forked from plusone/plusone-commons
75 lines
2.4 KiB
Java
75 lines
2.4 KiB
Java
/*
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* Copyright 2023-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://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 xyz.zhouxy.plusone.commons.util;
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import java.util.Objects;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.function.Function;
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import xyz.zhouxy.plusone.commons.base.JRE;
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import xyz.zhouxy.plusone.commons.collection.SafeConcurrentHashMap;
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/**
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* ConcurrentHashMapTools
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*
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* <p>
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* Java 8 的 {@link ConcurrentHashMap#computeIfAbsent(Object, Function)} 方法有 bug，
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* 可使用这个工具类的 {@link computeIfAbsentForJava8} 进行替换。
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*
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* <p>
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* <b>NOTE: 方法来自Dubbo，见：issues#2349</b>
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*
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* @author <a href="http://zhouxy.xyz:3000/ZhouXY108">ZhouXY</a>
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* @since 1.0
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* @see ConcurrentHashMap
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* @see SafeConcurrentHashMap
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*/
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public class ConcurrentHashMapTools {
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public static <K, V> V computeIfAbsent(
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ConcurrentHashMap<K, V> map, final K key, // NOSONAR
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final Function<? super K, ? extends V> mappingFunction) {
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Objects.requireNonNull(map, "map");
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return JRE.isJava8()
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? computeIfAbsentForJava8(map, key, mappingFunction)
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: map.computeIfAbsent(key, mappingFunction);
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}
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public static <K, V> V computeIfAbsentForJava8(
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ConcurrentHashMap<K, V> map, final K key, // NOSONAR
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final Function<? super K, ? extends V> mappingFunction) {
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Objects.requireNonNull(key);
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Objects.requireNonNull(mappingFunction);
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V v = map.get(key);
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if (null == v) {
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v = mappingFunction.apply(key);
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if (null == v) {
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return null;
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}
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final V res = map.putIfAbsent(key, v);
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if (null != res) {
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return res;
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}
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}
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return v;
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}
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private ConcurrentHashMapTools() {
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throw new IllegalStateException("Utility class");
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}
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}
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