org.apache.arrow.vector

Class BitVectorHelper

java.lang.Object

org.apache.arrow.vector.BitVectorHelper

public class BitVectorHelper
extends Object

Helper class for performing generic operations on a bit vector buffer. External use of this class is not recommended.

Method Summary

Modifier and Type	Method and Description
static int	bitIndex(int absoluteBitIndex) Get the relative index of bit within the byte in validity buffer.
static int	byteIndex(int absoluteBitIndex) Get the index of byte corresponding to bit index in validity buffer.
static boolean	checkAllBitsEqualTo(ArrowBuf validityBuffer, int valueCount, boolean checkOneBits) Tests if all bits in a validity buffer are equal 0 or 1, according to the specified parameter.
static int	get(ArrowBuf buffer, int index) Check if a bit at a given index is set or not.
static byte	getBitsFromCurrentByte(ArrowBuf data, int index, int offset) Returns the byte at index from data right-shifted by offset.
static byte	getBitsFromNextByte(ArrowBuf data, int index, int offset) Returns the byte at index from left-shifted by (8 - offset).
static int	getNullCount(ArrowBuf validityBuffer, int valueCount) Given a validity buffer, find the number of bits that are not set.
static int	getValidityBufferSize(int valueCount) Compute the size of validity buffer required to manage a given number of elements in a vector.
static ArrowBuf	loadValidityBuffer(ArrowFieldNode fieldNode, ArrowBuf sourceValidityBuffer, BufferAllocator allocator) Returns a new buffer if the source validity buffer is either all null or all not-null, otherwise returns a buffer pointing to the same memory as source.
static ArrowBuf	setValidityBit(ArrowBuf validityBuffer, BufferAllocator allocator, int valueCount, int index, int value) Set the bit at a given index to provided value (1 or 0).
static void	setValidityBit(ArrowBuf validityBuffer, int index, int value) Set the bit at a given index to provided value (1 or 0).
static void	setValidityBitToOne(ArrowBuf validityBuffer, int index) Set the bit at provided index to 1.

Methods inherited from class java.lang.Object

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

Method Detail

byteIndex

public static int byteIndex(int absoluteBitIndex)

Get the index of byte corresponding to bit index in validity buffer.

bitIndex

public static int bitIndex(int absoluteBitIndex)

Get the relative index of bit within the byte in validity buffer.

setValidityBitToOne

public static void setValidityBitToOne(ArrowBuf validityBuffer,
                                       int index)

Set the bit at provided index to 1.

Parameters:

validityBuffer - validity buffer of the vector

index - index to be set

setValidityBit

public static void setValidityBit(ArrowBuf validityBuffer,
                                  int index,
                                  int value)

Set the bit at a given index to provided value (1 or 0).

Parameters:

validityBuffer - validity buffer of the vector

index - index to be set

value - value to set

setValidityBit

public static ArrowBuf setValidityBit(ArrowBuf validityBuffer,
                                      BufferAllocator allocator,
                                      int valueCount,
                                      int index,
                                      int value)

Set the bit at a given index to provided value (1 or 0). Internally takes care of allocating the buffer if the caller didn't do so.

Parameters:

validityBuffer - validity buffer of the vector

allocator - allocator for the buffer

valueCount - number of values to allocate/set

index - index to be set

value - value to set

Returns:

ArrowBuf

get

public static int get(ArrowBuf buffer,
                      int index)

Check if a bit at a given index is set or not.

Parameters:

buffer - buffer to check

index - index of the buffer

Returns:

1 if bit is set, 0 otherwise.

getValidityBufferSize

public static int getValidityBufferSize(int valueCount)

Compute the size of validity buffer required to manage a given number of elements in a vector.

Parameters:

valueCount - number of elements in the vector

Returns:

buffer size

getNullCount

public static int getNullCount(ArrowBuf validityBuffer,
                               int valueCount)

Given a validity buffer, find the number of bits that are not set. This is used to compute the number of null elements in a nullable vector.

Parameters:

validityBuffer - validity buffer of the vector

valueCount - number of values in the vector

Returns:

number of bits not set.

checkAllBitsEqualTo

public static boolean checkAllBitsEqualTo(ArrowBuf validityBuffer,
                                          int valueCount,
                                          boolean checkOneBits)

Tests if all bits in a validity buffer are equal 0 or 1, according to the specified parameter.

Parameters:

validityBuffer - the validity buffer.

valueCount - the bit count.

checkOneBits - if set to true, the method checks if all bits are equal to 1; otherwise, it checks if all bits are equal to 0.

Returns:

true if all bits are 0 or 1 according to the parameter, and false otherwise.

getBitsFromCurrentByte

public static byte getBitsFromCurrentByte(ArrowBuf data,
                                          int index,
                                          int offset)

Returns the byte at index from data right-shifted by offset.

getBitsFromNextByte

public static byte getBitsFromNextByte(ArrowBuf data,
                                       int index,
                                       int offset)

Returns the byte at index from left-shifted by (8 - offset).

loadValidityBuffer

public static ArrowBuf loadValidityBuffer(ArrowFieldNode fieldNode,
                                          ArrowBuf sourceValidityBuffer,
                                          BufferAllocator allocator)

Returns a new buffer if the source validity buffer is either all null or all not-null, otherwise returns a buffer pointing to the same memory as source.

Parameters:

fieldNode - The fieldNode containing the null count

sourceValidityBuffer - The source validity buffer that will have its position copied if there is a mix of null and non-null values

allocator - The allocator to use for creating a new buffer if necessary.

Returns:

A new buffer that is either allocated or points to the same memory as sourceValidityBuffer.