org.apache.pig.data.utils

Class SedesHelper.Varint

java.lang.Object

org.apache.pig.data.utils.SedesHelper.Varint

Enclosing class:

SedesHelper

public static class SedesHelper.Varint
extends java.lang.Object

Encodes signed and unsigned values using a common variable-length scheme, found for example in Google's Protocol Buffers. It uses fewer bytes to encode smaller values, but will use slightly more bytes to encode large values.

Signed values are further encoded using so-called zig-zag encoding in order to make them "compatible" with variable-length encoding.

This is taken from mahout-core, and is included to avoid having to pull in the entirety of Mahout.

Method Summary

Modifier and Type	Method and Description
static int	readSignedVarInt(java.io.DataInput in)
static long	readSignedVarLong(java.io.DataInput in)
static int	readUnsignedVarInt(java.io.DataInput in)
static long	readUnsignedVarLong(java.io.DataInput in)
static void	writeSignedVarInt(int value, java.io.DataOutput out)
static void	writeSignedVarLong(long value, java.io.DataOutput out) Encodes a value using the variable-length encoding from Google Protocol Buffers.
static void	writeUnsignedVarInt(int value, java.io.DataOutput out)
static void	writeUnsignedVarLong(long value, java.io.DataOutput out) Encodes a value using the variable-length encoding from Google Protocol Buffers.

Methods inherited from class java.lang.Object

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

Method Detail

writeSignedVarLong

public static void writeSignedVarLong(long value,
                                      java.io.DataOutput out)
                               throws java.io.IOException

Encodes a value using the variable-length encoding from Google Protocol Buffers. It uses zig-zag encoding to efficiently encode signed values. If values are known to be nonnegative, writeUnsignedVarLong(long, DataOutput) should be used.

Parameters:

value - value to encode

out - to write bytes to

Throws:

java.io.IOException - if DataOutput throws IOException

writeUnsignedVarLong

public static void writeUnsignedVarLong(long value,
                                        java.io.DataOutput out)
                                 throws java.io.IOException

Encodes a value using the variable-length encoding from Google Protocol Buffers. Zig-zag is not used, so input must not be negative. If values can be negative, use writeSignedVarLong(long, DataOutput) instead. This method treats negative input as like a large unsigned value.

Parameters:

value - value to encode

out - to write bytes to

Throws:

java.io.IOException - if DataOutput throws IOException

writeSignedVarInt

public static void writeSignedVarInt(int value,
                                     java.io.DataOutput out)
                              throws java.io.IOException

Throws:

java.io.IOException

See Also:

writeSignedVarLong(long, DataOutput)

writeUnsignedVarInt

public static void writeUnsignedVarInt(int value,
                                       java.io.DataOutput out)
                                throws java.io.IOException

Throws:

java.io.IOException

See Also:

writeUnsignedVarLong(long, DataOutput)

readSignedVarLong

public static long readSignedVarLong(java.io.DataInput in)
                              throws java.io.IOException

Parameters:

in - to read bytes from

Returns:

decode value

Throws:

java.io.IOException - if DataInput throws IOException

java.lang.IllegalArgumentException - if variable-length value does not terminate after 9 bytes have been read

See Also:

writeSignedVarLong(long, DataOutput)

readUnsignedVarLong

public static long readUnsignedVarLong(java.io.DataInput in)
                                throws java.io.IOException

Parameters:

in - to read bytes from

Returns:

decode value

Throws:

java.io.IOException - if DataInput throws IOException

java.lang.IllegalArgumentException - if variable-length value does not terminate after 9 bytes have been read

See Also:

writeUnsignedVarLong(long, DataOutput)

readSignedVarInt

public static int readSignedVarInt(java.io.DataInput in)
                            throws java.io.IOException

Throws:

java.lang.IllegalArgumentException - if variable-length value does not terminate after 5 bytes have been read

java.io.IOException - if DataInput throws IOException

See Also:

readSignedVarLong(DataInput)

readUnsignedVarInt

public static int readUnsignedVarInt(java.io.DataInput in)
                              throws java.io.IOException

Throws:

java.lang.IllegalArgumentException - if variable-length value does not terminate after 5 bytes have been read

java.io.IOException - if DataInput throws IOException

See Also:

readUnsignedVarLong(DataInput)