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Posted to commits@hbase.apache.org by mi...@apache.org on 2016/02/12 22:25:47 UTC
[22/51] [partial] hbase-site git commit: Published site at
85e1d9a109341c5f4aabb0e82c96ab52e99a6d72.
http://git-wip-us.apache.org/repos/asf/hbase-site/blob/526c7822/devapidocs/src-html/org/apache/hadoop/hbase/regionserver/MemStore.html
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diff --git a/devapidocs/src-html/org/apache/hadoop/hbase/regionserver/MemStore.html b/devapidocs/src-html/org/apache/hadoop/hbase/regionserver/MemStore.html
index a23be36..c433853 100644
--- a/devapidocs/src-html/org/apache/hadoop/hbase/regionserver/MemStore.html
+++ b/devapidocs/src-html/org/apache/hadoop/hbase/regionserver/MemStore.html
@@ -25,124 +25,134 @@
<span class="sourceLineNo">017</span> */<a name="line.17"></a>
<span class="sourceLineNo">018</span>package org.apache.hadoop.hbase.regionserver;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
-<span class="sourceLineNo">020</span>import java.util.List;<a name="line.20"></a>
-<span class="sourceLineNo">021</span><a name="line.21"></a>
-<span class="sourceLineNo">022</span>import org.apache.hadoop.hbase.classification.InterfaceAudience;<a name="line.22"></a>
+<span class="sourceLineNo">020</span>import java.io.IOException;<a name="line.20"></a>
+<span class="sourceLineNo">021</span>import java.util.List;<a name="line.21"></a>
+<span class="sourceLineNo">022</span><a name="line.22"></a>
<span class="sourceLineNo">023</span>import org.apache.hadoop.hbase.Cell;<a name="line.23"></a>
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-<span class="sourceLineNo">026</span>/**<a name="line.26"></a>
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-<span class="sourceLineNo">028</span> * <p><a name="line.28"></a>
-<span class="sourceLineNo">029</span> * The MemStore functions should not be called in parallel. Callers should hold write and read<a name="line.29"></a>
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+<span class="sourceLineNo">025</span>import org.apache.hadoop.hbase.io.HeapSize;<a name="line.25"></a>
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+<span class="sourceLineNo">031</span> * locks. This is done in {@link HStore}.<a name="line.31"></a>
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+<span class="sourceLineNo">055</span> * @param id<a name="line.55"></a>
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-<span class="sourceLineNo">059</span> long getFlushableSize();<a name="line.59"></a>
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<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span> /**<a name="line.61"></a>
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-<span class="sourceLineNo">108</span> long updateColumnValue(byte[] row, byte[] family, byte[] qualifier, long newValue, long now);<a name="line.108"></a>
-<span class="sourceLineNo">109</span><a name="line.109"></a>
-<span class="sourceLineNo">110</span> /**<a name="line.110"></a>
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-<span class="sourceLineNo">112</span> * <p><a name="line.112"></a>
-<span class="sourceLineNo">113</span> * For each Cell, insert into MemStore. This will atomically upsert the value for that<a name="line.113"></a>
-<span class="sourceLineNo">114</span> * row/family/qualifier. If a Cell did already exist, it will then be removed.<a name="line.114"></a>
-<span class="sourceLineNo">115</span> * <p><a name="line.115"></a>
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+<span class="sourceLineNo">146</span> long size();<a name="line.146"></a>
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http://git-wip-us.apache.org/repos/asf/hbase-site/blob/526c7822/devapidocs/src-html/org/apache/hadoop/hbase/regionserver/MemStoreScanner.Type.html
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+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html lang="en">
+<head>
+<title>Source code</title>
+<link rel="stylesheet" type="text/css" href="../../../../../../stylesheet.css" title="Style">
+</head>
+<body>
+<div class="sourceContainer">
+<pre><span class="sourceLineNo">001</span>/**<a name="line.1"></a>
+<span class="sourceLineNo">002</span> *<a name="line.2"></a>
+<span class="sourceLineNo">003</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.3"></a>
