Module roaringbitmap

Package org.roaringbitmap.buffer

Class BufferUtil

java.lang.Object

org.roaringbitmap.buffer.BufferUtil

public final class BufferUtil
extends Object

Various useful methods for roaring bitmaps. This class is similar to org.roaringbitmap.Util but meant to be used with memory mapping.

Method Summary

Modifier and Type	Method	Description
static MappeableContainer[]	addOffset(MappeableContainer source, char offsets)	Add value "offset" to all values in the container, producing two new containers.
protected static int	advanceUntil(CharBuffer array, int pos, int length, char min)	Find the smallest integer larger than pos such that array[pos]>= min.
protected static void	arraycopy(CharBuffer src, int srcPos, CharBuffer dest, int destPos, int length)
protected static int	branchyUnsignedBinarySearch(ByteBuffer array, int position, int begin, int end, char k)
protected static int	branchyUnsignedBinarySearch(CharBuffer array, int begin, int end, char k)
static int	cardinalityInBitmapRange(LongBuffer bitmap, int start, int end)	Hamming weight of the bitset in the range start, start+1,..., end-1
protected static void	fillArrayAND(char[] container, LongBuffer bitmap1, LongBuffer bitmap2)
protected static void	fillArrayANDNOT(char[] container, LongBuffer bitmap1, LongBuffer bitmap2)
protected static void	fillArrayXOR(char[] container, LongBuffer bitmap1, LongBuffer bitmap2)
static void	flipBitmapRange(LongBuffer bitmap, int start, int end)	flip bits at start, start+1,..., end-1
static int	flipBitmapRangeAndCardinalityChange(LongBuffer bitmap, int start, int end)	Deprecated.
protected static int	getSizeInBytesFromCardinalityEtc(int card, int numRuns, boolean isRunEncoded)	From the cardinality of a container, compute the corresponding size in bytes of the container.
protected static char	highbits(int x)
protected static char	highbits(long x)
static int	intersectArrayIntoBitmap(long[] bitmap, CharBuffer array, int length)	Intersects the bitmap with the array, returning the cardinality of the result
static int	intersectArrayIntoBitmap(LongBuffer bitmap, CharBuffer array, int length)	Intersects the bitmap with the array, returning the cardinality of the result
protected static boolean	isBackedBySimpleArray(Buffer b)	Checks whether the Buffer is backed by a simple array.
static int	iterateUntil(CharBuffer array, int pos, int length, int min)	Find the smallest integer larger than pos such that array[pos]>= min.
protected static char	lowbits(int x)
protected static char	lowbits(long x)
protected static int	lowbitsAsInteger(long x)
protected static char	maxLowBit()
protected static int	maxLowBitAsInteger()
static void	resetBitmapRange(LongBuffer bitmap, int start, int end)	clear bits at start, start+1,..., end-1
static int	resetBitmapRangeAndCardinalityChange(LongBuffer bitmap, int start, int end)	Deprecated.
static void	setBitmapRange(LongBuffer bitmap, int start, int end)	set bits at start, start+1,..., end-1
static int	setBitmapRangeAndCardinalityChange(LongBuffer bitmap, int start, int end)	Deprecated.
static int	unsignedBinarySearch(ByteBuffer array, int position, int begin, int end, char k)	Look for value k in buffer in the range [begin,end).
static int	unsignedBinarySearch(CharBuffer array, int begin, int end, char k)	Look for value k in buffer in the range [begin,end).
protected static int	unsignedDifference(CharBuffer set1, int length1, CharBuffer set2, int length2, char[] buffer)
protected static int	unsignedExclusiveUnion2by2(CharBuffer set1, int length1, CharBuffer set2, int length2, char[] buffer)
protected static int	unsignedIntersect2by2(CharBuffer set1, int length1, CharBuffer set2, int length2, char[] buffer)
static boolean	unsignedIntersects(CharBuffer set1, int length1, CharBuffer set2, int length2)	Checks if two arrays intersect
protected static int	unsignedLocalIntersect2by2(CharBuffer set1, int length1, CharBuffer set2, int length2, char[] buffer)
protected static int	unsignedLocalIntersect2by2Cardinality(CharBuffer set1, int length1, CharBuffer set2, int length2)
protected static int	unsignedOneSidedGallopingIntersect2by2(CharBuffer smallSet, int smallLength, CharBuffer largeSet, int largeLength, char[] buffer)
protected static int	unsignedUnion2by2(CharBuffer set1, int offset1, int length1, CharBuffer set2, int offset2, int length2, char[] buffer)

Methods inherited from class java.lang.Object

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

Method Details

addOffset

public static MappeableContainer[] addOffset(MappeableContainer source,
 char offsets)

Add value "offset" to all values in the container, producing two new containers. The existing container remains unchanged. The new container are not converted, so they need to be checked: e.g., we could produce two bitmap containers having low cardinality.

