org.apache.drill.exec.util

Class ByteBufUtil.HadoopWritables

java.lang.Object

org.apache.drill.exec.util.ByteBufUtil.HadoopWritables

Enclosing class:

ByteBufUtil

public static class ByteBufUtil.HadoopWritables
extends Object

Modeled after org.apache.hadoop.io.WritableUtils. We copy the code to avoid wrapping DrillBuf to/from DataInput.

Constructor Summary

Constructors

Constructor and Description
HadoopWritables()

Method Summary

Modifier and Type	Method and Description
static int	decodeVIntSize(byte value) Parse the first byte of a vint/vlong to determine the number of bytes
static int	getVIntSize(long i) Get the encoded length if an integer is stored in a variable-length format
static boolean	isNegativeVInt(byte value) Given the first byte of a vint/vlong, determine the sign
static int	readVInt(DrillBuf buffer, int start, int end) Reads a zero-compressed encoded integer from input stream and returns it.
static long	readVLong(DrillBuf buffer, int start, int end) Reads a zero-compressed encoded long from input stream and returns it.
static void	writeVInt(DrillBuf buffer, int start, int end, int i) Serializes an integer to a binary stream with zero-compressed encoding.
static void	writeVLong(DrillBuf buffer, int start, int end, long i) Serializes a long to a binary stream with zero-compressed encoding.

Methods inherited from class java.lang.Object

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

Constructor Detail

HadoopWritables

public HadoopWritables()

Method Detail

writeVInt

public static void writeVInt(DrillBuf buffer,
                             int start,
                             int end,
                             int i)

Serializes an integer to a binary stream with zero-compressed encoding. For -120 <= i <= 127, only one byte is used with the actual value. For other values of i, the first byte value indicates whether the integer is positive or negative, and the number of bytes that follow. If the first byte value v is between -121 and -124, the following integer is positive, with number of bytes that follow are -(v+120). If the first byte value v is between -125 and -128, the following integer is negative, with number of bytes that follow are -(v+124). Bytes are stored in the high-non-zero-byte-first order.

Parameters:

buffer - DrillBuf to read from

i - Integer to be serialized

writeVLong

public static void writeVLong(DrillBuf buffer,
                              int start,
                              int end,
                              long i)

Serializes a long to a binary stream with zero-compressed encoding. For -112 <= i <= 127, only one byte is used with the actual value. For other values of i, the first byte value indicates whether the long is positive or negative, and the number of bytes that follow. If the first byte value v is between -113 and -120, the following long is positive, with number of bytes that follow are -(v+112). If the first byte value v is between -121 and -128, the following long is negative, with number of bytes that follow are -(v+120). Bytes are stored in the high-non-zero-byte-first order.

Parameters:

buffer - DrillBuf to write to

i - Long to be serialized

readVInt

public static int readVInt(DrillBuf buffer,
                           int start,
                           int end)

Reads a zero-compressed encoded integer from input stream and returns it.

Parameters:

buffer - DrillBuf to read from

Returns:

deserialized integer from stream.

readVLong

public static long readVLong(DrillBuf buffer,
                             int start,
                             int end)

Reads a zero-compressed encoded long from input stream and returns it.

Parameters:

buffer - DrillBuf to read from

Returns:

deserialized long from stream.

decodeVIntSize

public static int decodeVIntSize(byte value)

Parse the first byte of a vint/vlong to determine the number of bytes

Parameters:

value - the first byte of the vint/vlong

Returns:

the total number of bytes (1 to 9)

getVIntSize

public static int getVIntSize(long i)

Get the encoded length if an integer is stored in a variable-length format

Returns:

the encoded length

isNegativeVInt

public static boolean isNegativeVInt(byte value)

Given the first byte of a vint/vlong, determine the sign

Parameters:

value - the first byte

Returns:

is the value negative