
| // 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. |
| package com.googlesource.gerrit.modules.cache.chroniclemap; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import java.util.Collections; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| |
| public class InMemoryLRU<K> { |
| |
| private final Map<K, Boolean> LRUMap; |
| |
| private static final Boolean dummyValue = Boolean.TRUE; |
| private final int capacity; |
| |
| public InMemoryLRU(int capacity) { |
| this.capacity = capacity; |
| |
| LRUMap = |
| Collections.synchronizedMap( |
| new LinkedHashMap<K, Boolean>(capacity, 0.75f, true) { |
| private static final long serialVersionUID = 1L; |
| |
| @Override |
| protected boolean removeEldestEntry(Map.Entry<K, Boolean> eldest) { |
| return size() > capacity; |
| } |
| }); |
| } |
| |
| public void add(K objKey) { |
| LRUMap.putIfAbsent(objKey, dummyValue); |
| } |
| |
| public boolean contains(K key) { |
| return LRUMap.containsKey(key); |
| } |
| |
| /** |
| * Remove a key from the map |
| * |
| * @param key element to remove from the map |
| * @return true when key was in the map, null otherwise |
| */ |
| public Boolean remove(K key) { |
| return LRUMap.remove(key); |
| } |
| |
| public void invalidateAll() { |
| LRUMap.clear(); |
| } |
| |
| public int size() { |
| return LRUMap.size(); |
| } |
| |
| @VisibleForTesting |
| protected Object[] toArray() { |
| return LRUMap.keySet().toArray(); |
| } |
| |
| public int getCapacity() { |
| return capacity; |
| } |
| } |