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<FONT color="green">001</FONT>    /**<a name="line.1"></a>
<FONT color="green">002</FONT>     * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a>
<FONT color="green">003</FONT>     * or more contributor license agreements.  See the NOTICE file<a name="line.3"></a>
<FONT color="green">004</FONT>     * distributed with this work for additional information<a name="line.4"></a>
<FONT color="green">005</FONT>     * regarding copyright ownership.  The ASF licenses this file<a name="line.5"></a>
<FONT color="green">006</FONT>     * to you under the Apache License, Version 2.0 (the<a name="line.6"></a>
<FONT color="green">007</FONT>     * "License"); you may not use this file except in compliance<a name="line.7"></a>
<FONT color="green">008</FONT>     * with the License.  You may obtain a copy of the License at<a name="line.8"></a>
<FONT color="green">009</FONT>     *<a name="line.9"></a>
<FONT color="green">010</FONT>     *     http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a>
<FONT color="green">011</FONT>     *<a name="line.11"></a>
<FONT color="green">012</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.12"></a>
<FONT color="green">013</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<FONT color="green">014</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<FONT color="green">015</FONT>     * See the License for the specific language governing permissions and<a name="line.15"></a>
<FONT color="green">016</FONT>     * limitations under the License.<a name="line.16"></a>
<FONT color="green">017</FONT>     */<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    package org.apache.hadoop.mapreduce.lib.partition;<a name="line.19"></a>
<FONT color="green">020</FONT>    <a name="line.20"></a>
<FONT color="green">021</FONT>    import org.apache.hadoop.classification.InterfaceAudience;<a name="line.21"></a>
<FONT color="green">022</FONT>    import org.apache.hadoop.classification.InterfaceStability;<a name="line.22"></a>
<FONT color="green">023</FONT>    import org.apache.hadoop.conf.Configurable;<a name="line.23"></a>
<FONT color="green">024</FONT>    import org.apache.hadoop.conf.Configuration;<a name="line.24"></a>
<FONT color="green">025</FONT>    import org.apache.hadoop.io.BinaryComparable;<a name="line.25"></a>
<FONT color="green">026</FONT>    import org.apache.hadoop.io.WritableComparator;<a name="line.26"></a>
<FONT color="green">027</FONT>    import org.apache.hadoop.mapreduce.Partitioner;<a name="line.27"></a>
<FONT color="green">028</FONT>    <a name="line.28"></a>
<FONT color="green">029</FONT>    /**<a name="line.29"></a>
<FONT color="green">030</FONT>     * &lt;p&gt;Partition {@link BinaryComparable} keys using a configurable part of <a name="line.30"></a>
<FONT color="green">031</FONT>     * the bytes array returned by {@link BinaryComparable#getBytes()}.&lt;/p&gt;<a name="line.31"></a>
<FONT color="green">032</FONT>     * <a name="line.32"></a>
<FONT color="green">033</FONT>     * &lt;p&gt;The subarray to be used for the partitioning can be defined by means<a name="line.33"></a>
<FONT color="green">034</FONT>     * of the following properties:<a name="line.34"></a>
<FONT color="green">035</FONT>     * &lt;ul&gt;<a name="line.35"></a>
<FONT color="green">036</FONT>     *   &lt;li&gt;<a name="line.36"></a>
<FONT color="green">037</FONT>     *     &lt;i&gt;mapreduce.partition.binarypartitioner.left.offset&lt;/i&gt;:<a name="line.37"></a>
<FONT color="green">038</FONT>     *     left offset in array (0 by default)<a name="line.38"></a>
<FONT color="green">039</FONT>     *   &lt;/li&gt;<a name="line.39"></a>
<FONT color="green">040</FONT>     *   &lt;li&gt;<a name="line.40"></a>
<FONT color="green">041</FONT>     *     &lt;i&gt;mapreduce.partition.binarypartitioner.right.offset&lt;/i&gt;: <a name="line.41"></a>
<FONT color="green">042</FONT>     *     right offset in array (-1 by default)<a name="line.42"></a>
<FONT color="green">043</FONT>     *   &lt;/li&gt;<a name="line.43"></a>
<FONT color="green">044</FONT>     * &lt;/ul&gt;<a name="line.44"></a>
<FONT color="green">045</FONT>     * Like in Python, both negative and positive offsets are allowed, but<a name="line.45"></a>
<FONT color="green">046</FONT>     * the meaning is slightly different. In case of an array of length 5,<a name="line.46"></a>
<FONT color="green">047</FONT>     * for instance, the possible offsets are:<a name="line.47"></a>
