Package org.HdrHistogram

Class AtomicHistogram

java.lang.Object

org.HdrHistogram.EncodableHistogram

org.HdrHistogram.AbstractHistogram

org.HdrHistogram.Histogram

org.HdrHistogram.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

Nested Class Summary

Nested classes/interfaces inherited from class org.HdrHistogram.AbstractHistogram

AbstractHistogram.AllValues, AbstractHistogram.LinearBucketValues, AbstractHistogram.LogarithmicBucketValues, AbstractHistogram.Percentiles, AbstractHistogram.RecordedValues

Constructor Summary

Constructors

Constructor	Description
AtomicHistogram(long highestTrackableValue, int numberOfSignificantValueDigits)	Construct a AtomicHistogram given the Highest value to be tracked and a number of significant decimal digits.
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.
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)

Method Summary

Modifier and Type	Method	Description
AtomicHistogram	copy()	Create a copy of this histogram, complete with data and everything.
AtomicHistogram	copyCorrectedForCoordinatedOmission(long expectedIntervalBetweenValueSamples)	Get a copy of this histogram, corrected for coordinated omission.
static AtomicHistogram	decodeFromByteBuffer(ByteBuffer buffer, long minBarForHighestTrackableValue)	Construct a new histogram by decoding it from a ByteBuffer.
static AtomicHistogram	decodeFromCompressedByteBuffer(ByteBuffer buffer, long minBarForHighestTrackableValue)	Construct a new histogram by decoding it from a compressed form in a ByteBuffer.
long	getTotalCount()	Get the total count of all recorded values in the histogram
void	setAutoResize(boolean autoResize)	Control whether or not the histogram can auto-resize and auto-adjust it's highestTrackableValue
boolean	supportsAutoResize()	Indicate whether or not the histogram is capable of supporting auto-resize functionality.

Methods inherited from class org.HdrHistogram.AbstractHistogram

add, addWhileCorrectingForCoordinatedOmission, allValues, copyInto, copyIntoCorrectedForCoordinatedOmission, encodeIntoByteBuffer, encodeIntoCompressedByteBuffer, encodeIntoCompressedByteBuffer, equals, getCountAtValue, getCountBetweenValues, getEndTimeStamp, getEstimatedFootprintInBytes, getHighestTrackableValue, getLowestDiscernibleValue, getMaxValue, getMaxValueAsDouble, getMean, getMinNonZeroValue, getMinValue, getNeededByteBufferCapacity, getNumberOfSignificantValueDigits, getPercentileAtOrBelowValue, getStartTimeStamp, getStdDeviation, getTag, getValueAtPercentile, hashCode, highestEquivalentValue, isAutoResize, linearBucketValues, logarithmicBucketValues, lowestEquivalentValue, medianEquivalentValue, nextNonEquivalentValue, outputPercentileDistribution, outputPercentileDistribution, outputPercentileDistribution, percentiles, recordConvertedDoubleValueWithCount, recordedValues, recordValue, recordValue, recordValueWithCount, recordValueWithExpectedInterval, reset, setEndTimeStamp, setStartTimeStamp, setTag, shiftValuesLeft, shiftValuesRight, sizeOfEquivalentValueRange, subtract, valuesAreEquivalent

Methods inherited from class java.lang.Object

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

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