myPrecious
GitHub
parent
d6672afbee
commit
4dd5a0db57
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@ -0,0 +1,287 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* 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, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.dubbo.common.utils;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.concurrent.locks.ReentrantLock;
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public class LFUCache<K, V> {
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private Map<K, CacheNode<K, V>> map;
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private CacheDeque<K, V>[] freqTable;
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private final int capacity;
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private int evictionCount;
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private int curSize = 0;
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private final ReentrantLock lock = new ReentrantLock();
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private static final int DEFAULT_LOAD_FACTOR = 1000;
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private static final float DEFAULT_EVICTION_CAPACITY = 0.75f;
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public LFUCache() {
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this(DEFAULT_LOAD_FACTOR, DEFAULT_EVICTION_CAPACITY);
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}
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/**
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* Constructs and initializes cache with specified capacity and eviction
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* factor. Unacceptable parameter values followed with
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* {@link IllegalArgumentException}.
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*
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* @param maxCapacity cache max capacity
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* @param evictionFactor cache proceedEviction factor
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*/
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public LFUCache(final int maxCapacity, final float evictionFactor) {
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if (maxCapacity <= 0) {
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throw new IllegalArgumentException("Illegal initial capacity: " +
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maxCapacity);
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}
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boolean factorInRange = evictionFactor <= 1 || evictionFactor < 0;
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if (!factorInRange || Float.isNaN(evictionFactor)) {
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throw new IllegalArgumentException("Illegal eviction factor value:"
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+ evictionFactor);
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}
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this.capacity = maxCapacity;
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this.evictionCount = (int) (capacity * evictionFactor);
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this.map = new HashMap<>();
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this.freqTable = new CacheDeque[capacity + 1];
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for (int i = 0; i <= capacity; i++) {
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freqTable[i] = new CacheDeque<K, V>();
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}
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for (int i = 0; i < capacity; i++) {
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freqTable[i].nextDeque = freqTable[i + 1];
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}
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freqTable[capacity].nextDeque = freqTable[capacity];
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}
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public int getCapacity() {
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return capacity;
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}
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public V put(final K key, final V value) {
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CacheNode<K, V> node;
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lock.lock();
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try {
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if (map.containsKey(key)) {
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node = map.get(key);
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if (node != null) {
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CacheNode.withdrawNode(node);
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}
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node.value = value;
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freqTable[0].addLastNode(node);
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map.put(key, node);
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} else {
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node = freqTable[0].addLast(key, value);
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map.put(key, node);
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curSize++;
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if (curSize > capacity) {
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proceedEviction();
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}
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}
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} finally {
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lock.unlock();
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}
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return node.value;
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}
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public V remove(final K key) {
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CacheNode<K, V> node = null;
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lock.lock();
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try {
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if (map.containsKey(key)) {
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node = map.remove(key);
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if (node != null) {
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CacheNode.withdrawNode(node);
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}
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curSize--;
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}
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} finally {
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lock.unlock();
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}
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return (node != null) ? node.value : null;
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}
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public V get(final K key) {
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CacheNode<K, V> node = null;
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lock.lock();
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try {
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if (map.containsKey(key)) {
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node = map.get(key);
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CacheNode.withdrawNode(node);
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node.owner.nextDeque.addLastNode(node);
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}
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} finally {
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lock.unlock();
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}
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return (node != null) ? node.value : null;
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}
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/**
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* Evicts less frequently used elements corresponding to eviction factor,
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* specified at instantiation step.
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*
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* @return number of evicted elements
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*/
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private int proceedEviction() {
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int targetSize = capacity - evictionCount;
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int evictedElements = 0;
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FREQ_TABLE_ITER_LOOP:
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for (int i = 0; i <= capacity; i++) {
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CacheNode<K, V> node;
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while (!freqTable[i].isEmpty()) {
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node = freqTable[i].pollFirst();
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remove(node.key);
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if (targetSize >= curSize) {
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break FREQ_TABLE_ITER_LOOP;
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}
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evictedElements++;
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}
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}
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return evictedElements;
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}
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/**
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* Returns cache current size.
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*
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* @return cache size
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*/
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public int getSize() {
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return curSize;
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}
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static class CacheNode<K, V> {
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CacheNode<K, V> prev;
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CacheNode<K, V> next;
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K key;
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V value;
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CacheDeque owner;
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CacheNode() {
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}
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CacheNode(final K key, final V value) {
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this.key = key;
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this.value = value;
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}
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/**
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* This method takes specified node and reattaches it neighbors nodes
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* links to each other, so specified node will no longer tied with them.
