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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>package org.apache.hadoop.hbase.util;<a name="line.18"></a> |
| <span class="sourceLineNo">019</span><a name="line.19"></a> |
| <span class="sourceLineNo">020</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.20"></a> |
| <span class="sourceLineNo">021</span>import org.apache.yetus.audience.InterfaceStability;<a name="line.21"></a> |
| <span class="sourceLineNo">022</span><a name="line.22"></a> |
| <span class="sourceLineNo">023</span>/**<a name="line.23"></a> |
| <span class="sourceLineNo">024</span> * This is a very fast, non-cryptographic hash suitable for general hash-based lookup. See<a name="line.24"></a> |
| <span class="sourceLineNo">025</span> * http://code.google.com/p/smhasher/wiki/MurmurHash3 for details.<a name="line.25"></a> |
| <span class="sourceLineNo">026</span> * <p><a name="line.26"></a> |
| <span class="sourceLineNo">027</span> * MurmurHash3 is the successor to MurmurHash2. It comes in 3 variants, and the 32-bit version<a name="line.27"></a> |
| <span class="sourceLineNo">028</span> * targets low latency for hash table use.<a name="line.28"></a> |
| <span class="sourceLineNo">029</span> * </p><a name="line.29"></a> |
| <span class="sourceLineNo">030</span> */<a name="line.30"></a> |
| <span class="sourceLineNo">031</span>@InterfaceAudience.Private<a name="line.31"></a> |
| <span class="sourceLineNo">032</span>@InterfaceStability.Stable<a name="line.32"></a> |
| <span class="sourceLineNo">033</span>public class MurmurHash3 extends Hash {<a name="line.33"></a> |
| <span class="sourceLineNo">034</span> private static MurmurHash3 _instance = new MurmurHash3();<a name="line.34"></a> |
| <span class="sourceLineNo">035</span><a name="line.35"></a> |
| <span class="sourceLineNo">036</span> public static Hash getInstance() {<a name="line.36"></a> |
| <span class="sourceLineNo">037</span> return _instance;<a name="line.37"></a> |
| <span class="sourceLineNo">038</span> }<a name="line.38"></a> |
| <span class="sourceLineNo">039</span><a name="line.39"></a> |
| <span class="sourceLineNo">040</span> /** Returns the MurmurHash3_x86_32 hash. */<a name="line.40"></a> |
| <span class="sourceLineNo">041</span> @edu.umd.cs.findbugs.annotations.SuppressWarnings("SF")<a name="line.41"></a> |
| <span class="sourceLineNo">042</span> @Override<a name="line.42"></a> |
| <span class="sourceLineNo">043</span> public <T> int hash(HashKey<T> hashKey, int initval) {<a name="line.43"></a> |
| <span class="sourceLineNo">044</span> final int c1 = 0xcc9e2d51;<a name="line.44"></a> |
| <span class="sourceLineNo">045</span> final int c2 = 0x1b873593;<a name="line.45"></a> |
| <span class="sourceLineNo">046</span> int length = hashKey.length();<a name="line.46"></a> |
| <span class="sourceLineNo">047</span> int h1 = initval;<a name="line.47"></a> |
| <span class="sourceLineNo">048</span> int roundedEnd = (length & 0xfffffffc); // round down to 4 byte block<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 < roundedEnd; i += 4) {<a name="line.50"></a> |
| <span class="sourceLineNo">051</span> // little endian load order<a name="line.51"></a> |
| <span class="sourceLineNo">052</span> int k1 = (hashKey.get(i) & 0xff) | ((hashKey.get(i + 1) & 0xff) << 8)<a name="line.52"></a> |
| <span class="sourceLineNo">053</span> | ((hashKey.get(i + 2) & 0xff) << 16) | (hashKey.get(i + 3) << 24);<a name="line.53"></a> |
| <span class="sourceLineNo">054</span> k1 *= c1;<a name="line.54"></a> |
| <span class="sourceLineNo">055</span> k1 = (k1 << 15) | (k1 >>> 17); // ROTL32(k1,15);<a name="line.55"></a> |
| <span class="sourceLineNo">056</span> k1 *= c2;<a name="line.56"></a> |
| <span class="sourceLineNo">057</span><a name="line.57"></a> |
| <span class="sourceLineNo">058</span> h1 ^= k1;<a name="line.58"></a> |
| <span class="sourceLineNo">059</span> h1 = (h1 << 13) | (h1 >>> 19); // ROTL32(h1,13);<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> h1 = h1 * 5 + 0xe6546b64;<a name="line.60"></a> |
| <span class="sourceLineNo">061</span> }<a name="line.61"></a> |
| <span class="sourceLineNo">062</span><a name="line.62"></a> |
| <span class="sourceLineNo">063</span> // tail<a name="line.63"></a> |
| <span class="sourceLineNo">064</span> int k1 = 0;<a name="line.64"></a> |
| <span class="sourceLineNo">065</span><a name="line.65"></a> |
| <span class="sourceLineNo">066</span> switch (length & 0x03) {<a name="line.66"></a> |
| <span class="sourceLineNo">067</span> case 3:<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> k1 = (hashKey.get(roundedEnd + 2) & 0xff) << 16;<a name="line.68"></a> |
| <span class="sourceLineNo">069</span> // FindBugs SF_SWITCH_FALLTHROUGH<a name="line.69"></a> |
| <span class="sourceLineNo">070</span> case 2:<a name="line.70"></a> |
| <span class="sourceLineNo">071</span> k1 |= (hashKey.get(roundedEnd + 1) & 0xff) << 8;<a name="line.71"></a> |
| <span class="sourceLineNo">072</span> // FindBugs SF_SWITCH_FALLTHROUGH<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> case 1:<a name="line.73"></a> |
| <span class="sourceLineNo">074</span> k1 |= (hashKey.get(roundedEnd) & 0xff);<a name="line.74"></a> |
| <span class="sourceLineNo">075</span> k1 *= c1;<a name="line.75"></a> |
| <span class="sourceLineNo">076</span> k1 = (k1 << 15) | (k1 >>> 17); // ROTL32(k1,15);<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> k1 *= c2;<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> h1 ^= k1;<a name="line.78"></a> |
| <span class="sourceLineNo">079</span> default:<a name="line.79"></a> |
| <span class="sourceLineNo">080</span> // fall out<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> // finalization<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> h1 ^= length;<a name="line.84"></a> |
| <span class="sourceLineNo">085</span><a name="line.85"></a> |
| <span class="sourceLineNo">086</span> // fmix(h1);<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> h1 ^= h1 >>> 16;<a name="line.87"></a> |
| <span class="sourceLineNo">088</span> h1 *= 0x85ebca6b;<a name="line.88"></a> |
| <span class="sourceLineNo">089</span> h1 ^= h1 >>> 13;<a name="line.89"></a> |
| <span class="sourceLineNo">090</span> h1 *= 0xc2b2ae35;<a name="line.90"></a> |
| <span class="sourceLineNo">091</span> h1 ^= h1 >>> 16;<a name="line.91"></a> |
| <span class="sourceLineNo">092</span><a name="line.92"></a> |
| <span class="sourceLineNo">093</span> return h1;<a name="line.93"></a> |
| <span class="sourceLineNo">094</span> }<a name="line.94"></a> |
| <span class="sourceLineNo">095</span>}<a name="line.95"></a> |
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