@Beta @GwtCompatible public abstract class AbstractCache<K,V> extends Objectimplements Cache <K ,V>
Cache interface to minimize the effort required to implement this interface.
To implement a cache, the programmer needs only to extend this class and provide an implementation for the put(K, V) and Cache methods. getAllPresent(java.lang.Iterable<?>) is implemented in terms of Cache; putAll(java.util.Map<? extends K, ? extends V>) is implemented in terms of put(K, V), invalidateAll(Iterable) is implemented in terms of invalidate(java.lang.Object). The method cleanUp() is a no-op. All other methods throw an UnsupportedOperationException.
| Modifier and Type | Class and Description |
|---|---|
static class |
AbstractCache
A thread-safe
AbstractCache.StatsCounter implementation for use by
Cache implementors.
|
static interface |
AbstractCache
Accumulates statistics during the operation of a
Cache for presentation by
Cache.
|
| Modifier | Constructor and Description |
|---|---|
protected |
AbstractCache()
Constructor for use by subclasses.
|
| Modifier and Type | Method and Description |
|---|---|
ConcurrentMap |
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.
|
V |
get(K key, Callable
Returns the value associated with
key in this cache, obtaining that value from
valueLoader if necessary.
|
ImmutableMap |
getAllPresent(Iterable
This implementation of
getAllPresent lacks any insight into the internal cache data structure, and is thus forced to return the query keys instead of the cached keys.
|
void |
invalidate(Object
Discards any cached value for key
key.
|
void |
invalidateAll()
Discards all entries in the cache.
|
void |
invalidateAll(Iterable
Discards any cached values for keys
keys.
|
void |
put(K key, V value)
Associates
value with
key in this cache.
|
void |
putAll(Map
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.
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitgetIfPresentpublic V get(K key, Callable<? extends V> valueLoader) throws ExecutionException
Cache
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, 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 value
public ImmutableMap<K ,V> getAllPresent(Iterable <?> keys)
getAllPresent lacks any insight into the internal cache data structure, and is thus forced to return the query keys instead of the cached keys. This is only possible with an unsafe cast which requires
keys to actually be of type
K. 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.
getAllPresent in interface
Cache<K,V>
public void put(K key, V value)
Cache
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 when using the conventional "if cached, return; otherwise create, cache and return" pattern.
public void putAll(Map<? extends K ,? extends V> m)
Cache
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 cleanUp()
Cache
public long size()
Cache
public void invalidate(Objectkey)
Cache
key.
public void invalidateAll(Iterable<?> keys)
Cache
keys.
invalidateAll in interface
Cache<K,V>
public void invalidateAll()
Cache
public CacheStatsstats()
Cache
public ConcurrentMap<K ,V> asMap()
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.