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* Returns united node, returns null if argument is null.
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*
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* @param node note to retrieve
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* @param <K> key
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* @param <V> value
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* @return retrieved node
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*/
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static <K, V> CacheNode<K, V> withdrawNode(
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final CacheNode<K, V> node) {
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if (node != null && node.prev != null) {
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node.prev.next = node.next;
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if (node.next != null) {
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node.next.prev = node.prev;
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}
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}
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return node;
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}
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}
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/**
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* Custom deque implementation of LIFO type. Allows to place element at top
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* of deque and poll very last added elements. An arbitrary node from the
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* deque can be removed with {@link CacheNode#withdrawNode(CacheNode)}
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* method.
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*
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* @param <K> key
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* @param <V> value
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*/
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static class CacheDeque<K, V> {
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CacheNode<K, V> last;
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CacheNode<K, V> first;
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CacheDeque<K, V> nextDeque;
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/**
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* Constructs list and initializes last and first pointers.
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*/
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CacheDeque() {
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last = new CacheNode<>();
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first = new CacheNode<>();
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last.next = first;
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first.prev = last;
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}
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/**
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* Puts the node with specified key and value at the end of the deque
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* and returns node.
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*
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* @param key key
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* @param value value
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* @return added node
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*/
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CacheNode<K, V> addLast(final K key, final V value) {
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CacheNode<K, V> node = new CacheNode<>(key, value);
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node.owner = this;
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node.next = last.next;
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node.prev = last;
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node.next.prev = node;
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last.next = node;
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return node;
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}
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CacheNode<K, V> addLastNode(final CacheNode<K, V> node) {
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node.owner = this;
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node.next = last.next;
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node.prev = last;
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node.next.prev = node;
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last.next = node;
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return node;
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}
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/**
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* Retrieves and removes the first node of this deque.
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*
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* @return removed node
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*/
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CacheNode<K, V> pollFirst() {
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CacheNode<K, V> node = null;
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if (first.prev != last) {
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node = first.prev;
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first.prev = node.prev;
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first.prev.next = first;
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node.prev = null;
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node.next = null;
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}
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return node;
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}
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/**
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* Checks if link to the last node points to link to the first node.
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*
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* @return is deque empty
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*/
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boolean isEmpty() {
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return last.next == first;
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}
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}
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}
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@ -0,0 +1,72 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* 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, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.dubbo.common.utils;
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import org.junit.jupiter.api.Test;
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import static org.hamcrest.Matchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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public class LFUCacheTest {
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@Test
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public void testCacheEviction() throws Exception {
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LFUCache<String, Integer> cache = new LFUCache<String, Integer>(8, 0.8f);
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cache.put("one", 1);
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cache.put("two", 2);
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cache.put("three", 3);
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assertThat(cache.get("one"), equalTo(1));
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assertThat(cache.get("two"), equalTo(2));
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assertThat(cache.get("three"), equalTo(3));
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assertThat(cache.getSize(), equalTo(3));
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cache.put("four", 4);
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assertThat(cache.getSize(), equalTo(4));
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cache.put("five", 5);
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cache.put("six", 6);
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assertThat(cache.getSize(), equalTo(6));
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cache.put("seven", 7);
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cache.put("eight", 8);
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cache.put("nine", 9);
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assertThat(cache.getSize(), equalTo(2));
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}
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@Test
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public void testCacheRemove() throws Exception {
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LFUCache<String, Integer> cache = new LFUCache<String, Integer>(8, 0.8f);
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cache.put("one", 1);
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cache.put("two", 2);
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cache.put("three", 3);
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assertThat(cache.get("one"), equalTo(1));
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assertThat(cache.get("two"), equalTo(2));
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assertThat(cache.get("three"), equalTo(3));
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assertThat(cache.getSize(), equalTo(3));
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cache.put("four", 4);
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assertThat(cache.getSize(), equalTo(4));
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cache.remove("four");
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assertThat(cache.getSize(), equalTo(3));
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cache.put("five", 5);
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assertThat(cache.getSize(), equalTo(4));
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cache.put("six", 6);
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assertThat(cache.getSize(), equalTo(5));
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}
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@Test
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public void testCapacity() throws Exception {
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LFUCache<String, Integer> cache = new LFUCache<String, Integer>();
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assertThat(cache.getCapacity(), equalTo(1000));
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}
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}
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80
dubbo-filter/dubbo-filter-cache/src/main/java/org/apache/dubbo/cache/support/lfu/LfuCache.java
vendored
Normal file
80
dubbo-filter/dubbo-filter-cache/src/main/java/org/apache/dubbo/cache/support/lfu/LfuCache.java
vendored
Normal file
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@ -0,0 +1,80 @@
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/*
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* 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.
