org.apache.derby.impl.store.raw.log

Class ChecksumOperation

java.lang.Object

org.apache.derby.impl.store.raw.log.ChecksumOperation

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Formatable, TypedFormat, Loggable

public class ChecksumOperation
extends java.lang.Object
implements Loggable

A Log Operation that represents a checksum for a group of log records that are written to the tranaction log file.

See Also:

Loggable, Serialized Form

Format ID	LOGOP_CHECKSUM the formatId is written by FormatIdOutputStream when this object is written out by writeObject
Purpose	checksum one or more log records while writing to disk
Upgrade
Disk Layout	checksumAlgo(byte) the checksum algorithm checksumValue(long) the checksum value dataLength(int) number of bytes that the checksum is calculated

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.zip.Checksum	checksum
private byte	checksumAlgo
private long	checksumValue
static byte	CRC32_ALGORITHM
private int	dataLength
private static int	formatLength

Fields inherited from interface org.apache.derby.iapi.store.raw.Loggable

ABORT, BI_LOG, CHECKSUM, COMMIT, COMPENSATION, FILE_RESOURCE, FIRST, LAST, PREPARE, RAWSTORE, XA_NEEDLOCK

Constructor Summary

Constructors

Constructor and Description
ChecksumOperation()

Method Summary

Methods

Modifier and Type	Method and Description
void	doMe(Transaction xact, LogInstant instant, LimitObjectInput in) Nothing to do for the checksum log record because it does need to be applied during redo.
protected int	getDataLength() Access attributes of the checksum log record
ByteArray	getPreparedLog() the default for prepared log is always null for all the operations that don't have optionalData.
int	getStoredSize()
int	getTypeFormatId() Return my format identifier.
int	group() Checksum is a raw store operation
void	init()
private void	initializeChecksumAlgo()
protected boolean	isChecksumValid(byte[] data, int off, int length)
boolean	needsRedo(Transaction xact) Checksum does not need to be redone, it is used to just verify that log records are written completely.
void	readExternal(java.io.ObjectInput in)
void	releaseResource(Transaction xact) Checksum has no resources to release
protected void	reset()
java.lang.String	toString() DEBUG: Print self.
protected void	update(byte[] buf, int off, int len)
void	writeExternal(java.io.ObjectOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

checksumAlgo

private byte checksumAlgo

checksumValue

private long checksumValue

dataLength

private int dataLength

checksum

private java.util.zip.Checksum checksum

CRC32_ALGORITHM

public static final byte CRC32_ALGORITHM

See Also:

Constant Field Values

formatLength

private static final int formatLength

Constructor Detail

ChecksumOperation

public ChecksumOperation()

Method Detail

init

public void init()

update

protected void update(byte[] buf,
          int off,
          int len)

reset

protected void reset()

initializeChecksumAlgo

private void initializeChecksumAlgo()

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

java.lang.ClassNotFoundException

getStoredSize

public int getStoredSize()

getTypeFormatId

public int getTypeFormatId()

Return my format identifier.

Specified by:

getTypeFormatId in interface TypedFormat

Returns:

The identifier. (A UUID stuffed in an array of 16 bytes).

doMe

public void doMe(Transaction xact,
        LogInstant instant,
        LimitObjectInput in)
          throws StandardException

Nothing to do for the checksum log record because it does need to be applied during redo.

Specified by:

doMe in interface Loggable

Parameters:

xact - the Transaction

instant - the log instant of this operation

in - optional data

Throws:

StandardException - Standard Derby policy.

getPreparedLog

public ByteArray getPreparedLog()

the default for prepared log is always null for all the operations that don't have optionalData. If an operation has optional data, the operation need to prepare the optional data for this method. Checksum has no optional data to write out

Specified by:

getPreparedLog in interface Loggable

needsRedo

public boolean needsRedo(Transaction xact)

Checksum does not need to be redone, it is used to just verify that log records are written completely.

Specified by:

needsRedo in interface Loggable

Parameters:

xact - The transaction trying to redo this operation

Returns:

true if operation needs redoing, false if not.

See Also:

Loggable.releaseResource(org.apache.derby.iapi.store.raw.Transaction)

releaseResource

public void releaseResource(Transaction xact)

Checksum has no resources to release

Specified by:

releaseResource in interface Loggable

group

public int group()

Checksum is a raw store operation

Specified by:

group in interface Loggable

getDataLength

protected int getDataLength()

Access attributes of the checksum log record

isChecksumValid

protected boolean isChecksumValid(byte[] data,
                      int off,
                      int length)

toString

public java.lang.String toString()

DEBUG: Print self.

Overrides:

toString in class java.lang.Object