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Java example source code file (MinMaxPriorityQueueBenchmark.java)

This example Java source code file (MinMaxPriorityQueueBenchmark.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

benchmark, biginteger, cheap, comparator, comparatortype, double, expensivecomputation, function, heaptype, invertedminmaxpriorityqueue, math, override, param, queue, random, util

The MinMaxPriorityQueueBenchmark.java Java example source code

/*
 * Copyright (C) 2010 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 com.google.common.base.Function;
import com.google.common.collect.ForwardingQueue;
import com.google.common.collect.MinMaxPriorityQueue;
import com.google.common.collect.Ordering;

import java.math.BigInteger;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;

/**
 * Benchmarks to compare performance of MinMaxPriorityQueue and PriorityQueue.
 *
 * @author Sverre Sundsdal
 */
public class MinMaxPriorityQueueBenchmark {
  @Param private ComparatorType comparator;

  // TODO(kevinb): add 1000000 back when we have the ability to throw
  // NotApplicableException in the expensive comparator case.
  @Param({"100", "10000"}) private int size;

  @Param private HeapType heap;

  private Queue<Integer> queue;

  private final Random random = new Random();

  @BeforeExperiment void setUp() {
    queue = heap.create(comparator.get());
    for (int i = 0; i < size; i++) {
      queue.add(random.nextInt());
    }
  }

  @Benchmark void pollAndAdd(int reps) {
    for (int i = 0; i < reps; i++) {
      // TODO(kevinb): precompute random #s?
      queue.add(queue.poll() ^ random.nextInt());
    }
  }

  @Benchmark void populate(int reps) {
    for (int i = 0; i < reps; i++) {
      queue.clear();
      for (int j = 0; j < size; j++) {
        // TODO(kevinb): precompute random #s?
        queue.add(random.nextInt());
      }
    }
  }

  /**
   * Implementation of the InvertedMinMaxPriorityQueue which forwards all calls to
   * a MinMaxPriorityQueue, except poll, which is forwarded to pollMax. That way
   * we can benchmark pollMax using the same code that benchmarks poll.
   */
  static final class InvertedMinMaxPriorityQueue <T> extends ForwardingQueue {
    MinMaxPriorityQueue<T> mmHeap;
    public InvertedMinMaxPriorityQueue(Comparator<T> comparator) {
      mmHeap = MinMaxPriorityQueue.orderedBy(comparator).create();
    }

    @Override
    protected Queue<T> delegate() {
      return mmHeap;
    }

    @Override
    public T poll() {
      return mmHeap.pollLast();
    }

  }

  public enum HeapType {
    MIN_MAX {
      @Override public Queue<Integer> create(Comparator comparator) {
        return MinMaxPriorityQueue.orderedBy(comparator).create();
      }
    },
    PRIORITY_QUEUE {
      @Override public Queue<Integer> create(Comparator comparator) {
        return new PriorityQueue<Integer>(11, comparator);
      }
    },
    INVERTED_MIN_MAX {
      @Override public Queue<Integer> create(Comparator comparator) {
        return new InvertedMinMaxPriorityQueue<Integer>(comparator);
      }
    };

    public abstract Queue<Integer> create(Comparator comparator);
  }

  /**
   * Does a CPU intensive operation on Integer and returns a BigInteger
   * Used to implement an ordering that spends a lot of cpu.
   */
  static class ExpensiveComputation implements Function<Integer, BigInteger> {
    @Override
    public BigInteger apply(Integer from) {
      BigInteger v = BigInteger.valueOf(from);
      // Math.sin is very slow for values outside 4*pi
      // Need to take absolute value to avoid inverting the value.
      for (double i = 0; i < 100; i += 20) {
        v = v.add(v.multiply(
            BigInteger.valueOf(
                ((Double) Math.abs(Math.sin(i) * 10.0)).longValue())));
      }
      return v;
    }
  }

  public enum ComparatorType {
    CHEAP {
      @Override public Comparator<Integer> get() {
        return Ordering.natural();
      }
    },
    EXPENSIVE {
      @Override public Comparator<Integer> get() {
        return Ordering.natural().onResultOf(new ExpensiveComputation());
      }
    };
    public abstract Comparator<Integer> get();
  }
}

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