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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.regionserver;</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 java.io.IOException;</span>
<span class="source-line-no">021</span><span id="line-21">import java.util.List;</span>
<span class="source-line-no">022</span><span id="line-22">import java.util.NavigableSet;</span>
<span class="source-line-no">023</span><span id="line-23">import org.apache.hadoop.hbase.Cell;</span>
<span class="source-line-no">024</span><span id="line-24">import org.apache.hadoop.hbase.CellComparator;</span>
<span class="source-line-no">025</span><span id="line-25">import org.apache.hadoop.hbase.CellUtil;</span>
<span class="source-line-no">026</span><span id="line-26">import org.apache.hadoop.hbase.ExtendedCell;</span>
<span class="source-line-no">027</span><span id="line-27">import org.apache.hadoop.hbase.HConstants;</span>
<span class="source-line-no">028</span><span id="line-28">import org.apache.hadoop.hbase.client.Scan;</span>
<span class="source-line-no">029</span><span id="line-29">import org.apache.yetus.audience.InterfaceAudience;</span>
<span class="source-line-no">030</span><span id="line-30"></span>
<span class="source-line-no">031</span><span id="line-31">/**</span>
<span class="source-line-no">032</span><span id="line-32"> * ReversedStoreScanner extends from StoreScanner, and is used to support reversed scanning.</span>
<span class="source-line-no">033</span><span id="line-33"> */</span>
<span class="source-line-no">034</span><span id="line-34">@InterfaceAudience.Private</span>
<span class="source-line-no">035</span><span id="line-35">public class ReversedStoreScanner extends StoreScanner implements KeyValueScanner {</span>
<span class="source-line-no">036</span><span id="line-36"></span>
<span class="source-line-no">037</span><span id="line-37"> /**</span>
<span class="source-line-no">038</span><span id="line-38"> * Opens a scanner across memstore, snapshot, and all StoreFiles. Assumes we are not in a</span>
<span class="source-line-no">039</span><span id="line-39"> * compaction.</span>
<span class="source-line-no">040</span><span id="line-40"> * @param store who we scan</span>
<span class="source-line-no">041</span><span id="line-41"> * @param scan the spec</span>
<span class="source-line-no">042</span><span id="line-42"> * @param columns which columns we are scanning</span>
<span class="source-line-no">043</span><span id="line-43"> */</span>
<span class="source-line-no">044</span><span id="line-44"> public ReversedStoreScanner(HStore store, ScanInfo scanInfo, Scan scan,</span>
<span class="source-line-no">045</span><span id="line-45"> NavigableSet&lt;byte[]&gt; columns, long readPt) throws IOException {</span>
<span class="source-line-no">046</span><span id="line-46"> super(store, scanInfo, scan, columns, readPt);</span>
<span class="source-line-no">047</span><span id="line-47"> }</span>
<span class="source-line-no">048</span><span id="line-48"></span>
<span class="source-line-no">049</span><span id="line-49"> /** Constructor for testing. */</span>
<span class="source-line-no">050</span><span id="line-50"> public ReversedStoreScanner(Scan scan, ScanInfo scanInfo, NavigableSet&lt;byte[]&gt; columns,</span>
<span class="source-line-no">051</span><span id="line-51"> List&lt;? extends KeyValueScanner&gt; scanners) throws IOException {</span>
<span class="source-line-no">052</span><span id="line-52"> super(scan, scanInfo, columns, scanners);</span>
<span class="source-line-no">053</span><span id="line-53"> }</span>
<span class="source-line-no">054</span><span id="line-54"></span>
<span class="source-line-no">055</span><span id="line-55"> @Override</span>
<span class="source-line-no">056</span><span id="line-56"> protected KeyValueHeap newKVHeap(List&lt;? extends KeyValueScanner&gt; scanners,</span>
<span class="source-line-no">057</span><span id="line-57"> CellComparator comparator) throws IOException {</span>
<span class="source-line-no">058</span><span id="line-58"> return new ReversedKeyValueHeap(scanners, comparator);</span>
<span class="source-line-no">059</span><span id="line-59"> }</span>
<span class="source-line-no">060</span><span id="line-60"></span>
<span class="source-line-no">061</span><span id="line-61"> @Override</span>
<span class="source-line-no">062</span><span id="line-62"> protected void seekScanners(List&lt;? extends KeyValueScanner&gt; scanners, ExtendedCell seekKey,</span>
<span class="source-line-no">063</span><span id="line-63"> boolean isLazy, boolean isParallelSeek) throws IOException {</span>
<span class="source-line-no">064</span><span id="line-64"> // Seek all scanners to the start of the Row (or if the exact matching row</span>
<span class="source-line-no">065</span><span id="line-65"> // key does not exist, then to the start of the previous matching Row).</span>
<span class="source-line-no">066</span><span id="line-66"> if (CellUtil.matchingRows(seekKey, HConstants.EMPTY_START_ROW)) {</span>
<span class="source-line-no">067</span><span id="line-67"> for (KeyValueScanner scanner : scanners) {</span>
<span class="source-line-no">068</span><span id="line-68"> scanner.seekToLastRow();</span>
<span class="source-line-no">069</span><span id="line-69"> }</span>
<span class="source-line-no">070</span><span id="line-70"> } else {</span>
