1 /* 2 * Copyright (C) 2012 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.hash; 18 19 import com.google.caliper.BeforeExperiment; 20 import com.google.caliper.Benchmark; 21 import com.google.caliper.Param; 22 23 import java.util.Random; 24 import java.util.zip.Adler32; 25 import java.util.zip.CRC32; 26 import java.util.zip.Checksum; 27 28 /** 29 * Benchmarks for comparing {@link Checksum}s and {@link HashFunction}s that wrap {@link Checksum}s. 30 * 31 * <p>Parameters for the benchmark are: <ul> <li>size: The length of the byte array to hash. </ul> 32 * 33 * @author Colin Decker 34 */ 35 public class ChecksumBenchmark { 36 37 // Use a constant seed for all of the benchmarks to ensure apples to apples comparisons. 38 private static final int RANDOM_SEED = new Random().nextInt(); 39 40 @Param({"10", "1000", "100000", "1000000"}) 41 private int size; 42 43 private byte[] testBytes; 44 45 @BeforeExperiment 46 void setUp() { 47 testBytes = new byte[size]; 48 new Random(RANDOM_SEED).nextBytes(testBytes); 49 } 50 51 // CRC32 52 53 @Benchmark byte crc32HashFunction(int reps) { 54 return runHashFunction(reps, Hashing.crc32()); 55 } 56 57 @Benchmark byte crc32Checksum(int reps) throws Exception { 58 byte result = 0x01; 59 for (int i = 0; i < reps; i++) { 60 CRC32 checksum = new CRC32(); 61 checksum.update(testBytes); 62 result ^= checksum.getValue(); 63 } 64 return result; 65 } 66 67 // Adler32 68 69 @Benchmark byte adler32HashFunction(int reps) { 70 return runHashFunction(reps, Hashing.adler32()); 71 } 72 73 @Benchmark byte adler32Checksum(int reps) throws Exception { 74 byte result = 0x01; 75 for (int i = 0; i < reps; i++) { 76 Adler32 checksum = new Adler32(); 77 checksum.update(testBytes); 78 result ^= checksum.getValue(); 79 } 80 return result; 81 } 82 83 // Helpers + main 84 85 private byte runHashFunction(int reps, HashFunction hashFunction) { 86 byte result = 0x01; 87 // Trick the JVM to prevent it from using the hash function non-polymorphically 88 result ^= Hashing.crc32().hashInt(reps).asBytes()[0]; 89 result ^= Hashing.adler32().hashInt(reps).asBytes()[0]; 90 for (int i = 0; i < reps; i++) { 91 result ^= hashFunction.hashBytes(testBytes).asBytes()[0]; 92 } 93 return result; 94 } 95 } 96
