Java tutorial
/* * The MIT License * * Copyright (c) 2015 CloudBees, Inc. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package hudson.remoting; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.Locale; import java.util.jar.JarEntry; import java.util.jar.JarFile; import java.util.regex.Pattern; import org.junit.Ignore; import org.junit.Test; @Ignore("This is not a test just a benchmark and is here for ease of running") public class RegExpBenchmark { final Pattern p1 = Pattern.compile("^org\\.codehaus\\.groovy\\.runtime\\..*"); final Pattern p2 = Pattern.compile("^org\\.apache\\.commons\\.collections\\.functors\\..*"); final Pattern p3 = Pattern.compile("^.*org\\.apache\\.xalan\\..*"); final Pattern p4 = Pattern.compile( "^(?:(?:org\\.(?:codehaus\\.groovy\\.runtime|apache\\.commons\\.collections\\.functors))|.*?org\\.apache\\.xalan)\\..*"); final String s1 = "org.codehaus.groovy.runtime."; final String s2 = "org.apache.commons.collections.functors."; final String s3 = "org.apache.xalan."; @Test public void repeatedBenchMark() throws Exception { for (int i = 0; i < 10; i++) { benchmark(); System.gc(); System.gc(); System.gc(); } } @Test public void benchmark() throws Exception { System.out.println("there are " + getAllRTClasses().size()); List<String> classes = getAllRTClasses(); final long startRegExp = System.nanoTime(); final List<String> matchesRegExp = checkClassesRegExp(classes); final long durationRegexpNanos = System.nanoTime() - startRegExp; classes = null; System.gc(); System.gc(); System.gc(); // make sure we use new Strings each time so that hotpsot does not do funky caching (after all the strings we will be testing will come from the stream and be new). classes = getAllRTClasses(); final long startSingleRegExp = System.nanoTime(); final List<String> matchesSingleRegExp = checkClassesSingleRegExp(classes); final long durationSingleRegexpNanos = System.nanoTime() - startSingleRegExp; classes = null; System.gc(); System.gc(); System.gc(); // make sure we use new Strings each time so that hotpsot does not do funky caching (after all the strings we will be testing will come from the stream and be new). classes = getAllRTClasses(); final long startString = System.nanoTime(); final List<String> matchesString = checkClassesString(classes); final long durationStringNanos = System.nanoTime() - startString; System.out.println(String.format(Locale.ENGLISH, "%-13s: %d blacklisted classes in %9dns. Average class check time is %dns", new Object[] { "RegExp ", matchesRegExp.size(), durationRegexpNanos, durationRegexpNanos / classes.size() })); System.out.println(String.format(Locale.ENGLISH, "%-13s: %d blacklisted classes in %9dns. Average class check time is %dns", new Object[] { "SingleRegExp ", matchesSingleRegExp.size(), durationSingleRegexpNanos, durationSingleRegexpNanos / classes.size() })); System.out.println(String.format(Locale.ENGLISH, "%-13s: %d blacklisted classes in %9dns. Average class check time is %dns", new Object[] { "String ", matchesString.size(), durationStringNanos, durationStringNanos / classes.size() })); System.out.println("Regular Expression is " + durationRegexpNanos / durationStringNanos + " times slower"); System.out.println("Single Regular Expression is " + durationSingleRegexpNanos / durationStringNanos + " times slower\n"); } private List<String> checkClassesRegExp(List<String> classnames) { List<String> blacklistedClasses = new ArrayList<String>(); for (String s : classnames) { if (p1.matcher(s).matches() || p2.matcher(s).matches() || p3.matcher(s).matches()) { // something with a side effect blacklistedClasses.add(s); } } return blacklistedClasses; } private List<String> checkClassesSingleRegExp(List<String> classnames) { List<String> blacklistedClasses = new ArrayList<String>(); for (String s : classnames) { if (p4.matcher(s).matches()) { // something with a side effect blacklistedClasses.add(s); } } return blacklistedClasses; } private List<String> checkClassesString(List<String> classnames) { List<String> blacklistedClasses = new ArrayList<String>(); for (String s : classnames) { if (s.startsWith(s1) || s.startsWith(s2) || s.contains(s3)) { // something with a side effect blacklistedClasses.add(s); } } return blacklistedClasses; } private List<String> getAllRTClasses() throws Exception { List<String> classes = new ArrayList<String>(); // Object.class.getProtectionDomain().getCodeSource() returns null :( String javaHome = System.getProperty("java.home"); JarFile jf = new JarFile(javaHome + "/lib/rt.jar"); for (JarEntry je : Collections.list(jf.entries())) { if (!je.isDirectory() && je.getName().endsWith(".class")) { String name = je.getName().replace('/', '.'); // remove the .class name = name.substring(0, name.length() - 6); classes.add(name); } } jf.close(); // add in a couple from xalan and commons just for testing... classes.add(new String("org.apache.commons.collections.functors.EvilClass")); classes.add(new String("org.codehaus.groovy.runtime.IWIllHackYou")); classes.add(new String("org.apache.xalan.YouAreOwned")); return classes; } }