Top Description Inners Constructors Methods
com.google.common.cache

public abstract Class ForwardingCache<K, V>

extends ForwardingObject
implements Cache<K, V>
Class Inheritance
All Implemented Interfaces
com.google.common.cache.Cache
Known Direct Subclasses
com.google.common.cache.ForwardingCache.SimpleForwardingCache, com.google.common.cache.ForwardingLoadingCache, com.google.common.cache.LocalCache.ManualSerializationProxy
Annotations
@GwtIncompatible
@ElementTypesAreNonnullByDefault
Imports
com.google.common.annotations.GwtIncompatible, com.google.common.base.Preconditions, com.google.common.collect.ForwardingObject, .ImmutableMap, java.util.Map, java.util.concurrent.Callable, .ConcurrentMap, .ExecutionException, javax.annotation.CheckForNull
A cache which forwards all its method calls to another cache. Subclasses should override one or more methods to modify the behavior of the backing cache as desired per the decorator pattern.
Author
Charles Fry
Since
10.0

Nested and Inner Type Summary

Modifier and TypeClass and Description
public abstract static class
ForwardingCache.SimpleForwardingCache<K, V>

A simplified version of ForwardingCache where subclasses can pass in an already constructed Cache as the delegate.

Constructor Summary

AccessConstructor and Description
protected
ForwardingCache()

Constructor for use by subclasses.

Method Summary

Modifier and TypeMethod and Description
public ConcurrentMap<K, V>
asMap()

Implements com.google.common.cache.Cache.asMap.

Returns a view of the entries stored in this cache as a thread-safe map.
public void
cleanUp()

Implements com.google.common.cache.Cache.cleanUp.

Performs any pending maintenance operations needed by the cache.
protected abstract Cache<K, V>
delegate()

Implements abstract com.google.common.collect.ForwardingObject.delegate.

Returns the backing delegate instance that methods are forwarded to.
public V
get(K key, Callable<? extends V> valueLoader)

Implements com.google.common.cache.Cache.get.

Returns the value associated with key in this cache, obtaining that value from loader if necessary.
public ImmutableMap<K, V>
getAllPresent(Iterable<? extends Object> keys)

Implements com.google.common.cache.Cache.getAllPresent.

Returns a map of the values associated with keys in this cache.
public V
getIfPresent(Object key)

Implements com.google.common.cache.Cache.getIfPresent.

Returns the value associated with key in this cache, or null if there is no cached value for key.
public void
invalidate(Object key)

Implements com.google.common.cache.Cache.invalidate.

Discards any cached value for key key.
public void
invalidateAll(Iterable<? extends Object> keys)

Implements com.google.common.cache.Cache.invalidateAll.

Discards any cached values for keys keys.
public void
invalidateAll()

Implements com.google.common.cache.Cache.invalidateAll.

Discards all entries in the cache.
public void
put(K key, V value)

Implements com.google.common.cache.Cache.put.

Associates value with key in this cache.
public void
putAll(Map<? extends K, ? extends V> m)

Implements com.google.common.cache.Cache.putAll.

Copies all of the mappings from the specified map to the cache.
public long
size()

Implements com.google.common.cache.Cache.size.

Returns the approximate number of entries in this cache.
public CacheStats
stats()

Implements com.google.common.cache.Cache.stats.

Returns a current snapshot of this cache's cumulative statistics, or a set of default values if the cache is not recording statistics.
Inherited from com.google.common.collect.ForwardingObject:
toString

Constructor Detail

ForwardingCacheback to summary
protected ForwardingCache()

Constructor for use by subclasses.

Method Detail

asMapback to summary
public ConcurrentMap<K, V> asMap()

Implements com.google.common.cache.Cache.asMap.

Doc from com.google.common.cache.Cache.asMap.

Returns a view of the entries stored in this cache as a thread-safe map. Modifications made to the map directly affect the cache.

Iterators from the returned map are at least weakly consistent: they are safe for concurrent use, but if the cache is modified (including by eviction) after the iterator is created, it is undefined which of the changes (if any) will be reflected in that iterator.

Annotations
@Override
cleanUpback to summary
public void cleanUp()

Implements com.google.common.cache.Cache.cleanUp.

Doc from com.google.common.cache.Cache.cleanUp.

Performs any pending maintenance operations needed by the cache. Exactly which activities are performed -- if any -- is implementation-dependent.

Annotations
@Override
delegateback to summary
protected abstract Cache<K, V> delegate()

Implements abstract com.google.common.collect.ForwardingObject.delegate.

Doc from com.google.common.collect.ForwardingObject.delegate.

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet#delegate. Concrete subclasses override this method to supply the instance being decorated.

Annotations
@Override
getback to summary
public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException

Implements com.google.common.cache.Cache.get.

Doc from com.google.common.cache.Cache.get.

Returns the value associated with key in this cache, obtaining that value from loader if necessary. The method improves upon the conventional "if cached, return; otherwise create, cache and return" pattern. For further improvements, use LoadingCache and its get(K) method instead of this one.

