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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.util;</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.util.HashSet;</span> |
| <span class="source-line-no">021</span><span id="line-21">import java.util.Random;</span> |
| <span class="source-line-no">022</span><span id="line-22">import java.util.Set;</span> |
| <span class="source-line-no">023</span><span id="line-23">import java.util.concurrent.atomic.AtomicLong;</span> |
| <span class="source-line-no">024</span><span id="line-24">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">025</span><span id="line-25"></span> |
| <span class="source-line-no">026</span><span id="line-26">import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;</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"> * An instance of this class is used to generate a stream of pseudorandom numbers. The class uses a</span> |
| <span class="source-line-no">030</span><span id="line-30"> * 64-bit seed, which is modified using a linear congruential formula. see</span> |
| <span class="source-line-no">031</span><span id="line-31"> * https://en.wikipedia.org/wiki/Linear_congruential_generator</span> |
| <span class="source-line-no">032</span><span id="line-32"> */</span> |
| <span class="source-line-no">033</span><span id="line-33">@InterfaceAudience.Private</span> |
| <span class="source-line-no">034</span><span id="line-34">public class Random64 {</span> |
| <span class="source-line-no">035</span><span id="line-35"></span> |
| <span class="source-line-no">036</span><span id="line-36"> private static final long multiplier = 6364136223846793005L;</span> |
| <span class="source-line-no">037</span><span id="line-37"> private static final long addend = 1442695040888963407L;</span> |
| <span class="source-line-no">038</span><span id="line-38"></span> |
| <span class="source-line-no">039</span><span id="line-39"> private static final AtomicLong seedUniquifier = new AtomicLong(8682522807148012L);</span> |
| <span class="source-line-no">040</span><span id="line-40"></span> |
| <span class="source-line-no">041</span><span id="line-41"> private long seed;</span> |
| <span class="source-line-no">042</span><span id="line-42"></span> |
| <span class="source-line-no">043</span><span id="line-43"> /**</span> |
| <span class="source-line-no">044</span><span id="line-44"> * Copy from {@link Random#seedUniquifier()}</span> |
| <span class="source-line-no">045</span><span id="line-45"> */</span> |
| <span class="source-line-no">046</span><span id="line-46"> private static long seedUniquifier() {</span> |
| <span class="source-line-no">047</span><span id="line-47"> for (;;) {</span> |
| <span class="source-line-no">048</span><span id="line-48"> long current = seedUniquifier.get();</span> |
| <span class="source-line-no">049</span><span id="line-49"> long next = current * 181783497276652981L;</span> |
| <span class="source-line-no">050</span><span id="line-50"> if (seedUniquifier.compareAndSet(current, next)) {</span> |
| <span class="source-line-no">051</span><span id="line-51"> return next;</span> |
| <span class="source-line-no">052</span><span id="line-52"> }</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"></span> |
| <span class="source-line-no">056</span><span id="line-56"> public Random64() {</span> |
| <span class="source-line-no">057</span><span id="line-57"> this(seedUniquifier() ^ System.nanoTime());</span> |
| <span class="source-line-no">058</span><span id="line-58"> }</span> |
| <span class="source-line-no">059</span><span id="line-59"></span> |
| <span class="source-line-no">060</span><span id="line-60"> public Random64(long seed) {</span> |
| <span class="source-line-no">061</span><span id="line-61"> this.seed = seed;</span> |
| <span class="source-line-no">062</span><span id="line-62"> }</span> |
| <span class="source-line-no">063</span><span id="line-63"></span> |
| <span class="source-line-no">064</span><span id="line-64"> public long nextLong() {</span> |
| <span class="source-line-no">065</span><span id="line-65"> return next64(64);</span> |
| <span class="source-line-no">066</span><span id="line-66"> }</span> |
| <span class="source-line-no">067</span><span id="line-67"></span> |
| <span class="source-line-no">068</span><span id="line-68"> public void nextBytes(byte[] bytes) {</span> |
| <span class="source-line-no">069</span><span id="line-69"> for (int i = 0, len = bytes.length; i < len;) {</span> |
| <span class="source-line-no">070</span><span id="line-70"> // We regard seed as unsigned long, therefore used '>>>' instead of '>>'.</span> |
| <span class="source-line-no">071</span><span id="line-71"> for (long rnd = nextLong(), n = Math.min(len - i, Long.SIZE / Byte.SIZE); n-- > 0; rnd >>>=</span> |
| <span class="source-line-no">072</span><span id="line-72"> Byte.SIZE) {</span> |
| <span class="source-line-no">073</span><span id="line-73"> bytes[i++] = (byte) rnd;</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"></span> |
| <span class="source-line-no">078</span><span id="line-78"> private long next64(int bits) {</span> |
| <span class="source-line-no">079</span><span id="line-79"> seed = seed * multiplier + addend;</span> |
| <span class="source-line-no">080</span><span id="line-80"> return seed >>> (64 - bits);</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"> /**</span> |
