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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a>
<span class="sourceLineNo">003</span> * or more contributor license agreements. See the NOTICE file<a name="line.3"></a>
<span class="sourceLineNo">004</span> * distributed with this work for additional information<a name="line.4"></a>
<span class="sourceLineNo">005</span> * regarding copyright ownership. The ASF licenses this file<a name="line.5"></a>
<span class="sourceLineNo">006</span> * to you under the Apache License, Version 2.0 (the<a name="line.6"></a>
<span class="sourceLineNo">007</span> * "License"); you may not use this file except in compliance<a name="line.7"></a>
<span class="sourceLineNo">008</span> * with the License. You may obtain a copy of the License at<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a>
<span class="sourceLineNo">011</span> *<a name="line.11"></a>
<span class="sourceLineNo">012</span> * Unless required by applicable law or agreed to in writing, software<a name="line.12"></a>
<span class="sourceLineNo">013</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<span class="sourceLineNo">014</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<span class="sourceLineNo">015</span> * See the License for the specific language governing permissions and<a name="line.15"></a>
<span class="sourceLineNo">016</span> * limitations under the License.<a name="line.16"></a>
<span class="sourceLineNo">017</span> */<a name="line.17"></a>
<span class="sourceLineNo">018</span>package org.apache.hadoop.hbase.io.hfile;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import org.apache.hadoop.hbase.io.HeapSize;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.21"></a>
<span class="sourceLineNo">022</span><a name="line.22"></a>
<span class="sourceLineNo">023</span>import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.apache.hbase.thirdparty.com.google.common.collect.MinMaxPriorityQueue;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>/**<a name="line.26"></a>
<span class="sourceLineNo">027</span> * A memory-bound queue that will grow until an element brings total size &amp;gt;= maxSize. From then<a name="line.27"></a>
<span class="sourceLineNo">028</span> * on, only entries that are sorted larger than the smallest current entry will be<a name="line.28"></a>
<span class="sourceLineNo">029</span> * inserted/replaced.<a name="line.29"></a>
<span class="sourceLineNo">030</span> * &lt;p&gt;<a name="line.30"></a>
<span class="sourceLineNo">031</span> * Use this when you want to find the largest elements (according to their ordering, not their heap<a name="line.31"></a>
<span class="sourceLineNo">032</span> * size) that consume as close to the specified maxSize as possible. Default behavior is to grow<a name="line.32"></a>
<span class="sourceLineNo">033</span> * just above rather than just below specified max.<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> * Object used in this queue must implement {@link HeapSize} as well as {@link Comparable}.<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 LruCachedBlockQueue implements HeapSize {<a name="line.38"></a>
<span class="sourceLineNo">039</span><a name="line.39"></a>
<span class="sourceLineNo">040</span> private MinMaxPriorityQueue&lt;LruCachedBlock&gt; queue;<a name="line.40"></a>
<span class="sourceLineNo">041</span><a name="line.41"></a>
<span class="sourceLineNo">042</span> private long heapSize;<a name="line.42"></a>
<span class="sourceLineNo">043</span> private long maxSize;<a name="line.43"></a>
<span class="sourceLineNo">044</span><a name="line.44"></a>
<span class="sourceLineNo">045</span> /**<a name="line.45"></a>
<span class="sourceLineNo">046</span> * @param maxSize the target size of elements in the queue<a name="line.46"></a>
<span class="sourceLineNo">047</span> * @param blockSize expected average size of blocks<a name="line.47"></a>
<span class="sourceLineNo">048</span> */<a name="line.48"></a>
<span class="sourceLineNo">049</span> public LruCachedBlockQueue(long maxSize, long blockSize) {<a name="line.49"></a>
<span class="sourceLineNo">050</span> Preconditions.checkArgument(blockSize &gt; 0, "negative blockSize %s", blockSize);<a name="line.50"></a>
<span class="sourceLineNo">051</span> Preconditions.checkArgument(maxSize &gt; 0, "negative maxSize %s", maxSize);<a name="line.51"></a>
<span class="sourceLineNo">052</span> int initialSize = (int) (maxSize / blockSize);<a name="line.52"></a>
<span class="sourceLineNo">053</span> if (initialSize == 0) {<a name="line.53"></a>
<span class="sourceLineNo">054</span> initialSize++;<a name="line.54"></a>
