Package org.apache.jena.reasoner.rulesys.impl

Class Generator

java.lang.Object

org.apache.jena.reasoner.rulesys.impl.Generator

All Implemented Interfaces:

LPAgendaEntry, LPInterpreterContext, LPInterpreterState

public class Generator
extends java.lang.Object
implements LPAgendaEntry, LPInterpreterContext

A generator represents a set of memoized results for a single tabled subgoal. The generator may be complete (in which case it just contains the complete cached set of results for a goal), ready (not complete but likely to product more results if called) or blocked (not complete and awaiting results from a dependent generator).

Each generator may have multiple associated consumer choice points representing different choices in satisfying the generator's goal.

Constructor Summary

Constructors

Constructor	Description
Generator(LPInterpreter interpreter, TriplePattern goal)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	addConsumer(ConsumerChoicePointFrame ccp)	Add a new client choince point to consume results from this generator.
void	checkForCompletions()	Check for deadlocked states where none of the generators we are (indirectly) dependent on can run.
static void	checkForCompletions(java.util.Collection<? extends Generator> completions)	Check for deadlocked states across a collection of generators which have been run.
Generator	getGenerator()	Return the generator associated with this entry (might be the entry itself)
boolean	isComplete()	Return true if the generator is complete.
boolean	isReady()	Return true if the generator is ready to be scheduled (i.e.
void	notifyBlockedOn(ConsumerChoicePointFrame ccp)	Notify that the interpreter has now blocked on the given choice point.
void	notifyFinished(ConsumerChoicePointFrame ccp)	Notify this context that the given choice point has terminated and can be remove from the wait list.
void	notifyResults()	Signal dependents that we have new results.
int	numResults()	Return the number of results available from this context.
void	pump()	Start this generator running for the first time.
void	pump(LPInterpreterState context)	Start this generator running from the given previous blocked generating choice point.
void	removeConsumer(ConsumerChoicePointFrame ccp)	Remove a terminated consuming choice point from the state set.
void	setComplete()	Signal that this generator is complete, no more results can be created.
void	setReady(ConsumerChoicePointFrame ccp)	Directly set that this generator is ready (because the generator for one of its generatingCPs has produced new results).

Methods inherited from class java.lang.Object

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

Constructor Detail

Generator

public Generator(LPInterpreter interpreter,
                 TriplePattern goal)

Constructor.

Parameters:

interpreter - an initialized interpreter instance that will answer results for this generator.

Method Detail

numResults

public int numResults()

Return the number of results available from this context.

isReady

public boolean isReady()

Return true if the generator is ready to be scheduled (i.e. it is not known to be complete and not known to be waiting for a dependent generator).

Specified by:

isReady in interface LPAgendaEntry

Specified by:

isReady in interface LPInterpreterContext

setReady

public void setReady(ConsumerChoicePointFrame ccp)

Directly set that this generator is ready (because the generator for one of its generatingCPs has produced new results).

Specified by:

setReady in interface LPInterpreterContext

isComplete

public boolean isComplete()

Return true if the generator is complete.

setComplete

public void setComplete()

Signal that this generator is complete, no more results can be created.

addConsumer

public void addConsumer(ConsumerChoicePointFrame ccp)

Add a new client choince point to consume results from this generator.

removeConsumer

public void removeConsumer(ConsumerChoicePointFrame ccp)

Remove a terminated consuming choice point from the state set.

notifyResults

public void notifyResults()

Signal dependents that we have new results.

notifyBlockedOn

public void notifyBlockedOn(ConsumerChoicePointFrame ccp)

Notify that the interpreter has now blocked on the given choice point.

Specified by:

notifyBlockedOn in interface LPInterpreterContext

notifyFinished

public void notifyFinished(ConsumerChoicePointFrame ccp)

Notify this context that the given choice point has terminated and can be remove from the wait list.

Specified by:

notifyFinished in interface LPInterpreterContext

pump

public void pump()

Start this generator running for the first time. Should be called from within an appropriately synchronized block.

Specified by:

pump in interface LPAgendaEntry

pump

public void pump(LPInterpreterState context)

Start this generator running from the given previous blocked generating choice point. Should be called from within an appropriately synchronized block.

getGenerator

public Generator getGenerator()

Return the generator associated with this entry (might be the entry itself)

Specified by:

getGenerator in interface LPAgendaEntry

checkForCompletions

public void checkForCompletions()

Check for deadlocked states where none of the generators we are (indirectly) dependent on can run.

checkForCompletions

public static void checkForCompletions(java.util.Collection<? extends Generator> completions)

Check for deadlocked states across a collection of generators which have been run.