com.bigdata.rdf.changesets

Class InferenceChangeLogReporter

java.lang.Object

com.bigdata.rdf.changesets.InferenceChangeLogReporter

All Implemented Interfaces:

IChangeLog

public class InferenceChangeLogReporter
extends Object
implements IChangeLog

IChangeLog implementation reports inferences as RDF Statement s. You install this change listener before writing on the sail connection. After the commit, you use addedIterator() ( removedIterator()) to visit the inferences that were added to (removed from) the KB by the transaction. If the transaction is aborted, simply discard the InferenceChangeLogReporter object. Always use a new instance of this object for each transaction. TODO The present implementation uses a LinkedHashMap to store the ISPOs for the inferences. This should be scalable up to millions of inferences, and maybe the low 10s of millions. If very large sets of inferences will be drawn, then we could substitute an HTree index for the LinkedHashSet. The existing NativeDistinctFilter class automatically converts from a JVM hash collection to an HTree and and could be used trivially as a replacement for the LinkedHashSet in this class. In this case, the native memory associated with the HTree needs to be released, e.g., through an ICloseable protocol on the change listener.

Author:

Bryan Thompson

Constructor Summary

Constructors

Constructor and Description
InferenceChangeLogReporter(AbstractTripleStore kb)

Method Summary

Methods

Modifier and Type	Method and Description
BigdataStatementIterator	addedIterator() Return iterator visiting the inferences that were added to the KB.
void	changeEvent(IChangeRecord record) Occurs when a statement add or remove is flushed to the indices (but not yet committed).
void	clear() Clear the internal state.
void	close() Close any open resources.
BigdataStatementIterator	removedIterator() Return iterator visiting the inferences that were removed from the KB.
void	transactionAborted() Occurs if the current SAIL transaction is aborted.
void	transactionBegin() Message issued when a new transaction will begin.
void	transactionCommited(long commitTime) Occurs when the current SAIL transaction is committed.
void	transactionPrepare() Message issued when preparing for a commit.

Methods inherited from class java.lang.Object

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

Constructor Detail

InferenceChangeLogReporter

public InferenceChangeLogReporter(AbstractTripleStore kb)

Parameters:

kb - The KB (used to resolve IVs to Values).

Method Detail

clear

public void clear()

Clear the internal state. This may be used to reset the listener if multiple commits are used for the same connection.

Note: It is faster to get a new InferenceChangeLogReporter than to clear the internal maps, but you can not replace an IChangeLog listener once established on a connection.

changeEvent

public void changeEvent(IChangeRecord record)

Description copied from interface: IChangeLog

Occurs when a statement add or remove is flushed to the indices (but not yet committed).

Specified by:

changeEvent in interface IChangeLog

Parameters:

record - the IChangeRecord

transactionBegin

public void transactionBegin()

Description copied from interface: IChangeLog

Message issued when a new transaction will begin.

Specified by:

transactionBegin in interface IChangeLog

transactionPrepare

public void transactionPrepare()

Description copied from interface: IChangeLog

Message issued when preparing for a commit. The next message will be either IChangeLog.transactionCommited(long) or IChangeLog.transactionAborted().

Note: The listener will have observed all updates by the time this message is generated. Thus, this message can be used to validate post-conditions for the transaction.

Specified by:

transactionPrepare in interface IChangeLog

transactionCommited

public void transactionCommited(long commitTime)

Description copied from interface: IChangeLog

Occurs when the current SAIL transaction is committed.

Specified by:

transactionCommited in interface IChangeLog

Parameters:

commitTime - The timestamp associated with the commit point.

transactionAborted

public void transactionAborted()

Description copied from interface: IChangeLog

Occurs if the current SAIL transaction is aborted.

Specified by:

transactionAborted in interface IChangeLog

close

public void close()

Description copied from interface: IChangeLog

Close any open resources.

Specified by:

close in interface IChangeLog

addedIterator

public BigdataStatementIterator addedIterator()

Return iterator visiting the inferences that were added to the KB.

removedIterator

public BigdataStatementIterator removedIterator()

Return iterator visiting the inferences that were removed from the KB.