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93 lines
3.2 KiB
Java
93 lines
3.2 KiB
Java
/*
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* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package org.openjdk.bench.java.lang;
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import org.openjdk.jmh.annotations.Benchmark;
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import org.openjdk.jmh.annotations.BenchmarkMode;
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import org.openjdk.jmh.annotations.Fork;
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import org.openjdk.jmh.annotations.Measurement;
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import org.openjdk.jmh.annotations.Mode;
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import org.openjdk.jmh.annotations.OutputTimeUnit;
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import org.openjdk.jmh.annotations.Scope;
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import org.openjdk.jmh.annotations.State;
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import org.openjdk.jmh.annotations.Warmup;
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import java.lang.invoke.MethodHandle;
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import java.lang.invoke.MethodHandles;
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import java.util.Map;
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import java.util.concurrent.TimeUnit;
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/**
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* Performance test of String.hashCode() function with constant folding.
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* The tests are using a Map that holds a MethodHandle to better expose
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* any potential lack of constant folding.
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*/
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@BenchmarkMode(Mode.AverageTime)
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@OutputTimeUnit(TimeUnit.NANOSECONDS)
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@State(Scope.Thread)
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@Warmup(iterations = 5, time = 1)
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@Measurement(iterations = 5, time = 1)
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@Fork(value = 3)
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public class StringHashCodeStatic {
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private static final String HASHCODE = "abcdefghijkl";
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private static final String HASHCODE_0 = new String(new char[]{72, 90, 100, 89, 105, 2, 72, 90, 100, 89, 105, 2});
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private static final String EMPTY = new String();
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private static final Map<String, MethodHandle> MAP = Map.of(
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HASHCODE, mh(HASHCODE.hashCode()),
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HASHCODE_0, mh(HASHCODE_0.hashCode()),
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EMPTY, mh(EMPTY.hashCode()));
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/**
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* Benchmark testing String.hashCode() with a regular 12 char string with
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* the result possibly cached in String
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*/
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@Benchmark
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public int nonZero() throws Throwable {
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return (int)MAP.get(HASHCODE).invokeExact();
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}
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/**
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* Benchmark testing String.hashCode() with a 12 char string with the
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* hashcode = 0.
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*/
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@Benchmark
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public int zero() throws Throwable {
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return (int)MAP.get(HASHCODE_0).invokeExact();
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}
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/**
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* Benchmark testing String.hashCode() with the empty string. an
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* empty String has hashCode = 0.
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*/
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@Benchmark
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public int empty() throws Throwable {
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return (int)MAP.get(EMPTY).invokeExact();
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}
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static MethodHandle mh(int value) {
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return MethodHandles.constant(int.class, value);
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}
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} |