Package io.opentelemetry.sdk.metrics.internal.aggregator

Class Base2ExponentialHistogramIndexer

java.lang.Object

io.opentelemetry.sdk.metrics.internal.aggregator.Base2ExponentialHistogramIndexer

final class Base2ExponentialHistogramIndexer
extends Object

Field Summary

Fields

Modifier and Type	Field	Description
private static final Map<Integer,Base2ExponentialHistogramIndexer>	cache
private static final int	EXPONENT_BIAS	Bias used in representing the exponent of IEEE 754 double precision number.
private static final long	EXPONENT_BIT_MASK	Bit mask used to isolate exponent of IEEE 754 double precision number.
private static final int	EXPONENT_WIDTH	The number of bits used to represent the exponent of IEEE 754 double precision number.
private static final double	LOG_BASE2_E
private final int	scale
private final double	scaleFactor
private static final long	SIGNIFICAND_BIT_MASK	Bit mask used to isolate the significand of IEEE 754 double precision number.
private static final int	SIGNIFICAND_WIDTH	The number of bits used to represent the significand of IEEE 754 double precision number, excluding the implicit bit.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Base2ExponentialHistogramIndexer(int scale)

Method Summary

Modifier and Type	Method	Description
(package private) int	computeIndex(double value)	Compute the index for the given value.
private static double	computeScaleFactor(int scale)
(package private) static Base2ExponentialHistogramIndexer	get(int scale)	Get an indexer for the given scale.
private int	getIndexByLogarithm(double value)	Compute the bucket index using a logarithm based approach.
private static int	mapToIndexScaleZero(double value)	Compute the exact bucket index for scale zero by extracting the exponent.

Methods inherited from class java.lang.Object

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

Field Details

cache

private static final Map<Integer,Base2ExponentialHistogramIndexer> cache

EXPONENT_BIT_MASK

private static final long EXPONENT_BIT_MASK

Bit mask used to isolate exponent of IEEE 754 double precision number.

See Also:

• Constant Field Values

SIGNIFICAND_BIT_MASK

private static final long SIGNIFICAND_BIT_MASK

Bit mask used to isolate the significand of IEEE 754 double precision number.

See Also:

• Constant Field Values

EXPONENT_BIAS

private static final int EXPONENT_BIAS

Bias used in representing the exponent of IEEE 754 double precision number.

See Also:

• Constant Field Values

SIGNIFICAND_WIDTH

private static final int SIGNIFICAND_WIDTH

The number of bits used to represent the significand of IEEE 754 double precision number, excluding the implicit bit.

See Also:

• Constant Field Values

EXPONENT_WIDTH

private static final int EXPONENT_WIDTH

The number of bits used to represent the exponent of IEEE 754 double precision number.

See Also:

• Constant Field Values

LOG_BASE2_E

private static final double LOG_BASE2_E

scale

private final int scale

scaleFactor

private final double scaleFactor

Constructor Details

Base2ExponentialHistogramIndexer

private Base2ExponentialHistogramIndexer(int scale)

Method Details

get

static Base2ExponentialHistogramIndexer get(int scale)

Get an indexer for the given scale. Indexers are cached and reused for performance.

computeIndex

int computeIndex(double value)

Compute the index for the given value.

The algorithm to retrieve the index is specified in the OpenTelemetry specification.

Parameters:

value - Measured value (must be non-zero).

Returns:

the index of the bucket which the value maps to.

getIndexByLogarithm

private int getIndexByLogarithm(double value)

Compute the bucket index using a logarithm based approach.

See Also:

• All Scales: Use the Logarithm Function

mapToIndexScaleZero

private static int mapToIndexScaleZero(double value)

Compute the exact bucket index for scale zero by extracting the exponent.

See Also:

• Scale Zero: Extract the Exponent

computeScaleFactor

private static double computeScaleFactor(int scale)