1 /* 2 * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package org.openjdk.bench.java.lang; 26 27 import org.openjdk.jmh.annotations.BenchmarkMode; 28 import org.openjdk.jmh.annotations.Fork; 29 import org.openjdk.jmh.annotations.Benchmark; 30 import org.openjdk.jmh.annotations.Mode; 31 import org.openjdk.jmh.annotations.OutputTimeUnit; 32 33 import java.util.concurrent.TimeUnit; 34 35 /** 36 * This benchmark assesses different hashCode strategies in HotSpot 37 */ 38 @BenchmarkMode(Mode.AverageTime) 39 @OutputTimeUnit(TimeUnit.NANOSECONDS) 40 public class ObjectHashCode { 41 42 @Benchmark 43 @Fork 44 public int mode_default() { 45 return System.identityHashCode(new Object()); 46 } 47 48 @Benchmark 49 @Fork(jvmArgsPrepend = {"-XX:+UnlockExperimentalVMOptions", "-XX:hashCode=0"}) 50 public int mode_0() { 51 return System.identityHashCode(new Object()); 52 } 53 54 @Benchmark 55 @Fork(jvmArgsPrepend = {"-XX:+UnlockExperimentalVMOptions", "-XX:hashCode=1"}) 56 public int mode_1() { 57 return System.identityHashCode(new Object()); 58 } 59 60 @Benchmark 61 @Fork(jvmArgsPrepend = {"-XX:+UnlockExperimentalVMOptions", "-XX:hashCode=2"}) 62 public int mode_2() { 63 return System.identityHashCode(new Object()); 64 } 65 66 @Benchmark 67 @Fork(jvmArgsPrepend = {"-XX:+UnlockExperimentalVMOptions", "-XX:hashCode=3"}) 68 public int mode_3() { 69 return System.identityHashCode(new Object()); 70 } 71 72 @Benchmark 73 @Fork(jvmArgsPrepend = {"-XX:+UnlockExperimentalVMOptions", "-XX:hashCode=4"}) 74 public int mode_4() { 75 return System.identityHashCode(new Object()); 76 } 77 78 @Benchmark 79 @Fork(jvmArgsPrepend = {"-XX:+UnlockExperimentalVMOptions", "-XX:hashCode=5"}) 80 public int mode_5() { 81 return System.identityHashCode(new Object()); 82 } 83 84 }