| <span class="source-line-no">084</span><span id="line-84"> * Random64 is a pseudorandom algorithm(LCG). Therefore, we will get same sequence if seeds are</span> |
| <span class="source-line-no">085</span><span id="line-85"> * the same. This main will test how many calls nextLong() it will get the same seed. We do not</span> |
| <span class="source-line-no">086</span><span id="line-86"> * need to save all numbers (that is too large). We could save once every 100000 calls nextLong().</span> |
| <span class="source-line-no">087</span><span id="line-87"> * If it get a same seed, we can detect this by calling nextLong() 100000 times continuously.</span> |
| <span class="source-line-no">088</span><span id="line-88"> */</span> |
| <span class="source-line-no">089</span><span id="line-89"> public static void main(String[] args) {</span> |
| <span class="source-line-no">090</span><span id="line-90"> long defaultTotalTestCnt = 1000000000000L; // 1 trillion</span> |
| <span class="source-line-no">091</span><span id="line-91"></span> |
| <span class="source-line-no">092</span><span id="line-92"> if (args.length == 1) {</span> |
| <span class="source-line-no">093</span><span id="line-93"> defaultTotalTestCnt = Long.parseLong(args[0]);</span> |
| <span class="source-line-no">094</span><span id="line-94"> }</span> |
| <span class="source-line-no">095</span><span id="line-95"></span> |
| <span class="source-line-no">096</span><span id="line-96"> Preconditions.checkArgument(defaultTotalTestCnt > 0, "totalTestCnt <= 0");</span> |
| <span class="source-line-no">097</span><span id="line-97"></span> |
| <span class="source-line-no">098</span><span id="line-98"> final int precision = 100000;</span> |
| <span class="source-line-no">099</span><span id="line-99"> final long totalTestCnt = defaultTotalTestCnt + precision;</span> |
| <span class="source-line-no">100</span><span id="line-100"> final int reportPeriod = 100 * precision;</span> |
| <span class="source-line-no">101</span><span id="line-101"> final long startTime = EnvironmentEdgeManager.currentTime();</span> |
| <span class="source-line-no">102</span><span id="line-102"></span> |
| <span class="source-line-no">103</span><span id="line-103"> System.out.println("Do collision test, totalTestCnt=" + totalTestCnt);</span> |
| <span class="source-line-no">104</span><span id="line-104"></span> |
| <span class="source-line-no">105</span><span id="line-105"> Random64 rand = new Random64();</span> |
| <span class="source-line-no">106</span><span id="line-106"> Set<Long> longSet = new HashSet<>();</span> |
| <span class="source-line-no">107</span><span id="line-107"></span> |
| <span class="source-line-no">108</span><span id="line-108"> for (long cnt = 1; cnt <= totalTestCnt; cnt++) {</span> |
| <span class="source-line-no">109</span><span id="line-109"> final long randLong = rand.nextLong();</span> |
| <span class="source-line-no">110</span><span id="line-110"></span> |
| <span class="source-line-no">111</span><span id="line-111"> if (longSet.contains(randLong)) {</span> |
| <span class="source-line-no">112</span><span id="line-112"> System.err.println("Conflict! count=" + cnt);</span> |
| <span class="source-line-no">113</span><span id="line-113"> System.exit(1);</span> |
| <span class="source-line-no">114</span><span id="line-114"> }</span> |
| <span class="source-line-no">115</span><span id="line-115"></span> |
| <span class="source-line-no">116</span><span id="line-116"> if (cnt % precision == 0) {</span> |
| <span class="source-line-no">117</span><span id="line-117"> if (!longSet.add(randLong)) {</span> |
| <span class="source-line-no">118</span><span id="line-118"> System.err.println("Conflict! count=" + cnt);</span> |
| <span class="source-line-no">119</span><span id="line-119"> System.exit(1);</span> |
| <span class="source-line-no">120</span><span id="line-120"> }</span> |
| <span class="source-line-no">121</span><span id="line-121"></span> |
| <span class="source-line-no">122</span><span id="line-122"> if (cnt % reportPeriod == 0) {</span> |
| <span class="source-line-no">123</span><span id="line-123"> long cost = EnvironmentEdgeManager.currentTime() - startTime;</span> |
| <span class="source-line-no">124</span><span id="line-124"> long remainingMs = (long) (1.0 * (totalTestCnt - cnt) * cost / cnt);</span> |
| <span class="source-line-no">125</span><span id="line-125"> System.out.println(String.format("Progress: %.3f%%, remaining %d minutes",</span> |
| <span class="source-line-no">126</span><span id="line-126"> 100.0 * cnt / totalTestCnt, remainingMs / 60000));</span> |
| <span class="source-line-no">127</span><span id="line-127"> }</span> |
| <span class="source-line-no">128</span><span id="line-128"> }</span> |
| <span class="source-line-no">129</span><span id="line-129"></span> |
| <span class="source-line-no">130</span><span id="line-130"> }</span> |
| <span class="source-line-no">131</span><span id="line-131"></span> |
| <span class="source-line-no">132</span><span id="line-132"> System.out.println("No collision!");</span> |
| <span class="source-line-no">133</span><span id="line-133"> }</span> |
| <span class="source-line-no">134</span><span id="line-134"></span> |
| <span class="source-line-no">135</span><span id="line-135">}</span> |
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| </pre> |
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