+<span class="sourceLineNo">004</span> * or more contributor license agreements. See the NOTICE file<a name="line.4"></a>
+<span class="sourceLineNo">005</span> * distributed with this work for additional information<a name="line.5"></a>
+<span class="sourceLineNo">006</span> * regarding copyright ownership. The ASF licenses this file<a name="line.6"></a>
+<span class="sourceLineNo">007</span> * 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<a name="line.8"></a>
+<span class="sourceLineNo">009</span> * with the License. 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,<a name="line.14"></a>
+<span class="sourceLineNo">015</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.15"></a>
+<span class="sourceLineNo">016</span> * See the License for the specific language governing permissions and<a name="line.16"></a>
+<span class="sourceLineNo">017</span> * limitations under the License.<a name="line.17"></a>
+<span class="sourceLineNo">018</span> */<a name="line.18"></a>
+<span class="sourceLineNo">019</span><a name="line.19"></a>
+<span class="sourceLineNo">020</span>package org.apache.hadoop.hbase.regionserver;<a name="line.20"></a>
+<span class="sourceLineNo">021</span><a name="line.21"></a>
+<span class="sourceLineNo">022</span>import java.io.IOException;<a name="line.22"></a>
+<span class="sourceLineNo">023</span>import java.util.List;<a name="line.23"></a>
+<span class="sourceLineNo">024</span><a name="line.24"></a>
+<span class="sourceLineNo">025</span>import org.apache.hadoop.hbase.Cell;<a name="line.25"></a>
+<span class="sourceLineNo">026</span>import org.apache.hadoop.hbase.KeyValue;<a name="line.26"></a>
+<span class="sourceLineNo">027</span>import org.apache.hadoop.hbase.classification.InterfaceAudience;<a name="line.27"></a>
+<span class="sourceLineNo">028</span>import org.apache.hadoop.hbase.client.Scan;<a name="line.28"></a>
+<span class="sourceLineNo">029</span>import org.apache.htrace.Trace;<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> * This is the scanner for any MemStore implementation, derived from MemStore.<a name="line.32"></a>
+<span class="sourceLineNo">033</span> * The MemStoreScanner combines SegmentScanner from different Segments and<a name="line.33"></a>
+<span class="sourceLineNo">034</span> * uses the key-value heap and the reversed key-value heap for the aggregated key-values set.<a name="line.34"></a>
+<span class="sourceLineNo">035</span> * It is assumed that only traversing forward or backward is used (without zigzagging in between)<a name="line.35"></a>
+<span class="sourceLineNo">036</span> */<a name="line.36"></a>
+<span class="sourceLineNo">037</span>@InterfaceAudience.Private<a name="line.37"></a>
+<span class="sourceLineNo">038</span>public class MemStoreScanner extends NonLazyKeyValueScanner {<a name="line.38"></a>
+<span class="sourceLineNo">039</span> /**<a name="line.39"></a>
+<span class="sourceLineNo">040</span> * Types of cell MemStoreScanner<a name="line.40"></a>
+<span class="sourceLineNo">041</span> */<a name="line.41"></a>
+<span class="sourceLineNo">042</span> static public enum Type {<a name="line.42"></a>
+<span class="sourceLineNo">043</span> UNDEFINED,<a name="line.43"></a>
+<span class="sourceLineNo">044</span> COMPACT_FORWARD,<a name="line.44"></a>
+<span class="sourceLineNo">045</span> USER_SCAN_FORWARD,<a name="line.45"></a>
+<span class="sourceLineNo">046</span> USER_SCAN_BACKWARD<a name="line.46"></a>
+<span class="sourceLineNo">047</span> }<a name="line.47"></a>
+<span class="sourceLineNo">048</span><a name="line.48"></a>
+<span class="sourceLineNo">049</span> // heap of scanners used for traversing forward<a name="line.49"></a>
+<span class="sourceLineNo">050</span> private KeyValueHeap forwardHeap;<a name="line.50"></a>
+<span class="sourceLineNo">051</span> // reversed scanners heap for traversing backward<a name="line.51"></a>
+<span class="sourceLineNo">052</span> private ReversedKeyValueHeap backwardHeap;<a name="line.52"></a>
+<span class="sourceLineNo">053</span><a name="line.53"></a>
+<span class="sourceLineNo">054</span> // The type of the scan is defined by constructor<a name="line.54"></a>
+<span class="sourceLineNo">055</span> // or according to the first usage<a name="line.55"></a>
+<span class="sourceLineNo">056</span> private Type type = Type.UNDEFINED;<a name="line.56"></a>
+<span class="sourceLineNo">057</span><a name="line.57"></a>
