org.apache.hadoop.hbase.util.vint
Class UFIntTool

java.lang.Object
  org.apache.hadoop.hbase.util.vint.UFIntTool

@InterfaceAudience.Private
public class UFIntTool
extends Object

UFInt is an abbreviation for Unsigned Fixed-width Integer. This class converts between positive ints and 1-4 bytes that represent the int. All input ints must be positive. Max values stored in N bytes are: N=1: 2^8 => 256 N=2: 2^16 => 65,536 N=3: 2^24 => 16,777,216 N=4: 2^31 => 2,147,483,648 (Integer.MAX_VALUE) This was created to get most of the memory savings of a variable length integer when encoding an array of input integers, but to fix the number of bytes for each integer to the number needed to store the maximum integer in the array. This enables a binary search to be performed on the array of encoded integers. PrefixTree nodes often store offsets into a block that can fit into 1 or 2 bytes. Note that if the maximum value of an array of numbers needs 2 bytes, then it's likely that a majority of the numbers will also require 2 bytes. warnings: * no input validation for max performance * no negatives

Constructor Summary

UFIntTool()

Method Summary

static long	fromBytes(byte[] bytes)
static long	fromBytes(byte[] bytes, int offset, int width)
static byte[]	getBytes(int outputWidth, long value)
static long	maxValueForNumBytes(int numBytes)
static int	numBytes(long value)
static void	writeBytes(int outputWidth, long value, byte[] bytes, int offset)
static void	writeBytes(int outputWidth, long value, OutputStream os)

Methods inherited from class java.lang.Object

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

Constructor Detail

UFIntTool

public UFIntTool()

Method Detail

maxValueForNumBytes

public static long maxValueForNumBytes(int numBytes)

numBytes

public static int numBytes(long value)

getBytes

public static byte[] getBytes(int outputWidth,
                              long value)

writeBytes

public static void writeBytes(int outputWidth,
                              long value,
                              byte[] bytes,
                              int offset)

writeBytes

public static void writeBytes(int outputWidth,
                              long value,
                              OutputStream os)
                       throws IOException

Throws:

IOException

fromBytes

public static long fromBytes(byte[] bytes)

fromBytes

public static long fromBytes(byte[] bytes,
                             int offset,
                             int width)