io.opencensus.metrics

Class DoubleGauge

java.lang.Object

io.opencensus.metrics.DoubleGauge

@ThreadSafe
public abstract class DoubleGauge
extends Object

Double Gauge metric, to report instantaneous measurement of a double value. Gauges can go both up and down. The gauges values can be negative.

Example 1: Create a Gauge with default labels.

 class YourClass {

   private static final MetricRegistry metricRegistry = Metrics.getMetricRegistry();

   List<LabelKey> labelKeys = Arrays.asList(LabelKey.create("Name", "desc"));

   DoubleGauge gauge = metricRegistry.addDoubleGauge("queue_size",
                       "Pending jobs", "1", labelKeys);

   // It is recommended to keep a reference of a point for manual operations.
   DoublePoint defaultPoint = gauge.getDefaultTimeSeries();

   void doWork() {
      // Your code here.
      defaultPoint.add(10);
   }

 }
 

Example 2: You can also use labels(keys and values) to track different types of metric.

 class YourClass {

   private static final MetricRegistry metricRegistry = Metrics.getMetricRegistry();

   List<LabelKey> labelKeys = Arrays.asList(LabelKey.create("Name", "desc"));
   List<LabelValue> labelValues = Arrays.asList(LabelValue.create("Inbound"));

   DoubleGauge gauge = metricRegistry.addDoubleGauge("queue_size",
                       "Pending jobs", "1", labelKeys);

   // It is recommended to keep a reference of a point for manual operations.
   DoublePoint inboundPoint = gauge.getOrCreateTimeSeries(labelValues);

   void doSomeWork() {
      // Your code here.
      inboundPoint.set(15);
   }

 }
 

Since:

0.17

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DoubleGauge.DoublePoint The value of a single point in the Gauge.TimeSeries.

Constructor Summary

Constructors

Constructor and Description
DoubleGauge()

Method Summary

Modifier and Type	Method and Description
abstract void	clear() Removes all TimeSeries from the gauge metric.
abstract DoubleGauge.DoublePoint	getDefaultTimeSeries() Returns a DoublePoint for a gauge with all labels not set, or default labels.
abstract DoubleGauge.DoublePoint	getOrCreateTimeSeries(List<LabelValue> labelValues) Creates a TimeSeries and returns a DoublePoint if the specified labelValues is not already associated with this gauge, else returns an existing DoublePoint.
abstract void	removeTimeSeries(List<LabelValue> labelValues) Removes the TimeSeries from the gauge metric, if it is present.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DoubleGauge

public DoubleGauge()

Method Detail

getOrCreateTimeSeries

public abstract DoubleGauge.DoublePoint getOrCreateTimeSeries(List<LabelValue> labelValues)

Creates a TimeSeries and returns a DoublePoint if the specified labelValues is not already associated with this gauge, else returns an existing DoublePoint.

It is recommended to keep a reference to the DoublePoint instead of always calling this method for manual operations.

Parameters:

labelValues - the list of label values. The number of label values must be the same to that of the label keys passed to MetricRegistry.addDoubleGauge(java.lang.String, java.lang.String, java.lang.String, java.util.List<io.opencensus.metrics.LabelKey>).

Returns:

a DoublePoint the value of single gauge.

Throws:

NullPointerException - if labelValues is null OR any element of labelValues is null.

IllegalArgumentException - if number of labelValuess are not equal to the label keys.

Since:

0.17

getDefaultTimeSeries

public abstract DoubleGauge.DoublePoint getDefaultTimeSeries()

Returns a DoublePoint for a gauge with all labels not set, or default labels.

Returns:

a DoublePoint for a gauge with all labels not set, or default labels.

Since:

0.17

removeTimeSeries

public abstract void removeTimeSeries(List<LabelValue> labelValues)

Removes the TimeSeries from the gauge metric, if it is present. i.e. references to previous DoublePoint objects are invalid (not part of the metric).

Parameters:

labelValues - the list of label values.

Throws:

NullPointerException - if labelValues is null or any element of labelValues is null.

Since:

0.17

clear

public abstract void clear()

Removes all TimeSeries from the gauge metric. i.e. references to all previous DoublePoint objects are invalid (not part of the metric).

Since:

0.17