com.tangosol.util.MapIndex Maven / Gradle / Ivy
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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util;
import java.util.Comparator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
/**
* MapIndex is used to correlate values stored in an indexed Map (or
* attributes of those values) to the corresponding keys in the indexed Map.
*
* @param the key type
* @param the type of the value from which an extracted value is obtained
* @param the type of the extracted value that is being indexed
*
* @author cp/gg 2002.10.31
*/
public interface MapIndex
{
/**
* 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.
*
* @return a ValueExtractor object, never null
*/
public ValueExtractor getValueExtractor();
/**
* 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.
*
* @return true if the index contents are ordered, false otherwise
*/
public boolean isOrdered();
/**
* Determine if indexed information for any entry in the indexed Map has
* been excluded from this index. This information is used for
* {@link com.tangosol.util.filter.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.
*
* @return true if any entry of the indexed Map has been excluded from
* the index, false otherwise
* @since Coherence 3.6
*/
public boolean isPartial();
/**
* 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 {@link SortedMap}. The SortedMap may or may
* not have a {@link Comparator} object associated with it; see
* {@link SortedMap#comparator()}.
*
* A client should assume that the returned Map object is read-only and
* must not attempt to modify it.
*
* @return a Map (or a SortedMap) of the index contents
*/
public Map> getIndexContents();
/**
* 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.
*
* @param key the key that specifies the object to extract the value from
*
* @return 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
*/
public Object get(K key);
/**
* Get the Comparator used to sort the index.
*
* @return the comparator
*
* @since Coherence 3.5
*/
public Comparator getComparator();
/**
* Update this index in response to a insert operation on a cache.
*
* @param entry the entry representing the object being inserted
*
* @since Coherence 3.5
*/
public void insert(Map.Entry entry);
/**
* Update this index in response to an update operation on a cache.
*
* @param entry the entry representing the object being updated
*
* @since Coherence 3.5
*/
public void update(Map.Entry entry);
/**
* Update this index in response to a remove operation on a cache.
*
* @param entry the entry representing the object being removed
*
* @since Coherence 3.5
*/
public void delete(Map.Entry entry);
/**
* Constant used to indicate that the index does not contain requested
* value.
*/
public static final Object NO_VALUE = new Object();
}