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<pre><span class="sourceLineNo">001</span>/**<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright The Apache Software Foundation<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.4"></a>
<span class="sourceLineNo">005</span> * contributor license agreements. See the NOTICE file distributed with this<a name="line.5"></a>
<span class="sourceLineNo">006</span> * work for additional information regarding copyright ownership. The ASF<a name="line.6"></a>
<span class="sourceLineNo">007</span> * licenses this file 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 with the License.<a name="line.8"></a>
<span class="sourceLineNo">009</span> * 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, WITHOUT<a name="line.14"></a>
<span class="sourceLineNo">015</span> * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the<a name="line.15"></a>
<span class="sourceLineNo">016</span> * License for the specific language governing permissions and limitations<a name="line.16"></a>
<span class="sourceLineNo">017</span> * under the License.<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.regionserver;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.io.IOException;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.List;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.apache.commons.lang3.NotImplementedException;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import org.apache.hadoop.hbase.HConstants;<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.apache.hadoop.hbase.Cell;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import org.apache.hadoop.hbase.CellComparator;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import org.apache.hadoop.hbase.CellUtil;<a name="line.29"></a>
<span class="sourceLineNo">030</span><a name="line.30"></a>
<span class="sourceLineNo">031</span>/**<a name="line.31"></a>
<span class="sourceLineNo">032</span> * ReversedKeyValueHeap is used for supporting reversed scanning. Compared with<a name="line.32"></a>
<span class="sourceLineNo">033</span> * KeyValueHeap, its scanner comparator is a little different (see<a name="line.33"></a>
<span class="sourceLineNo">034</span> * ReversedKVScannerComparator), all seek is backward seek(see<a name="line.34"></a>
<span class="sourceLineNo">035</span> * {@link KeyValueScanner#backwardSeek}), and it will jump to the previous row<a name="line.35"></a>
<span class="sourceLineNo">036</span> * if it is already at the end of one row when calling next().<a name="line.36"></a>
<span class="sourceLineNo">037</span> */<a name="line.37"></a>
<span class="sourceLineNo">038</span>@InterfaceAudience.Private<a name="line.38"></a>
<span class="sourceLineNo">039</span>public class ReversedKeyValueHeap extends KeyValueHeap {<a name="line.39"></a>
<span class="sourceLineNo">040</span><a name="line.40"></a>
<span class="sourceLineNo">041</span> /**<a name="line.41"></a>
<span class="sourceLineNo">042</span> * @param scanners<a name="line.42"></a>
<span class="sourceLineNo">043</span> * @param comparator<a name="line.43"></a>
<span class="sourceLineNo">044</span> * @throws IOException<a name="line.44"></a>
<span class="sourceLineNo">045</span> */<a name="line.45"></a>
<span class="sourceLineNo">046</span> public ReversedKeyValueHeap(List&lt;? extends KeyValueScanner&gt; scanners,<a name="line.46"></a>
<span class="sourceLineNo">047</span> CellComparator comparator) throws IOException {<a name="line.47"></a>
<span class="sourceLineNo">048</span> super(scanners, new ReversedKVScannerComparator(comparator));<a name="line.48"></a>
<span class="sourceLineNo">049</span> }<a name="line.49"></a>
<span class="sourceLineNo">050</span><a name="line.50"></a>
<span class="sourceLineNo">051</span> @Override<a name="line.51"></a>
<span class="sourceLineNo">052</span> public boolean seek(Cell seekKey) throws IOException {<a name="line.52"></a>
