Package org.HdrHistogram

Class PackedDoubleHistogram

java.lang.Object
org.HdrHistogram.EncodableHistogram
org.HdrHistogram.DoubleHistogram
org.HdrHistogram.PackedDoubleHistogram
All Implemented Interfaces:
Serializable, DoubleValueRecorder
public class PackedDoubleHistogram extends DoubleHistogram

A floating point values High Dynamic Range (HDR) Histogram that uses a packed internal representation

It is important to note that PackedDoubleHistogram is not thread-safe, and does not support safe concurrent recording by multiple threads. If concurrent operation is required, consider using PackedConcurrentDoubleHistogram, or (recommended) DoubleRecorder or SingleWriterDoubleRecorder which are intended for this purpose.

PackedDoubleHistogram tracks 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.

PackedDoubleHistogram supports the recording and analyzing sampled data value counts across a configurable dynamic range of floating point (double) values, with configurable value precision within the range. Dynamic range is expressed as a ratio between the highest and lowest non-zero values trackable within the histogram at any given time. Value precision is expressed as the number of significant [decimal] digits in the value recording, and provides control over value quantization behavior across the value range and the subsequent value resolution at any given level.

Auto-ranging: Unlike integer value based histograms, the specific value range tracked by a PackedDoubleHistogram is not specified upfront. Only the dynamic range of values that the histogram can cover is (optionally) specified. E.g. When a PackedDoubleHistogram is created to track a dynamic range of 3600000000000 (enough to track values from a nanosecond to an hour), values could be recorded into into it in any consistent unit of time as long as the ratio between the highest and lowest non-zero values stays within the specified dynamic range, so recording in units of nanoseconds (1.0 thru 3600000000000.0), milliseconds (0.000001 thru 3600000.0) seconds (0.000000001 thru 3600.0), hours (1/3.6E12 thru 1.0) will all work just as well.

Auto-resizing: When constructed with no specified dynamic range (or when auto-resize is turned on with DoubleHistogram.setAutoResize(boolean)) a DoubleHistogram will auto-resize its dynamic range to include recorded values as they are encountered. Note that recording calls that cause auto-resizing may take longer to execute, as resizing incurs allocation and copying of internal data structures.

Attempts to record non-zero values that range outside of the specified dynamic range (or exceed the limits of of dynamic range when auto-resizing) may results in ArrayIndexOutOfBoundsException exceptions, either due to overflow or underflow conditions. These exceptions will only be thrown if recording the value would have resulted in discarding or losing the required value precision of values already recorded in the histogram.

See package description for org.HdrHistogram for details.

See Also:

  • Constructor Details

    • PackedDoubleHistogram

      public PackedDoubleHistogram(int numberOfSignificantValueDigits)
      Construct a new auto-resizing DoubleHistogram 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.

    • PackedDoubleHistogram

      public PackedDoubleHistogram(long highestToLowestValueRatio, int numberOfSignificantValueDigits)
      Construct a new DoubleHistogram with the specified dynamic range (provided in highestToLowestValueRatio) and using a precision stated as a number of significant decimal digits.
      Parameters:
      highestToLowestValueRatio - specifies the dynamic range to use
      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.

    • PackedDoubleHistogram

      public PackedDoubleHistogram(DoubleHistogram source)
      Construct a PackedDoubleHistogram with the same range settings as a given source, duplicating the source's start/end timestamps (but NOT it's contents)
      Parameters:
      source - The source histogram to duplicate

  • Method Details

    • decodeFromByteBuffer

      public static PackedDoubleHistogram decodeFromByteBuffer(ByteBuffer buffer, long minBarForHighestToLowestValueRatio)
      Construct a new ConcurrentDoubleHistogram by decoding it from a ByteBuffer.
      Parameters:
      buffer - The buffer to decode from
      minBarForHighestToLowestValueRatio - Force highestTrackableValue to be set at least this high
      Returns:
      The newly constructed ConcurrentDoubleHistogram

    • decodeFromCompressedByteBuffer

      public static PackedDoubleHistogram decodeFromCompressedByteBuffer(ByteBuffer buffer, long minBarForHighestToLowestValueRatio) throws DataFormatException
      Construct a new ConcurrentDoubleHistogram by decoding it from a compressed form in a ByteBuffer.
      Parameters:
      buffer - The buffer to decode from
      minBarForHighestToLowestValueRatio - Force highestTrackableValue to be set at least this high
      Returns:
      The newly constructed ConcurrentDoubleHistogram
      Throws:
      DataFormatException - on error parsing/decompressing the buffer