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| <pre><span class="sourceLineNo">001</span>/**<a name="line.1"></a> |
| <span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a> |
| <span class="sourceLineNo">003</span> * or more contributor license agreements. See the NOTICE file<a name="line.3"></a> |
| <span class="sourceLineNo">004</span> * distributed with this work for additional information<a name="line.4"></a> |
| <span class="sourceLineNo">005</span> * regarding copyright ownership. The ASF licenses this file<a name="line.5"></a> |
| <span class="sourceLineNo">006</span> * to you under the Apache License, Version 2.0 (the<a name="line.6"></a> |
| <span class="sourceLineNo">007</span> * "License"); you may not use this file except in compliance<a name="line.7"></a> |
| <span class="sourceLineNo">008</span> * with the License. You may obtain a copy of the License at<a name="line.8"></a> |
| <span class="sourceLineNo">009</span> *<a name="line.9"></a> |
| <span class="sourceLineNo">010</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a> |
| <span class="sourceLineNo">011</span> *<a name="line.11"></a> |
| <span class="sourceLineNo">012</span> * Unless required by applicable law or agreed to in writing, software<a name="line.12"></a> |
| <span class="sourceLineNo">013</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a> |
| <span class="sourceLineNo">014</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a> |
| <span class="sourceLineNo">015</span> * See the License for the specific language governing permissions and<a name="line.15"></a> |
| <span class="sourceLineNo">016</span> * limitations under the License.<a name="line.16"></a> |
| <span class="sourceLineNo">017</span> */<a name="line.17"></a> |
| <span class="sourceLineNo">018</span><a name="line.18"></a> |
| <span class="sourceLineNo">019</span>package org.apache.hadoop.hbase;<a name="line.19"></a> |
| <span class="sourceLineNo">020</span><a name="line.20"></a> |
| <span class="sourceLineNo">021</span>import java.util.HashMap;<a name="line.21"></a> |
| <span class="sourceLineNo">022</span>import java.util.Iterator;<a name="line.22"></a> |
| <span class="sourceLineNo">023</span>import java.util.Map;<a name="line.23"></a> |
| <span class="sourceLineNo">024</span>import java.util.ServiceLoader;<a name="line.24"></a> |
| <span class="sourceLineNo">025</span><a name="line.25"></a> |
| <span class="sourceLineNo">026</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.26"></a> |
| <span class="sourceLineNo">027</span>import org.slf4j.Logger;<a name="line.27"></a> |
| <span class="sourceLineNo">028</span>import org.slf4j.LoggerFactory;<a name="line.28"></a> |
| <span class="sourceLineNo">029</span><a name="line.29"></a> |
| <span class="sourceLineNo">030</span>/**<a name="line.30"></a> |
| <span class="sourceLineNo">031</span> * Factory for classes supplied by hadoop compatibility modules. Only one of each class will be<a name="line.31"></a> |
| <span class="sourceLineNo">032</span> * created.<a name="line.32"></a> |
| <span class="sourceLineNo">033</span> */<a name="line.33"></a> |
| <span class="sourceLineNo">034</span>@InterfaceAudience.Private<a name="line.34"></a> |
| <span class="sourceLineNo">035</span>public class CompatibilitySingletonFactory extends CompatibilityFactory {<a name="line.35"></a> |
| <span class="sourceLineNo">036</span> public static enum SingletonStorage {<a name="line.36"></a> |
| <span class="sourceLineNo">037</span> INSTANCE;<a name="line.37"></a> |
| <span class="sourceLineNo">038</span> private final Object lock = new Object();<a name="line.38"></a> |
| <span class="sourceLineNo">039</span> private final Map<Class, Object> instances = new HashMap<>();<a name="line.39"></a> |
| <span class="sourceLineNo">040</span> }<a name="line.40"></a> |
| <span class="sourceLineNo">041</span> private static final Logger LOG = LoggerFactory.getLogger(CompatibilitySingletonFactory.class);<a name="line.41"></a> |
| <span class="sourceLineNo">042</span><a name="line.42"></a> |
| <span class="sourceLineNo">043</span> /**<a name="line.43"></a> |
| <span class="sourceLineNo">044</span> * This is a static only class don't let anyone create an instance.<a name="line.44"></a> |
