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| <pre><span class="source-line-no">001</span><span id="line-1">/*</span> |
| <span class="source-line-no">002</span><span id="line-2"> * Licensed to the Apache Software Foundation (ASF) under one</span> |
| <span class="source-line-no">003</span><span id="line-3"> * or more contributor license agreements. See the NOTICE file</span> |
| <span class="source-line-no">004</span><span id="line-4"> * distributed with this work for additional information</span> |
| <span class="source-line-no">005</span><span id="line-5"> * regarding copyright ownership. The ASF licenses this file</span> |
| <span class="source-line-no">006</span><span id="line-6"> * to you under the Apache License, Version 2.0 (the</span> |
| <span class="source-line-no">007</span><span id="line-7"> * "License"); you may not use this file except in compliance</span> |
| <span class="source-line-no">008</span><span id="line-8"> * with the License. You may obtain a copy of the License at</span> |
| <span class="source-line-no">009</span><span id="line-9"> *</span> |
| <span class="source-line-no">010</span><span id="line-10"> * http://www.apache.org/licenses/LICENSE-2.0</span> |
| <span class="source-line-no">011</span><span id="line-11"> *</span> |
| <span class="source-line-no">012</span><span id="line-12"> * Unless required by applicable law or agreed to in writing, software</span> |
| <span class="source-line-no">013</span><span id="line-13"> * distributed under the License is distributed on an "AS IS" BASIS,</span> |
| <span class="source-line-no">014</span><span id="line-14"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span> |
| <span class="source-line-no">015</span><span id="line-15"> * See the License for the specific language governing permissions and</span> |
| <span class="source-line-no">016</span><span id="line-16"> * limitations under the License.</span> |
| <span class="source-line-no">017</span><span id="line-17"> */</span> |
| <span class="source-line-no">018</span><span id="line-18">package org.apache.hadoop.hbase.metrics.impl;</span> |
| <span class="source-line-no">019</span><span id="line-19"></span> |
| <span class="source-line-no">020</span><span id="line-20">import java.util.Collection;</span> |
| <span class="source-line-no">021</span><span id="line-21">import java.util.Set;</span> |
| <span class="source-line-no">022</span><span id="line-22">import java.util.concurrent.ConcurrentHashMap;</span> |
| <span class="source-line-no">023</span><span id="line-23">import java.util.function.Supplier;</span> |
| <span class="source-line-no">024</span><span id="line-24">import java.util.stream.Collectors;</span> |
| <span class="source-line-no">025</span><span id="line-25">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">026</span><span id="line-26"></span> |
| <span class="source-line-no">027</span><span id="line-27">/**</span> |
| <span class="source-line-no">028</span><span id="line-28"> * A map of K to V, but does ref counting for added and removed values. The values are not added</span> |
| <span class="source-line-no">029</span><span id="line-29"> * directly, but instead requested from the given Supplier if ref count == 0. Each put() call will</span> |
| <span class="source-line-no">030</span><span id="line-30"> * increment the ref count, and each remove() will decrement it. The values are removed from the map</span> |
| <span class="source-line-no">031</span><span id="line-31"> * iff ref count == 0.</span> |
| <span class="source-line-no">032</span><span id="line-32"> */</span> |
| <span class="source-line-no">033</span><span id="line-33">@InterfaceAudience.Private</span> |
| <span class="source-line-no">034</span><span id="line-34">class RefCountingMap<K, V> {</span> |
| <span class="source-line-no">035</span><span id="line-35"></span> |
| <span class="source-line-no">036</span><span id="line-36"> private ConcurrentHashMap<K, Payload<V>> map = new ConcurrentHashMap<>();</span> |
| <span class="source-line-no">037</span><span id="line-37"></span> |
| <span class="source-line-no">038</span><span id="line-38"> private static class Payload<V> {</span> |
| <span class="source-line-no">039</span><span id="line-39"> V v;</span> |
| <span class="source-line-no">040</span><span id="line-40"> int refCount;</span> |
