sirius.kernel.health.Average Maven / Gradle / Ivy
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/*
* Made with all the love in the world
* by scireum in Remshalden, Germany
*
* Copyright by scireum GmbH
* http://www.scireum.de - [email protected]
*/
package sirius.kernel.health;
import com.google.common.util.concurrent.AtomicDouble;
import java.util.concurrent.atomic.AtomicLong;
/**
* Represents an average value over a given set of values.
*
* Using the maxSamples can be used to implement something like a sliding avarage as the value is
* reset (computed) once the counter hits maxSamples.
*/
public class Average {
private static final long DEFAULT_MAX_SAMPLES = 100;
private AtomicLong sampleCount = new AtomicLong();
private AtomicLong count = new AtomicLong();
private AtomicDouble sum = new AtomicDouble();
private final long maxSamples;
/**
* Creates a new average which averages up to {@link #DEFAULT_MAX_SAMPLES} and then computes the effective
* avarage and resets the counter to 1 using that value.
*/
public Average() {
this(DEFAULT_MAX_SAMPLES);
}
/**
* Creates a new average which averages up to maxSamples and then computes the effective
* avarage and resets the counter to 1 using that value.
*
* @param maxSamples the max number of samples to use in order to build the average
*/
public Average(long maxSamples) {
this.maxSamples = maxSamples;
}
/**
* Adds the given value to the set of values on which the average is based.
*
* If the sum of all values is greater as Double.MAX_VALUE / 2 or the count of all values is greater as
* Long.Max_VALUE / 2, the average is resetted.
*
* @param value to value to add to the average
*/
public void addValue(long value) {
addValue((double) value);
}
/**
* Adds the given value to the set of values on which the average is based.
*
* If the sum of all values is greater as Double.MAX_VALUE / 2 or the count of all values is greater as
* Long.Max_VALUE / 2, the average is resetted.
*
* @param value to value to add to the average
*/
public void addValue(double value) {
addValues(1, value);
}
/**
* Adds the given number of values to the counter and increments the sum by the given delta.
*
* @param numberOfValues the number of values to add
* @param sumOfValue the total sum of the values to add
*/
public void addValues(long numberOfValues, double sumOfValue) {
long newSampleCount = sampleCount.addAndGet(numberOfValues);
double newSum = sum.addAndGet(sumOfValue);
if (Long.MAX_VALUE - count.get() < numberOfValues) {
count.set(numberOfValues);
} else {
count.addAndGet(numberOfValues);
}
if (newSampleCount >= maxSamples || newSum > Double.MAX_VALUE / 2) {
sampleCount.set(maxSamples / 2);
sum.set(newSum / newSampleCount * sampleCount.get());
}
}
/**
* Returns the average of the added values.
*
* Returns the sliding average of the last 100 values
*
* @return the average of the added values
*/
public double getAvg() {
long counter = sampleCount.get();
if (counter == 0) {
return 0d;
}
return sum.get() / counter;
}
/**
* Returns the average just like {@link #getAvg()} but then resets the internal buffers to zero.
*
* @return the average of the last 100 values
*/
public double getAndClear() {
double avg = getAvg();
count.set(0);
sampleCount.set(0);
sum.set(0);
return avg;
}
/**
* Returns the number of values used to compute the average.
*
* @return the number of value which will be considered when computing the average.
*/
public long getSampleCount() {
return sampleCount.get();
}
/**
* Returns the number of total values inserted in the average.
*
* @return the number of total values inserted in the average
*/
public long getCount() {
return count.get();
}
@Override
public String toString() {
return getAvg() + " (" + count + ")";
}
}