org.apache.flink.runtime.metrics.DescriptiveStatisticsHistogram Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.flink.runtime.metrics;
import org.apache.flink.metrics.Histogram;
import org.apache.flink.metrics.HistogramStatistics;
import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;
/**
* The {@link DescriptiveStatisticsHistogram} use a DescriptiveStatistics {@link
* DescriptiveStatistics} as a Flink {@link Histogram}.
*/
public class DescriptiveStatisticsHistogram implements org.apache.flink.metrics.Histogram {
private final CircularDoubleArray descriptiveStatistics;
public DescriptiveStatisticsHistogram(int windowSize) {
this.descriptiveStatistics = new CircularDoubleArray(windowSize);
}
@Override
public void update(long value) {
this.descriptiveStatistics.addValue(value);
}
@Override
public long getCount() {
return this.descriptiveStatistics.getElementsSeen();
}
@Override
public HistogramStatistics getStatistics() {
return new DescriptiveStatisticsHistogramStatistics(this.descriptiveStatistics);
}
/** Fixed-size array that wraps around at the end and has a dynamic start position. */
static class CircularDoubleArray {
private final double[] backingArray;
private int nextPos = 0;
private boolean fullSize = false;
private long elementsSeen = 0;
CircularDoubleArray(int windowSize) {
this.backingArray = new double[windowSize];
}
synchronized void addValue(double value) {
backingArray[nextPos] = value;
++elementsSeen;
++nextPos;
if (nextPos == backingArray.length) {
nextPos = 0;
fullSize = true;
}
}
synchronized double[] toUnsortedArray() {
final int size = getSize();
double[] result = new double[size];
System.arraycopy(backingArray, 0, result, 0, result.length);
return result;
}
private synchronized int getSize() {
return fullSize ? backingArray.length : nextPos;
}
private synchronized long getElementsSeen() {
return elementsSeen;
}
}
}