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com.tangosol.util
Class SimpleMapIndex

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.SimpleMapIndex

All Implemented Interfaces:

MapIndex

Direct Known Subclasses:

ConditionalIndex

public class SimpleMapIndex

extends Base

implements MapIndex

SimpleMapIndex is a MapIndex implemenation used to correlate property values extracted from resource map entries with corresponding keys using what is commonly known as an Inverted Index algorithm..

Since:

Coherence 3.5

Author:

tb 2009.03.19

Field Summary

protected Comparator	m_comparator Comparator used to sort the index.
protected ValueExtractor	m_extractor ValueExtractor object that this MapIndex uses to extract an indexable property value from a [converted] value stored in the resource map.
protected boolean	m_fOrdered Specifies whether or not this MapIndex orders the contents of the indexed information.
protected boolean	m_fSplitCollection If a value extracted by the ValueExtractor is a Collection, this property specifies whether or not it should be treated as a Collection of contained attributes or indexed as a single composite attribute.
protected Map	m_mapForward Map that contains the index values (forward index).
protected Map	m_mapInverse Map that contains the index contents (inverse index).

Fields inherited from interface com.tangosol.util.MapIndex

NO_VALUE

Constructor Summary

	SimpleMapIndex(ValueExtractor extractor, boolean fOrdered, Comparator comparator) Construct an index for the given map.
protected	SimpleMapIndex(ValueExtractor extractor, boolean fOrdered, Comparator comparator, boolean fInit) Construct an index for the given map.

Method Summary

protected Object	addInverseCollectionMapping(Map mapIndex, Object oIxValue, Object oKey) Add new mappings from the elements of the given value to the given key in the supplied index.
protected Object	addInverseMapping(Map mapIndex, Object oIxValue, Object oKey) Add a new mapping from the given indexed value to the given key in the supplied index.
protected Object	addInverseMapping(Object oIxValue, Object oKey) Add a new mapping from the given indexed value to the given key in the inverse index.
void	delete(Map.Entry entry) Update this index in response to a remove operation on a cache.
protected void	deleteInternal(Map.Entry entry) Update this index in response to a remove operation on a cache.
boolean	equals(Object o) Compares the specified object with this index for equality.
Object	get(Object oKey) Using the index information if possible, get the value associated with the specified key.
Comparator	getComparator() Get the Comparator used to sort the index.
protected Map.Entry	getForwardEntry(Object oKey) Get the forward index entry associated with the specified key.
Map	getIndexContents() Get the Map that contains the index contents.
ValueExtractor	getValueExtractor() Obtain the ValueExtractor object that the MapIndex uses to extract an indexable Object from a value stored in the indexed Map.
int	hashCode() Returns the hash code value for this MapIndex.
protected void	initialize() Initialize the index's data structures.
void	insert(Map.Entry entry) Update this index in response to a insert operation on a cache.
protected void	insertInternal(Map.Entry entry) Update this index in response to a insert operation on a cache.
protected Map	instantiateForwardIndex() Instantiate the forward index.
protected Map	instantiateInverseIndex(boolean fOrdered, Comparator comparator) Instantiate the inverse index.
protected Set	instantiateSet() Factory method used to create a new set containing the keys associated with a single value.
boolean	isOrdered() Determine if the MapIndex orders the contents of the indexed information.
boolean	isPartial() Determine if indexed information for any entry in the indexed Map has been excluded from this index.
protected void	removeInverseMapping(Map mapIndex, Object oIxValue, Object oKey) Remove the mapping from the given indexed value to the given key from the supplied index.
protected void	removeInverseMapping(Object oIxValue, Object oKey) Remove the mapping from the given indexed value to the given key from the inverse index.
String	toString() Returns a string representation of this SimpleMapIndex.
void	update(Map.Entry entry) Update this index in response to an update operation on a cache.
protected void	updateInternal(Map.Entry entry) Update this index in response to an update operation on a cache.

