| Package | Description | 
|---|---|
| org.apache.hadoop.metrics2.lib | A collection of library classes for implementing metrics sources | 
| Class and Description | 
|---|
| DefaultMetricsSystem The default metrics system singleton. | 
| MetricsRegistry An optional metrics registry class for creating and maintaining a
 collection of MetricsMutables, making writing metrics source easier. | 
| MutableCounter The mutable counter (monotonically increasing) metric interface | 
| MutableCounterInt A mutable int counter for implementing metrics sources | 
| MutableCounterLong A mutable long counter | 
| MutableGauge The mutable gauge metric interface | 
| MutableGaugeInt A mutable int gauge | 
| MutableGaugeLong A mutable long gauge | 
| MutableMetric The mutable metric interface | 
| MutableQuantiles Watches a stream of long values, maintaining online estimates of specific
 quantiles with provably low error bounds. | 
| MutableRate A convenient mutable metric for throughput measurement | 
| MutableRatesWithAggregation Helper class to manage a group of mutable rate metrics. | 
| MutableRollingAverages 
 This class maintains a group of rolling average metrics. | 
| MutableStat A mutable metric with stats. | 
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