<span class="sourceLineNo">053</span> throw new IllegalStateException(<a name="line.53"></a>
<span class="sourceLineNo">054</span> "seek cannot be called on ReversedKeyValueHeap");<a name="line.54"></a>
<span class="sourceLineNo">055</span> }<a name="line.55"></a>
<span class="sourceLineNo">056</span><a name="line.56"></a>
<span class="sourceLineNo">057</span> @Override<a name="line.57"></a>
<span class="sourceLineNo">058</span> public boolean reseek(Cell seekKey) throws IOException {<a name="line.58"></a>
<span class="sourceLineNo">059</span> throw new IllegalStateException(<a name="line.59"></a>
<span class="sourceLineNo">060</span> "reseek cannot be called on ReversedKeyValueHeap");<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> @Override<a name="line.63"></a>
<span class="sourceLineNo">064</span> public boolean requestSeek(Cell key, boolean forward, boolean useBloom)<a name="line.64"></a>
<span class="sourceLineNo">065</span> throws IOException {<a name="line.65"></a>
<span class="sourceLineNo">066</span> throw new IllegalStateException(<a name="line.66"></a>
<span class="sourceLineNo">067</span> "requestSeek cannot be called on ReversedKeyValueHeap");<a name="line.67"></a>
<span class="sourceLineNo">068</span> }<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span> @Override<a name="line.70"></a>
<span class="sourceLineNo">071</span> public boolean seekToPreviousRow(Cell seekKey) throws IOException {<a name="line.71"></a>
<span class="sourceLineNo">072</span> if (current == null) {<a name="line.72"></a>
<span class="sourceLineNo">073</span> return false;<a name="line.73"></a>
<span class="sourceLineNo">074</span> }<a name="line.74"></a>
<span class="sourceLineNo">075</span> heap.add(current);<a name="line.75"></a>
<span class="sourceLineNo">076</span> current = null;<a name="line.76"></a>
<span class="sourceLineNo">077</span><a name="line.77"></a>
<span class="sourceLineNo">078</span> KeyValueScanner scanner;<a name="line.78"></a>
<span class="sourceLineNo">079</span> while ((scanner = heap.poll()) != null) {<a name="line.79"></a>
<span class="sourceLineNo">080</span> Cell topKey = scanner.peek();<a name="line.80"></a>
<span class="sourceLineNo">081</span> if (comparator.getComparator().compareRows(topKey, seekKey) &lt; 0) {<a name="line.81"></a>
<span class="sourceLineNo">082</span> // Row of Top KeyValue is before Seek row.<a name="line.82"></a>
<span class="sourceLineNo">083</span> heap.add(scanner);<a name="line.83"></a>
<span class="sourceLineNo">084</span> current = pollRealKV();<a name="line.84"></a>
<span class="sourceLineNo">085</span> return current != null;<a name="line.85"></a>
<span class="sourceLineNo">086</span> }<a name="line.86"></a>
<span class="sourceLineNo">087</span><a name="line.87"></a>
<span class="sourceLineNo">088</span> if (!scanner.seekToPreviousRow(seekKey)) {<a name="line.88"></a>
<span class="sourceLineNo">089</span> this.scannersForDelayedClose.add(scanner);<a name="line.89"></a>
<span class="sourceLineNo">090</span> } else {<a name="line.90"></a>
<span class="sourceLineNo">091</span> heap.add(scanner);<a name="line.91"></a>
<span class="sourceLineNo">092</span> }<a name="line.92"></a>
<span class="sourceLineNo">093</span> }<a name="line.93"></a>
<span class="sourceLineNo">094</span><a name="line.94"></a>
<span class="sourceLineNo">095</span> // Heap is returning empty, scanner is done<a name="line.95"></a>
<span class="sourceLineNo">096</span> return false;<a name="line.96"></a>
<span class="sourceLineNo">097</span> }<a name="line.97"></a>
<span class="sourceLineNo">098</span><a name="line.98"></a>
<span class="sourceLineNo">099</span> @Override<a name="line.99"></a>
<span class="sourceLineNo">100</span> public boolean backwardSeek(Cell seekKey) throws IOException {<a name="line.100"></a>
<span class="sourceLineNo">101</span> if (current == null) {<a name="line.101"></a>
<span class="sourceLineNo">102</span> return false;<a name="line.102"></a>
