com.db4o.defragment

Class DatabaseIdMapping

java.lang.Object

com.db4o.defragment.AbstractIdMapping

com.db4o.defragment.DatabaseIdMapping

All Implemented Interfaces:

IdMapping

public class DatabaseIdMapping
extends AbstractIdMapping

Database based mapping for IDs during a defragmentation run. Use this mapping to keep memory consumption lower than when using the InMemoryIdMapping.

See Also:

Defragment

Constructor Summary

Constructors

Constructor and Description
DatabaseIdMapping(java.lang.String fileName) Will maintain the ID mapping as a BTree in the file with the given path.
DatabaseIdMapping(java.lang.String fileName, int nodeSize, int commitFrequency) Will maintain the ID mapping as a BTree in the file with the given path.

Method Summary

Methods

Modifier and Type	Method and Description
int	addressForId(int id) returns the slot address for an ID
void	close() Shuts down the mapping after use.
void	commit()
void	mapId(int id, Slot slot) Maps an ID to a slot
protected void	mapNonClassIDs(int origID, int mappedID)
int	mappedId(int oldID) Returns a previously registered mapping ID for the given ID if it exists.
void	open() Prepares the mapping for use.
Visitable<SlotChange>	slotChanges() provides a Visitable of all mappings of IDs to slots.

Methods inherited from class com.db4o.defragment.AbstractIdMapping

mapId, mappedClassID

Methods inherited from class java.lang.Object

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

Constructor Detail

DatabaseIdMapping

public DatabaseIdMapping(java.lang.String fileName)

Will maintain the ID mapping as a BTree in the file with the given path. If a file exists in this location, it will be DELETED. Node size and cache height of the tree will be the default values used by the BTree implementation. The tree will never commit.

Parameters:

fileName - The location where the BTree file should be created.

DatabaseIdMapping

public DatabaseIdMapping(java.lang.String fileName,
                 int nodeSize,
                 int commitFrequency)

Will maintain the ID mapping as a BTree in the file with the given path. If a file exists in this location, it will be DELETED.

Parameters:

fileName - The location where the BTree file should be created.

nodeSize - The size of a BTree node

commitFrequency - The number of inserts after which a commit should be issued (<=0: never commit)

Method Detail

mappedId

public int mappedId(int oldID)

Description copied from interface: IdMapping

Returns a previously registered mapping ID for the given ID if it exists.

Returns:

The mapping ID for the given original ID or 0, if none has been registered.

mapNonClassIDs

protected void mapNonClassIDs(int origID,
                  int mappedID)

Specified by:

mapNonClassIDs in class AbstractIdMapping

open

public void open()
          throws java.io.IOException

Description copied from interface: IdMapping

Prepares the mapping for use.

Throws:

java.io.IOException

close

public void close()

Description copied from interface: IdMapping

Shuts down the mapping after use.

mapId

public void mapId(int id,
         Slot slot)

Description copied from interface: IdMapping

Maps an ID to a slot

slotChanges

public Visitable<SlotChange> slotChanges()

Description copied from interface: IdMapping

provides a Visitable of all mappings of IDs to slots.

addressForId

public int addressForId(int id)

Description copied from interface: IdMapping

returns the slot address for an ID

commit

public void commit()