Package org.springframework.cache.support

Class NoOpCache

java.lang.Object
org.springframework.cache.support.NoOpCache
All Implemented Interfaces:
Cache
public class NoOpCache extends Object implements Cache
A no operation Cache implementation suitable for disabling caching.

Will simply accept any items into the cache not actually storing them.

Since:
4.3.4
Author:
Costin Leau, Stephane Nicoll
See Also:

  • Constructor Details

    • NoOpCache

      public NoOpCache(String name)
      Create a NoOpCache instance with the specified name.
      Parameters:
      name - the name of the cache

  • Method Details

    • getName

      public String getName()
      Description copied from interface: Cache
      Return the cache name.
      Specified by:
      getName in interface Cache

    • getNativeCache

      public Object getNativeCache()
      Description copied from interface: Cache
      Return the underlying native cache provider.
      Specified by:
      getNativeCache in interface Cache

    • get

      @Nullable public Cache.ValueWrapper get(Object key)
      Description copied from interface: Cache
      Return the value to which this cache maps the specified key.

      Returns null if the cache contains no mapping for this key; otherwise, the cached value (which may be null itself) will be returned in a Cache.ValueWrapper.

      Specified by:
      get in interface Cache
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which this cache maps the specified key, contained within a Cache.ValueWrapper which may also hold a cached null value. A straight null being returned means that the cache contains no mapping for this key.
      See Also:

    • get

      @Nullable public <T> T get(Object key, @Nullable Class<T> type)
      Description copied from interface: Cache
      Return the value to which this cache maps the specified key, generically specifying a type that return value will be cast to.

      Note: This variant of get does not allow for differentiating between a cached null value and no cache entry found at all. Use the standard Cache.get(Object) variant for that purpose instead.

      Specified by:
      get in interface Cache
      Parameters:
      key - the key whose associated value is to be returned
      type - the required type of the returned value (may be null to bypass a type check; in case of a null value found in the cache, the specified type is irrelevant)
      Returns:
      the value to which this cache maps the specified key (which may be null itself), or also null if the cache contains no mapping for this key
      See Also:

    • get

      @Nullable public <T> T get(Object key, Callable<T> valueLoader)
      Description copied from interface: Cache
      Return the value to which this cache maps the specified key, obtaining that value from valueLoader if necessary. This method provides a simple substitute for the conventional "if cached, return; otherwise create, cache and return" pattern.

      If possible, implementations should ensure that the loading operation is synchronized so that the specified valueLoader is only called once in case of concurrent access on the same key.

      If the valueLoader throws an exception, it is wrapped in a Cache.ValueRetrievalException

      Specified by:
      get in interface Cache
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which this cache maps the specified key
      See Also:

    • retrieve

      @Nullable public CompletableFuture<?> retrieve(Object key)
      Description copied from interface: Cache
      Return the value to which this cache maps the specified key, wrapped in a CompletableFuture. This operation must not block but is allowed to return a completed CompletableFuture if the corresponding value is immediately available.

      Can return null if the cache can immediately determine that it contains no mapping for this key (e.g. through an in-memory key map). Otherwise, the cached value will be returned in the CompletableFuture, with null indicating a late-determined cache miss. A nested Cache.ValueWrapper potentially indicates a nullable cached value; the cached value may also be represented as a plain element if null values are not supported. Calling code needs to be prepared to handle all those variants of the result returned by this method.

      Specified by:
      retrieve in interface Cache
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which this cache maps the specified key, contained within a CompletableFuture which may also be empty when a cache miss has been late-determined. A straight null being returned means that the cache immediately determined that it contains no mapping for this key. A Cache.ValueWrapper contained within the CompletableFuture indicates a cached value that is potentially null; this is sensible in a late-determined scenario where a regular CompletableFuture-contained null indicates a cache miss. However, a cache may also return a plain value if it does not support the actual caching of null values, avoiding the extra level of value wrapping. Spring's cache processing can deal with all such implementation strategies.
      See Also:

    • retrieve

      public <T> CompletableFuture<T> retrieve(Object key, Supplier<CompletableFuture<T>> valueLoader)
      Description copied from interface: Cache
      Return the value to which this cache maps the specified key, obtaining that value from valueLoader if necessary. This method provides a simple substitute for the conventional "if cached, return; otherwise create, cache and return" pattern, based on CompletableFuture. This operation must not block.