+<span class="sourceLineNo">058</span> private long readPoint;<a name="line.58"></a>
+<span class="sourceLineNo">059</span> // remember the initial version of the scanners list<a name="line.59"></a>
+<span class="sourceLineNo">060</span> List<SegmentScanner> scanners;<a name="line.60"></a>
+<span class="sourceLineNo">061</span> // pointer back to the relevant MemStore<a name="line.61"></a>
+<span class="sourceLineNo">062</span> // is needed for shouldSeek() method<a name="line.62"></a>
+<span class="sourceLineNo">063</span> private AbstractMemStore backwardReferenceToMemStore;<a name="line.63"></a>
+<span class="sourceLineNo">064</span><a name="line.64"></a>
+<span class="sourceLineNo">065</span> /**<a name="line.65"></a>
+<span class="sourceLineNo">066</span> * Constructor.<a name="line.66"></a>
+<span class="sourceLineNo">067</span> * If UNDEFINED type for MemStoreScanner is provided, the forward heap is used as default!<a name="line.67"></a>
+<span class="sourceLineNo">068</span> * After constructor only one heap is going to be initialized for entire lifespan<a name="line.68"></a>
+<span class="sourceLineNo">069</span> * of the MemStoreScanner. A specific scanner can only be one directional!<a name="line.69"></a>
+<span class="sourceLineNo">070</span> *<a name="line.70"></a>
+<span class="sourceLineNo">071</span> * @param ms Pointer back to the MemStore<a name="line.71"></a>
+<span class="sourceLineNo">072</span> * @param readPoint Read point below which we can safely remove duplicate KVs<a name="line.72"></a>
+<span class="sourceLineNo">073</span> * @param type The scan type COMPACT_FORWARD should be used for compaction<a name="line.73"></a>
+<span class="sourceLineNo">074</span> */<a name="line.74"></a>
+<span class="sourceLineNo">075</span> public MemStoreScanner(AbstractMemStore ms, long readPoint, Type type) throws IOException {<a name="line.75"></a>
+<span class="sourceLineNo">076</span> this(ms, ms.getListOfScanners(readPoint), readPoint, type);<a name="line.76"></a>
+<span class="sourceLineNo">077</span> }<a name="line.77"></a>
+<span class="sourceLineNo">078</span><a name="line.78"></a>
+<span class="sourceLineNo">079</span> /* Constructor used only when the scan usage is unknown<a name="line.79"></a>
+<span class="sourceLineNo">080</span> and need to be defined according to the first move */<a name="line.80"></a>
+<span class="sourceLineNo">081</span> public MemStoreScanner(AbstractMemStore ms, long readPt) throws IOException {<a name="line.81"></a>
+<span class="sourceLineNo">082</span> this(ms, readPt, Type.UNDEFINED);<a name="line.82"></a>
+<span class="sourceLineNo">083</span> }<a name="line.83"></a>
+<span class="sourceLineNo">084</span><a name="line.84"></a>
+<span class="sourceLineNo">085</span> public MemStoreScanner(AbstractMemStore ms, List<SegmentScanner> scanners, long readPoint,<a name="line.85"></a>
+<span class="sourceLineNo">086</span> Type type) throws IOException {<a name="line.86"></a>
+<span class="sourceLineNo">087</span> super();<a name="line.87"></a>
+<span class="sourceLineNo">088</span> this.readPoint = readPoint;<a name="line.88"></a>
+<span class="sourceLineNo">089</span> this.type = type;<a name="line.89"></a>
+<span class="sourceLineNo">090</span> switch (type) {<a name="line.90"></a>
+<span class="sourceLineNo">091</span> case UNDEFINED:<a name="line.91"></a>
+<span class="sourceLineNo">092</span> case USER_SCAN_FORWARD:<a name="line.92"></a>
+<span class="sourceLineNo">093</span> case COMPACT_FORWARD:<a name="line.93"></a>
+<span class="sourceLineNo">094</span> this.forwardHeap = new KeyValueHeap(scanners, ms.getComparator());<a name="line.94"></a>
+<span class="sourceLineNo">095</span> break;<a name="line.95"></a>
+<span class="sourceLineNo">096</span> case USER_SCAN_BACKWARD:<a name="line.96"></a>
+<span class="sourceLineNo">097</span> this.backwardHeap = new ReversedKeyValueHeap(scanners, ms.getComparator());<a name="line.97"></a>
+<span class="sourceLineNo">098</span> break;<a name="line.98"></a>
+<span class="sourceLineNo">099</span> default:<a name="line.99"></a>
+<span class="sourceLineNo">100</span> throw new IllegalArgumentException("Unknown scanner type in MemStoreScanner");<a name="line.100"></a>
+<span class="sourceLineNo">101</span> }<a name="line.101"></a>
+<span class="sourceLineNo">102</span> this.backwardReferenceToMemStore = ms;<a name="line.102"></a>