Field Detail

m_extractor

protected ValueExtractor m_extractor

ValueExtractor object that this MapIndex uses to extract an indexable property value from a [converted] value stored in the resource map.

m_comparator

protected Comparator m_comparator

Comparator used to sort the index. Used iff the Ordered flag is true. Null implies a natural order.

m_fOrdered

protected boolean m_fOrdered

Specifies whether or not this MapIndex orders the contents of the indexed information.

m_mapForward

protected Map m_mapForward

Map that contains the index values (forward index). The keys of the Map are the keys to the map being indexed and the values are the extracted values. This map is used by the IndexAwareComparators to avoid a conversion and value extraction steps.

m_mapInverse

protected Map m_mapInverse

Map that contains the index contents (inverse index). The keys of the Map are the return values from the ValueExtractor operating against the entries of the resource map, and for each key, the corresponding value stored in the Map is a Set of keys to the resource map.

m_fSplitCollection

protected boolean m_fSplitCollection

If a value extracted by the ValueExtractor is a Collection, this property specifies whether or not it should be treated as a Collection of contained attributes or indexed as a single composite attribute.

Constructor Detail

SimpleMapIndex

public SimpleMapIndex(ValueExtractor extractor,
                      boolean fOrdered,
                      Comparator comparator)

Construct an index for the given map.

Parameters:

extractor - the ValueExtractor that is used to extract an indexed value from a resource map entry

fOrdered - true iff the contents of the indexed information should be ordered; false otherwise

comparator - the Comparator object which imposes an ordering on entries in the index map; or null if the entries' values natural ordering should be used

SimpleMapIndex

protected SimpleMapIndex(ValueExtractor extractor,
                         boolean fOrdered,
                         Comparator comparator,
                         boolean fInit)

Construct an index for the given map.

Parameters:

extractor - the ValueExtractor that is used to extract an indexed value from a resource map entry

fOrdered - true iff the contents of the indexed information should be ordered; false otherwise

comparator - the Comparator object which imposes an ordering on entries in the index map; or null if the entries' values natural ordering should be used

fInit - initialize the index if true

Method Detail

getValueExtractor

public ValueExtractor getValueExtractor()

Obtain the ValueExtractor object that the MapIndex uses to extract an indexable Object from a value stored in the indexed Map. This property is never null.

Specified by:

getValueExtractor in interface MapIndex

Returns:

a ValueExtractor object, never null

isOrdered

public boolean isOrdered()

Determine if the MapIndex orders the contents of the indexed information. To determine in which way the contents are ordered, get the Comparator from the index contents SortedMap object.

Specified by:

isOrdered in interface MapIndex

Returns:

true if the index contents are ordered, false otherwise

isPartial

public boolean isPartial()

Determine if indexed information for any entry in the indexed Map has been excluded from this index. This information is used for IndexAwareFilter implementations to determine the most optimal way to apply the index.

Specified by:

isPartial in interface MapIndex

Returns:

true if any entry of the indexed Map has been excluded from the index, false otherwise

getComparator

public Comparator getComparator()

Get the Comparator used to sort the index.

Specified by:

getComparator in interface MapIndex

Returns:

the comparator

getIndexContents

public Map getIndexContents()

Get the Map that contains the index contents.

The keys of the Map are the return values from the ValueExtractor operating against the indexed Map's values, and for each key, the corresponding value stored in the Map is a Set of keys to the indexed Map.

If the MapIndex is known to be ordered, then the returned Map object will be an instance of SortedMap. The SortedMap may or may not have a Comparator object associated with it; see SortedMap.comparator().

A client should assume that the returned Map object is read-only and must not attempt to modify it.

Specified by:

getIndexContents in interface MapIndex

Returns:

a Map (or a SortedMap) of the index contents

get

public Object get(Object oKey)

Using the index information if possible, get the value associated with the specified key. This is expected to be more efficient than using the ValueExtractor against an object containing the value, because the index should already have the necessary information at hand.

Specified by:

get in interface MapIndex

Parameters:

oKey - the key that specifies the object to extract the value from

Returns:

the value that would be extracted by this MapIndex's ValueExtractor from the object specified by the passed key; NO_VALUE if the index does not have the necessary information

insert

public void insert(Map.Entry entry)

Update this index in response to a insert operation on a cache.

Specified by:

insert in interface MapIndex

Parameters:

entry - the entry representing the object being inserted

update

public void update(Map.Entry entry)

Update this index in response to an update operation on a cache.

