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com.tangosol.util.filter
Class ExtractorFilter

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.filter.AbstractQueryRecorderFilter
com.tangosol.util.filter.ExtractorFilter

All Implemented Interfaces:

ExternalizableLite, PortableObject, Filter, EntryFilter, IndexAwareFilter, QueryRecorderFilter, java.io.Serializable

Direct Known Subclasses:

ComparisonFilter, ValueChangeEventFilter

public abstract class ExtractorFilter

extends AbstractQueryRecorderFilter

implements ExternalizableLite, PortableObject, IndexAwareFilter

Base Filter implementation for doing extractor-based processing.

Author:

cp/gg 2002.11.01

Field Summary

static int	EVAL_COST The evaluation cost as a factor to the single index access operation.
protected ValueExtractor	m_extractor The ValueExtractor used by this filter.

Constructor Summary

ExtractorFilter()
Default constructor (necessary for the ExternalizableLite interface).

ExtractorFilter(java.lang.String sMethod)
Construct an ExtractorFilter for a given method name.

ExtractorFilter(ValueExtractor extractor)
Construct a ExtractorFilter for a given ValueExtractor.

Method Summary

Filter	applyIndex(java.util.Map mapIndexes, java.util.Set setKeys) Filter remaining keys using a Map of available indexes.
int	calculateEffectiveness(java.util.Map mapIndexes, java.util.Set 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.
static int	calculateIteratorEffectiveness(int cKeys) Helper method to calculate effectiveness (or rather ineffectiveness) of a simple iteration against a key set that has to be performed due to an absence of corresponding index.
boolean	evaluate(java.lang.Object oTarget) Apply the test to the object.
boolean	evaluateEntry(java.util.Map.Entry entry) Apply the test to a Map Entry.
protected abstract boolean	evaluateExtracted(java.lang.Object oExtracted) Evaluate the specified extracted value.
protected java.lang.Object	extract(java.lang.Object o) Get the result of ValueExtractor invocation.
ValueExtractor	getValueExtractor() Obtain the ValueExtractor used by this filter.
void	readExternal(java.io.DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object.
void	readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object.
void	writeExternal(java.io.DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object.
void	writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Methods inherited from class com.tangosol.util.filter.AbstractQueryRecorderFilter

explain, explain, trace, trace, trace, trace

Methods inherited from class com.tangosol.util.BitHelper

countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString, toBytes, toBytes, toBytes, toBytes, toInt, toInt, toLong, toLong

Field Detail

EVAL_COST

public static int EVAL_COST

The evaluation cost as a factor to the single index access operation.

See Also:

IndexAwareFilter.calculateEffectiveness(Map, Set)

m_extractor

protected ValueExtractor m_extractor

The ValueExtractor used by this filter.

Constructor Detail

ExtractorFilter

public ExtractorFilter()

Default constructor (necessary for the ExternalizableLite interface).

ExtractorFilter

public ExtractorFilter(ValueExtractor extractor)

Construct a ExtractorFilter for a given ValueExtractor.

Parameters:

extractor - the ValueExtractor to use by this filter

ExtractorFilter

public ExtractorFilter(java.lang.String sMethod)

Construct an ExtractorFilter for a given method name.

Parameters:

sMethod - a method name to make a ReflectionExtractor for; this parameter can also be a dot-delimited sequence of method names which would result in an ExtractorFilter based on the ChainedExtractor that is based on an array of corresponding ReflectionExtractor objects

Method Detail

evaluate

public boolean evaluate(java.lang.Object oTarget)

Apply the test to the object.

Specified by:

evaluate in interface Filter

Parameters:

oTarget - the object to test

Returns:

true if the test passes, false otherwise

evaluateEntry

public boolean evaluateEntry(java.util.Map.Entry entry)

Apply the test to a Map Entry.

Specified by:

evaluateEntry in interface EntryFilter

Parameters:

entry - the Map Entry to evaluate; never null

Returns:

true if the test passes, false otherwise

evaluateExtracted

protected abstract boolean evaluateExtracted(java.lang.Object oExtracted)

Evaluate the specified extracted value.

Parameters:

oExtracted - an extracted value to evaluate

Returns:

true iff the test passes

extract

protected java.lang.Object extract(java.lang.Object o)

Get the result of ValueExtractor invocation.

Parameters:

o - the object on which to invoke the ValueExtractor; must not be null

Returns:

the result of the method invocation

Throws:

WrapperException - if this ValueExtractor encounters an exception in the course of extracting the value

getValueExtractor

public ValueExtractor getValueExtractor()

Obtain the ValueExtractor used by this filter.

Returns:

the ValueExtractor used by this filter

calculateEffectiveness

public int calculateEffectiveness(java.util.Map mapIndexes,
                                  java.util.Set 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.

Specified by:

calculateEffectiveness in interface IndexAwareFilter

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

public Filter applyIndex(java.util.Map mapIndexes,
                         java.util.Set 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.

Specified by:

applyIndex in interface IndexAwareFilter

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

calculateIteratorEffectiveness

public static int calculateIteratorEffectiveness(int cKeys)

Helper method to calculate effectiveness (or rather ineffectiveness) of a simple iteration against a key set that has to be performed due to an absence of corresponding index.

Parameters:

cKeys - the number of keys to iterate through

Returns:

an effectiveness estimate

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

java.io.IOException - if an I/O exception occurs

java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Parameters:

in - the PofReader from which to read the object's state

Throws:

java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Parameters:

out - the PofWriter to which to write the object's state

Throws:

java.io.IOException - if an I/O error occurs

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