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| <pre><span class="sourceLineNo">001</span>/**<a name="line.1"></a> |
| <span class="sourceLineNo">002</span> *<a name="line.2"></a> |
| <span class="sourceLineNo">003</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.3"></a> |
| <span class="sourceLineNo">004</span> * or more contributor license agreements. See the NOTICE file<a name="line.4"></a> |
| <span class="sourceLineNo">005</span> * distributed with this work for additional information<a name="line.5"></a> |
| <span class="sourceLineNo">006</span> * regarding copyright ownership. The ASF licenses this file<a name="line.6"></a> |
| <span class="sourceLineNo">007</span> * to you under the Apache License, Version 2.0 (the<a name="line.7"></a> |
| <span class="sourceLineNo">008</span> * "License"); you may not use this file except in compliance<a name="line.8"></a> |
| <span class="sourceLineNo">009</span> * with the License. You may obtain a copy of the License at<a name="line.9"></a> |
| <span class="sourceLineNo">010</span> *<a name="line.10"></a> |
| <span class="sourceLineNo">011</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.11"></a> |
| <span class="sourceLineNo">012</span> *<a name="line.12"></a> |
| <span class="sourceLineNo">013</span> * Unless required by applicable law or agreed to in writing, software<a name="line.13"></a> |
| <span class="sourceLineNo">014</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.14"></a> |
| <span class="sourceLineNo">015</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.15"></a> |
| <span class="sourceLineNo">016</span> * See the License for the specific language governing permissions and<a name="line.16"></a> |
| <span class="sourceLineNo">017</span> * limitations under the License.<a name="line.17"></a> |
| <span class="sourceLineNo">018</span> */<a name="line.18"></a> |
| <span class="sourceLineNo">019</span><a name="line.19"></a> |
| <span class="sourceLineNo">020</span>package org.apache.hadoop.hbase.util;<a name="line.20"></a> |
| <span class="sourceLineNo">021</span><a name="line.21"></a> |
| <span class="sourceLineNo">022</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.22"></a> |
| <span class="sourceLineNo">023</span>import org.apache.yetus.audience.InterfaceStability;<a name="line.23"></a> |
| <span class="sourceLineNo">024</span><a name="line.24"></a> |
| <span class="sourceLineNo">025</span>/**<a name="line.25"></a> |
| <span class="sourceLineNo">026</span> * This is a very fast, non-cryptographic hash suitable for general hash-based<a name="line.26"></a> |
| <span class="sourceLineNo">027</span> * lookup. See http://murmurhash.googlepages.com/ for more details.<a name="line.27"></a> |
| <span class="sourceLineNo">028</span> *<a name="line.28"></a> |
| <span class="sourceLineNo">029</span> * <p>The C version of MurmurHash 2.0 found at that site was ported<a name="line.29"></a> |
| <span class="sourceLineNo">030</span> * to Java by Andrzej Bialecki (ab at getopt org).</p><a name="line.30"></a> |
| <span class="sourceLineNo">031</span> */<a name="line.31"></a> |
| <span class="sourceLineNo">032</span>@InterfaceAudience.Private<a name="line.32"></a> |
| <span class="sourceLineNo">033</span>@InterfaceStability.Stable<a name="line.33"></a> |
| <span class="sourceLineNo">034</span>public class MurmurHash extends Hash {<a name="line.34"></a> |
| <span class="sourceLineNo">035</span> private static MurmurHash _instance = new MurmurHash();<a name="line.35"></a> |
| <span class="sourceLineNo">036</span><a name="line.36"></a> |
| <span class="sourceLineNo">037</span> public static Hash getInstance() {<a name="line.37"></a> |
| <span class="sourceLineNo">038</span> return _instance;<a name="line.38"></a> |
| <span class="sourceLineNo">039</span> }<a name="line.39"></a> |
| <span class="sourceLineNo">040</span><a name="line.40"></a> |
| <span class="sourceLineNo">041</span> @Override<a name="line.41"></a> |