+<span class="sourceLineNo">103</span> this.scanners = scanners;<a name="line.103"></a>
+<span class="sourceLineNo">104</span> if (Trace.isTracing() && Trace.currentSpan() != null) {<a name="line.104"></a>
+<span class="sourceLineNo">105</span> Trace.currentSpan().addTimelineAnnotation("Creating MemStoreScanner");<a name="line.105"></a>
+<span class="sourceLineNo">106</span> }<a name="line.106"></a>
+<span class="sourceLineNo">107</span> }<a name="line.107"></a>
+<span class="sourceLineNo">108</span><a name="line.108"></a>
+<span class="sourceLineNo">109</span> /**<a name="line.109"></a>
+<span class="sourceLineNo">110</span> * Returns the cell from the top-most scanner without advancing the iterator.<a name="line.110"></a>
+<span class="sourceLineNo">111</span> * The backward traversal is assumed, only if specified explicitly<a name="line.111"></a>
+<span class="sourceLineNo">112</span> */<a name="line.112"></a>
+<span class="sourceLineNo">113</span> @Override<a name="line.113"></a>
+<span class="sourceLineNo">114</span> public synchronized Cell peek() {<a name="line.114"></a>
+<span class="sourceLineNo">115</span> if (type == Type.USER_SCAN_BACKWARD) {<a name="line.115"></a>
+<span class="sourceLineNo">116</span> return backwardHeap.peek();<a name="line.116"></a>
+<span class="sourceLineNo">117</span> }<a name="line.117"></a>
+<span class="sourceLineNo">118</span> return forwardHeap.peek();<a name="line.118"></a>
+<span class="sourceLineNo">119</span> }<a name="line.119"></a>
+<span class="sourceLineNo">120</span><a name="line.120"></a>
+<span class="sourceLineNo">121</span> /**<a name="line.121"></a>
+<span class="sourceLineNo">122</span> * Gets the next cell from the top-most scanner. Assumed forward scanning.<a name="line.122"></a>
+<span class="sourceLineNo">123</span> */<a name="line.123"></a>
+<span class="sourceLineNo">124</span> @Override<a name="line.124"></a>
+<span class="sourceLineNo">125</span> public synchronized Cell next() throws IOException {<a name="line.125"></a>
+<span class="sourceLineNo">126</span> KeyValueHeap heap = (Type.USER_SCAN_BACKWARD == type) ? backwardHeap : forwardHeap;<a name="line.126"></a>
+<span class="sourceLineNo">127</span><a name="line.127"></a>
+<span class="sourceLineNo">128</span> // loop over till the next suitable value<a name="line.128"></a>
+<span class="sourceLineNo">129</span> // take next value from the heap<a name="line.129"></a>
+<span class="sourceLineNo">130</span> for (Cell currentCell = heap.next();<a name="line.130"></a>
+<span class="sourceLineNo">131</span> currentCell != null;<a name="line.131"></a>
+<span class="sourceLineNo">132</span> currentCell = heap.next()) {<a name="line.132"></a>
+<span class="sourceLineNo">133</span><a name="line.133"></a>
+<span class="sourceLineNo">134</span> // all the logic of presenting cells is inside the internal SegmentScanners<a name="line.134"></a>
+<span class="sourceLineNo">135</span> // located inside the heap<a name="line.135"></a>
+<span class="sourceLineNo">136</span><a name="line.136"></a>
+<span class="sourceLineNo">137</span> return currentCell;<a name="line.137"></a>
+<span class="sourceLineNo">138</span> }<a name="line.138"></a>
+<span class="sourceLineNo">139</span> return null;<a name="line.139"></a>
+<span class="sourceLineNo">140</span> }<a name="line.140"></a>
+<span class="sourceLineNo">141</span><a name="line.141"></a>
+<span class="sourceLineNo">142</span> /**<a name="line.142"></a>
+<span class="sourceLineNo">143</span> * Set the scanner at the seek key. Assumed forward scanning.<a name="line.143"></a>
+<span class="sourceLineNo">144</span> * Must be called only once: there is no thread safety between the scanner<a name="line.144"></a>
+<span class="sourceLineNo">145</span> * and the memStore.<a name="line.145"></a>
+<span class="sourceLineNo">146</span> *<a name="line.146"></a>
+<span class="sourceLineNo">147</span> * @param cell seek value<a name="line.147"></a>
+<span class="sourceLineNo">148</span> * @return false if the key is null or if there is no data<a name="line.148"></a>
+<span class="sourceLineNo">149</span> */<a name="line.149"></a>
+<span class="sourceLineNo">150</span> @Override<a name="line.150"></a>
+<span class="sourceLineNo">151</span> public synchronized boolean seek(Cell cell) throws IOException {<a name="line.151"></a>
