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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.util;</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 org.apache.hadoop.conf.Configuration;</span> |
| <span class="source-line-no">021</span><span id="line-21">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">022</span><span id="line-22">import org.apache.yetus.audience.InterfaceStability;</span> |
| <span class="source-line-no">023</span><span id="line-23"></span> |
| <span class="source-line-no">024</span><span id="line-24">/**</span> |
| <span class="source-line-no">025</span><span id="line-25"> * This class represents a common API for hashing functions.</span> |
| <span class="source-line-no">026</span><span id="line-26"> */</span> |
| <span class="source-line-no">027</span><span id="line-27">@InterfaceAudience.Private</span> |
| <span class="source-line-no">028</span><span id="line-28">@InterfaceStability.Stable</span> |
| <span class="source-line-no">029</span><span id="line-29">public abstract class Hash {</span> |
| <span class="source-line-no">030</span><span id="line-30"> /** Constant to denote invalid hash type. */</span> |
| <span class="source-line-no">031</span><span id="line-31"> public static final int INVALID_HASH = -1;</span> |
| <span class="source-line-no">032</span><span id="line-32"> /** Constant to denote {@link JenkinsHash}. */</span> |
| <span class="source-line-no">033</span><span id="line-33"> public static final int JENKINS_HASH = 0;</span> |
| <span class="source-line-no">034</span><span id="line-34"> /** Constant to denote {@link MurmurHash}. */</span> |
| <span class="source-line-no">035</span><span id="line-35"> public static final int MURMUR_HASH = 1;</span> |
| <span class="source-line-no">036</span><span id="line-36"> /** Constant to denote {@link MurmurHash3}. */</span> |
| <span class="source-line-no">037</span><span id="line-37"> public static final int MURMUR_HASH3 = 2;</span> |
| <span class="source-line-no">038</span><span id="line-38"></span> |
| <span class="source-line-no">039</span><span id="line-39"> /**</span> |
| <span class="source-line-no">040</span><span id="line-40"> * This utility method converts String representation of hash function name to a symbolic</span> |
| <span class="source-line-no">041</span><span id="line-41"> * constant. Currently three function types are supported, "jenkins", "murmur" and "murmur3".</span> |
| <span class="source-line-no">042</span><span id="line-42"> * @param name hash function name</span> |
| <span class="source-line-no">043</span><span id="line-43"> * @return one of the predefined constants</span> |
| <span class="source-line-no">044</span><span id="line-44"> */</span> |
| <span class="source-line-no">045</span><span id="line-45"> public static int parseHashType(String name) {</span> |
| <span class="source-line-no">046</span><span id="line-46"> if ("jenkins".equalsIgnoreCase(name)) {</span> |
| <span class="source-line-no">047</span><span id="line-47"> return JENKINS_HASH;</span> |
| <span class="source-line-no">048</span><span id="line-48"> } else if ("murmur".equalsIgnoreCase(name)) {</span> |
| <span class="source-line-no">049</span><span id="line-49"> return MURMUR_HASH;</span> |
| <span class="source-line-no">050</span><span id="line-50"> } else if ("murmur3".equalsIgnoreCase(name)) {</span> |
| <span class="source-line-no">051</span><span id="line-51"> return MURMUR_HASH3;</span> |
| <span class="source-line-no">052</span><span id="line-52"> } else {</span> |
| <span class="source-line-no">053</span><span id="line-53"> return INVALID_HASH;</span> |
| <span class="source-line-no">054</span><span id="line-54"> }</span> |
| <span class="source-line-no">055</span><span id="line-55"> }</span> |
| <span class="source-line-no">056</span><span id="line-56"></span> |
| <span class="source-line-no">057</span><span id="line-57"> /**</span> |
| <span class="source-line-no">058</span><span id="line-58"> * This utility method converts the name of the configured hash type to a symbolic constant.</span> |
| <span class="source-line-no">059</span><span id="line-59"> * @param conf configuration</span> |
