Package org.forgerock.monitoring.api.instrument

Interface Gauge

All Superinterfaces:

Meter

All Known Subinterfaces:

TimeGauge

All Known Implementing Classes:

DropwizardTypes.DescribableGauge

public interface Gauge
extends Meter

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	Gauge.Builder<T>	Fluent builder for gauges.

Nested classes/interfaces inherited from interface org.forgerock.monitoring.api.instrument.Meter

Meter.Id, Meter.Type

Method Summary

Modifier and Type	Method	Description
static <T> Gauge.Builder<T>	builder(String name, T obj, ToDoubleFunction<T> f)	Setup a Gauge.Builder that will create a gauge that reports the value returned by the provided function.
static <T extends Number> Gauge.Builder<T>	constantGauge(String name, T number)	Setup a Gauge.Builder that will create a gauge that reports the value of the Number.
static <T> Gauge.Builder<T>	doubleGauge(String name, DoubleSupplier valueFunction)	Setup a Gauge.Builder that will create a gauge that reports the size of the Map.
static <T extends Collection<?>> Gauge.Builder<T>	gaugeCollectionSize(String name, T collection)	Setup a Gauge.Builder that will create a gauge that reports the size of the Collection.
static <T extends Map<?,?>> Gauge.Builder	gaugeMapSize(String name, T map)	Setup a Gauge.Builder that will create a gauge that reports the size of the Map.
default Iterable<Measurement>	measure()	Get a set of measurements.
double	value()	Returns the current value.

Methods inherited from interface org.forgerock.monitoring.api.instrument.Meter

getId

Method Detail

builder

static <T> Gauge.Builder<T> builder(String name,
                                    @Nullable
                                    T obj,
                                    ToDoubleFunction<T> f)

Setup a Gauge.Builder that will create a gauge that reports the value returned by the provided function.

Type Parameters:

T - The type of the object to monitor

Parameters:

name - Name of the gauge being registered.

obj - The object to monitor

f - The function to apply to the object to monitor

Returns:

A builder to create a Gauge.

doubleGauge

@Nullable
static <T> Gauge.Builder<T> doubleGauge(String name,
                                        DoubleSupplier valueFunction)

Setup a Gauge.Builder that will create a gauge that reports the size of the Map. The collection implementation used should be thread safe. Note that calling Map.size() can be expensive for some collection implementations and should be considered before registering.

Type Parameters:

T - The type of the state object from which the gauge value is extracted.

Parameters:

name - Name of the gauge being registered.

valueFunction - a function which returns a double

Returns:

A builder to create a Gauge.

constantGauge

static <T extends Number> Gauge.Builder<T> constantGauge(String name,
                                                         T number)

Setup a Gauge.Builder that will create a gauge that reports the value of the Number.

Type Parameters:

T - The type of the number from which the gauge value is extracted.

Parameters:

name - Name of the gauge being registered.

number - Thread-safe implementation of Number used to access the value.

Returns:

A builder to create a Gauge.

gaugeCollectionSize

@Nullable
static <T extends Collection<?>> Gauge.Builder<T> gaugeCollectionSize(String name,
                                                                      T collection)

Setup a Gauge.Builder that will create a gauge that reports the size of the Collection. The collection implementation used should be thread safe. Note that calling Collection.size() can be expensive for some collection implementations and should be considered before registering.

Type Parameters:

T - The type of the state object from which the gauge value is extracted.

Parameters:

name - Name of the gauge being registered.

collection - Thread-safe implementation of Collection used to access the value.

Returns:

A builder to create a Gauge.

gaugeMapSize

@Nullable
static <T extends Map<?,?>> Gauge.Builder gaugeMapSize(String name,
                                                             T map)

Setup a Gauge.Builder that will create a gauge that reports the size of the Map. The collection implementation used should be thread safe. Note that calling Map.size() can be expensive for some collection implementations and should be considered before registering.

Type Parameters:

T - The type of the state object from which the gauge value is extracted.

Parameters:

name - Name of the gauge being registered.

map - Thread-safe implementation of Map used to access the value.

Returns:

A builder to create a Gauge.

value

double value()

Returns the current value. The act of observing the value by calling this method triggers sampling of the underlying number or user-defined function that defines the value for the gauge.

measure

default Iterable<Measurement> measure()

Description copied from interface: Meter

Get a set of measurements. Should always return the same number of measurements and in the same order, regardless of the level of activity or the lack thereof.

Specified by:

measure in interface Meter

Returns:

The set of measurements that represents the instantaneous value of this meter.