+<span class="sourceLineNo">152</span> assertForward();<a name="line.152"></a>
+<span class="sourceLineNo">153</span><a name="line.153"></a>
+<span class="sourceLineNo">154</span> if (cell == null) {<a name="line.154"></a>
+<span class="sourceLineNo">155</span> close();<a name="line.155"></a>
+<span class="sourceLineNo">156</span> return false;<a name="line.156"></a>
+<span class="sourceLineNo">157</span> }<a name="line.157"></a>
+<span class="sourceLineNo">158</span><a name="line.158"></a>
+<span class="sourceLineNo">159</span> return forwardHeap.seek(cell);<a name="line.159"></a>
+<span class="sourceLineNo">160</span> }<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> * Move forward on the sub-lists set previously by seek. Assumed forward scanning.<a name="line.163"></a>
+<span class="sourceLineNo">164</span> *<a name="line.164"></a>
+<span class="sourceLineNo">165</span> * @param cell seek value (should be non-null)<a name="line.165"></a>
+<span class="sourceLineNo">166</span> * @return true if there is at least one KV to read, false otherwise<a name="line.166"></a>
+<span class="sourceLineNo">167</span> */<a name="line.167"></a>
+<span class="sourceLineNo">168</span> @Override<a name="line.168"></a>
+<span class="sourceLineNo">169</span> public synchronized boolean reseek(Cell cell) throws IOException {<a name="line.169"></a>
+<span class="sourceLineNo">170</span> /*<a name="line.170"></a>
+<span class="sourceLineNo">171</span> * See HBASE-4195 & HBASE-3855 & HBASE-6591 for the background on this implementation.<a name="line.171"></a>
+<span class="sourceLineNo">172</span> * This code is executed concurrently with flush and puts, without locks.<a name="line.172"></a>
+<span class="sourceLineNo">173</span> * Two points must be known when working on this code:<a name="line.173"></a>
+<span class="sourceLineNo">174</span> * 1) It's not possible to use the 'kvTail' and 'snapshot'<a name="line.174"></a>
+<span class="sourceLineNo">175</span> * variables, as they are modified during a flush.<a name="line.175"></a>
+<span class="sourceLineNo">176</span> * 2) The ideal implementation for performance would use the sub skip list<a name="line.176"></a>
+<span class="sourceLineNo">177</span> * implicitly pointed by the iterators 'kvsetIt' and<a name="line.177"></a>
+<span class="sourceLineNo">178</span> * 'snapshotIt'. Unfortunately the Java API does not offer a method to<a name="line.178"></a>
+<span class="sourceLineNo">179</span> * get it. So we remember the last keys we iterated to and restore<a name="line.179"></a>
+<span class="sourceLineNo">180</span> * the reseeked set to at least that point.<a name="line.180"></a>
+<span class="sourceLineNo">181</span> *<a name="line.181"></a>
+<span class="sourceLineNo">182</span> * TODO: The above comment copied from the original MemStoreScanner<a name="line.182"></a>
+<span class="sourceLineNo">183</span> */<a name="line.183"></a>
+<span class="sourceLineNo">184</span> assertForward();<a name="line.184"></a>
+<span class="sourceLineNo">185</span> return forwardHeap.reseek(cell);<a name="line.185"></a>
+<span class="sourceLineNo">186</span> }<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> * MemStoreScanner returns max value as sequence id because it will<a name="line.189"></a>
+<span class="sourceLineNo">190</span> * always have the latest data among all files.<a name="line.190"></a>
+<span class="sourceLineNo">191</span> */<a name="line.191"></a>
+<span class="sourceLineNo">192</span> @Override<a name="line.192"></a>
+<span class="sourceLineNo">193</span> public synchronized long getSequenceID() {<a name="line.193"></a>
+<span class="sourceLineNo">194</span> return Long.MAX_VALUE;<a name="line.194"></a>
+<span class="sourceLineNo">195</span> }<a name="line.195"></a>
+<span class="sourceLineNo">196</span><a name="line.196"></a>
+<span class="sourceLineNo">197</span> @Override<a name="line.197"></a>
+<span class="sourceLineNo">198</span> public synchronized void close() {<a name="line.198"></a>
+<span class="sourceLineNo">199</span><a name="line.199"></a>
+<span class="sourceLineNo">200</span> if (forwardHeap != null) {<a name="line.200"></a>
+<span class="sourceLineNo">201</span> assert ((type == Type.USER_SCAN_FORWARD) ||<a name="line.201"></a>
+<span class="sourceLineNo">202</span> (type == Type.COMPACT_FORWARD) || (type == Type.UNDEFINED));<a name="line.202"></a>
