package com.twitter.common.metrics;
import java.util.Collection;
import com.google.common.base.Supplier;
/**
* Convenience functions for working with {@link Gauge}s.
*/
public final class Gauges {
private Gauges() {
// Utility class.
}
/**
* Creates a supplier that serves as an accessor for gauge values.
*
* @param gauge Gauge to turn into a supplier.
* @return Supplier of values from {@code gauge}.
*/
public static Supplier<Number> asSupplier(final Gauge gauge) {
return new Supplier<Number>() {
@Override public Number get() {
return gauge.read();
}
};
}
/**
* Registers the size of a collection as a gauge.
*
* @param registry Registry to register the gauge with.
* @param name Name for the gauge.
* @param collection Collection to register size of.
*/
public static void registerSize(MetricRegistry registry, String name,
final Collection collection) {
registry.register(new AbstractGauge<Integer>(name) {
@Override public Integer read() {
return collection.size();
}
});
}
}