See: Description
| Class | Description | 
|---|---|
| AggregatorMetric | An adapter between the  NamedAggregatorsand Codahale'sMetricinterface. | 
| AggregatorMetricSource | A Spark  Sourcethat is tailored to expose anAggregatorMetric, wrapping an
 underlyingNamedAggregatorsinstance. | 
| CompositeSource | Composite source made up of several  MetricRegistryinstances. | 
| MetricsAccumulator | For resilience,  Accumulatorsare required to be wrapped in a Singleton. | 
| MetricsAccumulator.AccumulatorCheckpointingSparkListener | Spark Listener which checkpoints  MetricsContainerStepMapvalues for fault-tolerance. | 
| MetricsContainerStepMapAccumulator | AccumulatorV2implementation forMetricsContainerStepMap. | 
| SparkBeamMetricSource | A Spark  Sourcethat is tailored to expose aSparkBeamMetric, wrapping an
 underlyingMetricResultsinstance. | 
| WithMetricsSupport |