com.netflix.hollow.core.memory

Interface FixedLengthData

All Known Implementing Classes:

EncodedLongBuffer, FixedLengthElementArray

public interface FixedLengthData

Each record in Hollow begins with a fixed-length number of bits. At the lowest level, these bits are held in FixedLengthData data structures which can be either backed by long arrays or ByteBuffers. For example, if an EncodedLongBuffer was queried for the 6-bit value starting at bit 7 in the following example range of bits:

     0001000100100001101000010100101001111010101010010010101
 

the value 100100 in binary, or 36 in base 10, would be returned.

As a result there two ways to obtain an element value from the bit string at a given bit index. The first, using getElementValue(long, int) for values less than 61 bits in length and the second, using getLargeElementValue(long, int) that is recommended for values of upto 64 bits in length.

Method Summary

Modifier and Type	Method and Description
static int	bitsRequiredToRepresentValue(long value)
void	clearElementValue(long index, int bitsPerElement)
void	copyBits(FixedLengthData copyFrom, long sourceStartBit, long destStartBit, long numBits)
static void	discardFrom(HollowBlobInput in) Discard fixed length data from input.
long	getElementValue(long index, int bitsPerElement) Gets an element value, comprising of bitsPerElement bits, at the given bit index.
long	getElementValue(long index, int bitsPerElement, long mask) Gets a masked element value, comprising of bitsPerElement bits, at the given bit index.
long	getLargeElementValue(long index, int bitsPerElement) Gets a large element value, comprising of bitsPerElement bits, at the given bit index.
long	getLargeElementValue(long index, int bitsPerElement, long mask) Gets a masked large element value, comprising of bitsPerElement bits, at the given bit index.
void	incrementMany(long startBit, long increment, long bitsBetweenIncrements, int numIncrements)
void	setElementValue(long index, int bitsPerElement, long value)

Method Detail

getElementValue

long getElementValue(long index,
                     int bitsPerElement)

Gets an element value, comprising of bitsPerElement bits, at the given bit index. bitsPerElement should be less than 61 bits.

Parameters:

index - the bit index

bitsPerElement - bits per element, must be less than 61 otherwise the result is undefined

Returns:

the element value

getElementValue

long getElementValue(long index,
                     int bitsPerElement,
                     long mask)

Gets a masked element value, comprising of bitsPerElement bits, at the given bit index.

Parameters:

index - the bit index

bitsPerElement - bits per element, must be less than 61 otherwise the result is undefined

mask - the mask to apply to an element value before it is returned. The mask should be less than or equal to (1L << bitsPerElement) - 1 to guarantee that one or more (possibly) partial element values occurring before and after the desired element value are not included in the returned value.

Returns:

the masked element value

getLargeElementValue

long getLargeElementValue(long index,
                          int bitsPerElement)

Gets a large element value, comprising of bitsPerElement bits, at the given bit index.

This method should be utilized if the bitsPerElement may exceed 60 bits, otherwise the method getLargeElementValue(long, int) can be utilized instead.

Parameters:

index - the bit index

bitsPerElement - bits per element, may be greater than 60

Returns:

the large element value

getLargeElementValue

long getLargeElementValue(long index,
                          int bitsPerElement,
                          long mask)

Gets a masked large element value, comprising of bitsPerElement bits, at the given bit index.

This method should be utilized if the bitsPerElement may exceed 60 bits, otherwise the method getLargeElementValue(long, int, long) can be utilized instead.

Parameters:

index - the bit index

bitsPerElement - bits per element, may be greater than 60

mask - the mask to apply to an element value before it is returned. The mask should be less than or equal to (1L << bitsPerElement) - 1 to guarantee that one or more (possibly) partial element values occurring before and after the desired element value are not included in the returned value.

Returns:

the masked large element value

setElementValue

void setElementValue(long index,
                     int bitsPerElement,
                     long value)

copyBits

void copyBits(FixedLengthData copyFrom,
              long sourceStartBit,
              long destStartBit,
              long numBits)

incrementMany

void incrementMany(long startBit,
                   long increment,
                   long bitsBetweenIncrements,
                   int numIncrements)

clearElementValue

void clearElementValue(long index,
                       int bitsPerElement)

discardFrom

static void discardFrom(HollowBlobInput in)
                 throws java.io.IOException

Discard fixed length data from input. The input contains the number of longs to discard.

Parameters:

in - Hollow Blob Input to discard data from

Throws:

java.io.IOException

bitsRequiredToRepresentValue

static int bitsRequiredToRepresentValue(long value)