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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;</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.HashMap;</span> |
| <span class="source-line-no">021</span><span id="line-21">import java.util.Iterator;</span> |
| <span class="source-line-no">022</span><span id="line-22">import java.util.Map;</span> |
| <span class="source-line-no">023</span><span id="line-23">import java.util.ServiceLoader;</span> |
| <span class="source-line-no">024</span><span id="line-24">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">025</span><span id="line-25">import org.slf4j.Logger;</span> |
| <span class="source-line-no">026</span><span id="line-26">import org.slf4j.LoggerFactory;</span> |
| <span class="source-line-no">027</span><span id="line-27"></span> |
| <span class="source-line-no">028</span><span id="line-28">/**</span> |
| <span class="source-line-no">029</span><span id="line-29"> * Factory for classes supplied by hadoop compatibility modules. Only one of each class will be</span> |
| <span class="source-line-no">030</span><span id="line-30"> * created.</span> |
| <span class="source-line-no">031</span><span id="line-31"> */</span> |
| <span class="source-line-no">032</span><span id="line-32">@InterfaceAudience.Private</span> |
| <span class="source-line-no">033</span><span id="line-33">public class CompatibilitySingletonFactory extends CompatibilityFactory {</span> |
| <span class="source-line-no">034</span><span id="line-34"></span> |
| <span class="source-line-no">035</span><span id="line-35"> @SuppressWarnings("ImmutableEnumChecker")</span> |
| <span class="source-line-no">036</span><span id="line-36"> public static enum SingletonStorage {</span> |
| <span class="source-line-no">037</span><span id="line-37"> INSTANCE;</span> |
| <span class="source-line-no">038</span><span id="line-38"></span> |
| <span class="source-line-no">039</span><span id="line-39"> private final Object lock = new Object();</span> |
| <span class="source-line-no">040</span><span id="line-40"> private final Map<Class, Object> instances = new HashMap<>();</span> |
| <span class="source-line-no">041</span><span id="line-41"> }</span> |
| <span class="source-line-no">042</span><span id="line-42"></span> |
| <span class="source-line-no">043</span><span id="line-43"> private static final Logger LOG = LoggerFactory.getLogger(CompatibilitySingletonFactory.class);</span> |
| <span class="source-line-no">044</span><span id="line-44"></span> |
| <span class="source-line-no">045</span><span id="line-45"> /**</span> |
| <span class="source-line-no">046</span><span id="line-46"> * This is a static only class don't let anyone create an instance.</span> |
| <span class="source-line-no">047</span><span id="line-47"> */</span> |
| <span class="source-line-no">048</span><span id="line-48"> protected CompatibilitySingletonFactory() {</span> |
| <span class="source-line-no">049</span><span id="line-49"> }</span> |
| <span class="source-line-no">050</span><span id="line-50"></span> |
| <span class="source-line-no">051</span><span id="line-51"> /**</span> |
| <span class="source-line-no">052</span><span id="line-52"> * Get the singleton instance of Any classes defined by compatibiliy jar's</span> |
| <span class="source-line-no">053</span><span id="line-53"> * @return the singleton</span> |
| <span class="source-line-no">054</span><span id="line-54"> */</span> |
| <span class="source-line-no">055</span><span id="line-55"> @SuppressWarnings("unchecked")</span> |
| <span class="source-line-no">056</span><span id="line-56"> public static <T> T getInstance(Class<T> klass) {</span> |
| <span class="source-line-no">057</span><span id="line-57"> synchronized (SingletonStorage.INSTANCE.lock) {</span> |
| <span class="source-line-no">058</span><span id="line-58"> T instance = (T) SingletonStorage.INSTANCE.instances.get(klass);</span> |
| <span class="source-line-no">059</span><span id="line-59"> if (instance == null) {</span> |
| <span class="source-line-no">060</span><span id="line-60"> try {</span> |
| <span class="source-line-no">061</span><span id="line-61"> ServiceLoader<T> loader = ServiceLoader.load(klass);</span> |
| <span class="source-line-no">062</span><span id="line-62"> Iterator<T> it = loader.iterator();</span> |
| <span class="source-line-no">063</span><span id="line-63"> instance = it.next();</span> |
| <span class="source-line-no">064</span><span id="line-64"> if (it.hasNext()) {</span> |
| <span class="source-line-no">065</span><span id="line-65"> StringBuilder msg = new StringBuilder();</span> |
| <span class="source-line-no">066</span><span id="line-66"> msg.append("ServiceLoader provided more than one implementation for class: ")</span> |
| <span class="source-line-no">067</span><span id="line-67"> .append(klass).append(", using implementation: ").append(instance.getClass())</span> |
| <span class="source-line-no">068</span><span id="line-68"> .append(", other implementations: {");</span> |
| <span class="source-line-no">069</span><span id="line-69"> while (it.hasNext()) {</span> |
| <span class="source-line-no">070</span><span id="line-70"> msg.append(it.next()).append(" ");</span> |
| <span class="source-line-no">071</span><span id="line-71"> }</span> |
| <span class="source-line-no">072</span><span id="line-72"> msg.append("}");</span> |
| <span class="source-line-no">073</span><span id="line-73"> LOG.warn(msg.toString());</span> |
| <span class="source-line-no">074</span><span id="line-74"> }</span> |
| <span class="source-line-no">075</span><span id="line-75"> } catch (Exception e) {</span> |
| <span class="source-line-no">076</span><span id="line-76"> throw new RuntimeException(createExceptionString(klass), e);</span> |
| <span class="source-line-no">077</span><span id="line-77"> } catch (Error e) {</span> |
| <span class="source-line-no">078</span><span id="line-78"> throw new RuntimeException(createExceptionString(klass), e);</span> |
| <span class="source-line-no">079</span><span id="line-79"> }</span> |
| <span class="source-line-no">080</span><span id="line-80"></span> |
| <span class="source-line-no">081</span><span id="line-81"> // If there was nothing returned and no exception then throw an exception.</span> |
| <span class="source-line-no">082</span><span id="line-82"> if (instance == null) {</span> |
| <span class="source-line-no">083</span><span id="line-83"> throw new RuntimeException(createExceptionString(klass));</span> |
| <span class="source-line-no">084</span><span id="line-84"> }</span> |
| <span class="source-line-no">085</span><span id="line-85"> SingletonStorage.INSTANCE.instances.put(klass, instance);</span> |
| <span class="source-line-no">086</span><span id="line-86"> }</span> |
| <span class="source-line-no">087</span><span id="line-87"> return instance;</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> |
| <span class="source-line-no">090</span><span id="line-90"> }</span> |
| <span class="source-line-no">091</span><span id="line-91">}</span> |
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