| /* |
| * Copyright (C) 2012 The Guava Authors |
| * |
| * Licensed 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 com.google.common.hash; |
| |
| import com.google.caliper.BeforeExperiment; |
| import com.google.caliper.Benchmark; |
| import com.google.caliper.Param; |
| import java.util.Random; |
| import java.util.zip.Adler32; |
| import java.util.zip.CRC32; |
| import java.util.zip.Checksum; |
| |
| /** |
| * Benchmarks for comparing {@link Checksum}s and {@link HashFunction}s that wrap {@link Checksum}s. |
| * |
| * <p>Parameters for the benchmark are: |
| * |
| * <ul> |
| * <li>size: The length of the byte array to hash. |
| * </ul> |
| * |
| * @author Colin Decker |
| */ |
| public class ChecksumBenchmark { |
| |
| // Use a constant seed for all of the benchmarks to ensure apples to apples comparisons. |
| private static final int RANDOM_SEED = new Random().nextInt(); |
| |
| @Param({"10", "1000", "100000", "1000000"}) |
| private int size; |
| |
| private byte[] testBytes; |
| |
| @BeforeExperiment |
| void setUp() { |
| testBytes = new byte[size]; |
| new Random(RANDOM_SEED).nextBytes(testBytes); |
| } |
| |
| // CRC32 |
| |
| @Benchmark |
| byte crc32HashFunction(int reps) { |
| return runHashFunction(reps, Hashing.crc32()); |
| } |
| |
| @Benchmark |
| byte crc32Checksum(int reps) throws Exception { |
| byte result = 0x01; |
| for (int i = 0; i < reps; i++) { |
| CRC32 checksum = new CRC32(); |
| checksum.update(testBytes); |
| result = (byte) (result ^ checksum.getValue()); |
| } |
| return result; |
| } |
| |
| // Adler32 |
| |
| @Benchmark |
| byte adler32HashFunction(int reps) { |
| return runHashFunction(reps, Hashing.adler32()); |
| } |
| |
| @Benchmark |
| byte adler32Checksum(int reps) throws Exception { |
| byte result = 0x01; |
| for (int i = 0; i < reps; i++) { |
| Adler32 checksum = new Adler32(); |
| checksum.update(testBytes); |
| result = (byte) (result ^ checksum.getValue()); |
| } |
| return result; |
| } |
| |
| // Helpers + main |
| |
| private byte runHashFunction(int reps, HashFunction hashFunction) { |
| byte result = 0x01; |
| // Trick the JVM to prevent it from using the hash function non-polymorphically |
| result ^= Hashing.crc32().hashInt(reps).asBytes()[0]; |
| result ^= Hashing.adler32().hashInt(reps).asBytes()[0]; |
| for (int i = 0; i < reps; i++) { |
| result ^= hashFunction.hashBytes(testBytes).asBytes()[0]; |
| } |
| return result; |
| } |
| } |