org.apache.storm.metrics.hdrhistogram

## Class HistogramMetric

- java.lang.Object
- - org.apache.storm.metrics.hdrhistogram.HistogramMetric

- All Implemented Interfaces:
    IMetric

      public class HistogramMetric
      extends Object
      implements IMetric

  A metric wrapping an HdrHistogram.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `HistogramMetric(int numberOfSignificantValueDigits)`
    `HistogramMetric(Long highestTrackableValue, int numberOfSignificantValueDigits)`
    `HistogramMetric(Long lowestDiscernibleValue, Long highestTrackableValue, int numberOfSignificantValueDigits)` (From the Constructor of Histogram) Construct a Histogram given the Lowest and Highest values to be tracked and a number of significant decimal digits.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Object` | `getValueAndReset()` Get value and reset.
    `void` | `recordValue(long val)`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### HistogramMetric

          public HistogramMetric(int numberOfSignificantValueDigits)

    - #### HistogramMetric

          public HistogramMetric(Long highestTrackableValue,
                                 int numberOfSignificantValueDigits)

    - #### HistogramMetric

          public HistogramMetric(Long lowestDiscernibleValue,
                                 Long highestTrackableValue,
                                 int numberOfSignificantValueDigits)

      (From the Constructor of Histogram) Construct a Histogram given the Lowest and Highest values to be tracked and a number of significant decimal digits. Providing a lowestDiscernibleValue is useful is situations where the units used for the histogram’s values are much smaller that the minimal accuracy required. E.g. when tracking time values stated in nanosecond units, where the minimal accuracy required is a microsecond, the proper value for lowestDiscernibleValue would be 1000.

      Parameters:
        `lowestDiscernibleValue` - The lowest value that can be discerned (distinguished from 0) by the histogram. Must be a positive integer that is >= 1. May be internally rounded down to nearest power of 2 (if null 1 is used).
        `highestTrackableValue` - The highest value to be tracked by the histogram. Must be a positive integer that is >= (2 * lowestDiscernibleValue). (if null 2 * lowestDiscernibleValue is used and auto-resize is enabled)
        `numberOfSignificantValueDigits` - Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5.

  - ### Method Detail

    - #### recordValue

          public void recordValue(long val)

    - #### getValueAndReset

          public Object getValueAndReset()

      Description copied from interface: `IMetric`

      Get value and reset.

      Specified by:
        `getValueAndReset` in interface `IMetric`
      Returns:
        an object that will be sent sent to `IMetricsConsumer#handleDataPoints(org.apache.storm.metric.api.IMetricsConsumer .TaskInfo, java.util.Collection)`. If null is returned nothing will be sent. If this value can be reset, like with a counter, a side effect of calling this should be that the value is reset.

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