<span class="source-line-no">071</span><span id="line-71"> for (KeyValueScanner scanner : scanners) {</span>
<span class="source-line-no">072</span><span id="line-72"> scanner.backwardSeek(seekKey);</span>
<span class="source-line-no">073</span><span id="line-73"> }</span>
<span class="source-line-no">074</span><span id="line-74"> }</span>
<span class="source-line-no">075</span><span id="line-75"> }</span>
<span class="source-line-no">076</span><span id="line-76"></span>
<span class="source-line-no">077</span><span id="line-77"> @Override</span>
<span class="source-line-no">078</span><span id="line-78"> protected boolean seekToNextRow(ExtendedCell kv) throws IOException {</span>
<span class="source-line-no">079</span><span id="line-79"> return seekToPreviousRow(kv);</span>
<span class="source-line-no">080</span><span id="line-80"> }</span>
<span class="source-line-no">081</span><span id="line-81"></span>
<span class="source-line-no">082</span><span id="line-82"> /**</span>
<span class="source-line-no">083</span><span id="line-83"> * Do a backwardSeek in a reversed StoreScanner(scan backward)</span>
<span class="source-line-no">084</span><span id="line-84"> */</span>
<span class="source-line-no">085</span><span id="line-85"> @Override</span>
<span class="source-line-no">086</span><span id="line-86"> protected boolean seekAsDirection(ExtendedCell kv) throws IOException {</span>
<span class="source-line-no">087</span><span id="line-87"> return backwardSeek(kv);</span>
<span class="source-line-no">088</span><span id="line-88"> }</span>
<span class="source-line-no">089</span><span id="line-89"></span>
<span class="source-line-no">090</span><span id="line-90"> @Override</span>
<span class="source-line-no">091</span><span id="line-91"> protected void checkScanOrder(Cell prevKV, Cell kv, CellComparator comparator)</span>
<span class="source-line-no">092</span><span id="line-92"> throws IOException {</span>
<span class="source-line-no">093</span><span id="line-93"> // Check that the heap gives us KVs in an increasing order for same row and</span>
<span class="source-line-no">094</span><span id="line-94"> // decreasing order for different rows.</span>
<span class="source-line-no">095</span><span id="line-95"> assert prevKV == null || comparator == null || comparator.compareRows(kv, prevKV) &lt; 0</span>
<span class="source-line-no">096</span><span id="line-96"> || (CellUtil.matchingRows(kv, prevKV) &amp;&amp; comparator.compare(kv, prevKV) &gt;= 0)</span>
<span class="source-line-no">097</span><span id="line-97"> : "Key " + prevKV + " followed by a " + "error order key " + kv + " in cf " + store</span>
<span class="source-line-no">098</span><span id="line-98"> + " in reversed scan";</span>
<span class="source-line-no">099</span><span id="line-99"> }</span>
<span class="source-line-no">100</span><span id="line-100"></span>
<span class="source-line-no">101</span><span id="line-101"> @Override</span>
<span class="source-line-no">102</span><span id="line-102"> public boolean reseek(ExtendedCell kv) throws IOException {</span>
<span class="source-line-no">103</span><span id="line-103"> throw new IllegalStateException("reseek cannot be called on ReversedStoreScanner");</span>
<span class="source-line-no">104</span><span id="line-104"> }</span>
<span class="source-line-no">105</span><span id="line-105"></span>
<span class="source-line-no">106</span><span id="line-106"> @Override</span>
<span class="source-line-no">107</span><span id="line-107"> public boolean seek(ExtendedCell key) throws IOException {</span>
<span class="source-line-no">108</span><span id="line-108"> throw new IllegalStateException("seek cannot be called on ReversedStoreScanner");</span>
<span class="source-line-no">109</span><span id="line-109"> }</span>
<span class="source-line-no">110</span><span id="line-110"></span>
<span class="source-line-no">111</span><span id="line-111"> @Override</span>
<span class="source-line-no">112</span><span id="line-112"> public boolean seekToPreviousRow(ExtendedCell key) throws IOException {</span>
<span class="source-line-no">113</span><span id="line-113"> if (checkFlushed()) {</span>
<span class="source-line-no">114</span><span id="line-114"> reopenAfterFlush();</span>
<span class="source-line-no">115</span><span id="line-115"> }</span>
<span class="source-line-no">116</span><span id="line-116"> return this.heap.seekToPreviousRow(key);</span>
<span class="source-line-no">117</span><span id="line-117"> }</span>
<span class="source-line-no">118</span><span id="line-118"></span>
<span class="source-line-no">119</span><span id="line-119"> @Override</span>
<span class="source-line-no">120</span><span id="line-120"> public boolean backwardSeek(ExtendedCell key) throws IOException {</span>
<span class="source-line-no">121</span><span id="line-121"> if (checkFlushed()) {</span>
<span class="source-line-no">122</span><span id="line-122"> reopenAfterFlush();</span>
<span class="source-line-no">123</span><span id="line-123"> }</span>
<span class="source-line-no">124</span><span id="line-124"> return this.heap.backwardSeek(key);</span>
<span class="source-line-no">125</span><span id="line-125"> }</span>
<span class="source-line-no">126</span><span id="line-126">}</span>
</pre>
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