| <span class="sourceLineNo">045</span> */<a name="line.45"></a> |
| <span class="sourceLineNo">046</span> protected CompatibilitySingletonFactory() { }<a name="line.46"></a> |
| <span class="sourceLineNo">047</span><a name="line.47"></a> |
| <span class="sourceLineNo">048</span> /**<a name="line.48"></a> |
| <span class="sourceLineNo">049</span> * Get the singleton instance of Any classes defined by compatibiliy jar's<a name="line.49"></a> |
| <span class="sourceLineNo">050</span> *<a name="line.50"></a> |
| <span class="sourceLineNo">051</span> * @return the singleton<a name="line.51"></a> |
| <span class="sourceLineNo">052</span> */<a name="line.52"></a> |
| <span class="sourceLineNo">053</span> @SuppressWarnings("unchecked")<a name="line.53"></a> |
| <span class="sourceLineNo">054</span> public static <T> T getInstance(Class<T> klass) {<a name="line.54"></a> |
| <span class="sourceLineNo">055</span> synchronized (SingletonStorage.INSTANCE.lock) {<a name="line.55"></a> |
| <span class="sourceLineNo">056</span> T instance = (T) SingletonStorage.INSTANCE.instances.get(klass);<a name="line.56"></a> |
| <span class="sourceLineNo">057</span> if (instance == null) {<a name="line.57"></a> |
| <span class="sourceLineNo">058</span> try {<a name="line.58"></a> |
| <span class="sourceLineNo">059</span> ServiceLoader<T> loader = ServiceLoader.load(klass);<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> Iterator<T> it = loader.iterator();<a name="line.60"></a> |
| <span class="sourceLineNo">061</span> instance = it.next();<a name="line.61"></a> |
| <span class="sourceLineNo">062</span> if (it.hasNext()) {<a name="line.62"></a> |
| <span class="sourceLineNo">063</span> StringBuilder msg = new StringBuilder();<a name="line.63"></a> |
| <span class="sourceLineNo">064</span> msg.append("ServiceLoader provided more than one implementation for class: ")<a name="line.64"></a> |
| <span class="sourceLineNo">065</span> .append(klass)<a name="line.65"></a> |
| <span class="sourceLineNo">066</span> .append(", using implementation: ").append(instance.getClass())<a name="line.66"></a> |
| <span class="sourceLineNo">067</span> .append(", other implementations: {");<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> while (it.hasNext()) {<a name="line.68"></a> |
| <span class="sourceLineNo">069</span> msg.append(it.next()).append(" ");<a name="line.69"></a> |
| <span class="sourceLineNo">070</span> }<a name="line.70"></a> |
| <span class="sourceLineNo">071</span> msg.append("}");<a name="line.71"></a> |
| <span class="sourceLineNo">072</span> LOG.warn(msg.toString());<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> }<a name="line.73"></a> |
| <span class="sourceLineNo">074</span> } catch (Exception e) {<a name="line.74"></a> |
| <span class="sourceLineNo">075</span> throw new RuntimeException(createExceptionString(klass), e);<a name="line.75"></a> |
| <span class="sourceLineNo">076</span> } catch (Error e) {<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> throw new RuntimeException(createExceptionString(klass), e);<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> }<a name="line.78"></a> |
| <span class="sourceLineNo">079</span><a name="line.79"></a> |
| <span class="sourceLineNo">080</span> // If there was nothing returned and no exception then throw an exception.<a name="line.80"></a> |
| <span class="sourceLineNo">081</span> if (instance == null) {<a name="line.81"></a> |
| <span class="sourceLineNo">082</span> throw new RuntimeException(createExceptionString(klass));<a name="line.82"></a> |
| <span class="sourceLineNo">083</span> }<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> SingletonStorage.INSTANCE.instances.put(klass, instance);<a name="line.84"></a> |
| <span class="sourceLineNo">085</span> }<a name="line.85"></a> |
| <span class="sourceLineNo">086</span> return instance;<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> }<a name="line.87"></a> |
| <span class="sourceLineNo">088</span><a name="line.88"></a> |
| <span class="sourceLineNo">089</span> }<a name="line.89"></a> |
| <span class="sourceLineNo">090</span>}<a name="line.90"></a> |
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| </pre> |
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