org.opendaylight.yangtools.concepts

Class WritableObjects

java.lang.Object

org.opendaylight.yangtools.concepts.WritableObjects

@Beta
 @NonNullByDefault
public final class WritableObjects
extends Object

Utility methods for working with WritableObjects.

Author:

Robert Varga

Method Summary

Modifier and Type	Method and Description
static int	longHeaderFlags(byte header) Extract user-defined flags from a compressed long header.
static long	readFirstLong(DataInput in, byte header) Read first long value from an input.
static long	readLong(DataInput in) Read a long value from a DataInput which was previously written via writeLong(DataOutput, long).
static long	readLongBody(DataInput in, byte header) Read a long value from a DataInput as hinted by the result of readLongHeader(DataInput).
static byte	readLongHeader(DataInput in) Read the header of a compressed long value.
static long	readSecondLong(DataInput in, byte header) Read second long value from an input.
static void	writeLong(DataOutput out, long value) Shorthand for writeLong(DataOutput, long, int) with zero flags.
static void	writeLong(DataOutput out, long value, int flags) Write a long value into a DataOutput, compressing potential zero bytes.
static void	writeLongs(DataOutput out, long value0, long value1) Write two consecutive long values.

Methods inherited from class java.lang.Object

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

Method Detail

writeLong

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

Shorthand for writeLong(DataOutput, long, int) with zero flags.

Parameters:

out - Data output

value - long value to write

Throws:

IOException - if an I/O error occurs

NullPointerException - if output is null

writeLong

public static void writeLong(DataOutput out,
                             long value,
                             int flags)
                      throws IOException

Write a long value into a DataOutput, compressing potential zero bytes. This method is useful for serializing counters and similar, which have a wide range, but typically do not use it. The value provided is treated as unsigned.

This methods writes the number of trailing non-zero in the value. It then writes the minimum required bytes to reconstruct the value by left-padding zeroes. Inverse operation is performed by readLong(DataInput) or a combination of readLongHeader(DataInput) and readLongBody(DataInput, byte).

Additionally the caller can use the top four bits (i.e. 0xF0) for caller-specific flags. These will be ignored by readLong(DataInput), but can be extracted via readLongHeader(DataInput).

Parameters:

out - Data output

value - long value to write

flags - flags to store

Throws:

IOException - if an I/O error occurs

NullPointerException - if output is null

readLong

public static long readLong(DataInput in)
                     throws IOException

Read a long value from a DataInput which was previously written via writeLong(DataOutput, long).

Parameters:

in - Data input

Returns:

long value extracted from the data input

Throws:

IOException - if an I/O error occurs

NullPointerException - if input is null

readLongHeader

public static byte readLongHeader(DataInput in)
                           throws IOException

Read the header of a compressed long value. The header may contain user-defined flags, which can be extracted via longHeaderFlags(byte).

Parameters:

in - Data input

Returns:

Header of next value

Throws:

IOException - if an I/O error occurs

NullPointerException - if input is null

longHeaderFlags

public static int longHeaderFlags(byte header)

Extract user-defined flags from a compressed long header. This will return 0 if the long value originates from writeLong(DataOutput, long).

Parameters:

header - Value header, as returned by readLongHeader(DataInput)

Returns:

User-defined flags

readLongBody

public static long readLongBody(DataInput in,
                                byte header)
                         throws IOException

Read a long value from a DataInput as hinted by the result of readLongHeader(DataInput).

Parameters:

in - Data input

header - Value header, as returned by readLongHeader(DataInput)

Returns:

long value

Throws:

IOException - if an I/O error occurs

NullPointerException - if input is null

writeLongs

public static void writeLongs(DataOutput out,
                              long value0,
                              long value1)
                       throws IOException

Write two consecutive long values. These values can be read back using readLongHeader(DataInput), readFirstLong(DataInput, byte) and readSecondLong(DataInput, byte).

This is a more efficient way of serializing two longs than writeLong(DataOutput, long). This is achieved by using the flags field to hold the length of the second long -- hence saving one byte.

Parameters:

out - Data output

value0 - first long value to write

value1 - second long value to write

Throws:

IOException - if an I/O error occurs

NullPointerException - if output is null

readFirstLong

public static long readFirstLong(DataInput in,
                                 byte header)
                          throws IOException

Read first long value from an input.

Parameters:

in - Data input

header - Value header, as returned by readLongHeader(DataInput)

Returns:

First long specified in writeLongs(DataOutput, long, long)

Throws:

IOException - if an I/O error occurs

NullPointerException - if input is null

readSecondLong

public static long readSecondLong(DataInput in,
                                  byte header)
                           throws IOException

Read second long value from an input.

Parameters:

in - Data input

header - Value header, as returned by readLongHeader(DataInput)

Returns:

Second long specified in writeLongs(DataOutput, long, long)

Throws:

IOException - if an I/O error occurs

NullPointerException - if input is null