Package org.HdrHistogram

Class DoubleRecorder

  • All Implemented Interfaces:
    DoubleValueRecorder, IntervalHistogramProvider<DoubleHistogram>
    public class DoubleRecorder
extends Object
implements DoubleValueRecorder, IntervalHistogramProvider<DoubleHistogram>
    Records floating point (double) values, and provides stable interval DoubleHistogram 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.

    DoubleRecorder supports concurrent recordValue(double) or recordValueWithExpectedInterval(double, double) 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 DoubleRecorder looks like this: 

    
 DoubleRecorder recorder = new DoubleRecorder(2); // Two decimal point accuracy
 DoubleHistogram 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 Detail

      • DoubleRecorder

        public DoubleRecorder​(int numberOfSignificantValueDigits,
                      boolean packed)
        Construct an auto-resizing DoubleRecorder using a precision stated as a number of significant decimal digits.

        Depending on the valuer of the packed parameter DoubleRecorder 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.

      • DoubleRecorder

        public DoubleRecorder​(int numberOfSignificantValueDigits)
        Construct an auto-resizing DoubleRecorder using a precision stated as a number of significant decimal digits.
        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.

      • DoubleRecorder

        public DoubleRecorder​(long highestToLowestValueRatio,
                      int numberOfSignificantValueDigits)
        Construct a DoubleRecorder dynamic range of values to cover and a number of significant decimal digits.
        Parameters:
        highestToLowestValueRatio - specifies the dynamic range to use (as a ratio)
        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.