Module io.helidon.metrics.api

Package io.helidon.metrics.api

Interface Gauge<N extends Number>

Type Parameters:

N - subtype of Number which a specific gauge reports

All Superinterfaces:

Meter, Wrapper

public interface Gauge<N extends Number>
extends Meter

Exposes as a meter a value that can increase or decrease and is updated by external logic, not by explicit invocations of methods on this type.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	Gauge.Builder<N extends Number>	Builder for a new gauge.

Nested classes/interfaces inherited from interface io.helidon.metrics.api.Meter

Meter.BaseUnits, Meter.Id, Meter.Scope, Meter.Type

Method Summary

Modifier and Type	Method	Description
static <N extends Number> Gauge.Builder<N>	builder(String name, Supplier<N> numberSupplier)	Creates a builder for a supplier-based gauge.
static <T> Gauge.Builder<Double>	builder(String name, T stateObject, ToDoubleFunction<T> fn)	Creates a builder for creating a new gauge based on applying a function to a state object.
N	value()	Returns the value of the gauge.

Methods inherited from interface io.helidon.metrics.api.Meter

baseUnit, description, id, scope, type

Methods inherited from interface io.helidon.metrics.api.Wrapper

unwrap

Method Details

builder

static <T> Gauge.Builder<Double> builder(String name,
 T stateObject,
 ToDoubleFunction<T> fn)

Creates a builder for creating a new gauge based on applying a function to a state object.

For new code, prefer MetricsFactory.gaugeBuilder(String, Object, java.util.function.ToDoubleFunction) on the MetricsFactory instance used by the application.

Type Parameters:

T - type of the state object

Parameters:

name - gauge name

stateObject - state object which maintains the gauge value

fn - function which, when applied to the state object, returns the gauge value

Returns:

new builder

builder

static <N extends Number> Gauge.Builder<N> builder(String name,
 Supplier<N> numberSupplier)

Creates a builder for a supplier-based gauge.

For new code, prefer MetricsFactory.gaugeBuilder(String, java.util.function.Supplier) on the MetricsFactory instance used by the application.

Type Parameters:

N - subtype of Number which the supplier provides

Parameters:

name - gauge name

numberSupplier - Supplier for an instance of a type which extends Number

Returns:

new builder

value

N value()

Returns the value of the gauge.

Invoking this method triggers the sampling of the value or invocation of the function provided when the gauge was registered.

Returns:

current value of the gauge