org.eclipse.rdf4j.federated.cache

Class SourceSelectionMemoryCache

java.lang.Object

org.eclipse.rdf4j.federated.cache.SourceSelectionMemoryCache

All Implemented Interfaces:

SourceSelectionCache

public class SourceSelectionMemoryCache
extends Object
implements SourceSelectionCache

An implementation of SourceSelectionCache which uses an in memory Guava Cache as data structure to maintain information.

Author:

Andreas Schwarte

Nested Class Summary

Nested classes/interfaces inherited from interface org.eclipse.rdf4j.federated.cache.SourceSelectionCache

SourceSelectionCache.StatementSourceAssurance

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_CACHE_SPEC

Constructor Summary

Constructors

Constructor and Description
SourceSelectionMemoryCache()
SourceSelectionMemoryCache(String cacheSpec)

Method Summary

Modifier and Type	Method and Description
SourceSelectionCache.StatementSourceAssurance	getAssurance(SubQuery subQuery, Endpoint endpoint) Ask the cache if a given endpoint can provide results for a SubQuery.
void	updateInformation(SubQuery subQuery, Endpoint endpoint, boolean hasStatements) Update the information for a given SubQuery and Endpoint.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_CACHE_SPEC

public static final String DEFAULT_CACHE_SPEC

See Also:

Constant Field Values

Constructor Detail

SourceSelectionMemoryCache

public SourceSelectionMemoryCache()

SourceSelectionMemoryCache

public SourceSelectionMemoryCache(String cacheSpec)

Parameters:

cacheSpec - a Guava compatible CacheBuilderSpec, if null the DEFAULT_CACHE_SPEC is used

Method Detail

getAssurance

public SourceSelectionCache.StatementSourceAssurance getAssurance(SubQuery subQuery,
                                                                  Endpoint endpoint)

Description copied from interface: SourceSelectionCache

Ask the cache if a given endpoint can provide results for a SubQuery.

Implementations may infer information by applying logical rules, e.g. if a cache knows that an endpoint can provide statements {s, foaf:name, "Alan"}, it can also provide results for {s, foaf:name, ?name}.

If a cache cannot provide information for the given arguments, it must return SourceSelectionCache.StatementSourceAssurance.POSSIBLY_HAS_STATEMENTS in order to trigger a remote check.

Specified by:

getAssurance in interface SourceSelectionCache

Returns:

the SourceSelectionCache.StatementSourceAssurance

updateInformation

public void updateInformation(SubQuery subQuery,
                              Endpoint endpoint,
                              boolean hasStatements)

Description copied from interface: SourceSelectionCache

Update the information for a given SubQuery and Endpoint.

Implementations must make sure that any operations are thread-safe

Specified by:

updateInformation in interface SourceSelectionCache