com.google.uzaygezen.core

Class MapRegionInspector<T,V extends Content<V>>

java.lang.Object

com.google.uzaygezen.core.MapRegionInspector<T,V>

Type Parameters:

T - filter type

All Implemented Interfaces:

RegionInspector<T,V>

public class MapRegionInspector<T,V extends Content<V>>
extends Object
implements RegionInspector<T,V>

Assessor of spatial relationships that first check the input into an internal rollup map, and keeps track of whether the current zooming level is still covered by the map or not. It only works if no assess(com.google.uzaygezen.core.Pow2LengthBitSetRange, java.util.List<com.google.uzaygezen.core.Pow2LengthBitSetRange>) calls are skipped. It is designed to improve region inspection in a couple of ways:

• If we receive as input a query region that hangs from an internal node in the map, then we know for sure that that particular region is all vacuum and no further region assessment is required, but even more importantly, the backtracking query builder will join the vacuum to adjacent ranges thus reducing the number of index intervals generated.
• If the current region is found in the map, but it is evaluated as disjoint by the delegate, it provides as the estimate the smaller of the latest node's count from the map proportional to the index range length, and the one provided by the delegate, improving the estimate over the one provided by the delegate.
• When disguiseCacheHits is set, if the current region is found in the map, and it is evaluated as covered, with no potential over selectivity by the delegate, it produces a disjoint assessment and it remembers in an internal cache the skipped values. Caveat: when using this option, since the internal cache doesn't remember the filter produced by the delegate inspector, the delegate inspector must never return a meaningful filter for covered regions with no potential over-selectivity.

Author:

Daniel Aioanei

Method Summary

Methods

Modifier and Type	Method and Description
Assessment<T,V>	assess(Pow2LengthBitSetRange indexRange, List<Pow2LengthBitSetRange> orthotope) Assesses the spatial relationship of an orthotope with respect to the query region.
static <T,V extends Content<V>> MapRegionInspector<T,V>	create(Map<Pow2LengthBitSetRange,NodeValue<V>> rolledupMap, RegionInspector<T,V> delegate, boolean disguiseCacheHits, V zero, V one)
Map<BitVector,V>	getDisguisedCacheHits()
int	getNumberOfDimensions()
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

create

public static <T,V extends Content<V>> MapRegionInspector<T,V> create(Map<Pow2LengthBitSetRange,NodeValue<V>> rolledupMap,
                                                      RegionInspector<T,V> delegate,
                                                      boolean disguiseCacheHits,
                                                      V zero,
                                                      V one)

getNumberOfDimensions

public int getNumberOfDimensions()

Specified by:

getNumberOfDimensions in interface RegionInspector<T,V extends Content<V>>

assess

public Assessment<T,V> assess(Pow2LengthBitSetRange indexRange,
                     List<Pow2LengthBitSetRange> orthotope)

Description copied from interface: RegionInspector

Assesses the spatial relationship of an orthotope with respect to the query region. The space filling query framework doesn't know any particulars of the query region. Instead it will try and find out about it piece by piece by calling this method. The method can approximate the query region by making it look larger, to minimise the amount of work needed to build the index query corresponding to the query region in question. For instance an implementation could use a histogram to better estimate the size of the gaps, or approximate the surface of the query region with hypercubes that have on each dimension the lowest k bits going from all zeros to all ones.

When the framework calls this method it is guaranteed that the size of the index range is equal to the content of the orthotope.

Specified by:

assess in interface RegionInspector<T,V extends Content<V>>

Parameters:

indexRange - space filling curve index range

orthotope - orthotope specification. The caller might reuse this parameter so no reference should be kept to it by any concrete region inspector.

Returns:

the immutable assessment result

getDisguisedCacheHits

public Map<BitVector,V> getDisguisedCacheHits()

toString

public String toString()

Overrides:

toString in class Object