openconsensus.metrics

Interface DerivedDoubleGauge

All Superinterfaces:

Metric

@ThreadSafe
public interface DerivedDoubleGauge
extends Metric

Derived 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: Create a Gauge with an object and a callback function.

 class YourClass {

   private static final Meter meter = Metrics.getMeter();
   private static final MetricRegistry metricRegistry = meter.metricRegistryBuilder().build();

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

   DerivedDoubleGauge gauge = metricRegistry.addDerivedDoubleGauge(
       "queue_size", "Pending jobs in a queue", "1", labelKeys);

   QueueManager queueManager = new QueueManager();
   gauge.createTimeSeries(labelValues, queueManager,
         new ToDoubleFunction<QueueManager>() {
           {@literal @}Override
           public double applyAsDouble(QueueManager queue) {
             return queue.size();
           }
         });

   void doWork() {
      // Your code here.
   }
 }

 

Since:

0.1.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	DerivedDoubleGauge.Builder Builder class for DerivedDoubleGauge.

Method Summary

Modifier and Type	Method and Description
<T> void	createTimeSeries(List<LabelValue> labelValues, T obj, ToDoubleFunction<T> function) Creates a TimeSeries.

Methods inherited from interface openconsensus.metrics.Metric

clear, removeTimeSeries

Method Detail

createTimeSeries

<T> void createTimeSeries(List<LabelValue> labelValues,
                          T obj,
                          ToDoubleFunction<T> function)

Creates a TimeSeries. The value of a single point in the TimeSeries is observed from a callback function. This function is invoked whenever metrics are collected, meaning the reported value is up-to-date. It keeps a WeakReference to the object and it is the user's responsibility to manage the lifetime of the object.

Type Parameters:

T - the type of the object upon which the function derives a measurement.

Parameters:

labelValues - the list of label values.

obj - the state object from which the function derives a measurement.

function - the function to be called.

Throws:

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

IllegalArgumentException - if different time series with the same labels already exists OR if number of labelValuess are not equal to the label keys.

Since:

0.1.0