org.apache.hadoop.metrics2
Interfaces 
MetricsBuilder
MetricsPlugin
MetricsRecord
MetricsSink
MetricsSource
MetricsSystem
MetricsSystem.Callback
MetricsSystemMXBean
MetricsVisitor
Classes 
Metric
MetricCounter
MetricGauge
MetricsFilter
MetricsRecordBuilder
MetricsSystem.AbstractCallback
MetricsTag
Exceptions 
MetricsException