/*
* 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.hadoop.fs.swift.util;
/**
* Build ongoing statistics from duration data
*/
public class DurationStats {
final String operation;
int n;
long sum;
long min;
long max;
double mean, m2;
/**
* Construct statistics for a given operation.
* @param operation operation
*/
public DurationStats(String operation) {
this.operation = operation;
reset();
}
/**
* construct from anothr stats entry;
* all value are copied.
* @param that the source statistics
*/
public DurationStats(DurationStats that) {
operation = that.operation;
n = that.n;
sum = that.sum;
min = that.min;
max = that.max;
mean = that.mean;
m2 = that.m2;
}
/**
* Add a duration
* @param duration the new duration
*/
public void add(Duration duration) {
add(duration.value());
}
/**
* Add a number
* @param x the number
*/
public void add(long x) {
n++;
sum += x;
double delta = x - mean;
mean += delta / n;
m2 += delta * (x - mean);
if (x < min) {
min = x;
}
if (x > max) {
max = x;
}
}
/**
* Reset the data
*/
public void reset() {
n = 0;
sum = 0;
sum = 0;
min = 10000000;
max = 0;
mean = 0;
m2 = 0;
}
/**
* Get the number of entries sampled
* @return the number of durations added
*/
public int getCount() {
return n;
}
/**
* Get the sum of all durations
* @return all the durations
*/
public long getSum() {
return sum;
}
/**
* Get the arithmetic mean of the aggregate statistics
* @return the arithmetic mean
*/
public double getArithmeticMean() {
return mean;
}
/**
* Variance, sigma^2
* @return variance, or, if no samples are there, 0.
*/
public double getVariance() {
return n > 0 ? (m2 / (n - 1)) : 0;
}
/**
* Get the std deviation, sigma
* @return the stddev, 0 may mean there are no samples.
*/
public double getDeviation() {
double variance = getVariance();
return (variance > 0) ? Math.sqrt(variance) : 0;
}
/**
* Covert to a useful string
* @return a human readable summary
*/
@Override
public String toString() {
return String.format(
"%s count=%d total=%.3fs mean=%.3fs stddev=%.3fs min=%.3fs max=%.3fs",
operation,
n,
sum / 1000.0,
mean / 1000.0,
getDeviation() / 1000000.0,
min / 1000.0,
max / 1000.0);
}
}