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 SourceSelectionCache

SourceSelectionCache.StatementSourceAssurance

Field Summary

Fields

Modifier and Type	Field	Description
static final String	DEFAULT_CACHE_SPEC

Constructor Summary

Constructors

Constructor	Description
SourceSelectionMemoryCache()
SourceSelectionMemoryCache(String cacheSpec)
SourceSelectionMemoryCache(Supplier<com.google.common.cache.Cache<SubQuery, org.eclipse.rdf4j.federated.cache.SourceSelectionMemoryCache.Entry>> cacheSupplier)

Method Summary

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

Methods inherited from class Object

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

Field Details

DEFAULT_CACHE_SPEC

public static final String DEFAULT_CACHE_SPEC

See Also:

• Constant Field Values

Constructor Details

SourceSelectionMemoryCache

public SourceSelectionMemoryCache()

SourceSelectionMemoryCache

public SourceSelectionMemoryCache(String cacheSpec)

Parameters:

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

SourceSelectionMemoryCache

public SourceSelectionMemoryCache(Supplier<com.google.common.cache.Cache<SubQuery, org.eclipse.rdf4j.federated.cache.SourceSelectionMemoryCache.Entry>> cacheSupplier)

Parameters:

cacheSupplier - provider for an instantiated Guava cache

Method Details

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.invalid input: '<'/p

Specified by:

getAssurance in interface SourceSelectionCache

Parameters:

subQuery -

endpoint -

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

Parameters:

subQuery -

endpoint -

hasStatements -

invalidate

public void invalidate()

Description copied from interface: SourceSelectionCache

Invalidate the underlying cache

Specified by:

invalidate in interface SourceSelectionCache