Parameters:

source - source container

offsets - value to add to each value in the container

Returns:

return an array made of two containers

advanceUntil

protected static int advanceUntil(CharBuffer array,
 int pos,
 int length,
 char min)

Find the smallest integer larger than pos such that array[pos]>= min. If none can be found, return length. Based on code by O. Kaser.

Parameters:

array - container where we search

pos - initial position

length - how big should the array consider to be

min - minimal threshold

Returns:

x greater than pos such that array[pos] is at least as large as min, pos is is equal to length if it is not possible.

iterateUntil

public static int iterateUntil(CharBuffer array,
 int pos,
 int length,
 int min)

Find the smallest integer larger than pos such that array[pos]>= min. If none can be found, return length.

Parameters:

array - array to search within

pos - starting position of the search

length - length of the array to search

min - minimum value

Returns:

x greater than pos such that array[pos] is at least as large as min, pos is is equal to length if it is not possible.

arraycopy

protected static void arraycopy(CharBuffer src,
 int srcPos,
 CharBuffer dest,
 int destPos,
 int length)

branchyUnsignedBinarySearch

protected static int branchyUnsignedBinarySearch(CharBuffer array,
 int begin,
 int end,
 char k)

branchyUnsignedBinarySearch

protected static int branchyUnsignedBinarySearch(ByteBuffer array,
 int position,
 int begin,
 int end,
 char k)

fillArrayAND

protected static void fillArrayAND(char[] container,
 LongBuffer bitmap1,
 LongBuffer bitmap2)

fillArrayANDNOT

protected static void fillArrayANDNOT(char[] container,
 LongBuffer bitmap1,
 LongBuffer bitmap2)

fillArrayXOR

protected static void fillArrayXOR(char[] container,
 LongBuffer bitmap1,
 LongBuffer bitmap2)

flipBitmapRange

public static void flipBitmapRange(LongBuffer bitmap,
 int start,
 int end)

flip bits at start, start+1,..., end-1

Parameters:

bitmap - array of words to be modified

start - first index to be modified (inclusive)

end - last index to be modified (exclusive)

cardinalityInBitmapRange

public static int cardinalityInBitmapRange(LongBuffer bitmap,
 int start,
 int end)

Hamming weight of the bitset in the range start, start+1,..., end-1

Parameters:

bitmap - array of words representing a bitset

start - first index (inclusive)

end - last index (exclusive)

Returns:

the hamming weight of the corresponding range

setBitmapRangeAndCardinalityChange

@Deprecated
public static int setBitmapRangeAndCardinalityChange(LongBuffer bitmap,
 int start,
 int end)

Deprecated.

set bits at start, start+1,..., end-1 and report the cardinality change

Parameters:

bitmap - array of words to be modified

start - first index to be modified (inclusive)

end - last index to be modified (exclusive)

Returns:

cardinality change

flipBitmapRangeAndCardinalityChange

@Deprecated
public static int flipBitmapRangeAndCardinalityChange(LongBuffer bitmap,
 int start,
 int end)

Deprecated.

flip bits at start, start+1,..., end-1 and report the cardinality change

Parameters:

bitmap - array of words to be modified

start - first index to be modified (inclusive)

end - last index to be modified (exclusive)

Returns:

cardinality change

resetBitmapRangeAndCardinalityChange

@Deprecated
public static int resetBitmapRangeAndCardinalityChange(LongBuffer bitmap,
 int start,
 int end)

Deprecated.

reset bits at start, start+1,..., end-1 and report the cardinality change

Parameters:

bitmap - array of words to be modified

start - first index to be modified (inclusive)

end - last index to be modified (exclusive)

Returns:

cardinality change

getSizeInBytesFromCardinalityEtc

protected static int getSizeInBytesFromCardinalityEtc(int card,
 int numRuns,
 boolean isRunEncoded)

From the cardinality of a container, compute the corresponding size in bytes of the container. Additional information is required if the container is run encoded.

Parameters:

card - the cardinality if this is not run encoded, otherwise ignored

numRuns - number of runs if run encoded, othewise ignored

isRunEncoded - boolean

Returns:

the size in bytes

highbits

protected static char highbits(int x)

highbits

protected static char highbits(long x)

isBackedBySimpleArray

protected static boolean isBackedBySimpleArray(Buffer b)

Checks whether the Buffer is backed by a simple array. In java, a Buffer is an abstraction that can represent various data, from data on disk all the way to native Java arrays. Like all abstractions, a Buffer might carry a performance penalty. Thus, we sometimes check whether the Buffer is simply a wrapper around a Java array. In these instances, it might be best, from a performance point of view, to access the underlying array (using the array()) method.

