Java example source code file (AsciiStringBenchmark.java)

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Java - Java tags/keywords

abstractmicrobenchmark, asciistring, asciistringbenchmark, benchmark, measurement, param, random, string, threads, util, warmup

The AsciiStringBenchmark.java Java example source code

/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.microbenchmark.common;

import io.netty.microbench.util.AbstractMicrobenchmark;
import io.netty.util.AsciiString;
import io.netty.util.CharsetUtil;
import io.netty.util.internal.PlatformDependent;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;

import java.util.Random;

@Threads(1)
@Measurement(iterations = 5)
@Warmup(iterations = 5)
public class AsciiStringBenchmark extends AbstractMicrobenchmark {

    @Param({ "3", "5", "7", "8", "10", "20", "50" })
    public int size;

    private AsciiString asciiString;
    private String string;
    private static final Random random = new Random();

    @Setup(Level.Trial)
    public void setup() {
        byte[] bytes = new byte[size];
        random.nextBytes(bytes);
        asciiString = new AsciiString(bytes, false);
        string = new String(bytes, CharsetUtil.US_ASCII);
    }

    @Benchmark
    public int hashCodeBenchBytesOld() {
        int h = 0;
        final int end = asciiString.arrayOffset() + asciiString.length();
        for (int i = asciiString.arrayOffset(); i < end; ++i) {
            // masking with 0x1F reduces the number of overall bits that impact the hash code but makes the hash
            // code the same regardless of character case (upper case or lower case hash is the same).
            h = h * 31 + (asciiString.array()[i] & 0x1F);
        }
        return h;
    }

    @Benchmark
    public int hashCodeBenchBytesNew() {
        return PlatformDependent.hashCodeAscii(asciiString.array(), asciiString.arrayOffset(), asciiString.length());
    }

    @Benchmark
    public int hashCodeBenchCharSequenceOld() {
        int h = 0;
        for (int i = 0; i < string.length(); ++i) {
            // masking with 0x1F reduces the number of overall bits that impact the hash code but makes the hash
            // code the same regardless of character case (upper case or lower case hash is the same).
            h = h * 31 + (string.charAt(i) & 0x1F);
        }
        return h;
    }

    @Benchmark
    public int hashCodeBenchCharSequenceNew() {
        return PlatformDependent.hashCodeAscii(string);
    }
}