+<span class="sourceLineNo">203</span> forwardHeap.close();<a name="line.203"></a>
+<span class="sourceLineNo">204</span> forwardHeap = null;<a name="line.204"></a>
+<span class="sourceLineNo">205</span> if (backwardHeap != null) {<a name="line.205"></a>
+<span class="sourceLineNo">206</span> backwardHeap.close();<a name="line.206"></a>
+<span class="sourceLineNo">207</span> backwardHeap = null;<a name="line.207"></a>
+<span class="sourceLineNo">208</span> }<a name="line.208"></a>
+<span class="sourceLineNo">209</span> } else if (backwardHeap != null) {<a name="line.209"></a>
+<span class="sourceLineNo">210</span> assert (type == Type.USER_SCAN_BACKWARD);<a name="line.210"></a>
+<span class="sourceLineNo">211</span> backwardHeap.close();<a name="line.211"></a>
+<span class="sourceLineNo">212</span> backwardHeap = null;<a name="line.212"></a>
+<span class="sourceLineNo">213</span> }<a name="line.213"></a>
+<span class="sourceLineNo">214</span> }<a name="line.214"></a>
+<span class="sourceLineNo">215</span><a name="line.215"></a>
+<span class="sourceLineNo">216</span> /**<a name="line.216"></a>
+<span class="sourceLineNo">217</span> * Set the scanner at the seek key. Assumed backward scanning.<a name="line.217"></a>
+<span class="sourceLineNo">218</span> *<a name="line.218"></a>
+<span class="sourceLineNo">219</span> * @param cell seek value<a name="line.219"></a>
+<span class="sourceLineNo">220</span> * @return false if the key is null or if there is no data<a name="line.220"></a>
+<span class="sourceLineNo">221</span> */<a name="line.221"></a>
+<span class="sourceLineNo">222</span> @Override<a name="line.222"></a>
+<span class="sourceLineNo">223</span> public synchronized boolean backwardSeek(Cell cell) throws IOException {<a name="line.223"></a>
+<span class="sourceLineNo">224</span> initBackwardHeapIfNeeded(cell, false);<a name="line.224"></a>
+<span class="sourceLineNo">225</span> return backwardHeap.backwardSeek(cell);<a name="line.225"></a>
+<span class="sourceLineNo">226</span> }<a name="line.226"></a>
+<span class="sourceLineNo">227</span><a name="line.227"></a>
+<span class="sourceLineNo">228</span> /**<a name="line.228"></a>
+<span class="sourceLineNo">229</span> * Assumed backward scanning.<a name="line.229"></a>
+<span class="sourceLineNo">230</span> *<a name="line.230"></a>
+<span class="sourceLineNo">231</span> * @param cell seek value<a name="line.231"></a>
+<span class="sourceLineNo">232</span> * @return false if the key is null or if there is no data<a name="line.232"></a>
+<span class="sourceLineNo">233</span> */<a name="line.233"></a>
+<span class="sourceLineNo">234</span> @Override<a name="line.234"></a>
+<span class="sourceLineNo">235</span> public synchronized boolean seekToPreviousRow(Cell cell) throws IOException {<a name="line.235"></a>
+<span class="sourceLineNo">236</span> initBackwardHeapIfNeeded(cell, false);<a name="line.236"></a>
+<span class="sourceLineNo">237</span> if (backwardHeap.peek() == null) {<a name="line.237"></a>
+<span class="sourceLineNo">238</span> restartBackwardHeap(cell);<a name="line.238"></a>
+<span class="sourceLineNo">239</span> }<a name="line.239"></a>
+<span class="sourceLineNo">240</span> return backwardHeap.seekToPreviousRow(cell);<a name="line.240"></a>
+<span class="sourceLineNo">241</span> }<a name="line.241"></a>
+<span class="sourceLineNo">242</span><a name="line.242"></a>
+<span class="sourceLineNo">243</span> @Override<a name="line.243"></a>
+<span class="sourceLineNo">244</span> public synchronized boolean seekToLastRow() throws IOException {<a name="line.244"></a>
+<span class="sourceLineNo">245</span> // TODO: it looks like this is how it should be, however ReversedKeyValueHeap class doesn't<a name="line.245"></a>
+<span class="sourceLineNo">246</span> // implement seekToLastRow() method :(<a name="line.246"></a>
+<span class="sourceLineNo">247</span> // however seekToLastRow() was implemented in internal MemStoreScanner<a name="line.247"></a>
+<span class="sourceLineNo">248</span> // so I wonder whether we need to come with our own workaround, or to update<a name="line.248"></a>
+<span class="sourceLineNo">249</span> // ReversedKeyValueHeap<a name="line.249"></a>
+<span class="sourceLineNo">250</span> return initBackwardHeapIfNeeded(KeyValue.LOWESTKEY, true);<a name="line.250"></a>
