Package com.tangosol.util

Class ForwardOnlyMapIndex

  • All Implemented Interfaces:
    MapIndex
    public class ForwardOnlyMapIndex
extends Object
implements MapIndex
    ForwardOnlyMapIndex is a MapIndex implementation that unlike the SimpleMapIndex maintains only a forward index and not the inverse index. As a result, the content of getIndexContents() is always empty, so this index cannot be used for querying by IndexAwareFilter, with its primary use as a deserialization optimization.
    Since:
    Coherence 12.1.3
    Author:
    gg/hr/jh 2014.03.07

    • Field Detail

      • f_extractor

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

      • f_mapForward

        protected final Map f_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.

      • f_fLazy

        protected boolean f_fLazy
        The "lazy" flag.

    • Constructor Detail

      • ForwardOnlyMapIndex

        public ForwardOnlyMapIndex​(ValueExtractor extractor,
                           BackingMapContext ctx,
                           boolean fOnDemand)
        Construct an index for the given map.
        Parameters:
        extractor - the ValueExtractor that is used to extract an indexed value from a resource map entry
        ctx - the context associated with the indexed cache
        fOnDemand - if true, the forward index will be created "on-demand" as the values are attempted to be accessed; otherwise the forward index is populated proactively

    • 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.

        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
        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

      • instantiateForwardIndex

        protected Map instantiateForwardIndex()
        Instantiate the forward index.
        Returns:
        the forward index

      • 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

      • toString

        public String toString()
        Returns a string representation of this SimpleMapIndex.
        Overrides:
        toString in class Object
        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.
        Overrides:
        equals in class Object
        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.
        Overrides:
        hashCode in class Object
        Returns:
        the hash code value for this MapIndex