1e4f0e6a09
Motivation: decodeHexNibble can be a lot faster using a lookup table Modifications: decodeHexNibble is made faster by using a lookup table Result: decodeHexNibble is faster
137 lines
4.0 KiB
Java
137 lines
4.0 KiB
Java
/*
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* Copyright 2019 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.http;
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import io.netty.microbench.util.AbstractMicrobenchmark;
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import io.netty.util.internal.PlatformDependent;
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import io.netty.util.internal.StringUtil;
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import org.openjdk.jmh.annotations.Benchmark;
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import org.openjdk.jmh.annotations.Measurement;
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import org.openjdk.jmh.annotations.OutputTimeUnit;
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import org.openjdk.jmh.annotations.Param;
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import org.openjdk.jmh.annotations.Scope;
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import org.openjdk.jmh.annotations.Setup;
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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.util.Arrays;
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import java.util.concurrent.TimeUnit;
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@State(Scope.Benchmark)
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@Warmup(iterations = 5, time = 1)
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@Measurement(iterations = 5, time = 1)
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@OutputTimeUnit(TimeUnit.MICROSECONDS)
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public class DecodeHexBenchmark extends AbstractMicrobenchmark {
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@Param({
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//with HEX chars
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"135aBa9BBCEA030b947d79fCcaf48Bde",
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//with HEX chars + 'g'
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"4DDeA5gDD1C6fE567E1b6gf0C40FEcDg",
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})
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private String hex;
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private char[] hexDigits;
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@Setup
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public void init() {
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hexDigits = hex.toCharArray();
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}
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@Benchmark
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public long hexDigits() {
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long v = 0;
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final char[] hexDigits = this.hexDigits;
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for (int i = 0, size = hexDigits.length; i < size; i++) {
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v += StringUtil.decodeHexNibble(hexDigits[i]);
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}
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return v;
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}
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@Benchmark
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public long hexDigitsWithChecks() {
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long v = 0;
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final char[] hexDigits = this.hexDigits;
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for (int i = 0, size = hexDigits.length; i < size; i++) {
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v += decodeHexNibbleWithCheck(hexDigits[i]);
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}
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return v;
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}
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@Benchmark
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public long hexDigitsOriginal() {
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long v = 0;
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final char[] hexDigits = this.hexDigits;
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for (int i = 0, size = hexDigits.length; i < size; i++) {
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v += decodeHexNibble(hexDigits[i]);
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}
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return v;
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}
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private static int decodeHexNibble(final char c) {
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if (c >= '0' && c <= '9') {
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return c - '0';
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}
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if (c >= 'A' && c <= 'F') {
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return c - ('A' - 0xA);
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}
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if (c >= 'a' && c <= 'f') {
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return c - ('a' - 0xA);
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}
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return -1;
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}
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private static final byte[] HEX2B;
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static {
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HEX2B = new byte['f' + 1];
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Arrays.fill(HEX2B, (byte) -1);
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HEX2B['0'] = (byte) 0;
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HEX2B['1'] = (byte) 1;
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HEX2B['2'] = (byte) 2;
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HEX2B['3'] = (byte) 3;
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HEX2B['4'] = (byte) 4;
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HEX2B['5'] = (byte) 5;
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HEX2B['6'] = (byte) 6;
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HEX2B['7'] = (byte) 7;
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HEX2B['8'] = (byte) 8;
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HEX2B['9'] = (byte) 9;
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HEX2B['A'] = (byte) 10;
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HEX2B['B'] = (byte) 11;
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HEX2B['C'] = (byte) 12;
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HEX2B['D'] = (byte) 13;
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HEX2B['E'] = (byte) 14;
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HEX2B['F'] = (byte) 15;
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HEX2B['a'] = (byte) 10;
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HEX2B['b'] = (byte) 11;
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HEX2B['c'] = (byte) 12;
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HEX2B['d'] = (byte) 13;
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HEX2B['e'] = (byte) 14;
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HEX2B['f'] = (byte) 15;
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}
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private static int decodeHexNibbleWithCheck(final char c) {
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final int index = c;
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if (index >= HEX2B.length) {
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return -1;
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}
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if (PlatformDependent.hasUnsafe()) {
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return PlatformDependent.getByte(HEX2B, index);
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}
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return HEX2B[index];
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}
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}
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