Specified by:

update in interface MapIndex

Parameters:

entry - the entry representing the object being updated

delete

public void delete(Map.Entry entry)

Update this index in response to a remove operation on a cache.

Specified by:

delete in interface MapIndex

Parameters:

entry - the entry representing the object being removed

initialize

protected void initialize()

Initialize the index's data structures.

getForwardEntry

protected Map.Entry getForwardEntry(Object oKey)

Get the forward index entry associated with the specified key.

Parameters:

oKey - the key

Returns:

the entry associated with the given key.

instantiateForwardIndex

protected Map instantiateForwardIndex()

Instantiate the forward index. <p/> Note: To optimize the memory footprint of the forward index, any subclasses of the SimpleMapIndex that override this method must also implement the getForwardEntry(Object) method accordingly.

Returns:

the forward index

instantiateInverseIndex

protected Map instantiateInverseIndex(boolean fOrdered,
                                      Comparator comparator)

Instantiate the inverse index.

Parameters:

fOrdered - true iff the contents of the indexed information should be ordered; false otherwise

comparator - the Comparator object which imposes an ordering on entries in the index map; or null if the entries' values natural ordering should be used

Returns:

the inverse index

insertInternal

protected void insertInternal(Map.Entry entry)

Update this index in response to a insert operation on a cache.

Parameters:

entry - the entry representing the object being inserted

updateInternal

protected void updateInternal(Map.Entry entry)

Update this index in response to an update operation on a cache.

Parameters:

entry - the entry representing the object being updated

deleteInternal

protected void deleteInternal(Map.Entry entry)

Update this index in response to a remove operation on a cache.

Parameters:

entry - the entry representing the object being removed

addInverseMapping

protected Object addInverseMapping(Object oIxValue,
                                   Object oKey)

Add a new mapping from the given indexed value to the given key in the inverse index.

Parameters:

oIxValue - the indexed value (serves as a key in the inverse index)

oKey - the key to insert into the inverse index

Returns:

an already existing reference that is "equal" to the specified value (if available)

addInverseMapping

protected Object addInverseMapping(Map mapIndex,
                                   Object oIxValue,
                                   Object oKey)

Add a new mapping from the given indexed value to the given key in the supplied index.

Parameters:

mapIndex - the index to which to add the mapping

oIxValue - the indexed value (serves as a key in the inverse index)

oKey - the key to insert into the inverse index

Returns:

an already existing reference that is "equal" to the specified value (if available)

addInverseCollectionMapping

protected Object addInverseCollectionMapping(Map mapIndex,
                                             Object oIxValue,
                                             Object oKey)

Add new mappings from the elements of the given value to the given key in the supplied index. The given value is expected to be either a Collection or an Object array.

Parameters:

mapIndex - the index to which to add the mapping

oIxValue - the indexed Collection value (each element serves as a key in the inverse index)

oKey - the key to insert into the inverse index

Returns:

an already existing reference that is "equal" to the specified value (if available)

removeInverseMapping

protected void removeInverseMapping(Object oIxValue,
                                    Object oKey)

Remove the mapping from the given indexed value to the given key from the inverse index.

Parameters:

oIxValue - the indexed value

oKey - the key

removeInverseMapping

protected void removeInverseMapping(Map mapIndex,
                                    Object oIxValue,
                                    Object oKey)

Remove the mapping from the given indexed value to the given key from the supplied index.

Parameters:

mapIndex - the index from which to remove the mapping

oIxValue - the indexed value

oKey - the key

instantiateSet

protected Set instantiateSet()

Factory method used to create a new set containing the keys associated with a single value.

Returns:

a Set

toString

public String toString()

Returns a string representation of this SimpleMapIndex. The string representation consists of the index's extractor, the ordered value, and the contents of the index (the inverse index).

Returns:

a String representation of this SimpleMapIndex

equals

public boolean equals(Object o)

Compares the specified object with this index for equality. Returns true if the given object is also a SimpleMapIndex and the two represent the same index.

Parameters:

o - object to be compared for equality with this MapIndex

Returns:

true if the specified object is equal to this index

hashCode

public int hashCode()

Returns the hash code value for this MapIndex.

Returns:

the hash code value for this MapIndex

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