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/*
* Copyright (c) 2005-2022 Xceptance Software Technologies GmbH
*
* 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.xceptance.xlt.engine.metrics;
/**
* A metric for rate values. All reported counts are added to the total count and converted to the corresponding rate
* value.
*
* Note: This class is thread-safe.
*/
public class RateMetric implements Metric
{
/**
* The total count (the sum of all values added).
*/
private long sum;
/**
* The time the metric was reported the last time.
*/
private long time;
/**
* The interval [ms] the rate is based on (e.g. 1000 for a per-sec rate).
*/
private final long rateInterval;
/**
* The reporting interval [ms]. Used only once, for the very first rate calculation.
*/
private final long reportingInterval;
/**
* Whether this metric has unreported data.
*/
private boolean hasData;
/**
* Constructor.
*
* @param rateInterval
* the rate interval [ms]
* @param reportingInterval
* the reporting interval [ms]
*/
public RateMetric(final long rateInterval, final long reportingInterval)
{
this.rateInterval = rateInterval;
this.reportingInterval = reportingInterval;
}
/**
* {@inheritDoc}
*/
@Override
public synchronized void update(final int value)
{
sum += value;
hasData = true;
}
/**
* Returns the rate based on the total count, the rate interval, and the time passed. Resets the internal state.
*
* @return the rate, or null if no values have been added to this metric since last call
*/
public synchronized Double getRateAndClear()
{
final Double rate;
if (hasData)
{
// calculate rate
final long now = System.nanoTime() / 1000000;
final double duration = (time == 0) ? reportingInterval : now - time;
rate = (double) sum * rateInterval / duration;
// reset internal state
sum = 0;
time = now;
hasData = false;
}
else
{
rate = null;
}
return rate;
}
}