com.google.uzaygezen.core

Class BacktrackingQueryBuilder<F,T,V extends Content<V>,R extends Range<T,V>>

java.lang.Object

com.google.uzaygezen.core.BacktrackingQueryBuilder<F,T,V,R>

Type Parameters:

T - filter type

All Implemented Interfaces:

com.google.common.base.Supplier<Query<F,R>>, QueryBuilder<F,R>, QueryFactory<F,R>, SpaceVisitor

public class BacktrackingQueryBuilder<F,T,V extends Content<V>,R extends Range<T,V>>
extends Object
implements QueryBuilder<F,R>

Query builder that can be configured with a maximum number of filtered index ranges. That is useful for data storage systems that are somewhat limited in the number of ranges they can accept in a query. But the builder can also be configured to never try to join together two filtered ranges, by specifying a very high maximum number of ranges and that it should never try to combine two ranges with vacuum in between. In the latter case the filters are guaranteed not to be used at all, unless they are created by the region inspector itself.

Author:

Daniel Aioanei

Constructor Summary

Constructors

Constructor and Description
BacktrackingQueryBuilder(RegionInspector<F,V> regionInspector, FilterCombiner<F,V,R> intervalCombiner, int maxFilteredIndexRanges, boolean alwaysRemoveVacuum, RangeHome<T,V,R> rangeHome, V zero)

Method Summary

Methods

Modifier and Type	Method and Description
static <F,T,V extends Content<V>,R extends Range<T,V>> BacktrackingQueryBuilder<F,T,V,R>	create(RegionInspector<F,V> regionInspector, FilterCombiner<F,V,R> intervalCombiner, int maxFilteredIndexRanges, boolean removeVacuum, RangeHome<T,V,R> rangeHome, V zero)
Query<F,R>	get() Returns the query constructed so far as a random access list.
boolean	visit(Pow2LengthBitSetRange indexRange, List<Pow2LengthBitSetRange> orthotope) Checks the relationship of the input orthotope against the query region and if it is: SpatialRelation.DISJOINT: Augments the current gap with the othotope's estimated number of points. SpatialRelation.OVERLAPS: Asks to see the children. SpatialRelation.COVERED: If the current gap is zero and alwaysRemoveVacuum is true, then it joins the new index range to the previous one. Otherwise it adds the current range to the internal min-heap of ranges, with the current gap as the key.

Methods inherited from class java.lang.Object

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

Constructor Detail

BacktrackingQueryBuilder

public BacktrackingQueryBuilder(RegionInspector<F,V> regionInspector,
                        FilterCombiner<F,V,R> intervalCombiner,
                        int maxFilteredIndexRanges,
                        boolean alwaysRemoveVacuum,
                        RangeHome<T,V,R> rangeHome,
                        V zero)

Method Detail

visit

public boolean visit(Pow2LengthBitSetRange indexRange,
            List<Pow2LengthBitSetRange> orthotope)

Checks the relationship of the input orthotope against the query region and if it is:

• SpatialRelation.DISJOINT: Augments the current gap with the othotope's estimated number of points.
• SpatialRelation.OVERLAPS: Asks to see the children.
• SpatialRelation.COVERED:
  • If the current gap is zero and alwaysRemoveVacuum is true, then it joins the new index range to the previous one.
  • Otherwise it adds the current range to the internal min-heap of ranges, with the current gap as the key. Iff the number of filtered ranges exceeds as a result maxFilteredIndexRanges, does it then combine together the two ranges with the minimum gap between them. If multiple such consecutive ranges exists, one of them will be picked.

Implementation note: PriorityQueue.remove(java.lang.Object) does not specify if the removal of the least value is deterministic or not. Instead it only says that ties are broken arbitrarily. If PriorityQueue is deterministic on a specific platform, then this class is also deterministic on that particular platform.

Specified by:

visit in interface SpaceVisitor

Parameters:

indexRange - When its length is 1, the return value will be ignored since there are no more children to visit anyway on the current path. Its value is guaranteed to be greater than its value in all previous calls that either returned false, or they had an index range length of 1.

Returns:

Whether the visitor wants to zoom in.

get

public Query<F,R> get()

Returns the query constructed so far as a random access list.

Specified by:

get in interface com.google.common.base.Supplier<Query<F,R extends Range<T,V>>>

create

public static <F,T,V extends Content<V>,R extends Range<T,V>> BacktrackingQueryBuilder<F,T,V,R> create(RegionInspector<F,V> regionInspector,
                                                                                       FilterCombiner<F,V,R> intervalCombiner,
                                                                                       int maxFilteredIndexRanges,
                                                                                       boolean removeVacuum,
                                                                                       RangeHome<T,V,R> rangeHome,
                                                                                       V zero)