Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.wake.metrics;
020
021import java.util.concurrent.atomic.AtomicLong;
022import java.util.concurrent.atomic.AtomicLongArray;
023
024/**
025 * An {@link Histogram} that implements uniform binning of numbers ({@code >=0}).
026 */
027public class UniformHistogram implements Histogram {
028  private final AtomicLong count;
029  private final AtomicLongArray values;
030  private final long binWidth;
031  private final int numBins;
032
033  /**
034   * Constructs a histogram.
035   *
036   * @param binWidth the width of each bin
037   * @param numBins  the number of bins
038   */
039  public UniformHistogram(final long binWidth, final int numBins) {
040    this.count = new AtomicLong(0);
041    this.values = new AtomicLongArray(numBins);
042    this.binWidth = binWidth;
043    this.numBins = numBins;
044  }
045
046  /**
047   * Updates the value.
048   *
049   * @param value
050   */
051  @Override
052  public void update(final long value) {
053    count.incrementAndGet();
054    int index = (int) (value / binWidth);
055    if (index >= numBins) {
056      index = numBins - 1;
057    }
058    values.incrementAndGet(index);
059  }
060
061  /**
062   * Returns the number of recorded values.
063   *
064   * @return the number of recorded values
065   */
066  @Override
067  public long getCount() {
068    return count.get();
069  }
070
071  /**
072   * Returns the value of the index.
073   *
074   * @param index the index
075   * @return the value of the index
076   */
077  @Override
078  public long getValue(final int index) {
079    return values.get(index);
080  }
081
082  /**
083   * Returns the number of bins.
084   *
085   * @return the number of bins
086   */
087  @Override
088  public int getNumBins() {
089    return numBins;
090  }
091}