|
||||
*/
|
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package org.apache.dubbo.cache.support.lfu;
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import org.apache.dubbo.cache.Cache;
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import org.apache.dubbo.common.URL;
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import org.apache.dubbo.common.utils.LFUCache;
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/**
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* This class store the cache value per thread. If a service,method,consumer or provided is configured with key <b>cache</b>
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* with value <b>lfu</b>, dubbo initialize the instance of this class using {@link LfuCacheFactory} to store method's returns value
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* to server from store without making method call.
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* <pre>
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* e.g. 1) <dubbo:service cache="lfu" cache.size="5000" cache.evictionFactor="0.3"/>
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* 2) <dubbo:consumer cache="lfu" />
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* </pre>
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* <pre>
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* LfuCache uses url's <b>cache.size</b> value for its max store size, url's <b>cache.evictionFactor</b> value for its eviction factor,
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* default store size value will be 1000, default eviction factor will be 0.3
|
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* </pre>
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*
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* @see Cache
|
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* @see LfuCacheFactory
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* @see org.apache.dubbo.cache.support.AbstractCacheFactory
|
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* @see org.apache.dubbo.cache.filter.CacheFilter
|
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*/
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public class LfuCache implements Cache {
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/**
|
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* This is used to store cache records
|
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*/
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private final LFUCache store;
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|
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/**
|
||||
* Initialize LfuCache, it uses constructor argument <b>cache.size</b> value as its storage max size.
|
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* If nothing is provided then it will use 1000 as default size value. <b>cache.evictionFactor</b> value as its eviction factor.
|
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* If nothing is provided then it will use 0.3 as default value.
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* @param url A valid URL instance
|
||||
*/
|
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public LfuCache (URL url) {
|
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final int max = url.getParameter("cache.size", 1000);
|
||||
final float factor = url.getParameter("cache.evictionFactor", 0.75f);
|
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this.store = new LFUCache(max, factor);
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}
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|
||||
/**
|
||||
* API to store value against a key in the calling thread scope.
|
||||
* @param key Unique identifier for the object being store.
|
||||
* @param value Value getting store
|
||||
*/
|
||||
@Override
|
||||
public void put(Object key, Object value) {
|
||||
store.put(key, value);
|
||||
}
|
||||
|
||||
/**
|
||||
* API to return stored value using a key against the calling thread specific store.
|
||||
* @param key Unique identifier for cache lookup
|
||||
* @return Return stored object against key
|
||||
*/
|
||||
@Override
|
||||
public Object get(Object key) {
|
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return store.get(key);
|
||||
}
|
||||
|
||||
}
|
||||
|
|
@ -0,0 +1,43 @@
|
|||
/*
|
||||
* 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.dubbo.cache.support.lfu;
|
||||
|
||||
import org.apache.dubbo.cache.Cache;
|
||||
import org.apache.dubbo.cache.support.AbstractCacheFactory;
|
||||
import org.apache.dubbo.common.URL;
|
||||
|
||||
/**
|
||||
* Implement {@link org.apache.dubbo.cache.CacheFactory} by extending {@link AbstractCacheFactory} and provide
|
||||
* instance of new {@link LfuCache}.
|
||||
*
|
||||
* @see AbstractCacheFactory
|
||||
* @see LfuCache
|
||||
* @see Cache
|
||||
*/
|
||||
public class LfuCacheFactory extends AbstractCacheFactory {
|
||||
|
||||
/**
|
||||
* Takes url as an method argument and return new instance of cache store implemented by LfuCache.
|
||||
* @param url url of the method
|
||||
* @return ThreadLocalCache instance of cache
|
||||
*/
|
||||
@Override
|
||||
protected Cache createCache(URL url) {
|
||||
return new LfuCache(url);
|
||||
}
|
||||
|
||||
}
|
||||
Loading…
Reference in New Issue