public abstract class ForwardingCache<K,V> extends ForwardingObject implements Cache<K,V>
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.
| Modifier and Type | Class and Description |
|---|---|
static class |
ForwardingCache.SimpleForwardingCache<K,V>
A simplified version of
ForwardingCache where subclasses can pass in an already constructed Cache as the delegate. |
| Modifier | Constructor and Description |
|---|---|
protected |
ForwardingCache()
Constructor for use by subclasses.
|
| Modifier and Type | Method and Description |
|---|---|
ConcurrentMap<K,V> |
asMap()
Returns a view of the entries stored in this cache as a thread-safe map.
|
void |
cleanUp()
Performs any pending maintenance operations needed by the cache.
|
protected abstract Cache<K,V> |
delegate() |
V |
get(K key,
Callable<? extends V> valueLoader)
Returns the value associated with
key in this cache, obtaining that value from valueLoader if necessary. |
ImmutableMap<K,V> |
getAllPresent(Iterable<?> keys)
Returns a map of the values associated with
keys in this cache. |
V |
getIfPresent(Object key)
Returns the value associated with
key in this cache, or null if there is no cached value for key. |
void |
invalidate(Object key)
Discards any cached value for key
key. |
void |
invalidateAll()
Discards all entries in the cache.
|
void |
invalidateAll(Iterable<?> keys)
Discards any cached values for keys
keys. |
void |
put(K key,
V value)
Associates
value with key in this cache. |
void |
putAll(Map<? extends K,? extends V> m)
Copies all of the mappings from the specified map to the cache.
|
long |
size()
Returns the approximate number of entries in this cache.
|
CacheStats |
stats()
Returns a current snapshot of this cache’s cumulative statistics.
|
toStringprotected abstract Cache<K,V> delegate()
delegate in class ForwardingObject@Nullable public V getIfPresent(Object key)
CacheReturns the value associated with key in this cache, or null if there is no cached value for key.
getIfPresent in interface Cache<K,V>public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException
CacheReturns the value associated with key in this cache, obtaining that value from valueLoader if necessary. No observable state associated with this cache is modified until loading completes. This method provides a simple substitute for the conventional “if cached, return; otherwise create, cache and return” pattern.
Warning: as with CacheLoader.load(K), valueLoader must not return null; it may either return a non-null value or throw an exception.
get in interface Cache<K,V>ExecutionException - if a checked exception was thrown while loading the valuepublic ImmutableMap<K,V> getAllPresent(Iterable<?> keys)
CacheReturns 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.
getAllPresent in interface Cache<K,V>public void put(K key, V value)
CacheAssociates value with key in this cache. If the cache previously contained a value associated with key, the old value is replaced by value.
Prefer Cache.get(Object, Callable) when using the conventional “if cached, return; otherwise create, cache and return” pattern.
public void putAll(Map<? extends K,? extends V> m)
CacheCopies 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.
public void invalidate(Object key)
CacheDiscards any cached value for key key.
invalidate in interface Cache<K,V>public void invalidateAll(Iterable<?> keys)
CacheDiscards any cached values for keys keys.
invalidateAll in interface Cache<K,V>public void invalidateAll()
CacheDiscards all entries in the cache.
invalidateAll in interface Cache<K,V>public long size()
CacheReturns the approximate number of entries in this cache.
public CacheStats stats()
CacheReturns a current snapshot of this cache’s cumulative statistics. All stats are initialized to zero, and are monotonically increasing over the lifetime of the cache.
public ConcurrentMap<K,V> asMap()
CacheReturns 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.