org.planx.xmlstore.regions
Class Region

java.lang.Object
  org.planx.xmlstore.regions.Region

public class Region
extends Object

A Region is a collection of nodes. There are only two ways a Region is changed: When it is first not closed and exists only in memory, new nodes can be added with the save method and outgoing inter-region pointers will be found at once and the incoming sets of the target regions updated. Thus, in this case, when persisting the (non-closed) region it is not necessary to scan for outgoing pointers. Also, in this case, the identifier of the region is not changed.

Second, the Sharer may update data through the use of a region node. This is obtained by calling getRegionRoot(org.planx.xmlstore.regions.Region). See the Sharer code for the sequence of steps needed to ensure consistency of incoming and outgoing sets when several regions are shared at the same time.

Should be synchronized externally.

Author:

Thomas Ambus

Nested Class Summary

static class

Region.Statistics

Method Summary

void	cache() Load this Region to memory.
void	flush() Flushes this Region from memory by persisting it and releasing memory.
LocalLocator	getBound()
Group	getGroup()
FileSystemIdentifier	getIdentifier()
int	getLocalId() A local unique identifier useful for making a total order on regions for consistent canonical node choosing policies.
int	incomingSize()
boolean	isCached() Returns true if this Region is currently in memory.
boolean	isClosed() Returns true if this Region is closed for¨ further application writes (the sharer may still modify the region).
boolean	isContained(LocalLocator loc) Returns true if the specified LocalLocator points to data in this Region.
boolean	isPersisted() Returns true if the on-disk representation of this Region is up-to-date.
SystemNode	load(LocalLocator loc, Reference secondaryRef) Loads the node with the specified locator from this region.
int	originalSize()
int	outgoingSize()
void	persist() Persists the in-memory version of this Region to disk.
LocalLocator	save(SystemNode node) Can only save to non-closed Region.
void	setGroup(Group group)
int	size()
Region.Statistics	statistics()
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

isContained

public boolean isContained(LocalLocator loc)

Returns true if the specified LocalLocator points to data in this Region.

isClosed

public boolean isClosed()

Returns true if this Region is closed for¨ further application writes (the sharer may still modify the region).

isCached

public boolean isCached()

Returns true if this Region is currently in memory.

isPersisted

public boolean isPersisted()

Returns true if the on-disk representation of this Region is up-to-date.

getGroup

public Group getGroup()

setGroup

public void setGroup(Group group)

getLocalId

public int getLocalId()

A local unique identifier useful for making a total order on regions for consistent canonical node choosing policies.

getIdentifier

public FileSystemIdentifier getIdentifier()

getBound

public LocalLocator getBound()

load

public SystemNode load(LocalLocator loc,
                       Reference secondaryRef)
                throws IOException,
                       UnknownReferenceException

Loads the node with the specified locator from this region. TODO: The second argument has been deprecated, please remove.

Throws:

IOException

UnknownReferenceException

save

public LocalLocator save(SystemNode node)
                  throws IOException

Can only save to non-closed Region.

Throws:

IOException

cache

public void cache()
           throws IOException,
                  UnknownReferenceException

Load this Region to memory.

Throws:

IOException

UnknownReferenceException

flush

public void flush()
           throws IOException,
                  UnknownReferenceException

Flushes this Region from memory by persisting it and releasing memory.

Throws:

IOException

UnknownReferenceException

persist

public void persist()
             throws IOException,
                    UnknownReferenceException

Persists the in-memory version of this Region to disk.

Throws:

IOException

UnknownReferenceException

toString

public String toString()

Overrides:

toString in class Object

size

public int size()

originalSize

public int originalSize()

incomingSize

public int incomingSize()

outgoingSize

public int outgoingSize()

statistics

public Region.Statistics statistics()