Package com.tangosol.util.filter

Interface IndexAwareFilter<K,V>

All Superinterfaces:

EntryFilter<K,V>, Filter<V>, Serializable

All Known Implementing Classes:

AllFilter, AlwaysFilter, AndFilter, AnyFilter, ArrayFilter, BetweenFilter, ComparisonFilter, ContainsAllFilter, ContainsAnyFilter, ContainsFilter, EqualsFilter, ExtractorFilter, GreaterEqualsFilter, GreaterFilter, InFilter, InKeySetFilter, IsNotNullFilter, IsNullFilter, KeyFilter, LessEqualsFilter, LessFilter, LikeFilter, LimitFilter, NeverFilter, NotEqualsFilter, NotFilter, OrFilter, PredicateFilter, PresentFilter, PriorityFilter, RegexFilter, XorFilter

public interface IndexAwareFilter<K,V>
extends EntryFilter<K,V>

IndexAwareFilter is an extension to the EntryFilter interface that allows a filter to use a Map index to fully or partially evaluate itself.

Author:

cp/gg 2002.10.31

Method Summary

Modifier and Type	Method	Description
Filter<?>	applyIndex(Map<? extends ValueExtractor<? extends V,?>,? extends MapIndex<? extends K,? extends V,?>> mapIndexes, Set<? extends K> setKeys)	Filter remaining keys using a Map of available indexes.
int	calculateEffectiveness(Map<? extends ValueExtractor<? extends V,?>,? extends MapIndex<? extends K,? extends V,?>> mapIndexes, Set<? extends K> setKeys)	Given a Map of available indexes, determine if this IndexAwareFilter can use any of the indexes to assist in its processing, and if so, determine how effective the use of that index would be.

Methods inherited from interface com.tangosol.util.filter.EntryFilter

evaluateEntry

Methods inherited from interface com.tangosol.util.Filter

and, asLimitFilter, associatedWith, evaluate, forKeys, forPartitions, or, xor

Method Detail

calculateEffectiveness

int calculateEffectiveness(Map<? extends ValueExtractor<? extends V,?>,? extends MapIndex<? extends K,? extends V,?>> mapIndexes,
                           Set<? extends K> setKeys)

Given a Map of available indexes, determine if this IndexAwareFilter can use any of the indexes to assist in its processing, and if so, determine how effective the use of that index would be.

The returned value is an effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys. An operation that requires no more than a single access to the index content (i.e. Equals, NotEquals) has an effectiveness of one. Evaluation of a single entry is assumed to have an effectiveness that depends on the index implementation and is usually measured as a constant number of the single operations. This number is referred to as evaluation cost.

If the effectiveness of a filter evaluates to a number larger than the keySet.size() * <evaluation cost> then a user could avoid using the index and iterate through the keySet calling evaluate rather then applyIndex.

Parameters:

mapIndexes - the available MapIndex objects keyed by the related ValueExtractor; read-only

setKeys - the set of keys that will be filtered; read-only

Returns:

an effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys

applyIndex

Filter<?> applyIndex(Map<? extends ValueExtractor<? extends V,?>,? extends MapIndex<? extends K,? extends V,?>> mapIndexes,
                     Set<? extends K> setKeys)

Filter remaining keys using a Map of available indexes.

The filter is responsible for removing all keys from the passed set of keys that the applicable indexes can prove should be filtered. If the filter does not fully evaluate the remaining keys using just the index information, it must return a filter (which may be an EntryFilter) that can complete the task using an iterating implementation. If, on the other hand, the filter does fully evaluate the remaining keys using just the index information, then it should return null to indicate that no further filtering is necessary.

Parameters:

mapIndexes - the available MapIndex objects keyed by the related ValueExtractor; read-only

setKeys - the mutable set of keys that remain to be filtered

Returns:

a Filter object (which may be an EntryFilter) that can be used to process the remaining keys, or null if no additional filter processing is necessary