<FONT color="green">048</FONT>     * &lt;pre&gt;&lt;code&gt;<a name="line.48"></a>
<FONT color="green">049</FONT>     *  +---+---+---+---+---+<a name="line.49"></a>
<FONT color="green">050</FONT>     *  | B | B | B | B | B |<a name="line.50"></a>
<FONT color="green">051</FONT>     *  +---+---+---+---+---+<a name="line.51"></a>
<FONT color="green">052</FONT>     *    0   1   2   3   4<a name="line.52"></a>
<FONT color="green">053</FONT>     *   -5  -4  -3  -2  -1<a name="line.53"></a>
<FONT color="green">054</FONT>     * &lt;/code&gt;&lt;/pre&gt;<a name="line.54"></a>
<FONT color="green">055</FONT>     * The first row of numbers gives the position of the offsets 0...5 in <a name="line.55"></a>
<FONT color="green">056</FONT>     * the array; the second row gives the corresponding negative offsets. <a name="line.56"></a>
<FONT color="green">057</FONT>     * Contrary to Python, the specified subarray has byte &lt;code&gt;i&lt;/code&gt; <a name="line.57"></a>
<FONT color="green">058</FONT>     * and &lt;code&gt;j&lt;/code&gt; as first and last element, repectively, when <a name="line.58"></a>
<FONT color="green">059</FONT>     * &lt;code&gt;i&lt;/code&gt; and &lt;code&gt;j&lt;/code&gt; are the left and right offset.<a name="line.59"></a>
<FONT color="green">060</FONT>     * <a name="line.60"></a>
<FONT color="green">061</FONT>     * &lt;p&gt;For Hadoop programs written in Java, it is advisable to use one of <a name="line.61"></a>
<FONT color="green">062</FONT>     * the following static convenience methods for setting the offsets:<a name="line.62"></a>
<FONT color="green">063</FONT>     * &lt;ul&gt;<a name="line.63"></a>
<FONT color="green">064</FONT>     *   &lt;li&gt;{@link #setOffsets}&lt;/li&gt;<a name="line.64"></a>
<FONT color="green">065</FONT>     *   &lt;li&gt;{@link #setLeftOffset}&lt;/li&gt;<a name="line.65"></a>
<FONT color="green">066</FONT>     *   &lt;li&gt;{@link #setRightOffset}&lt;/li&gt;<a name="line.66"></a>
<FONT color="green">067</FONT>     * &lt;/ul&gt;&lt;/p&gt;<a name="line.67"></a>
<FONT color="green">068</FONT>     */<a name="line.68"></a>
<FONT color="green">069</FONT>    @InterfaceAudience.Public<a name="line.69"></a>
<FONT color="green">070</FONT>    @InterfaceStability.Evolving<a name="line.70"></a>
<FONT color="green">071</FONT>    public class BinaryPartitioner&lt;V&gt; extends Partitioner&lt;BinaryComparable, V&gt; <a name="line.71"></a>
<FONT color="green">072</FONT>      implements Configurable {<a name="line.72"></a>
<FONT color="green">073</FONT>    <a name="line.73"></a>
<FONT color="green">074</FONT>      public static final String LEFT_OFFSET_PROPERTY_NAME = <a name="line.74"></a>
<FONT color="green">075</FONT>        "mapreduce.partition.binarypartitioner.left.offset";<a name="line.75"></a>
<FONT color="green">076</FONT>      public static final String RIGHT_OFFSET_PROPERTY_NAME = <a name="line.76"></a>
<FONT color="green">077</FONT>        "mapreduce.partition.binarypartitioner.right.offset";<a name="line.77"></a>
<FONT color="green">078</FONT>      <a name="line.78"></a>
<FONT color="green">079</FONT>      /**<a name="line.79"></a>
<FONT color="green">080</FONT>       * Set the subarray to be used for partitioning to <a name="line.80"></a>
<FONT color="green">081</FONT>       * &lt;code&gt;bytes[left:(right+1)]&lt;/code&gt; in Python syntax.<a name="line.81"></a>
<FONT color="green">082</FONT>       * <a name="line.82"></a>
<FONT color="green">083</FONT>       * @param conf configuration object<a name="line.83"></a>
<FONT color="green">084</FONT>       * @param left left Python-style offset<a name="line.84"></a>
<FONT color="green">085</FONT>       * @param right right Python-style offset<a name="line.85"></a>
<FONT color="green">086</FONT>       */<a name="line.86"></a>
<FONT color="green">087</FONT>      public static void setOffsets(Configuration conf, int left, int right) {<a name="line.87"></a>
<FONT color="green">088</FONT>        conf.setInt(LEFT_OFFSET_PROPERTY_NAME, left);<a name="line.88"></a>
<FONT color="green">089</FONT>        conf.setInt(RIGHT_OFFSET_PROPERTY_NAME, right);<a name="line.89"></a>
<FONT color="green">090</FONT>      }<a name="line.90"></a>
<FONT color="green">091</FONT>      <a name="line.91"></a>
<FONT color="green">092</FONT>      /**<a name="line.92"></a>
<FONT color="green">093</FONT>       * Set the subarray to be used for partitioning to <a name="line.93"></a>