| <span class="source-line-no">060</span><span id="line-60"> * @return one of the predefined constants</span> |
| <span class="source-line-no">061</span><span id="line-61"> */</span> |
| <span class="source-line-no">062</span><span id="line-62"> public static int getHashType(Configuration conf) {</span> |
| <span class="source-line-no">063</span><span id="line-63"> String name = conf.get("hbase.hash.type", "murmur");</span> |
| <span class="source-line-no">064</span><span id="line-64"> return parseHashType(name);</span> |
| <span class="source-line-no">065</span><span id="line-65"> }</span> |
| <span class="source-line-no">066</span><span id="line-66"></span> |
| <span class="source-line-no">067</span><span id="line-67"> /**</span> |
| <span class="source-line-no">068</span><span id="line-68"> * Get a singleton instance of hash function of a given type.</span> |
| <span class="source-line-no">069</span><span id="line-69"> * @param type predefined hash type</span> |
| <span class="source-line-no">070</span><span id="line-70"> * @return hash function instance, or null if type is invalid</span> |
| <span class="source-line-no">071</span><span id="line-71"> */</span> |
| <span class="source-line-no">072</span><span id="line-72"> public static Hash getInstance(int type) {</span> |
| <span class="source-line-no">073</span><span id="line-73"> switch (type) {</span> |
| <span class="source-line-no">074</span><span id="line-74"> case JENKINS_HASH:</span> |
| <span class="source-line-no">075</span><span id="line-75"> return JenkinsHash.getInstance();</span> |
| <span class="source-line-no">076</span><span id="line-76"> case MURMUR_HASH:</span> |
| <span class="source-line-no">077</span><span id="line-77"> return MurmurHash.getInstance();</span> |
| <span class="source-line-no">078</span><span id="line-78"> case MURMUR_HASH3:</span> |
| <span class="source-line-no">079</span><span id="line-79"> return MurmurHash3.getInstance();</span> |
| <span class="source-line-no">080</span><span id="line-80"> default:</span> |
| <span class="source-line-no">081</span><span id="line-81"> return null;</span> |
| <span class="source-line-no">082</span><span id="line-82"> }</span> |
| <span class="source-line-no">083</span><span id="line-83"> }</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"> * Get a singleton instance of hash function of a type defined in the configuration.</span> |
| <span class="source-line-no">087</span><span id="line-87"> * @param conf current configuration</span> |
| <span class="source-line-no">088</span><span id="line-88"> * @return defined hash type, or null if type is invalid</span> |
| <span class="source-line-no">089</span><span id="line-89"> */</span> |
| <span class="source-line-no">090</span><span id="line-90"> public static Hash getInstance(Configuration conf) {</span> |
| <span class="source-line-no">091</span><span id="line-91"> int type = getHashType(conf);</span> |
| <span class="source-line-no">092</span><span id="line-92"> return getInstance(type);</span> |
| <span class="source-line-no">093</span><span id="line-93"> }</span> |
| <span class="source-line-no">094</span><span id="line-94"></span> |
| <span class="source-line-no">095</span><span id="line-95"> /**</span> |
| <span class="source-line-no">096</span><span id="line-96"> * Calculate a hash using bytes from HashKey and the provided seed value.</span> |
| <span class="source-line-no">097</span><span id="line-97"> * @param hashKey key to extract the hash</span> |
| <span class="source-line-no">098</span><span id="line-98"> * @param initval the seed value</span> |
| <span class="source-line-no">099</span><span id="line-99"> * @return hash value</span> |
| <span class="source-line-no">100</span><span id="line-100"> */</span> |
| <span class="source-line-no">101</span><span id="line-101"> public abstract <T> int hash(HashKey<T> hashKey, int initval);</span> |
| <span class="source-line-no">102</span><span id="line-102">}</span> |
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| </pre> |
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