Package org.apache.hadoop.metrics2.lib

Class MutableRollingAverages

java.lang.Object
org.apache.hadoop.metrics2.lib.MutableMetric
org.apache.hadoop.metrics2.lib.MutableRollingAverages
All Implemented Interfaces:
Closeable, AutoCloseable
@Public @Evolving public class MutableRollingAverages extends MutableMetric implements Closeable

This class maintains a group of rolling average metrics. It implements the algorithm of rolling average, i.e. a number of sliding windows are kept to roll over and evict old subsets of samples. Each window has a subset of samples in a stream, where sub-sum and sub-total are collected. All sub-sums and sub-totals in all windows will be aggregated to final-sum and final-total used to compute final average, which is called rolling average.

  • Constructor Details

    • MutableRollingAverages

      public MutableRollingAverages(String metricValueName)
      Constructor for MutableRollingAverages.
      Parameters:
      metricValueName - input metricValueName.

  • Method Details

    • snapshot

      public void snapshot(MetricsRecordBuilder builder, boolean all)
      Description copied from class: MutableMetric
      Get a snapshot of the metric
      Specified by:
      snapshot in class MutableMetric
      Parameters:
      builder - the metrics record builder
      all - if true, snapshot unchanged metrics as well

    • collectThreadLocalStates

      public void collectThreadLocalStates()
      Collects states maintained in ThreadLocal, if any.

    • add

      public void add(String name, long value)
      Parameters:
      name - name of metric
      value - value of metric

    • close

      public void close() throws IOException
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException

    • getStats

      public Map<String,Double> getStats(long minSamples)
      Retrieve a map of metric name -> (aggregate). Filter out entries that don't have at least minSamples.
      Parameters:
      minSamples - input minSamples.
      Returns:
      a map of peer DataNode Id to the average latency to that node seen over the measurement period.

    • setRecordValidityMs

      @VisibleForTesting public void setRecordValidityMs(long value)
      Use for test only.
      Parameters:
      value - input value.