org.apache.ignite.internal.processors.query.stat.hll.serialization

Class BigEndianAscendingWordSerializer

java.lang.Object

org.apache.ignite.internal.processors.query.stat.hll.serialization.BigEndianAscendingWordSerializer

All Implemented Interfaces:

IWordSerializer

public class BigEndianAscendingWordSerializer
extends Object
implements IWordSerializer

A serializer that writes a sequence of fixed bit-width 'words' to a byte array. Bitwise OR is used to write words into bytes, so a low bit in a word is also a low bit in a byte. However, a high byte in a word is written at a lower index in the array than a low byte in a word. The first word is written at the lowest array index. Each serializer is one time use and returns its backing byte array.

This encoding was chosen so that when reading bytes as octets in the typical first-octet-is-the-high-nibble fashion, an octet-to-binary conversion would yield a high-to-low, left-to-right view of the "short words".

Example:

Say short words are 5 bits wide. Our word sequence is the values [31, 1, 5]. In big-endian binary format, the values are [0b11111, 0b00001, 0b00101]. We use 15 of 16 bits in two bytes and pad the last (lowest) bit of the last byte with a zero: [0b11111000, 0b01001010] = [0xF8, 0x4A] .

Constructor Summary

Constructors

Constructor and Description
BigEndianAscendingWordSerializer(int wordLength, int wordCount, int bytePadding)

Method Summary

Modifier and Type	Method and Description
byte[]	getBytes() Returns the backing array of bytes that contain the serialized words.
void	writeWord(long word) Writes the word to the backing array.

Methods inherited from class java.lang.Object

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

Constructor Detail

BigEndianAscendingWordSerializer

public BigEndianAscendingWordSerializer(int wordLength,
                                        int wordCount,
                                        int bytePadding)

Parameters:

wordLength - the length in bits of the words to be serialized. Must be greater than or equal to 1 and less than or equal to 64.

wordCount - the number of words to be serialized. Must be greater than or equal to zero.

bytePadding - the number of leading bytes that should pad the serialized words. Must be greater than or equal to zero.

Method Detail

writeWord

public void writeWord(long word)

Description copied from interface: IWordSerializer

Writes the word to the backing array.

Specified by:

writeWord in interface IWordSerializer

Parameters:

word - the word to write.

getBytes

public byte[] getBytes()

Description copied from interface: IWordSerializer

Returns the backing array of bytes that contain the serialized words.

Specified by:

getBytes in interface IWordSerializer

Returns:

the serialized words as a byte[].