| <span class="source-line-no">041</span><span id="line-41"></span> |
| <span class="source-line-no">042</span><span id="line-42"> Payload(V v) {</span> |
| <span class="source-line-no">043</span><span id="line-43"> this.v = v;</span> |
| <span class="source-line-no">044</span><span id="line-44"> this.refCount = 1; // create with ref count = 1</span> |
| <span class="source-line-no">045</span><span id="line-45"> }</span> |
| <span class="source-line-no">046</span><span id="line-46"> }</span> |
| <span class="source-line-no">047</span><span id="line-47"></span> |
| <span class="source-line-no">048</span><span id="line-48"> V put(K k, Supplier<V> supplier) {</span> |
| <span class="source-line-no">049</span><span id="line-49"> return ((Payload<V>) map.compute(k, (k1, oldValue) -> {</span> |
| <span class="source-line-no">050</span><span id="line-50"> if (oldValue != null) {</span> |
| <span class="source-line-no">051</span><span id="line-51"> oldValue.refCount++;</span> |
| <span class="source-line-no">052</span><span id="line-52"> return oldValue;</span> |
| <span class="source-line-no">053</span><span id="line-53"> } else {</span> |
| <span class="source-line-no">054</span><span id="line-54"> return new Payload(supplier.get());</span> |
| <span class="source-line-no">055</span><span id="line-55"> }</span> |
| <span class="source-line-no">056</span><span id="line-56"> })).v;</span> |
| <span class="source-line-no">057</span><span id="line-57"> }</span> |
| <span class="source-line-no">058</span><span id="line-58"></span> |
| <span class="source-line-no">059</span><span id="line-59"> V get(K k) {</span> |
| <span class="source-line-no">060</span><span id="line-60"> Payload<V> p = map.get(k);</span> |
| <span class="source-line-no">061</span><span id="line-61"> return p == null ? null : p.v;</span> |
| <span class="source-line-no">062</span><span id="line-62"> }</span> |
| <span class="source-line-no">063</span><span id="line-63"></span> |
| <span class="source-line-no">064</span><span id="line-64"> /**</span> |
| <span class="source-line-no">065</span><span id="line-65"> * Decrements the ref count of k, and removes from map if ref count == 0.</span> |
| <span class="source-line-no">066</span><span id="line-66"> * @param k the key to remove</span> |
| <span class="source-line-no">067</span><span id="line-67"> * @return the value associated with the specified key or null if key is removed from map.</span> |
| <span class="source-line-no">068</span><span id="line-68"> */</span> |
| <span class="source-line-no">069</span><span id="line-69"> V remove(K k) {</span> |
| <span class="source-line-no">070</span><span id="line-70"> Payload<V> p = map.computeIfPresent(k, (k1, v) -> --v.refCount <= 0 ? null : v);</span> |
| <span class="source-line-no">071</span><span id="line-71"> return p == null ? null : p.v;</span> |
| <span class="source-line-no">072</span><span id="line-72"> }</span> |
| <span class="source-line-no">073</span><span id="line-73"></span> |
| <span class="source-line-no">074</span><span id="line-74"> void clear() {</span> |
| <span class="source-line-no">075</span><span id="line-75"> map.clear();</span> |
| <span class="source-line-no">076</span><span id="line-76"> }</span> |
| <span class="source-line-no">077</span><span id="line-77"></span> |
| <span class="source-line-no">078</span><span id="line-78"> Set<K> keySet() {</span> |
| <span class="source-line-no">079</span><span id="line-79"> return map.keySet();</span> |
| <span class="source-line-no">080</span><span id="line-80"> }</span> |
| <span class="source-line-no">081</span><span id="line-81"></span> |
| <span class="source-line-no">082</span><span id="line-82"> Collection<V> values() {</span> |
| <span class="source-line-no">083</span><span id="line-83"> return map.values().stream().map(v -> v.v).collect(Collectors.toList());</span> |
| <span class="source-line-no">084</span><span id="line-84"> }</span> |
| <span class="source-line-no">085</span><span id="line-85"></span> |
| <span class="source-line-no">086</span><span id="line-86"> int size() {</span> |
| <span class="source-line-no">087</span><span id="line-87"> return map.size();</span> |
| <span class="source-line-no">088</span><span id="line-88"> }</span> |
| <span class="source-line-no">089</span><span id="line-89">}</span> |
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