<span class="sourceLineNo">103</span> }<a name="line.103"></a>
<span class="sourceLineNo">104</span> heap.add(current);<a name="line.104"></a>
<span class="sourceLineNo">105</span> current = null;<a name="line.105"></a>
<span class="sourceLineNo">106</span><a name="line.106"></a>
<span class="sourceLineNo">107</span> KeyValueScanner scanner;<a name="line.107"></a>
<span class="sourceLineNo">108</span> while ((scanner = heap.poll()) != null) {<a name="line.108"></a>
<span class="sourceLineNo">109</span> Cell topKey = scanner.peek();<a name="line.109"></a>
<span class="sourceLineNo">110</span> if ((CellUtil.matchingRows(seekKey, topKey) &amp;&amp; comparator<a name="line.110"></a>
<span class="sourceLineNo">111</span> .getComparator().compare(seekKey, topKey) &lt;= 0)<a name="line.111"></a>
<span class="sourceLineNo">112</span> || comparator.getComparator().compareRows(seekKey, topKey) &gt; 0) {<a name="line.112"></a>
<span class="sourceLineNo">113</span> heap.add(scanner);<a name="line.113"></a>
<span class="sourceLineNo">114</span> current = pollRealKV();<a name="line.114"></a>
<span class="sourceLineNo">115</span> return current != null;<a name="line.115"></a>
<span class="sourceLineNo">116</span> }<a name="line.116"></a>
<span class="sourceLineNo">117</span> if (!scanner.backwardSeek(seekKey)) {<a name="line.117"></a>
<span class="sourceLineNo">118</span> this.scannersForDelayedClose.add(scanner);<a name="line.118"></a>
<span class="sourceLineNo">119</span> } else {<a name="line.119"></a>
<span class="sourceLineNo">120</span> heap.add(scanner);<a name="line.120"></a>
<span class="sourceLineNo">121</span> }<a name="line.121"></a>
<span class="sourceLineNo">122</span> }<a name="line.122"></a>
<span class="sourceLineNo">123</span> return false;<a name="line.123"></a>
<span class="sourceLineNo">124</span> }<a name="line.124"></a>
<span class="sourceLineNo">125</span><a name="line.125"></a>
<span class="sourceLineNo">126</span> @Override<a name="line.126"></a>
<span class="sourceLineNo">127</span> public Cell next() throws IOException {<a name="line.127"></a>
<span class="sourceLineNo">128</span> if (this.current == null) {<a name="line.128"></a>
<span class="sourceLineNo">129</span> return null;<a name="line.129"></a>
<span class="sourceLineNo">130</span> }<a name="line.130"></a>
<span class="sourceLineNo">131</span> Cell kvReturn = this.current.next();<a name="line.131"></a>
<span class="sourceLineNo">132</span> Cell kvNext = this.current.peek();<a name="line.132"></a>
<span class="sourceLineNo">133</span> if (kvNext == null<a name="line.133"></a>
<span class="sourceLineNo">134</span> || this.comparator.kvComparator.compareRows(kvNext, kvReturn) &gt; 0) {<a name="line.134"></a>
<span class="sourceLineNo">135</span> if (this.current.seekToPreviousRow(kvReturn)) {<a name="line.135"></a>
<span class="sourceLineNo">136</span> this.heap.add(this.current);<a name="line.136"></a>
<span class="sourceLineNo">137</span> } else {<a name="line.137"></a>
<span class="sourceLineNo">138</span> this.scannersForDelayedClose.add(this.current);<a name="line.138"></a>
<span class="sourceLineNo">139</span> }<a name="line.139"></a>
<span class="sourceLineNo">140</span> this.current = null;<a name="line.140"></a>
<span class="sourceLineNo">141</span> this.current = pollRealKV();<a name="line.141"></a>
<span class="sourceLineNo">142</span> } else {<a name="line.142"></a>
<span class="sourceLineNo">143</span> KeyValueScanner topScanner = this.heap.peek();<a name="line.143"></a>
<span class="sourceLineNo">144</span> if (topScanner != null<a name="line.144"></a>
<span class="sourceLineNo">145</span> &amp;&amp; this.comparator.compare(this.current, topScanner) &gt; 0) {<a name="line.145"></a>
<span class="sourceLineNo">146</span> this.heap.add(this.current);<a name="line.146"></a>
<span class="sourceLineNo">147</span> this.current = null;<a name="line.147"></a>
<span class="sourceLineNo">148</span> this.current = pollRealKV();<a name="line.148"></a>
