org.exist.storage.btree
Class BTree.BTreeNode

java.lang.Object
  org.exist.storage.btree.BTree.BTreeNode

All Implemented Interfaces:

Cacheable

Enclosing class:

BTree

protected final class BTree.BTreeNode

extends java.lang.Object

implements Cacheable

A node in the B+-tree. Every node is backed by a Page for storing the node's data. Both, branch and leaf nodes are represented by this class. Each node stores its keys as instances of Value and its values as pointers of type long. If the node is a branch, the long pointers point to the child nodes of the branch. If it is a leaf, the pointers contain the virtual storage of the data section associated to the key.

Author:

wolf

Field Summary

Fields inherited from interface org.exist.storage.cache.Cacheable

MAX_REF

Constructor Summary

BTree.BTreeNode(Paged.Page page, boolean newPage)

Method Summary

boolean	allowUnload() Is it safe to unload the Cacheable from the cache? Called before an object is actually removed.
int	decReferenceCount() Decrease the reference count of this object by one and return it.
long	getKey() Get a unique key for the object.
BTree.BTreeNode	getParent()
int	getReferenceCount() Get the current reference count.
int	getTimestamp() Get the current timestamp marker.
int	incReferenceCount() Increase the reference count of this object by one and return it.
boolean	isDirty()
void	setParent(BTree.BTreeNode parent) Set the link to the parent of this node.
void	setReferenceCount(int count) Set the reference count of this object.
void	setTimestamp(int timestamp) Set the timestamp marker.
boolean	sync(boolean syncJournal) Called before the object is released by the cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

BTree.BTreeNode

public BTree.BTreeNode(Paged.Page page,
                       boolean newPage)

Method Detail

setParent

public void setParent(BTree.BTreeNode parent)

Set the link to the parent of this node.

Parameters:

parent -

getParent

public BTree.BTreeNode getParent()

Returns:

the parent of this node.

getReferenceCount

public int getReferenceCount()

Description copied from interface: Cacheable

Get the current reference count.

Specified by:

getReferenceCount in interface Cacheable

Returns:

See Also:

Cacheable.getReferenceCount()

incReferenceCount

public int incReferenceCount()

Description copied from interface: Cacheable

Increase the reference count of this object by one and return it.

Specified by:

incReferenceCount in interface Cacheable

Returns:

the reference count

See Also:

Cacheable.incReferenceCount()

setReferenceCount

public void setReferenceCount(int count)

Description copied from interface: Cacheable

Set the reference count of this object.

Specified by:

setReferenceCount in interface Cacheable

Parameters:

count -

See Also:

Cacheable.setReferenceCount(int)

setTimestamp

public void setTimestamp(int timestamp)

Description copied from interface: Cacheable

Set the timestamp marker.

Specified by:

setTimestamp in interface Cacheable

Parameters:

timestamp -

See Also:

Cacheable.setTimestamp(int)

allowUnload

public boolean allowUnload()

Description copied from interface: Cacheable

Is it safe to unload the Cacheable from the cache? Called before an object is actually removed. Return false to avoid being removed.

Specified by:

allowUnload in interface Cacheable

Returns:

See Also:

Cacheable.allowUnload()

getTimestamp

public int getTimestamp()

Description copied from interface: Cacheable

Get the current timestamp marker.

Specified by:

getTimestamp in interface Cacheable

Returns:

timestamp marker

See Also:

Cacheable.getTimestamp()

sync

public boolean sync(boolean syncJournal)

Description copied from interface: Cacheable

Called before the object is released by the cache. The object should prepare to be garbage collected. All unwritten data should be flushed to disk.

Specified by:

sync in interface Cacheable

See Also:

org.exist.storage.cache.Cacheable#sync()

getKey

public long getKey()

Description copied from interface: Cacheable

Get a unique key for the object. Usually this is the page number.

Specified by:

getKey in interface Cacheable

Returns:

unique key

See Also:

Cacheable.getKey()

decReferenceCount

public int decReferenceCount()

Description copied from interface: Cacheable

Decrease the reference count of this object by one and return it.

Specified by:

decReferenceCount in interface Cacheable

Returns:

the reference count

See Also:

Cacheable.decReferenceCount()

isDirty

public boolean isDirty()

Specified by:

isDirty in interface Cacheable

See Also:

Cacheable.isDirty()