com.sleepycat.je.rep.util.ldiff
Class Window

java.lang.Object
  com.sleepycat.je.rep.util.ldiff.Window

public class Window
extends Object

A rolling window of key/data pairs used by the ldiff algorithm.

Constructor Summary

Window(Cursor cursor, int windowSize)
Create a window of the given size, starting at the next record pointed at by the Cursor.

Method Summary

byte[]	getBeginData()
byte[]	getBeginKey()
long	getChecksum() The checksum for the window.
long	getDiffSize()
byte[]	getMd5Hash() Compute the MD5 hash for the window.
void	nextWindow() Advance the window to the next block of records and update the rolling checksum.
void	rollWindow() Roll a window forward by one key.
int	size() The number of records in the window.

Methods inherited from class java.lang.Object

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

Constructor Detail

Window

public Window(Cursor cursor,
              int windowSize)
       throws Exception

Create a window of the given size, starting at the next record pointed at by the Cursor.

Parameters:

cursor - an open cursor on the database being diff'd

windowSize - the number of records to include in the window

Throws:

Exception

Method Detail

rollWindow

public void rollWindow()
                throws Exception

Roll a window forward by one key. The rolling checksum is adjusted to account for this move past one key/value pair. Note that the md5 hash associated with the window is computed on demand and is not updated here.

Throws:

Exception

nextWindow

public void nextWindow()

Advance the window to the next block of records and update the rolling checksum.

getChecksum

public long getChecksum()

The checksum for the window.

Returns:

the checksum for the window.

getBeginKey

public byte[] getBeginKey()

getBeginData

public byte[] getBeginData()

getDiffSize

public long getDiffSize()

getMd5Hash

public byte[] getMd5Hash()

Compute the MD5 hash for the window. This is an expensive operation and should be used sparingly.

Returns:

the MD5 for the window.

size

public int size()

The number of records in the window. The size of the window will match the value set during instantiation, until the end of the database is reached.

Returns:

the number of records in the window.