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




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
ChecksumOperation()



           
 



Method Summary




 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