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Java example source code file (ChecksumBenchmark.java)

This example Java source code file (ChecksumBenchmark.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

adler32, beforeexperiment, benchmark, checksumbenchmark, crc32, exception, hashfunction, param, random_seed, util, zip

The ChecksumBenchmark.java Java example source code

/*
 * 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: 
  • size: The length of the byte array to hash.
* * @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; } }

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