Package org.HdrHistogram

Class AtomicHistogram

  • All Implemented Interfaces:
    Serializable, ValueRecorder
    public class AtomicHistogram
extends Histogram

    A High Dynamic Range (HDR) Histogram using atomic long count type

    An AtomicHistogram guarantees lossless recording of values into the histogram even when the histogram is updated by multiple threads. It is important to note though that this lossless recording capability is the only thread-safe behavior provided by AtomicHistogram, and that it is not otherwise synchronized. Specifically, AtomicHistogram does not support auto-resizing, does not support value shift operations, and provides no implicit synchronization that would prevent the contents of the histogram from changing during iterations, copies, or addition operations on the histogram. Callers wishing to make potentially concurrent, multi-threaded updates that would safely work in the presence of queries, copies, or additions of histogram objects should either take care to externally synchronize and/or order their access, use the SynchronizedHistogram variant, or (recommended) use the Recorder class, which is intended for this purpose.

    See package description for org.HdrHistogram for details.

    See Also:
    Serialized Form

    • Constructor Detail

      • AtomicHistogram

        public AtomicHistogram​(long highestTrackableValue,
                       int numberOfSignificantValueDigits)
        Construct a AtomicHistogram 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.

      • AtomicHistogram

        public AtomicHistogram​(long lowestDiscernibleValue,
                       long highestTrackableValue,
                       int numberOfSignificantValueDigits)
        Construct a AtomicHistogram 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.

      • AtomicHistogram

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

    • Method Detail

      • setAutoResize

        public void setAutoResize​(boolean autoResize)
        Description copied from class: AbstractHistogram
        Control whether or not the histogram can auto-resize and auto-adjust it's highestTrackableValue
        Overrides:
        setAutoResize in class AbstractHistogram
        Parameters:
        autoResize - autoResize setting

      • supportsAutoResize

        public boolean supportsAutoResize()
        Description copied from class: AbstractHistogram
        Indicate whether or not the histogram is capable of supporting auto-resize functionality. Note that this is an indication that enabling auto-resize by calling setAutoResize() is allowed, and NOT that the histogram will actually auto-resize. Use isAutoResize() to determine if the histogram is in auto-resize mode.
        Overrides:
        supportsAutoResize in class AbstractHistogram
        Returns:
        autoResize setting

      • copy

        public AtomicHistogram copy()
        Description copied from class: AbstractHistogram
        Create a copy of this histogram, complete with data and everything.
        Overrides:
        copy in class Histogram
        Returns:
        A distinct copy of this histogram.

      • copyCorrectedForCoordinatedOmission

        public AtomicHistogram copyCorrectedForCoordinatedOmission​(long expectedIntervalBetweenValueSamples)
        Description copied from class: AbstractHistogram
        Get a copy of this histogram, corrected for coordinated omission.

        To compensate for the loss of sampled values when a recorded value is larger than the expected interval between value samples, the new histogram will include an auto-generated additional series of decreasingly-smaller (down to the expectedIntervalBetweenValueSamples) value records for each count found in the current histogram that is larger than the expectedIntervalBetweenValueSamples. Note: This is a post-correction method, as opposed to the at-recording correction method provided by recordValueWithExpectedInterval. The two methods are mutually exclusive, and only one of the two should be be used on a given data set to correct for the same coordinated omission issue. by

        See notes in the description of the Histogram calls for an illustration of why this corrective behavior is important.

        Overrides:
        copyCorrectedForCoordinatedOmission in class Histogram
        Parameters:
        expectedIntervalBetweenValueSamples - If expectedIntervalBetweenValueSamples is larger than 0, add auto-generated value records as appropriate if value is larger than expectedIntervalBetweenValueSamples
        Returns:
        a copy of this histogram, corrected for coordinated omission.

      • getTotalCount

        public long getTotalCount()
        Description copied from class: AbstractHistogram
        Get the total count of all recorded values in the histogram
        Overrides:
        getTotalCount in class Histogram
        Returns:
        the total count of all recorded values in the histogram

      • decodeFromByteBuffer

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

      • decodeFromCompressedByteBuffer

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

      • fromString

        public static AtomicHistogram fromString​(String base64CompressedHistogramString)
                                  throws DataFormatException
        Construct a new AtomicHistogram by decoding it from a String containing a base64 encoded compressed histogram representation.
        Parameters:
        base64CompressedHistogramString - A string containing a base64 encoding of a compressed histogram
        Returns:
        A AtomicHistogram decoded from the string
        Throws:
        DataFormatException - on error parsing/decompressing the input