com.bigdata.relation.rule.eval

Class RuleState

java.lang.Object

com.bigdata.relation.rule.eval.RuleState

All Implemented Interfaces:

IRuleState

Direct Known Subclasses:

TestRuleState.RuleState2

public class RuleState
extends Object
implements IRuleState

State for a rule execution.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.apache.log4j.Logger	log
protected IVariable[][]	requiredVars Each step in the join has a set of variables that are required, either by that tail or by something downstream, be it another tail or the projection (select or construct) or the aggregation phase.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RuleState(IRule rule) For test cases.
	RuleState(IRule rule, IJoinNexus joinNexus)

Method Summary

Methods

Modifier and Type	Method and Description
protected IKeyOrder[]	computeKeyOrderForEachTail(IRule rule, IJoinNexus joinNexus, int[] order, int[] nvars) Return an array indicating the IKeyOrder that will be used when reading on each of the tail predicates.
static IVariable[][]	computeRequiredVarsForEachTail(IRule rule, int[] order) Return an array indicated what variables are required for each tail index.
IKeyOrder[]	getKeyOrder() An array of the IKeyOrder that will be used for each predicate in the tail of the rule.
int[]	getNVars() The #of unbound variables for the predicates in the tail of the Rule for the evaluation plan.
IEvaluationPlan	getPlan() The evaluation plan.
IVariable[][]	getRequiredVars() A list of variables required for each tail, by tailIndex.
IRule	getRule() The IRule being evaluated.
String	toString() Externalizes the rule and the evaluation order.
String	toString(IBindingSet bindingSet) Shows the bindings (if given), the computed evaluation order, the computed IKeyOrder, and the required variables for each IPredicate in the rule.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static final transient org.apache.log4j.Logger log

requiredVars

protected final IVariable[][] requiredVars

Each step in the join has a set of variables that are required, either by that tail or by something downstream, be it another tail or the projection (select or construct) or the aggregation phase. If a variable is not required any longer, it will be filtered out of the binding set that is passed downstream to the next tail. So right before a binding set is cloned and sent downstream, we will check the RuleState to see what variables can be dropped based on what is required at the next tail downstream.

Constructor Detail

RuleState

protected RuleState(IRule rule)

For test cases.

RuleState

public RuleState(IRule rule,
         IJoinNexus joinNexus)

Parameters:

rule - The rule.

joinNexus - The IJoinNexus.

Method Detail

getRule

public IRule getRule()

Description copied from interface: IRuleState

The IRule being evaluated.

Specified by:

getRule in interface IRuleState

getPlan

public IEvaluationPlan getPlan()

Description copied from interface: IRuleState

The evaluation plan.

Specified by:

getPlan in interface IRuleState

getNVars

public int[] getNVars()

Description copied from interface: IRuleState

The #of unbound variables for the predicates in the tail of the Rule for the evaluation plan. The array is correlated with the predicates index in the tail of the rule NOT with its evaluation order.

Specified by:

getNVars in interface IRuleState

getKeyOrder

public IKeyOrder[] getKeyOrder()

Description copied from interface: IRuleState

An array of the IKeyOrder that will be used for each predicate in the tail of the rule. The array is correlated with the predicates index in the tail of the rule NOT with its evaluation order.

Note: The fully qualified index name for a given predicate is the name of the relation for that predicate plus IKeyOrder.getIndexName().

Specified by:

getKeyOrder in interface IRuleState

getRequiredVars

public IVariable[][] getRequiredVars()

Description copied from interface: IRuleState

A list of variables required for each tail, by tailIndex. Used to filter downstream variable binding sets.

Specified by:

getRequiredVars in interface IRuleState

toString

public String toString()

Externalizes the rule and the evaluation order.

Specified by:

toString in interface IRuleState

Overrides:

toString in class Object

toString

public String toString(IBindingSet bindingSet)

Shows the bindings (if given), the computed evaluation order, the computed IKeyOrder, and the required variables for each IPredicate in the rule.

Specified by:

toString in interface IRuleState

Parameters:

bindingSet - When non-null, the current variable bindings will be displayed. Otherwise, the names of variables will be displayed rather than their bindings.

computeKeyOrderForEachTail

protected IKeyOrder[] computeKeyOrderForEachTail(IRule rule,
                                     IJoinNexus joinNexus,
                                     int[] order,
                                     int[] nvars)

Return an array indicating the IKeyOrder that will be used when reading on each of the tail predicates. The array is formed using a private IBindingSet and propagating fake bindings to each predicate in turn using the given evaluation order.

Parameters:

order - The evaluation order.

nvars - The #of unbound variables for each tail predicate is assigned by side-effect.

Returns:

An array of the IKeyOrders for each tail predicate. The array is correlated with the predicates index in the tail of the rule NOT its evaluation order.

computeRequiredVarsForEachTail

public static IVariable[][] computeRequiredVarsForEachTail(IRule rule,
                                           int[] order)

Return an array indicated what variables are required for each tail index. The rule itself has a set of required variables outside of the join (for select, construct, aggregation, etc), so these variables will automatically appear in the list for each tail. In addition, each tail will need its own variables, plus any variables that appear later in the join.

Parameters:

rule - The rule being executed.

order - The evaluation order.

Returns:

The array of required variables for each tail index.