com.bigdata.util
Class ChecksumUtility

java.lang.Object
  com.bigdata.util.ChecksumUtility

public class ChecksumUtility
extends Object

Utility class for computing the Adler32 checksum of a buffer. This class is NOT thread-safe.

Version:

$Id: ChecksumUtility.java 4069 2011-01-09 20:58:02Z thompsonbry $

Author:

Bryan Thompson

TODO:

This could stand some review in its API and its usage.

Field Summary

protected Adler32	chk Used to compute the checksums.
static ThreadLocal<ChecksumUtility>	threadChk ThreadLocal ChecksumUtility factory.

Constructor Summary

ChecksumUtility()

Method Summary

int	checksum(byte[] buf)
int	checksum(byte[] buf, int sze)
int	checksum(byte[] buf, int off, int sze)
int	checksum(ByteBuffer buf) Compute the Adler32 checksum of the buffer.
int	checksum(ByteBuffer buf, int pos, int limit) Compute the Adler32 checksum of the buffer.
int	checksum(IByteArraySlice slice)
protected int	getChecksum() Return the Alder checksum, which is a 32bit value.
static ChecksumUtility	getCHK() Deprecated. Use threadChk and ThreadLocal.get().
protected void	reset() Reset the checksum.
protected void	update(ByteBuffer buf) Updates the Adler32 checksum from the data in the buffer.
protected void	update(ByteBuffer buf, int pos, int limit) Core implementation updates the Adler32 checksum from the data in the buffer.

Methods inherited from class java.lang.Object

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

Field Detail

threadChk

public static final ThreadLocal<ChecksumUtility> threadChk

ThreadLocal ChecksumUtility factory.

chk

protected final Adler32 chk

Used to compute the checksums. Exposed to subclasses so they can update the checksum for additional fields.

Constructor Detail

ChecksumUtility

public ChecksumUtility()

Method Detail

getCHK

public static ChecksumUtility getCHK()

Deprecated. Use threadChk and ThreadLocal.get().

static access to a ThreadLocal Checksum utility

Returns:

the ChecksumUtility

checksum

public int checksum(ByteBuffer buf)

Compute the Adler32 checksum of the buffer. The position, mark, and limit are unchanged by this operation. The operation is optimized when the buffer is backed by an array.

Parameters:

buf - The buffer.

Returns:

The checksum.

checksum

public int checksum(ByteBuffer buf,
                    int pos,
                    int limit)

Compute the Adler32 checksum of the buffer. The position, mark, and limit are unchanged by this operation. The operation is optimized when the buffer is backed by an array.

Parameters:

buf - The buffer.

pos - The starting position.

limit - The limit.

Returns:

The checksum.

TODO:

why pass in the pos/lim when [buf] could incorporate them?

reset

protected void reset()

Reset the checksum.

getChecksum

protected int getChecksum()

Return the Alder checksum, which is a 32bit value.

update

protected void update(ByteBuffer buf)

Updates the Adler32 checksum from the data in the buffer. The position, mark, and limit are unchanged by this operation. The operation is optimized when the buffer is backed by an array.

Parameters:

buf -

update

protected void update(ByteBuffer buf,
                      int pos,
                      int limit)

Core implementation updates the Adler32 checksum from the data in the buffer. The position, mark, and limit are unchanged by this operation. The operation is optimized when the buffer is backed by an array.

Parameters:

buf -

pos -

limit -

checksum

public int checksum(IByteArraySlice slice)

checksum

public int checksum(byte[] buf)

checksum

public int checksum(byte[] buf,
                    int sze)

checksum

public int checksum(byte[] buf,
                    int off,
                    int sze)