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 import com.google.common.hash.HashFunction;
23 
24 import java.util.Random;
25 
26 /**
27  * Benchmarks for comparing the various {@link HashFunction functions} that we provide.
28  *
29  * <p>Parameters for the benchmark are:
30  * <ul>
31  * <li>size: The length of the byte array to hash.
32  * <li>hashFunctionEnum: The {@link HashFunction} to use for hashing.
33  * </ul>
34  *
35  * @author Kurt Alfred Kluever
36  */
37 public class HashFunctionBenchmark {
38 
39   // Use a statically configured random instance for all of the benchmarks
40   private static final Random random = new Random(42);
41 
42   @Param({"10", "1000", "100000", "1000000"})
43   private int size;
44 
45   @Param HashFunctionEnum hashFunctionEnum;
46 
47   private byte[] testBytes;
48 
setUp()49   @BeforeExperiment void setUp() {
50     testBytes = new byte[size];
51     random.nextBytes(testBytes);
52   }
53 
hashFunction(int reps)54   @Benchmark int hashFunction(int reps) {
55     HashFunction hashFunction = hashFunctionEnum.getHashFunction();
56     int result = 37;
57     for (int i = 0; i < reps; i++) {
58       result ^= hashFunction.hashBytes(testBytes).asBytes()[0];
59     }
60     return result;
61   }
62 }
63