Package org.HdrHistogram

Class Recorder

java.lang.Object
org.HdrHistogram.Recorder
All Implemented Interfaces:
IntervalHistogramProvider<Histogram>, ValueRecorder
public class Recorder extends Object implements ValueRecorder, IntervalHistogramProvider<Histogram>
Records integer values, and provides stable interval Histogram samples from live recorded data without interrupting or stalling active recording of values. Each interval histogram provided contains all value counts accumulated since the previous interval histogram was taken.

This pattern is commonly used in logging interval histogram information while recording is ongoing.

Recorder supports concurrent recordValue(long) or recordValueWithExpectedInterval(long, long) calls. Recording calls are wait-free on architectures that support atomic increment operations, and are lock-free on architectures that do not.

A common pattern for using a Recorder looks like this: 


 Recorder recorder = new Recorder(2); // Two decimal point accuracy
 Histogram intervalHistogram = null;
 ...
 [start of some loop construct that periodically wants to grab an interval histogram]
   ...
   // Get interval histogram, recycling previous interval histogram:
   intervalHistogram = recorder.getIntervalHistogram(intervalHistogram);
   histogramLogWriter.outputIntervalHistogram(intervalHistogram);
   ...
 [end of loop construct]

  • Constructor Summary

    Constructors
    Constructor
    Description
    Recorder(int numberOfSignificantValueDigits)
    Construct an auto-resizing Recorder with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue.
    Recorder(int numberOfSignificantValueDigits, boolean packed)
    Construct an auto-resizing Recorder with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue.
    Recorder(long highestTrackableValue, int numberOfSignificantValueDigits)
    Construct a Recorder given the highest value to be tracked and a number of significant decimal digits.
    Recorder(long lowestDiscernibleValue, long highestTrackableValue, int numberOfSignificantValueDigits)
    Construct a Recorder given the Lowest and highest values to be tracked and a number of significant decimal digits.

  • Method Summary

    Modifier and Type
    Method
    Description
    Histogram
    getIntervalHistogram()
    Get a new instance of an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.
    Histogram
    getIntervalHistogram(Histogram histogramToRecycle)
    Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.
    Histogram
    getIntervalHistogram(Histogram histogramToRecycle, boolean enforceContainingInstance)
    Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.
    void
    getIntervalHistogramInto(Histogram targetHistogram)
    Place a copy of the value counts accumulated since accumulated (since the last interval histogram was taken) into targetHistogram.
    void
    recordValue(long value)
    Record a value
    void
    recordValueWithCount(long value, long count)
    Record a value in the histogram (adding to the value's current count)
    void
    recordValueWithExpectedInterval(long value, long expectedIntervalBetweenValueSamples)
    Record a value
    void
    reset()
    Reset any value counts accumulated thus far.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Recorder

      public Recorder(int numberOfSignificantValueDigits, boolean packed)
      Construct an auto-resizing Recorder with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue. Can auto-resize up to track values up to (Long.MAX_VALUE / 2).

      Depending on the valuer of the packed parameter Recorder can be configured to track value counts in a packed internal representation optimized for typical histogram recoded values are sparse in the value range and tend to be incremented in small unit counts. This packed representation tends to require significantly smaller amounts of storage when compared to unpacked representations, but can incur additional recording cost due to resizing and repacking operations that may occur as previously unrecorded values are encountered.

      Parameters:
      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.
      packed - Specifies whether the recorder will uses a packed internal representation or not.

    • Recorder

      public Recorder(int numberOfSignificantValueDigits)
      Construct an auto-resizing Recorder with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue. Can auto-resize up to track values up to (Long.MAX_VALUE / 2).
      Parameters:
      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.

    • Recorder

      public Recorder(long highestTrackableValue, int numberOfSignificantValueDigits)
      Construct a Recorder given the highest value to be tracked and a number of significant decimal digits. The histogram will be constructed to implicitly track (distinguish from 0) values as low as 1.
      Parameters:
      highestTrackableValue - The highest value to be tracked by the histogram. Must be a positive integer that is >= 2.
      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.

    • Recorder

      public Recorder(long lowestDiscernibleValue, long highestTrackableValue, int numberOfSignificantValueDigits)
      Construct a Recorder 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 tracked (distinguished from 0) by the histogram. Must be a positive integer that is >= 1. May be internally rounded down to nearest power of 2.
      highestTrackableValue - The highest value to be tracked by the histogram. Must be a positive integer that is >= (2 * lowestDiscernibleValue).
      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 Details