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Java example source code file (ComparatorDelegationOverheadBenchmark.java)

This example Java source code file (ComparatorDelegationOverheadBenchmark.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

beforeexperiment, benchmark, comparator, comparatordelegationoverheadbenchmark, exception, integer, natural_integer, override, param, random, util

The ComparatorDelegationOverheadBenchmark.java Java example source code

/*
 * Copyright (C) 2013 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.collect;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;

import java.util.Arrays;
import java.util.Comparator;
import java.util.Random;

/**
 * A benchmark to determine the overhead of sorting with {@link Ordering#from(Comparator)}, or with
 * {@link Ordering#natural()}, as opposed to using the inlined {@link Arrays#sort(Object[])}
 * implementation, which uses {@link Comparable#compareTo} directly.
 *
 * @author Louis Wasserman
 */
public class ComparatorDelegationOverheadBenchmark {
  private final Integer[][] inputArrays = new Integer[0x100][];

  @Param({"10000"})
  int n;

  @BeforeExperiment
  void setUp() throws Exception {
    Random rng = new Random();
    for (int i = 0; i < 0x100; i++) {
      Integer[] array = new Integer[n];
      for (int j = 0; j < n; j++) {
        array[j] = rng.nextInt();
      }
      inputArrays[i] = array;
    }
  }

  @Benchmark int arraysSortNoComparator(int reps) {
    int tmp = 0;
    for (int i = 0; i < reps; i++) {
      Integer[] copy = inputArrays[i & 0xFF].clone();
      Arrays.sort(copy);
      tmp += copy[0];
    }
    return tmp;
  }

  @Benchmark int arraysSortOrderingNatural(int reps) {
    int tmp = 0;
    for (int i = 0; i < reps; i++) {
      Integer[] copy = inputArrays[i & 0xFF].clone();
      Arrays.sort(copy, Ordering.natural());
      tmp += copy[0];
    }
    return tmp;
  }

  private static final Comparator<Integer> NATURAL_INTEGER = new Comparator() {
    @Override
    public int compare(Integer o1, Integer o2) {
      return o1.compareTo(o2);
    }
  };

  @Benchmark int arraysSortOrderingFromNatural(int reps) {
    int tmp = 0;
    for (int i = 0; i < reps; i++) {
      Integer[] copy = inputArrays[i & 0xFF].clone();
      Arrays.sort(copy, Ordering.from(NATURAL_INTEGER));
      tmp += copy[0];
    }
    return tmp;
  }
}

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