Oracle Fusion Middleware C++ API Reference for Oracle Coherence: XorFilter Class Reference

Detailed Description

Filter

Author:

djl 2008.04.14

Public Types

typedef spec::Handle

Handle

XorFilter Handle definition.

typedef spec::View

View

XorFilter View definition.

typedef spec::Holder

Holder

XorFilter Holder definition.

Public Member Functions

virtual bool

evaluateEntry (Map::Entry::View vEntry) const

Apply the test to a Map::Entry.

Parameters:

vEntry

the Map::Entry to evaluate; never NULL

Returns:: true if the test passes, false otherwise

virtual bool

evaluate (Object::View v) const

Apply the test to the object.

Parameters:

the object to test

Returns:: true if the test passes, false otherwise

virtual size32_t

calculateEffectiveness (Map::View vMapIndexes, Set::View vSetKeys) const

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:

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

virtual Filter::View

applyIndex (Map::View vMapIndexes, Set::Handle hSetKeys) const

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:

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

Protected Member Functions

XorFilter ()

Default constructor (necessary for the PortableObject interface).

XorFilter (Filter::View vFilterLeft, Filter::View vFilterRight)

Construct an XorFilter.

Constructor & Destructor Documentation

XorFilter	(	Filter::View	vFilterLeft,
		Filter::View	vFilterRight
	)			`[protected]`

Construct an XorFilter.

The result is defined as: vFilterLeft ^ vFilterRight

Parameters:

	vFilterLeft	the "left" filter
	vFilterRight	the "right" filter

coherence/util/filter/XorFilter.hpp