Among the improvements that this method and LoadingCache.get(K) both provide are:

Among the further improvements that LoadingCache can provide but this method cannot:

Warning

For any given key, every loader used with it should compute the same value. Otherwise, a call that passes one loader may return the result of another call with a differently behaving loader. For example, a call that requests a short timeout for an RPC may wait for a similar call that requests a long timeout, or a call by an unprivileged user may return a resource accessible only to a privileged user making a similar call. To prevent this problem, create a key object that includes all values that affect the result of the query. Or use LoadingCache.get(K), which lacks the ability to refer to state other than that in the key.

Warning

as with CacheLoader#load, loader must not return null; it may either return a non-null value or throw an exception.

No observable state associated with this cache is modified until loading completes.

Annotations
@Override
Exceptions
ExecutionException:
if a checked exception was thrown while loading the value
Since
11.0
getAllPresentback to summary
public ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys)

Implements com.google.common.cache.Cache.getAllPresent.

Doc from com.google.common.cache.Cache.getAllPresent.

Returns a map of the values associated with keys in this cache. The returned map will only contain entries which are already present in the cache.

Annotations
@Override
Since
11.0
getIfPresentback to summary
public V getIfPresent(Object key)

Implements com.google.common.cache.Cache.getIfPresent.

Doc from com.google.common.cache.Cache.getIfPresent.

Returns the value associated with key in this cache, or null if there is no cached value for key.

Annotations
@Override
@CheckForNull
Since
11.0
invalidateback to summary
public void invalidate(Object key)

Implements com.google.common.cache.Cache.invalidate.

Doc from com.google.common.cache.Cache.invalidate.

Discards any cached value for key key.

Annotations
@Override
invalidateAllback to summary
public void invalidateAll(Iterable<? extends Object> keys)

Implements com.google.common.cache.Cache.invalidateAll.

Doc from com.google.common.cache.Cache.invalidateAll.

Discards any cached values for keys keys.

Annotations
@Override
Since
11.0
invalidateAllback to summary
public void invalidateAll()

Implements com.google.common.cache.Cache.invalidateAll.

Doc from com.google.common.cache.Cache.invalidateAll.

Discards all entries in the cache.

Annotations
@Override
putback to summary
public void put(K key, V value)

Implements com.google.common.cache.Cache.put.

Doc from com.google.common.cache.Cache.put.

Associates value with key in this cache. If the cache previously contained a value associated with key, the old value is replaced by value.

Prefer get(Object, Callable) when using the conventional "if cached, return; otherwise create, cache and return" pattern.

Annotations
@Override
Since
11.0
putAllback to summary
public void putAll(Map<? extends K, ? extends V> m)

Implements com.google.common.cache.Cache.putAll.

Doc from com.google.common.cache.Cache.putAll.

Copies all of the mappings from the specified map to the cache. The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Annotations
@Override
Since
12.0
sizeback to summary
public long size()

Implements com.google.common.cache.Cache.size.

Doc from com.google.common.cache.Cache.size.

Returns the approximate number of entries in this cache.

Annotations
@Override
statsback to summary
public CacheStats stats()

Implements com.google.common.cache.Cache.stats.

Doc from com.google.common.cache.Cache.stats.

Returns a current snapshot of this cache's cumulative statistics, or a set of default values if the cache is not recording statistics. All statistics begin at zero and never decrease over the lifetime of the cache.

Warning

this cache may not be recording statistical data. For example, a cache created using CacheBuilder only does so if the CacheBuilder#recordStats method was called. If statistics are not being recorded, a CacheStats instance with zero for all values is returned.

Annotations
@Override
com.google.common.cache back to summary

public abstract Class ForwardingCache.SimpleForwardingCache<K, V>

extends ForwardingCache<K, V>
Class Inheritance
A simplified version of ForwardingCache where subclasses can pass in an already constructed Cache as the delegate.
Since
10.0

Field Summary

Modifier and TypeField and Description
private final Cache<K, V>
delegate

Constructor Summary

AccessConstructor and Description
protected
SimpleForwardingCache(Cache<K, V> delegate)

Method Summary

Modifier and TypeMethod and Description
protected final Cache<K, V>
delegate()

Implements abstract com.google.common.cache.ForwardingCache.delegate.

Returns the backing delegate instance that methods are forwarded to.
Inherited from com.google.common.cache.ForwardingCache:
asMapcleanUpgetgetAllPresentgetIfPresentinvalidateinvalidateAllinvalidateAllputputAllsizestats

Field Detail

delegateback to summary
private final Cache<K, V> delegate

Constructor Detail

SimpleForwardingCacheback to summary
protected SimpleForwardingCache(Cache<K, V> delegate)

Method Detail

delegateback to summary
protected final Cache<K, V> delegate()

Implements abstract com.google.common.cache.ForwardingCache.delegate.

Doc from com.google.common.collect.ForwardingObject.delegate.

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet#delegate. Concrete subclasses override this method to supply the instance being decorated.

Annotations
@Override