103 lines
2.7 KiB
Java
103 lines
2.7 KiB
Java
/*
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* Copyright (C) 2012 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* 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,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.hash;
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import com.google.caliper.BeforeExperiment;
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import com.google.caliper.Benchmark;
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import com.google.caliper.Param;
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import java.util.Random;
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import java.util.zip.Adler32;
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import java.util.zip.CRC32;
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import java.util.zip.Checksum;
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/**
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* Benchmarks for comparing {@link Checksum}s and {@link HashFunction}s that wrap {@link Checksum}s.
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*
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* <p>Parameters for the benchmark are:
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*
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* <ul>
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* <li>size: The length of the byte array to hash.
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* </ul>
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*
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* @author Colin Decker
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*/
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public class ChecksumBenchmark {
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// Use a constant seed for all of the benchmarks to ensure apples to apples comparisons.
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private static final int RANDOM_SEED = new Random().nextInt();
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@Param({"10", "1000", "100000", "1000000"})
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private int size;
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private byte[] testBytes;
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@BeforeExperiment
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void setUp() {
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testBytes = new byte[size];
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new Random(RANDOM_SEED).nextBytes(testBytes);
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}
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// CRC32
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@Benchmark
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byte crc32HashFunction(int reps) {
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return runHashFunction(reps, Hashing.crc32());
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}
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@Benchmark
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byte crc32Checksum(int reps) throws Exception {
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byte result = 0x01;
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for (int i = 0; i < reps; i++) {
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CRC32 checksum = new CRC32();
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checksum.update(testBytes);
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result = (byte) (result ^ checksum.getValue());
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}
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return result;
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}
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// Adler32
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@Benchmark
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byte adler32HashFunction(int reps) {
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return runHashFunction(reps, Hashing.adler32());
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}
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@Benchmark
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byte adler32Checksum(int reps) throws Exception {
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byte result = 0x01;
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for (int i = 0; i < reps; i++) {
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Adler32 checksum = new Adler32();
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checksum.update(testBytes);
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result = (byte) (result ^ checksum.getValue());
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}
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return result;
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}
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// Helpers + main
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private byte runHashFunction(int reps, HashFunction hashFunction) {
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byte result = 0x01;
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// Trick the JVM to prevent it from using the hash function non-polymorphically
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result ^= Hashing.crc32().hashInt(reps).asBytes()[0];
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result ^= Hashing.adler32().hashInt(reps).asBytes()[0];
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for (int i = 0; i < reps; i++) {
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result ^= hashFunction.hashBytes(testBytes).asBytes()[0];
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}
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return result;
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}
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}
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