com.codahale.metrics.RatioGauge Maven / Gradle / Ivy
package com.codahale.metrics;
import static java.lang.Double.isInfinite;
import static java.lang.Double.isNaN;
/**
* A gauge which measures the ratio of one value to another.
*
* If the denominator is zero, not a number, or infinite, the resulting ratio is not a number.
*/
public abstract class RatioGauge implements Gauge {
/**
* A ratio of one quantity to another.
*/
public static class Ratio {
/**
* Creates a new ratio with the given numerator and denominator.
*
* @param numerator the numerator of the ratio
* @param denominator the denominator of the ratio
* @return {@code numerator:denominator}
*/
public static Ratio of(double numerator, double denominator) {
return new Ratio(numerator, denominator);
}
private final double numerator;
private final double denominator;
private Ratio(double numerator, double denominator) {
this.numerator = numerator;
this.denominator = denominator;
}
/**
* Returns the ratio, which is either a {@code double} between 0 and 1 (inclusive) or
* {@code NaN}.
*
* @return the ratio
*/
public double getValue() {
final double d = denominator;
if (isNaN(d) || isInfinite(d) || d == 0) {
return Double.NaN;
}
return numerator / d;
}
@Override
public String toString() {
return numerator + ":" + denominator;
}
}
/**
* Returns the {@link Ratio} which is the gauge's current value.
*
* @return the {@link Ratio} which is the gauge's current value
*/
protected abstract Ratio getRatio();
@Override
public Double getValue() {
return getRatio().getValue();
}
}