<span class="sourceLineNo">149</span> }<a name="line.149"></a>
<span class="sourceLineNo">150</span> }<a name="line.150"></a>
<span class="sourceLineNo">151</span> return kvReturn;<a name="line.151"></a>
<span class="sourceLineNo">152</span> }<a name="line.152"></a>
<span class="sourceLineNo">153</span><a name="line.153"></a>
<span class="sourceLineNo">154</span> /**<a name="line.154"></a>
<span class="sourceLineNo">155</span> * In ReversedKVScannerComparator, we compare the row of scanners' peek values<a name="line.155"></a>
<span class="sourceLineNo">156</span> * first, sort bigger one before the smaller one. Then compare the KeyValue if<a name="line.156"></a>
<span class="sourceLineNo">157</span> * they have the equal row, sort smaller one before the bigger one<a name="line.157"></a>
<span class="sourceLineNo">158</span> */<a name="line.158"></a>
<span class="sourceLineNo">159</span> private static class ReversedKVScannerComparator extends<a name="line.159"></a>
<span class="sourceLineNo">160</span> KVScannerComparator {<a name="line.160"></a>
<span class="sourceLineNo">161</span><a name="line.161"></a>
<span class="sourceLineNo">162</span> /**<a name="line.162"></a>
<span class="sourceLineNo">163</span> * Constructor<a name="line.163"></a>
<span class="sourceLineNo">164</span> * @param kvComparator<a name="line.164"></a>
<span class="sourceLineNo">165</span> */<a name="line.165"></a>
<span class="sourceLineNo">166</span> public ReversedKVScannerComparator(CellComparator kvComparator) {<a name="line.166"></a>
<span class="sourceLineNo">167</span> super(kvComparator);<a name="line.167"></a>
<span class="sourceLineNo">168</span> }<a name="line.168"></a>
<span class="sourceLineNo">169</span><a name="line.169"></a>
<span class="sourceLineNo">170</span> @Override<a name="line.170"></a>
<span class="sourceLineNo">171</span> public int compare(KeyValueScanner left, KeyValueScanner right) {<a name="line.171"></a>
<span class="sourceLineNo">172</span> int rowComparison = compareRows(left.peek(), right.peek());<a name="line.172"></a>
<span class="sourceLineNo">173</span> if (rowComparison != 0) {<a name="line.173"></a>
<span class="sourceLineNo">174</span> return -rowComparison;<a name="line.174"></a>
<span class="sourceLineNo">175</span> }<a name="line.175"></a>
<span class="sourceLineNo">176</span> return super.compare(left, right);<a name="line.176"></a>
<span class="sourceLineNo">177</span> }<a name="line.177"></a>
<span class="sourceLineNo">178</span><a name="line.178"></a>
<span class="sourceLineNo">179</span> /**<a name="line.179"></a>
<span class="sourceLineNo">180</span> * Compares rows of two KeyValue<a name="line.180"></a>
<span class="sourceLineNo">181</span> * @param left<a name="line.181"></a>
<span class="sourceLineNo">182</span> * @param right<a name="line.182"></a>
<span class="sourceLineNo">183</span> * @return less than 0 if left is smaller, 0 if equal etc..<a name="line.183"></a>
<span class="sourceLineNo">184</span> */<a name="line.184"></a>
<span class="sourceLineNo">185</span> public int compareRows(Cell left, Cell right) {<a name="line.185"></a>
<span class="sourceLineNo">186</span> return super.kvComparator.compareRows(left, right);<a name="line.186"></a>
<span class="sourceLineNo">187</span> }<a name="line.187"></a>
<span class="sourceLineNo">188</span> }<a name="line.188"></a>
<span class="sourceLineNo">189</span><a name="line.189"></a>
<span class="sourceLineNo">190</span> @Override<a name="line.190"></a>
<span class="sourceLineNo">191</span> public boolean seekToLastRow() throws IOException {<a name="line.191"></a>
<span class="sourceLineNo">192</span> throw new NotImplementedException(HConstants.NOT_IMPLEMENTED);<a name="line.192"></a>
<span class="sourceLineNo">193</span> }<a name="line.193"></a>
<span class="sourceLineNo">194</span>}<a name="line.194"></a>
</pre>
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