Package com.tangosol.util

Class ConditionalIndex

  • All Implemented Interfaces:
    MapIndex
    public class ConditionalIndex
extends SimpleMapIndex
    ConditionalIndex is a MapIndex implementation that uses an associated filter to evaluate whether or not an entry should be indexed. An entry's extracted value is only added to the index if the filter evaluates to true.
    Since:
    Coherence 3.6
    Author:
    tb 2010.02.08

    • Constructor Detail

      • ConditionalIndex

        public ConditionalIndex​(Filter filter,
                        ValueExtractor extractor,
                        boolean fOrdered,
                        Comparator comparator,
                        boolean fForwardIndex,
                        BackingMapContext ctx)
        Construct a ConditionalIndex.
        Parameters:
        filter - the filter that is used to evaluate the entries of the resource map that is being indexed
        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
        fForwardIndex - specifies whether or not this index supports a forward map
        ctx - the context associated with this index

    • Method Detail

      • 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
        Overrides:
        get in class SimpleMapIndex
        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

      • getForwardEntry

        protected Map.Entry getForwardEntry​(Object oKey)
        Get the forward index entry associated with the specified key.
        Overrides:
        getForwardEntry in class SimpleMapIndex
        Parameters:
        oKey - the key
        Returns:
        the entry associated with the given key

      • removeForwardEntry

        protected void removeForwardEntry​(Object oKey)
        Remove the forward index entry for the specified key.
        Overrides:
        removeForwardEntry in class SimpleMapIndex
        Parameters:
        oKey - the key to remove the forward index entry for

      • instantiateForwardIndex

        protected Map instantiateForwardIndex()
        Instantiate the forward index.

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

        Overrides:
        instantiateForwardIndex in class SimpleMapIndex
        Returns:
        the forward index

      • 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.

        Note: Queries that use a partial index are allowed not to return entries that are not indexed even though they would match the corresponding filter were they evaluated during the full scan (if there were no index). However, it's not allowable for a query to return entries that do not match the corresponding filter, regardless of their presence in the index.

        Specified by:
        isPartial in interface MapIndex
        Overrides:
        isPartial in class SimpleMapIndex
        Returns:
        true if any entry of the indexed Map has been excluded from the index, false otherwise

      • getFilter

        public Filter getFilter()
        Get the associated filter.
        Returns:
        the filter

      • evaluateEntry

        protected boolean evaluateEntry​(Map.Entry entry)
        Evaluate the given entry using this index's filter. If the entry does not pass the filter then it should be excluded from this index, making this a partial index.
        Parameters:
        entry - the entry to evaluate
        Returns:
        true if the entry passes the filter, false otherwise

      • insertInternal

        protected void insertInternal​(Map.Entry entry)
        Update this index in response to a insert operation on a cache.
        Overrides:
        insertInternal in class SimpleMapIndex
        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.
        Overrides:
        updateInternal in class SimpleMapIndex
        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.
        Overrides:
        deleteInternal in class SimpleMapIndex
        Parameters:
        entry - the entry representing the object being removed

      • toString

        public String toString()
        Returns a string representation of this ConditionalIndex. The string representation consists of the SimpleMapIndex representation concatenated by the Filter and the ForwardIndexSupported flag.
        Overrides:
        toString in class SimpleMapIndex
        Returns:
        a String representation of this ConditionalIndex

      • 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.
        Overrides:
        equals in class SimpleMapIndex
        Parameters:
        o - object to be compared for equality with this MapIndex
        Returns:
        true if the specified object is equal to this index