Module org.apache.jena.serviceplugins

Package org.apache.jena.sparql.service.enhancer.claimingcache

Class AsyncClaimingCacheImplGuava<K,V>

java.lang.Object

org.apache.jena.sparql.service.enhancer.claimingcache.AsyncClaimingCacheImplGuava<K,V>

Type Parameters:

K - The key type

V - The value type

All Implemented Interfaces:

AsyncClaimingCache<K,V>

public class AsyncClaimingCacheImplGuava<K,V>
extends Object
implements AsyncClaimingCache<K,V>

Implementation of async claiming cache. Claimed entries will never be evicted. Conversely, unclaimed items remain are added to a cache such that timely re-claiming will be fast. Use cases:

• Resource sharing: Ensure that the same resource is handed to all clients requesting one by key.
• Resource pooling: Claimed resources will never be closed, but unclaimed resources (e.g. something backed by an input stream) may remain on standby for a while.

Another way to view this class is as a mix of a map with weak values and a cache.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AsyncClaimingCacheImplGuava.Builder<K,V>

Constructor Summary

Constructors

Constructor	Description
AsyncClaimingCacheImplGuava(Map<K,RefFuture<V>> level1, com.google.common.cache.LoadingCache<K,CompletableFuture<V>> level2, Map<K,V> level3, Collection<Predicate<? super K>> evictionGuards, BiConsumer<K,RefFuture<V>> claimListener, BiConsumer<K,RefFuture<V>> unclaimListener, com.google.common.cache.RemovalListener<K,V> atomicRemovalListener, Set<K> suppressedRemovalEvents)

Method Summary

Modifier and Type	Method	Description
Disposable	addEvictionGuard(Predicate<? super K> predicate)	Registers a predicate that 'caches' entries about to be evicted When closing the registration then keys that have not moved back into the ache by reference will be immediately evicted.
RefFuture<V>	claim(K key)	Claim a reference to the key's entry.
RefFuture<V>	claimIfPresent(K key)	Claim a key only if it is already present.
Collection<K>	getPresentKeys()	Return a snapshot of all present keys
void	invalidateAll()
void	invalidateAll(Iterable<? extends K> keys)
static void	main(String[] args)
static <K, V> AsyncClaimingCacheImplGuava.Builder<K,V>	newBuilder(com.google.common.cache.CacheBuilder<Object,Object> caffeine)

Methods inherited from class java.lang.Object

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

Constructor Details

AsyncClaimingCacheImplGuava

public AsyncClaimingCacheImplGuava(Map<K,RefFuture<V>> level1,
 com.google.common.cache.LoadingCache<K,CompletableFuture<V>> level2,
 Map<K,V> level3,
 Collection<Predicate<? super K>> evictionGuards,
 BiConsumer<K,RefFuture<V>> claimListener,
 BiConsumer<K,RefFuture<V>> unclaimListener,
 com.google.common.cache.RemovalListener<K,V> atomicRemovalListener,
 Set<K> suppressedRemovalEvents)

Method Details

addEvictionGuard

public Disposable addEvictionGuard(Predicate<? super K> predicate)

Registers a predicate that 'caches' entries about to be evicted When closing the registration then keys that have not moved back into the ache by reference will be immediately evicted.

Specified by:

addEvictionGuard in interface AsyncClaimingCache<K,V>

claim

public RefFuture<V> claim(K key)

Description copied from interface: AsyncClaimingCache

Claim a reference to the key's entry.

Specified by:

claim in interface AsyncClaimingCache<K,V>

newBuilder

public static <K,
V>
AsyncClaimingCacheImplGuava.Builder<K,V> newBuilder(com.google.common.cache.CacheBuilder<Object,Object> caffeine)

main

public static void main(String[] args)
                 throws InterruptedException

Throws:

InterruptedException

claimIfPresent

public RefFuture<V> claimIfPresent(K key)

Claim a key only if it is already present. This implementation is a best effort approach: There is a very slim chance that just between testing a key for presence and claiming its entry an eviction occurs - causing claiming of a non-present key and thus triggering a load action.

Specified by:

claimIfPresent in interface AsyncClaimingCache<K,V>

invalidateAll

public void invalidateAll()

Specified by:

invalidateAll in interface AsyncClaimingCache<K,V>

invalidateAll

public void invalidateAll(Iterable<? extends K> keys)

Specified by:

invalidateAll in interface AsyncClaimingCache<K,V>

getPresentKeys

public Collection<K> getPresentKeys()

Description copied from interface: AsyncClaimingCache

Return a snapshot of all present keys

Specified by:

getPresentKeys in interface AsyncClaimingCache<K,V>