io.milton.zsync

Class ChecksumPair

java.lang.Object

io.milton.zsync.ChecksumPair

All Implemented Interfaces:

Serializable, Cloneable

public class ChecksumPair
extends Object
implements Cloneable, Serializable

A pair of weak and strong checksums for use with the Rsync algorithm. The weak "rolling" checksum is typically a 32-bit sum derived from the Adler32 algorithm; the strong checksum is usually a 128-bit MD4 checksum.

Version:

$Revision: 1.9 $

Author:

Casey Marshall

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ChecksumPair(int weak) Create a new checksum pair with only weak checksum
ChecksumPair(int weak, byte[] strong) Create a new checksum pair with no associated offset.
ChecksumPair(int weak, byte[] strong, int seq) Create a new checksum pair with no associated offset.
ChecksumPair(int weak, byte[] strong, long offset) Create a new checksum pair with no length or sequence fields.
ChecksumPair(int weak, byte[] strong, long offset, int length, int seq) Create a new checksum pair.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj) We define equality for this object as equality between two weak sums and equality between two strong sums.
int	getLength() Return the length of the data for which this checksum pair was generated.
long	getOffset() Return the offset from where this checksum pair was generated.
int	getSequence() Return the sequence number of this checksum pair, if any.
byte[]	getStrong() Get the strong checksum.
String	getStrongHex() Get the strong checksum in hexadecimal format.
int	getWeak() Get the weak checksum.
String	getWeakHex() Get the weak checksum in hexadecimal format.
int	hashCode() Hashcode is produced from summing 4bytes of weakSum into 2bytes
String	toString() Returns a String representation of this pair.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ChecksumPair

public ChecksumPair(int weak,
                    byte[] strong,
                    long offset,
                    int length,
                    int seq)

Create a new checksum pair.

Parameters:

weak - The weak, rolling checksum.

strong - The strong checksum.

offset - The offset at which this checksum was computed.

length - The length of the data over which this sum was computed.

seq - The sequence number of this checksum pair.

ChecksumPair

public ChecksumPair(int weak,
                    byte[] strong,
                    long offset)

Create a new checksum pair with no length or sequence fields.

Parameters:

weak - The weak checksum.

strong - The strong checksum.

offset - The offset at which this checksum was computed.

ChecksumPair

public ChecksumPair(int weak,
                    byte[] strong)

Create a new checksum pair with no associated offset.

Parameters:

weak - The weak checksum.

strong - The strong checksum.

ChecksumPair

public ChecksumPair(int weak)

Create a new checksum pair with only weak checksum

Parameters:

weak - The weak checksum.

ChecksumPair

public ChecksumPair(int weak,
                    byte[] strong,
                    int seq)

Create a new checksum pair with no associated offset.

Parameters:

weak - The weak checksum.

strong - The strong checksum.

seq - The sequence number

Method Detail

getWeak

public int getWeak()

Get the weak checksum.

Returns:

The weak checksum.

Since:

1.1

getWeakHex

public String getWeakHex()

Get the weak checksum in hexadecimal format.

Returns:

The weak checksum.

getStrongHex

public String getStrongHex()

Get the strong checksum in hexadecimal format.

Returns:

The strong checksum.

getStrong

public byte[] getStrong()

Get the strong checksum.

Returns:

The strong checksum.

Since:

1.1

getOffset

public long getOffset()

Return the offset from where this checksum pair was generated.

Returns:

The offset.

getLength

public int getLength()

Return the length of the data for which this checksum pair was generated.

Returns:

The length.

getSequence

public int getSequence()

Return the sequence number of this checksum pair, if any.

Returns:

The sequence number.

hashCode

public int hashCode()

Hashcode is produced from summing 4bytes of weakSum into 2bytes

Overrides:

hashCode in class Object

Returns:

Hash value of weaksum

equals

public boolean equals(Object obj)

We define equality for this object as equality between two weak sums and equality between two strong sums.

Overrides:

equals in class Object

Parameters:

obj - The Object to test.

Returns:

True if both checksum pairs are equal.

toString

public String toString()

Returns a String representation of this pair.

Overrides:

toString in class Object

Returns:

The String representation of this pair.

Since:

1.2