+<span class="sourceLineNo">251</span> }<a name="line.251"></a>
+<span class="sourceLineNo">252</span><a name="line.252"></a>
+<span class="sourceLineNo">253</span> /**<a name="line.253"></a>
+<span class="sourceLineNo">254</span> * Check if this memstore may contain the required keys<a name="line.254"></a>
+<span class="sourceLineNo">255</span> * @return False if the key definitely does not exist in this Memstore<a name="line.255"></a>
+<span class="sourceLineNo">256</span> */<a name="line.256"></a>
+<span class="sourceLineNo">257</span> @Override<a name="line.257"></a>
+<span class="sourceLineNo">258</span> public synchronized boolean shouldUseScanner(Scan scan, Store store, long oldestUnexpiredTS) {<a name="line.258"></a>
+<span class="sourceLineNo">259</span><a name="line.259"></a>
+<span class="sourceLineNo">260</span> if (type == Type.COMPACT_FORWARD) {<a name="line.260"></a>
+<span class="sourceLineNo">261</span> return true;<a name="line.261"></a>
+<span class="sourceLineNo">262</span> }<a name="line.262"></a>
+<span class="sourceLineNo">263</span><a name="line.263"></a>
+<span class="sourceLineNo">264</span> for (SegmentScanner sc : scanners) {<a name="line.264"></a>
+<span class="sourceLineNo">265</span> if (sc.shouldSeek(scan, oldestUnexpiredTS)) {<a name="line.265"></a>
+<span class="sourceLineNo">266</span> return true;<a name="line.266"></a>
+<span class="sourceLineNo">267</span> }<a name="line.267"></a>
+<span class="sourceLineNo">268</span> }<a name="line.268"></a>
+<span class="sourceLineNo">269</span> return false;<a name="line.269"></a>
+<span class="sourceLineNo">270</span> }<a name="line.270"></a>
+<span class="sourceLineNo">271</span><a name="line.271"></a>
+<span class="sourceLineNo">272</span> // debug method<a name="line.272"></a>
+<span class="sourceLineNo">273</span> @Override<a name="line.273"></a>
+<span class="sourceLineNo">274</span> public String toString() {<a name="line.274"></a>
+<span class="sourceLineNo">275</span> StringBuffer buf = new StringBuffer();<a name="line.275"></a>
+<span class="sourceLineNo">276</span> int i = 1;<a name="line.276"></a>
+<span class="sourceLineNo">277</span> for (SegmentScanner scanner : scanners) {<a name="line.277"></a>
+<span class="sourceLineNo">278</span> buf.append("scanner (" + i + ") " + scanner.toString() + " ||| ");<a name="line.278"></a>
+<span class="sourceLineNo">279</span> i++;<a name="line.279"></a>
+<span class="sourceLineNo">280</span> }<a name="line.280"></a>
+<span class="sourceLineNo">281</span> return buf.toString();<a name="line.281"></a>
+<span class="sourceLineNo">282</span> }<a name="line.282"></a>
+<span class="sourceLineNo">283</span> /****************** Private methods ******************/<a name="line.283"></a>
+<span class="sourceLineNo">284</span> /**<a name="line.284"></a>
+<span class="sourceLineNo">285</span> * Restructure the ended backward heap after rerunning a seekToPreviousRow()<a name="line.285"></a>
+<span class="sourceLineNo">286</span> * on each scanner<a name="line.286"></a>
+<span class="sourceLineNo">287</span> * @return false if given Cell does not exist in any scanner<a name="line.287"></a>
+<span class="sourceLineNo">288</span> */<a name="line.288"></a>
+<span class="sourceLineNo">289</span> private boolean restartBackwardHeap(Cell cell) throws IOException {<a name="line.289"></a>
+<span class="sourceLineNo">290</span> boolean res = false;<a name="line.290"></a>
+<span class="sourceLineNo">291</span> for (SegmentScanner scan : scanners) {<a name="line.291"></a>
+<span class="sourceLineNo">292</span> res |= scan.seekToPreviousRow(cell);<a name="line.292"></a>
+<span class="sourceLineNo">293</span> }<a name="line.293"></a>
+<span class="sourceLineNo">294</span> this.backwardHeap =<a name="line.294"></a>
+<span class="sourceLineNo">295</span> new ReversedKeyValueHeap(scanners, backwardReferenceToMemStore.getComparator());<a name="line.295"></a>
+<span class="sourceLineNo">296</span> return res;<a name="line.296"></a>
+<span class="sourceLineNo">297</span> }<a name="line.297"></a>
+<span class="sourceLineNo">298</span><a name="line.298"></a>
+<span class="sourceLineNo">299</span> /**<a name="line.299"></a>
+<span class="sourceLineNo">300</span> * Checks whether the type of the scan suits the assumption of moving backward<a name="line.300"></a>
+<span class="sourceLineNo">301</span> */<a name="line.301"></a>
