org.apache.giraph.utils

Class Varint

java.lang.Object

org.apache.giraph.utils.Varint

public final class Varint
extends 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.

Method Summary

Modifier and Type	Method and Description
static int	readSignedVarInt(DataInput in)
static long	readSignedVarLong(DataInput in)
static int	readUnsignedVarInt(DataInput in)
static long	readUnsignedVarLong(DataInput in)
static int	sizeOfSignedVarInt(int value) Simulation for what will happen when writing a signed int value as varint.
static long	sizeOfSignedVarLong(long value) Simulation for what will happen when writing a signed long value as varlong.
static int	sizeOfUnsignedVarInt(int value) Simulation for what will happen when writing an unsigned int value as varint.
static long	sizeOfUnsignedVarLong(long value) Simulation for what will happen when writing an unsigned long value as varlong.
static void	writeSignedVarInt(int value, DataOutput out) Zig-zag encoding for signed ints
static void	writeSignedVarLong(long value, DataOutput out) Zig-zag encoding for signed longs
static void	writeUnsignedVarInt(int value, DataOutput out)
static void	writeUnsignedVarLong(long value, 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

writeUnsignedVarLong

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

Encodes a value using the variable-length encoding from Google Protocol Buffers.

Parameters:

value - to encode

out - to write bytes to

Throws:

IOException - if DataOutput throws IOException

writeSignedVarLong

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

Zig-zag encoding for signed longs

Parameters:

value - to encode

out - to write bytes to

Throws:

IOException - if DataOutput throws IOException

writeUnsignedVarInt

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

Parameters:

value - to encode

out - to write bytes to

Throws:

IOException

See Also:

writeVarLong(long, DataOutput)

writeSignedVarInt

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

Zig-zag encoding for signed ints

Parameters:

value - to encode

out - to write bytes to

Throws:

IOException

See Also:

writeUnsignedVarInt(int, DataOutput)

readUnsignedVarLong

public static long readUnsignedVarLong(DataInput in)
                                throws IOException

Parameters:

in - to read bytes from

Returns:

decode value

Throws:

IOException - if DataInput throws IOException

readSignedVarLong

public static long readSignedVarLong(DataInput in)
                              throws IOException

Parameters:

in - to read bytes from

Returns:

decode value

Throws:

IOException - if DataInput throws IOException

readUnsignedVarInt

public static int readUnsignedVarInt(DataInput in)
                              throws IOException

Parameters:

in - to read bytes from

Returns:

decode value

Throws:

IOException - if DataInput throws IOException

readSignedVarInt

public static int readSignedVarInt(DataInput in)
                            throws IOException

Parameters:

in - to read bytes from

Returns:

decode value

Throws:

IOException - if DataInput throws IOException

sizeOfUnsignedVarLong

public static long sizeOfUnsignedVarLong(long value)
                                  throws IOException

Simulation for what will happen when writing an unsigned long value as varlong.

Parameters:

value - to consider

Returns:

the number of bytes needed to write value.

Throws:

IOException

sizeOfSignedVarLong

public static long sizeOfSignedVarLong(long value)
                                throws IOException

Simulation for what will happen when writing a signed long value as varlong.

Parameters:

value - to consider

Returns:

the number of bytes needed to write value.

Throws:

IOException

sizeOfUnsignedVarInt

public static int sizeOfUnsignedVarInt(int value)
                                throws IOException

Simulation for what will happen when writing an unsigned int value as varint.

Parameters:

value - to consider

Returns:

the number of bytes needed to write value.

Throws:

IOException

sizeOfSignedVarInt

public static int sizeOfSignedVarInt(int value)
                              throws IOException

Simulation for what will happen when writing a signed int value as varint.

Parameters:

value - to consider

Returns:

the number of bytes needed to write value.

Throws:

IOException