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

Field Summary

Fields
Modifier and Type	Field	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 Description

ChecksumOperation()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	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

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

Class ChecksumOperation

Field Summary

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

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

checksumAlgo

checksumValue

dataLength

checksum

CRC32_ALGORITHM

formatLength

Constructor Detail

ChecksumOperation

Method Detail

init

update

reset

initializeChecksumAlgo

writeExternal

readExternal

getStoredSize

getTypeFormatId

doMe

getPreparedLog

needsRedo

releaseResource

group

getDataLength

isChecksumValid

toString