Class AdaptingIntegerArray

java.lang.Object

io.opentelemetry.sdk.metrics.internal.aggregator.AdaptingIntegerArray

final class AdaptingIntegerArray
extends Object

An integer array that automatically expands its memory consumption (via copy/allocation) when reaching limits. This assumes counts remain low, to lower memory overhead.

This class is NOT thread-safe. It is expected to be behind a synchronized incrementer.

Instances start by attempting to store one-byte per-cell in the integer array. As values grow, this will automatically instantiate the next-size integer array (byte => short => int => long) and copy over values into the larger array. This class expects most usage to remain within the byte boundary (e.g. cell values invalid input: '<' 128).

This class lives in the (very) hot path of metric recording. As such, we do "fun" things, like switch on markers and assume non-null based on presence of the markers, as such we suppress NullAway as it can't understand/express this level of guarantee.

Implementations MUST preserve the following:

• If cellSize == BYTE then byteBacking is not null
• If cellSize == SHORT then shortBacking is not null
• If cellSize == INT then intBacking is not null
• If cellSize == LONG then longBacking is not null

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static enum	AdaptingIntegerArray.ArrayCellSize	Possible sizes of backing arrays.

Field Summary

Fields

Modifier and Type	Field	Description
private byte[]	byteBacking
private AdaptingIntegerArray.ArrayCellSize	cellSize	The current byte size of integer cells in this array.
private int[]	intBacking
private long[]	longBacking
private short[]	shortBacking

Constructor Summary

Constructors

Modifier	Constructor	Description
(package private)	AdaptingIntegerArray(int size)	Construct an adapting integer array of a given size.
private	AdaptingIntegerArray(AdaptingIntegerArray toCopy)	Creates deep copy of another adapting integer array.

Method Summary

Modifier and Type	Method	Description
(package private) void	clear()	Zeroes out all counts in this array.
(package private) AdaptingIntegerArray	copy()	Returns a deep-copy of this array, preserving cell size.
(package private) long	get(int index)	Grab the value stored at index.
(package private) void	increment(int idx, long count)	Add count to the value stored at index.
(package private) int	length()	Return the length of this integer array.
private void	resizeToInt()	Convert from short => int backing array.
private void	resizeToLong()	convert from int => long backing array.
private void	resizeToShort()	Convert from byte => short backing array.

Methods inherited from class Object

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

Field Details

byteBacking

@Nullable
private byte[] byteBacking

shortBacking

@Nullable
private short[] shortBacking

intBacking

@Nullable
private int[] intBacking

longBacking

@Nullable
private long[] longBacking

cellSize

private AdaptingIntegerArray.ArrayCellSize cellSize

The current byte size of integer cells in this array.

Constructor Details

AdaptingIntegerArray

AdaptingIntegerArray(int size)

Construct an adapting integer array of a given size.

AdaptingIntegerArray

private AdaptingIntegerArray(AdaptingIntegerArray toCopy)

Creates deep copy of another adapting integer array.

Method Details

copy

AdaptingIntegerArray copy()

Returns a deep-copy of this array, preserving cell size.

increment

void increment(int idx,
 long count)

Add count to the value stored at index.

get

long get(int index)

Grab the value stored at index.

length

int length()

Return the length of this integer array.

clear

void clear()

Zeroes out all counts in this array.

resizeToShort

private void resizeToShort()

Convert from byte => short backing array.

resizeToInt

private void resizeToInt()

Convert from short => int backing array.

resizeToLong

private void resizeToLong()

convert from int => long backing array.