<span class="sourceLineNo">055</span> }<a name="line.55"></a>
<span class="sourceLineNo">056</span> queue = MinMaxPriorityQueue.expectedSize(initialSize).create();<a name="line.56"></a>
<span class="sourceLineNo">057</span> heapSize = 0;<a name="line.57"></a>
<span class="sourceLineNo">058</span> this.maxSize = maxSize;<a name="line.58"></a>
<span class="sourceLineNo">059</span> }<a name="line.59"></a>
<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span> /**<a name="line.61"></a>
<span class="sourceLineNo">062</span> * Attempt to add the specified cached block to this queue.<a name="line.62"></a>
<span class="sourceLineNo">063</span> * &lt;p&gt;<a name="line.63"></a>
<span class="sourceLineNo">064</span> * If the queue is smaller than the max size, or if the specified element is ordered before the<a name="line.64"></a>
<span class="sourceLineNo">065</span> * smallest element in the queue, the element will be added to the queue. Otherwise, there is no<a name="line.65"></a>
<span class="sourceLineNo">066</span> * side effect of this call.<a name="line.66"></a>
<span class="sourceLineNo">067</span> * @param cb block to try to add to the queue<a name="line.67"></a>
<span class="sourceLineNo">068</span> */<a name="line.68"></a>
<span class="sourceLineNo">069</span> @edu.umd.cs.findbugs.annotations.SuppressWarnings(<a name="line.69"></a>
<span class="sourceLineNo">070</span> value = "NP_NULL_ON_SOME_PATH_FROM_RETURN_VALUE",<a name="line.70"></a>
<span class="sourceLineNo">071</span> justification = "head can not be null as heapSize is greater than maxSize,"<a name="line.71"></a>
<span class="sourceLineNo">072</span> + " which means we have something in the queue")<a name="line.72"></a>
<span class="sourceLineNo">073</span> public void add(LruCachedBlock cb) {<a name="line.73"></a>
<span class="sourceLineNo">074</span> if (heapSize &lt; maxSize) {<a name="line.74"></a>
<span class="sourceLineNo">075</span> queue.add(cb);<a name="line.75"></a>
<span class="sourceLineNo">076</span> heapSize += cb.heapSize();<a name="line.76"></a>
<span class="sourceLineNo">077</span> } else {<a name="line.77"></a>
<span class="sourceLineNo">078</span> LruCachedBlock head = queue.peek();<a name="line.78"></a>
<span class="sourceLineNo">079</span> if (cb.compareTo(head) &gt; 0) {<a name="line.79"></a>
<span class="sourceLineNo">080</span> heapSize += cb.heapSize();<a name="line.80"></a>
<span class="sourceLineNo">081</span> heapSize -= head.heapSize();<a name="line.81"></a>
<span class="sourceLineNo">082</span> if (heapSize &gt; maxSize) {<a name="line.82"></a>
<span class="sourceLineNo">083</span> queue.poll();<a name="line.83"></a>
<span class="sourceLineNo">084</span> } else {<a name="line.84"></a>
<span class="sourceLineNo">085</span> heapSize += head.heapSize();<a name="line.85"></a>
<span class="sourceLineNo">086</span> }<a name="line.86"></a>
<span class="sourceLineNo">087</span> queue.add(cb);<a name="line.87"></a>
<span class="sourceLineNo">088</span> }<a name="line.88"></a>
<span class="sourceLineNo">089</span> }<a name="line.89"></a>
<span class="sourceLineNo">090</span> }<a name="line.90"></a>
<span class="sourceLineNo">091</span><a name="line.91"></a>
<span class="sourceLineNo">092</span> /** Returns The next element in this queue, or {@code null} if the queue is empty. */<a name="line.92"></a>
<span class="sourceLineNo">093</span> public LruCachedBlock poll() {<a name="line.93"></a>
<span class="sourceLineNo">094</span> return queue.poll();<a name="line.94"></a>
<span class="sourceLineNo">095</span> }<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span> /** Returns The last element in this queue, or {@code null} if the queue is empty. */<a name="line.97"></a>
<span class="sourceLineNo">098</span> public LruCachedBlock pollLast() {<a name="line.98"></a>
<span class="sourceLineNo">099</span> return queue.pollLast();<a name="line.99"></a>
<span class="sourceLineNo">100</span> }<a name="line.100"></a>
<span class="sourceLineNo">101</span><a name="line.101"></a>
<span class="sourceLineNo">102</span> /**<a name="line.102"></a>
<span class="sourceLineNo">103</span> * Total size of all elements in this queue.<a name="line.103"></a>
<span class="sourceLineNo">104</span> * @return size of all elements currently in queue, in bytes<a name="line.104"></a>
<span class="sourceLineNo">105</span> */<a name="line.105"></a>
<span class="sourceLineNo">106</span> @Override<a name="line.106"></a>
<span class="sourceLineNo">107</span> public long heapSize() {<a name="line.107"></a>
<span class="sourceLineNo">108</span> return heapSize;<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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