Parameters:

b - the provided Buffer

Returns:

whether the Buffer is backed by a simple array

lowbits

protected static char lowbits(int x)

lowbits

protected static char lowbits(long x)

lowbitsAsInteger

protected static int lowbitsAsInteger(long x)

maxLowBit

protected static char maxLowBit()

maxLowBitAsInteger

protected static int maxLowBitAsInteger()

resetBitmapRange

public static void resetBitmapRange(LongBuffer bitmap,
 int start,
 int end)

clear bits at start, start+1,..., end-1

Parameters:

bitmap - array of words to be modified

start - first index to be modified (inclusive)

end - last index to be modified (exclusive)

setBitmapRange

public static void setBitmapRange(LongBuffer bitmap,
 int start,
 int end)

set bits at start, start+1,..., end-1

Parameters:

bitmap - array of words to be modified

start - first index to be modified (inclusive)

end - last index to be modified (exclusive)

unsignedBinarySearch

public static int unsignedBinarySearch(CharBuffer array,
 int begin,
 int end,
 char k)

Look for value k in buffer in the range [begin,end). If the value is found, return its index. If not, return -(i+1) where i is the index where the value would be inserted. The buffer is assumed to contain sorted values where chars are interpreted as unsigned integers.

Parameters:

array - buffer where we search

begin - first index (inclusive)

end - last index (exclusive)

k - value we search for

Returns:

count

unsignedBinarySearch

public static int unsignedBinarySearch(ByteBuffer array,
 int position,
 int begin,
 int end,
 char k)

Look for value k in buffer in the range [begin,end). If the value is found, return its index. If not, return -(i+1) where i is the index where the value would be inserted. The buffer is assumed to contain sorted values where chars are interpreted as unsigned integers.

Parameters:

array - buffer where we search

position - starting position of the container in the ByteBuffer

begin - first index (inclusive)

end - last index (exclusive)

k - value we search for

Returns:

count

unsignedDifference

protected static int unsignedDifference(CharBuffer set1,
 int length1,
 CharBuffer set2,
 int length2,
 char[] buffer)

intersectArrayIntoBitmap

public static int intersectArrayIntoBitmap(long[] bitmap,
 CharBuffer array,
 int length)

Intersects the bitmap with the array, returning the cardinality of the result

Parameters:

bitmap - the bitmap, modified

array - the array, not modified

length - how much of the array to consume

Returns:

the size of the intersection, i.e. how many bits still set in the bitmap

intersectArrayIntoBitmap

public static int intersectArrayIntoBitmap(LongBuffer bitmap,
 CharBuffer array,
 int length)

Intersects the bitmap with the array, returning the cardinality of the result

Parameters:

bitmap - the bitmap, modified

array - the array, not modified

length - how much of the array to consume

Returns:

the size of the intersection, i.e. how many bits still set in the bitmap

unsignedExclusiveUnion2by2

protected static int unsignedExclusiveUnion2by2(CharBuffer set1,
 int length1,
 CharBuffer set2,
 int length2,
 char[] buffer)

unsignedIntersect2by2

protected static int unsignedIntersect2by2(CharBuffer set1,
 int length1,
 CharBuffer set2,
 int length2,
 char[] buffer)

unsignedIntersects

public static boolean unsignedIntersects(CharBuffer set1,
 int length1,
 CharBuffer set2,
 int length2)

Checks if two arrays intersect

Parameters:

set1 - first array

length1 - length of first array

set2 - second array

length2 - length of second array

Returns:

true if they intersect

unsignedLocalIntersect2by2

protected static int unsignedLocalIntersect2by2(CharBuffer set1,
 int length1,
 CharBuffer set2,
 int length2,
 char[] buffer)

unsignedLocalIntersect2by2Cardinality

protected static int unsignedLocalIntersect2by2Cardinality(CharBuffer set1,
 int length1,
 CharBuffer set2,
 int length2)

unsignedOneSidedGallopingIntersect2by2

protected static int unsignedOneSidedGallopingIntersect2by2(CharBuffer smallSet,
 int smallLength,
 CharBuffer largeSet,
 int largeLength,
 char[] buffer)

unsignedUnion2by2

protected static int unsignedUnion2by2(CharBuffer set1,
 int offset1,
 int length1,
 CharBuffer set2,
 int offset2,
 int length2,
 char[] buffer)