+<span class="sourceLineNo">302</span> private boolean initBackwardHeapIfNeeded(Cell cell, boolean toLast) throws IOException {<a name="line.302"></a>
+<span class="sourceLineNo">303</span> boolean res = false;<a name="line.303"></a>
+<span class="sourceLineNo">304</span> if (toLast && (type != Type.UNDEFINED)) {<a name="line.304"></a>
+<span class="sourceLineNo">305</span> throw new IllegalStateException(<a name="line.305"></a>
+<span class="sourceLineNo">306</span> "Wrong usage of initBackwardHeapIfNeeded in parameters. The type is:" + type.toString());<a name="line.306"></a>
+<span class="sourceLineNo">307</span> }<a name="line.307"></a>
+<span class="sourceLineNo">308</span> if (type == Type.UNDEFINED) {<a name="line.308"></a>
+<span class="sourceLineNo">309</span> // In case we started from peek, release the forward heap<a name="line.309"></a>
+<span class="sourceLineNo">310</span> // and build backward. Set the correct type. Thus this turn<a name="line.310"></a>
+<span class="sourceLineNo">311</span> // can happen only once<a name="line.311"></a>
+<span class="sourceLineNo">312</span> if ((backwardHeap == null) && (forwardHeap != null)) {<a name="line.312"></a>
+<span class="sourceLineNo">313</span> forwardHeap.close();<a name="line.313"></a>
+<span class="sourceLineNo">314</span> forwardHeap = null;<a name="line.314"></a>
+<span class="sourceLineNo">315</span> // before building the heap seek for the relevant key on the scanners,<a name="line.315"></a>
+<span class="sourceLineNo">316</span> // for the heap to be built from the scanners correctly<a name="line.316"></a>
+<span class="sourceLineNo">317</span> for (SegmentScanner scan : scanners) {<a name="line.317"></a>
+<span class="sourceLineNo">318</span> if (toLast) {<a name="line.318"></a>
+<span class="sourceLineNo">319</span> res |= scan.seekToLastRow();<a name="line.319"></a>
+<span class="sourceLineNo">320</span> } else {<a name="line.320"></a>
+<span class="sourceLineNo">321</span> res |= scan.backwardSeek(cell);<a name="line.321"></a>
+<span class="sourceLineNo">322</span> }<a name="line.322"></a>
+<span class="sourceLineNo">323</span> }<a name="line.323"></a>
+<span class="sourceLineNo">324</span> this.backwardHeap =<a name="line.324"></a>
+<span class="sourceLineNo">325</span> new ReversedKeyValueHeap(scanners, backwardReferenceToMemStore.getComparator());<a name="line.325"></a>
+<span class="sourceLineNo">326</span> type = Type.USER_SCAN_BACKWARD;<a name="line.326"></a>
+<span class="sourceLineNo">327</span> }<a name="line.327"></a>
+<span class="sourceLineNo">328</span> }<a name="line.328"></a>
+<span class="sourceLineNo">329</span><a name="line.329"></a>
+<span class="sourceLineNo">330</span> if (type == Type.USER_SCAN_FORWARD) {<a name="line.330"></a>
+<span class="sourceLineNo">331</span> throw new IllegalStateException("Traversing backward with forward scan");<a name="line.331"></a>
+<span class="sourceLineNo">332</span> }<a name="line.332"></a>
+<span class="sourceLineNo">333</span> return res;<a name="line.333"></a>
+<span class="sourceLineNo">334</span> }<a name="line.334"></a>
+<span class="sourceLineNo">335</span><a name="line.335"></a>
+<span class="sourceLineNo">336</span> /**<a name="line.336"></a>
+<span class="sourceLineNo">337</span> * Checks whether the type of the scan suits the assumption of moving forward<a name="line.337"></a>
+<span class="sourceLineNo">338</span> */<a name="line.338"></a>
+<span class="sourceLineNo">339</span> private void assertForward() throws IllegalStateException {<a name="line.339"></a>
+<span class="sourceLineNo">340</span> if (type == Type.UNDEFINED) {<a name="line.340"></a>
+<span class="sourceLineNo">341</span> type = Type.USER_SCAN_FORWARD;<a name="line.341"></a>
+<span class="sourceLineNo">342</span> }<a name="line.342"></a>
+<span class="sourceLineNo">343</span><a name="line.343"></a>
+<span class="sourceLineNo">344</span> if (type == Type.USER_SCAN_BACKWARD) {<a name="line.344"></a>
+<span class="sourceLineNo">345</span> throw new IllegalStateException("Traversing forward with backward scan");<a name="line.345"></a>
+<span class="sourceLineNo">346</span> }<a name="line.346"></a>
+<span class="sourceLineNo">347</span> }<a name="line.347"></a>
+<span class="sourceLineNo">348</span>}<a name="line.348"></a>
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+</pre>
+</div>
+</body>
+</html>