| <span class="sourceLineNo">042</span> public <T> int hash(HashKey<T> hashKey, int seed) {<a name="line.42"></a> |
| <span class="sourceLineNo">043</span> int m = 0x5bd1e995;<a name="line.43"></a> |
| <span class="sourceLineNo">044</span> int r = 24;<a name="line.44"></a> |
| <span class="sourceLineNo">045</span> int length = hashKey.length();<a name="line.45"></a> |
| <span class="sourceLineNo">046</span> int h = seed ^ length;<a name="line.46"></a> |
| <span class="sourceLineNo">047</span><a name="line.47"></a> |
| <span class="sourceLineNo">048</span> int len_4 = length >> 2;<a name="line.48"></a> |
| <span class="sourceLineNo">049</span><a name="line.49"></a> |
| <span class="sourceLineNo">050</span> for (int i = 0; i < len_4; i++) {<a name="line.50"></a> |
| <span class="sourceLineNo">051</span> int i_4 = (i << 2);<a name="line.51"></a> |
| <span class="sourceLineNo">052</span> int k = hashKey.get(i_4 + 3);<a name="line.52"></a> |
| <span class="sourceLineNo">053</span> k = k << 8;<a name="line.53"></a> |
| <span class="sourceLineNo">054</span> k = k | (hashKey.get(i_4 + 2) & 0xff);<a name="line.54"></a> |
| <span class="sourceLineNo">055</span> k = k << 8;<a name="line.55"></a> |
| <span class="sourceLineNo">056</span> k = k | (hashKey.get(i_4 + 1) & 0xff);<a name="line.56"></a> |
| <span class="sourceLineNo">057</span> k = k << 8;<a name="line.57"></a> |
| <span class="sourceLineNo">058</span> // noinspection PointlessArithmeticExpression<a name="line.58"></a> |
| <span class="sourceLineNo">059</span> k = k | (hashKey.get(i_4 + 0) & 0xff);<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> k *= m;<a name="line.60"></a> |
| <span class="sourceLineNo">061</span> k ^= k >>> r;<a name="line.61"></a> |
| <span class="sourceLineNo">062</span> k *= m;<a name="line.62"></a> |
| <span class="sourceLineNo">063</span> h *= m;<a name="line.63"></a> |
| <span class="sourceLineNo">064</span> h ^= k;<a name="line.64"></a> |
| <span class="sourceLineNo">065</span> }<a name="line.65"></a> |
| <span class="sourceLineNo">066</span><a name="line.66"></a> |
| <span class="sourceLineNo">067</span> // avoid calculating modulo<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> int len_m = len_4 << 2;<a name="line.68"></a> |
| <span class="sourceLineNo">069</span> int left = length - len_m;<a name="line.69"></a> |
| <span class="sourceLineNo">070</span> int i_m = len_m;<a name="line.70"></a> |
| <span class="sourceLineNo">071</span><a name="line.71"></a> |
| <span class="sourceLineNo">072</span> if (left != 0) {<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> if (left >= 3) {<a name="line.73"></a> |
| <span class="sourceLineNo">074</span> h ^= hashKey.get(i_m + 2) << 16;<a name="line.74"></a> |
| <span class="sourceLineNo">075</span> }<a name="line.75"></a> |
| <span class="sourceLineNo">076</span> if (left >= 2) {<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> h ^= hashKey.get(i_m + 1) << 8;<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> }<a name="line.78"></a> |
| <span class="sourceLineNo">079</span> if (left >= 1) {<a name="line.79"></a> |
| <span class="sourceLineNo">080</span> h ^= hashKey.get(i_m);<a name="line.80"></a> |
| <span class="sourceLineNo">081</span> }<a name="line.81"></a> |
| <span class="sourceLineNo">082</span><a name="line.82"></a> |
| <span class="sourceLineNo">083</span> h *= m;<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> }<a name="line.84"></a> |
| <span class="sourceLineNo">085</span><a name="line.85"></a> |
| <span class="sourceLineNo">086</span> h ^= h >>> 13;<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> h *= m;<a name="line.87"></a> |
| <span class="sourceLineNo">088</span> h ^= h >>> 15;<a name="line.88"></a> |
| <span class="sourceLineNo">089</span><a name="line.89"></a> |
| <span class="sourceLineNo">090</span> return h;<a name="line.90"></a> |
| <span class="sourceLineNo">091</span> }<a name="line.91"></a> |
| <span class="sourceLineNo">092</span>}<a name="line.92"></a> |
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