| /* |
| * 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. |
| */ |
| package org.apache.cassandra.cache; |
| |
| import static com.google.common.base.Preconditions.checkState; |
| |
| import java.util.Iterator; |
| |
| import com.github.benmanes.caffeine.cache.Cache; |
| import com.github.benmanes.caffeine.cache.Caffeine; |
| import com.github.benmanes.caffeine.cache.Policy.Eviction; |
| import com.github.benmanes.caffeine.cache.Weigher; |
| import org.apache.cassandra.concurrent.ImmediateExecutor; |
| |
| /** |
| * An adapter from a Caffeine cache to the ICache interface. This provides an on-heap cache using |
| * the W-TinyLFU eviction policy (http://arxiv.org/pdf/1512.00727.pdf), which has a higher hit rate |
| * than an LRU. |
| */ |
| public class CaffeineCache<K extends IMeasurableMemory, V extends IMeasurableMemory> implements ICache<K, V> |
| { |
| private final Cache<K, V> cache; |
| private final Eviction<K, V> policy; |
| |
| private CaffeineCache(Cache<K, V> cache) |
| { |
| this.cache = cache; |
| this.policy = cache.policy().eviction().orElseThrow(() -> |
| new IllegalArgumentException("Expected a size bounded cache")); |
| checkState(policy.isWeighted(), "Expected a weighted cache"); |
| } |
| |
| /** |
| * Initialize a cache with initial capacity with weightedCapacity |
| */ |
| public static <K extends IMeasurableMemory, V extends IMeasurableMemory> CaffeineCache<K, V> create(long weightedCapacity, Weigher<K, V> weigher) |
| { |
| Cache<K, V> cache = Caffeine.newBuilder() |
| .maximumWeight(weightedCapacity) |
| .weigher(weigher) |
| .executor(ImmediateExecutor.INSTANCE) |
| .build(); |
| return new CaffeineCache<>(cache); |
| } |
| |
| public static <K extends IMeasurableMemory, V extends IMeasurableMemory> CaffeineCache<K, V> create(long weightedCapacity) |
| { |
| return create(weightedCapacity, (key, value) -> { |
| long size = key.unsharedHeapSize() + value.unsharedHeapSize(); |
| if (size > Integer.MAX_VALUE) { |
| throw new IllegalArgumentException("Serialized size cannot be more than 2GiB/Integer.MAX_VALUE"); |
| } |
| return (int) size; |
| }); |
| } |
| |
| public long capacity() |
| { |
| return policy.getMaximum(); |
| } |
| |
| public void setCapacity(long capacity) |
| { |
| policy.setMaximum(capacity); |
| } |
| |
| public boolean isEmpty() |
| { |
| return cache.asMap().isEmpty(); |
| } |
| |
| public int size() |
| { |
| return cache.asMap().size(); |
| } |
| |
| public long weightedSize() |
| { |
| return policy.weightedSize().getAsLong(); |
| } |
| |
| public void clear() |
| { |
| cache.invalidateAll(); |
| } |
| |
| public V get(K key) |
| { |
| return cache.getIfPresent(key); |
| } |
| |
| public void put(K key, V value) |
| { |
| cache.put(key, value); |
| } |
| |
| public boolean putIfAbsent(K key, V value) |
| { |
| return cache.asMap().putIfAbsent(key, value) == null; |
| } |
| |
| public boolean replace(K key, V old, V value) |
| { |
| return cache.asMap().replace(key, old, value); |
| } |
| |
| public void remove(K key) |
| { |
| cache.invalidate(key); |
| } |
| |
| public Iterator<K> keyIterator() |
| { |
| return cache.asMap().keySet().iterator(); |
| } |
| |
| public Iterator<K> hotKeyIterator(int n) |
| { |
| return policy.hottest(n).keySet().iterator(); |
| } |
| |
| public boolean containsKey(K key) |
| { |
| return cache.asMap().containsKey(key); |
| } |
| } |