org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.StartStep Java Examples

/**
 * Many parent traversals drip feed their start vertices in one at a time. To best exploit
 * the multiQuery we need to load all possible starts in one go so this method will attempt
 * to find a JanusGraphMultiQueryStep with the starts of the parent, and if found cache it.
 */
private void setParentMultiQueryStep() {
    Step firstStep = traversal.getStartStep();
    while (firstStep instanceof StartStep || firstStep instanceof SideEffectStep) {
        // Want the next step if this is a side effect
        firstStep = firstStep.getNextStep();
    }
    if (this.equals(firstStep)) {
        Step<?, ?> parentStep = traversal.getParent().asStep();
        if (JanusGraphTraversalUtil.isMultiQueryCompatibleStep(parentStep)) {
            Step<?, ?> parentPreviousStep = parentStep.getPreviousStep();
            if (parentStep instanceof RepeatStep) {
                RepeatStep repeatStep = (RepeatStep) parentStep;
                List<RepeatEndStep> repeatEndSteps = TraversalHelper.getStepsOfClass(RepeatEndStep.class, repeatStep.getRepeatTraversal());
                if (repeatEndSteps.size() == 1) {
                    parentPreviousStep = repeatEndSteps.get(0).getPreviousStep();
                }
            }
            if (parentPreviousStep instanceof ProfileStep) {
                parentPreviousStep = parentPreviousStep.getPreviousStep();
            }
            if (parentPreviousStep instanceof JanusGraphMultiQueryStep) {
                parentMultiQueryStep = (JanusGraphMultiQueryStep) parentPreviousStep;
            }
        }
    }
}
 

private static void getMultiQueryCompatibleStepsFromChildTraversal(Traversal.Admin<?, ?> childTraversal, Step parentStep, Set<Step> multiQueryCompatibleSteps) {
    Step firstStep = childTraversal.getStartStep();
    while (firstStep instanceof StartStep || firstStep instanceof SideEffectStep) {
        // Want the next step if this is a side effect
        firstStep = firstStep.getNextStep();
    }
    if (firstStep.getClass().isAssignableFrom(VertexStep.class)) {
        multiQueryCompatibleSteps.add(parentStep);
    }
}
 

/**
 * A step modulator that provides a label to the step that can be accessed later in the traversal by other steps.
 *
 * @param stepLabel  the name of the step
 * @param stepLabels additional names for the label
 * @return the traversal with the modified end step
 * @see <a href="http://tinkerpop.apache.org/docs/${project.version}/reference/#as-step" target="_blank">Reference Documentation - As Step</a>
 * @since 3.0.0-incubating
 */
public default GraphTraversal<S, E> as(final String stepLabel, final String... stepLabels) {
    this.asAdmin().getBytecode().addStep(Symbols.as, stepLabel, stepLabels);
    if (this.asAdmin().getSteps().size() == 0) this.asAdmin().addStep(new StartStep<>(this.asAdmin()));
    final Step<?, E> endStep = this.asAdmin().getEndStep();
    endStep.addLabel(stepLabel);
    for (final String label : stepLabels) {
        endStep.addLabel(label);
    }
    return this;
}
 

private static Set<Scoping.Variable> getVariableLocations(final Set<Scoping.Variable> variables, final Traversal.Admin<?, ?> traversal) {
    if (variables.size() == 2) return variables;    // has both START and END so no need to compute further
    final Step<?, ?> startStep = traversal.getStartStep();
    if (StartStep.isVariableStartStep(startStep))
        variables.add(Scoping.Variable.START);
    else if (startStep instanceof WherePredicateStep) {
        if (((WherePredicateStep) startStep).getStartKey().isPresent())
            variables.add(Scoping.Variable.START);
    } else if (startStep instanceof WhereTraversalStep.WhereStartStep) {
        if (!((WhereTraversalStep.WhereStartStep) startStep).getScopeKeys().isEmpty())
            variables.add(Scoping.Variable.START);
    } else if (startStep instanceof MatchStep.MatchStartStep) {
        if (((MatchStep.MatchStartStep) startStep).getSelectKey().isPresent())
            variables.add(Scoping.Variable.START);
    } else if (startStep instanceof MatchStep) {
        for (final Traversal.Admin<?, ?> global : ((MatchStep<?, ?>) startStep).getGlobalChildren()) {
            TraversalHelper.getVariableLocations(variables, global);
        }
    } else if (startStep instanceof ConnectiveStep || startStep instanceof NotStep || startStep instanceof WhereTraversalStep) {
        for (final Traversal.Admin<?, ?> local : ((TraversalParent) startStep).getLocalChildren()) {
            TraversalHelper.getVariableLocations(variables, local);
        }
    }
    ///
    final Step<?, ?> endStep = traversal.getEndStep();
    if (endStep instanceof WherePredicateStep) {
        if (((WherePredicateStep) endStep).getStartKey().isPresent())
            variables.add(Scoping.Variable.END);
    } else if (endStep instanceof WhereTraversalStep.WhereEndStep) {
        if (!((WhereTraversalStep.WhereEndStep) endStep).getScopeKeys().isEmpty())
            variables.add(Scoping.Variable.END);
    } else if (endStep instanceof MatchStep.MatchEndStep) {
        if (((MatchStep.MatchEndStep) endStep).getMatchKey().isPresent())
            variables.add(Scoping.Variable.END);
    } else if (!endStep.getLabels().isEmpty())
        variables.add(Scoping.Variable.END);
    ///
    return variables;
}
 

@Override
public void apply(final Traversal.Admin<?, ?> traversal) {
    //Only optimize SqlgGraph. StarGraph also passes through here.
    if (!(traversal.getGraph().orElseThrow(IllegalStateException::new) instanceof SqlgGraph)) {
        return;
    }
    if (!SqlgTraversalUtil.mayOptimize(traversal)) {
        return;
    }
    while (true) {
        Optional<StartStep> startStepOptional = TraversalHelper.getLastStepOfAssignableClass(StartStep.class, traversal);
        if (startStepOptional.isPresent()) {
            StartStep<?> startStep = startStepOptional.get();


            SqlgStartStepBarrier<?> sqlgStartStepBarrier = new SqlgStartStepBarrier<>(traversal, startStep);
            for (String label : startStep.getLabels()) {
                sqlgStartStepBarrier.addLabel(label);
            }

            //noinspection unchecked
            TraversalHelper.replaceStep((Step) startStep, sqlgStartStepBarrier, traversal);
        } else {
            break;
        }
    }
}
 

private static boolean legalCurrentStep(final Step<?, ?> step) {
    return !(step instanceof EmptyStep || step instanceof ProfileSideEffectStep || step instanceof HasNextStep ||
            step instanceof ComputerAwareStep.EndStep || (step instanceof StartStep && !StartStep.isVariableStartStep(step)) ||
            GraphStep.isStartStep(step));
}
 

public SqlgStartStepBarrier(final Traversal.Admin traversal, StartStep<S> startStep) {
    super(traversal);
    this.start = startStep.getStart();
}