<FONT color="green">094</FONT>       * &lt;code&gt;bytes[offset:]&lt;/code&gt; in Python syntax.<a name="line.94"></a>
<FONT color="green">095</FONT>       * <a name="line.95"></a>
<FONT color="green">096</FONT>       * @param conf configuration object<a name="line.96"></a>
<FONT color="green">097</FONT>       * @param offset left Python-style offset<a name="line.97"></a>
<FONT color="green">098</FONT>       */<a name="line.98"></a>
<FONT color="green">099</FONT>      public static void setLeftOffset(Configuration conf, int offset) {<a name="line.99"></a>
<FONT color="green">100</FONT>        conf.setInt(LEFT_OFFSET_PROPERTY_NAME, offset);<a name="line.100"></a>
<FONT color="green">101</FONT>      }<a name="line.101"></a>
<FONT color="green">102</FONT>      <a name="line.102"></a>
<FONT color="green">103</FONT>      /**<a name="line.103"></a>
<FONT color="green">104</FONT>       * Set the subarray to be used for partitioning to <a name="line.104"></a>
<FONT color="green">105</FONT>       * &lt;code&gt;bytes[:(offset+1)]&lt;/code&gt; in Python syntax.<a name="line.105"></a>
<FONT color="green">106</FONT>       * <a name="line.106"></a>
<FONT color="green">107</FONT>       * @param conf configuration object<a name="line.107"></a>
<FONT color="green">108</FONT>       * @param offset right Python-style offset<a name="line.108"></a>
<FONT color="green">109</FONT>       */<a name="line.109"></a>
<FONT color="green">110</FONT>      public static void setRightOffset(Configuration conf, int offset) {<a name="line.110"></a>
<FONT color="green">111</FONT>        conf.setInt(RIGHT_OFFSET_PROPERTY_NAME, offset);<a name="line.111"></a>
<FONT color="green">112</FONT>      }<a name="line.112"></a>
<FONT color="green">113</FONT>      <a name="line.113"></a>
<FONT color="green">114</FONT>      <a name="line.114"></a>
<FONT color="green">115</FONT>      private Configuration conf;<a name="line.115"></a>
<FONT color="green">116</FONT>      private int leftOffset, rightOffset;<a name="line.116"></a>
<FONT color="green">117</FONT>      <a name="line.117"></a>
<FONT color="green">118</FONT>      public void setConf(Configuration conf) {<a name="line.118"></a>
<FONT color="green">119</FONT>        this.conf = conf;<a name="line.119"></a>
<FONT color="green">120</FONT>        leftOffset = conf.getInt(LEFT_OFFSET_PROPERTY_NAME, 0);<a name="line.120"></a>
<FONT color="green">121</FONT>        rightOffset = conf.getInt(RIGHT_OFFSET_PROPERTY_NAME, -1);<a name="line.121"></a>
<FONT color="green">122</FONT>      }<a name="line.122"></a>
<FONT color="green">123</FONT>      <a name="line.123"></a>
<FONT color="green">124</FONT>      public Configuration getConf() {<a name="line.124"></a>
<FONT color="green">125</FONT>        return conf;<a name="line.125"></a>
<FONT color="green">126</FONT>      }<a name="line.126"></a>
<FONT color="green">127</FONT>      <a name="line.127"></a>
<FONT color="green">128</FONT>      /** <a name="line.128"></a>
<FONT color="green">129</FONT>       * Use (the specified slice of the array returned by) <a name="line.129"></a>
<FONT color="green">130</FONT>       * {@link BinaryComparable#getBytes()} to partition. <a name="line.130"></a>
<FONT color="green">131</FONT>       */<a name="line.131"></a>
<FONT color="green">132</FONT>      @Override<a name="line.132"></a>
<FONT color="green">133</FONT>      public int getPartition(BinaryComparable key, V value, int numPartitions) {<a name="line.133"></a>
<FONT color="green">134</FONT>        int length = key.getLength();<a name="line.134"></a>
<FONT color="green">135</FONT>        int leftIndex = (leftOffset + length) % length;<a name="line.135"></a>
<FONT color="green">136</FONT>        int rightIndex = (rightOffset + length) % length;<a name="line.136"></a>
<FONT color="green">137</FONT>        int hash = WritableComparator.hashBytes(key.getBytes(), <a name="line.137"></a>
<FONT color="green">138</FONT>          leftIndex, rightIndex - leftIndex + 1);<a name="line.138"></a>
<FONT color="green">139</FONT>        return (hash &amp; Integer.MAX_VALUE) % numPartitions;<a name="line.139"></a>
<FONT color="green">140</FONT>      }<a name="line.140"></a>
<FONT color="green">141</FONT>      <a name="line.141"></a>
<FONT color="green">142</FONT>    }<a name="line.142"></a>




























































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