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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.io.compress;</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 org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">021</span><span id="line-21"></span> |
| <span class="source-line-no">022</span><span id="line-22">@InterfaceAudience.Private</span> |
| <span class="source-line-no">023</span><span id="line-23">public final class CompressionUtil {</span> |
| <span class="source-line-no">024</span><span id="line-24"></span> |
| <span class="source-line-no">025</span><span id="line-25"> private CompressionUtil() {</span> |
| <span class="source-line-no">026</span><span id="line-26"> }</span> |
| <span class="source-line-no">027</span><span id="line-27"></span> |
| <span class="source-line-no">028</span><span id="line-28"> /**</span> |
| <span class="source-line-no">029</span><span id="line-29"> * Round up to the next power of two, unless the value would become negative (ints are signed), in</span> |
| <span class="source-line-no">030</span><span id="line-30"> * which case just return Integer.MAX_VALUE.</span> |
| <span class="source-line-no">031</span><span id="line-31"> */</span> |
| <span class="source-line-no">032</span><span id="line-32"> public static int roundInt2(int v) {</span> |
| <span class="source-line-no">033</span><span id="line-33"> v = Integer.highestOneBit(v) << 1;</span> |
| <span class="source-line-no">034</span><span id="line-34"> if (v < 0) {</span> |
| <span class="source-line-no">035</span><span id="line-35"> return Integer.MAX_VALUE;</span> |
| <span class="source-line-no">036</span><span id="line-36"> }</span> |
| <span class="source-line-no">037</span><span id="line-37"> return v;</span> |
| <span class="source-line-no">038</span><span id="line-38"> }</span> |
| <span class="source-line-no">039</span><span id="line-39"></span> |
| <span class="source-line-no">040</span><span id="line-40"> /**</span> |
| <span class="source-line-no">041</span><span id="line-41"> * Most compression algorithms can be presented with pathological input that causes an expansion</span> |
| <span class="source-line-no">042</span><span id="line-42"> * rather than a compression. Hadoop's compression API requires that we calculate additional</span> |
| <span class="source-line-no">043</span><span id="line-43"> * buffer space required for the worst case. There is a formula developed for gzip that applies as</span> |
| <span class="source-line-no">044</span><span id="line-44"> * a ballpark to all LZ variants. It should be good enough for now and has been tested as such</span> |
| <span class="source-line-no">045</span><span id="line-45"> * with a range of different inputs.</span> |
| <span class="source-line-no">046</span><span id="line-46"> */</span> |
| <span class="source-line-no">047</span><span id="line-47"> public static int compressionOverhead(int bufferSize) {</span> |
| <span class="source-line-no">048</span><span id="line-48"> // Given an input buffer of 'buffersize' bytes we presume a worst case expansion of</span> |
| <span class="source-line-no">049</span><span id="line-49"> // 32 bytes (block header) and addition 1/6th of the input size.</span> |
| <span class="source-line-no">050</span><span id="line-50"> return (bufferSize / 6) + 32;</span> |
| <span class="source-line-no">051</span><span id="line-51"> }</span> |
| <span class="source-line-no">052</span><span id="line-52">}</span> |
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