      If possible, implementations should ensure that the loading operation is synchronized so that the specified valueLoader is only called once in case of concurrent access on the same key.

      Null values always indicate a user-level null value with this method. The provided CompletableFuture handle produces a value or raises an exception. If the valueLoader raises an exception, it will be propagated to the returned CompletableFuture handle.

      Specified by:
      retrieve in interface Cache
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which this cache maps the specified key, contained within a CompletableFuture which will never be null. The provided future is expected to produce a value or raise an exception.
      See Also:

    • put

      public void put(Object key, @Nullable Object value)
      Description copied from interface: Cache
      Associate the specified value with the specified key in this cache.

      If the cache previously contained a mapping for this key, the old value is replaced by the specified value.

      Actual registration may be performed in an asynchronous or deferred fashion, with subsequent lookups possibly not seeing the entry yet. This may for example be the case with transactional cache decorators. Use Cache.putIfAbsent(java.lang.Object, java.lang.Object) for guaranteed immediate registration.

      If the cache is supposed to be compatible with CompletableFuture and reactive interactions, the put operation needs to be effectively non-blocking, with any backend write-through happening asynchronously. This goes along with a cache implemented and configured to support Cache.retrieve(Object) and Cache.retrieve(Object, Supplier).

      Specified by:
      put in interface Cache
      Parameters:
      key - the key with which the specified value is to be associated
      value - the value to be associated with the specified key
      See Also:

    • putIfAbsent

      @Nullable public Cache.ValueWrapper putIfAbsent(Object key, @Nullable Object value)
      Description copied from interface: Cache
      Atomically associate the specified value with the specified key in this cache if it is not set already.

      This is equivalent to: 

      
 ValueWrapper existingValue = cache.get(key);
 if (existingValue == null) {
     cache.put(key, value);
 }
 return existingValue;
      except that the action is performed atomically. While all out-of-the-box CacheManager implementations are able to perform the put atomically, the operation may also be implemented in two steps, e.g. with a check for presence and a subsequent put, in a non-atomic way. Check the documentation of the native cache implementation that you are using for more details.

      The default implementation delegates to Cache.get(Object) and Cache.put(Object, Object) along the lines of the code snippet above.

      Specified by:
      putIfAbsent in interface Cache
      Parameters:
      key - the key with which the specified value is to be associated
      value - the value to be associated with the specified key
      Returns:
      the value to which this cache maps the specified key (which may be null itself), or also null if the cache did not contain any mapping for that key prior to this call. Returning null is therefore an indicator that the given value has been associated with the key.
      See Also:

    • evict

      public void evict(Object key)
      Description copied from interface: Cache
      Evict the mapping for this key from this cache if it is present.

      Actual eviction may be performed in an asynchronous or deferred fashion, with subsequent lookups possibly still seeing the entry. This may for example be the case with transactional cache decorators. Use Cache.evictIfPresent(java.lang.Object) for guaranteed immediate removal.

      If the cache is supposed to be compatible with CompletableFuture and reactive interactions, the evict operation needs to be effectively non-blocking, with any backend write-through happening asynchronously. This goes along with a cache implemented and configured to support Cache.retrieve(Object) and Cache.retrieve(Object, Supplier).

      Specified by:
      evict in interface Cache
      Parameters:
      key - the key whose mapping is to be removed from the cache
      See Also:

    • evictIfPresent

      public boolean evictIfPresent(Object key)
      Description copied from interface: Cache
      Evict the mapping for this key from this cache if it is present, expecting the key to be immediately invisible for subsequent lookups.

      The default implementation delegates to Cache.evict(Object), returning false for not-determined prior presence of the key. Cache providers and in particular cache decorators are encouraged to perform immediate eviction if possible (e.g. in case of generally deferred cache operations within a transaction) and to reliably determine prior presence of the given key.

      Specified by:
      evictIfPresent in interface Cache
      Parameters:
      key - the key whose mapping is to be removed from the cache
      Returns:
      true if the cache was known to have a mapping for this key before, false if it did not (or if prior presence could not be determined)
      See Also:

    • clear

      public void clear()
      Description copied from interface: Cache
      Clear the cache through removing all mappings.

      Actual clearing may be performed in an asynchronous or deferred fashion, with subsequent lookups possibly still seeing the entries. This may for example be the case with transactional cache decorators. Use Cache.invalidate() for guaranteed immediate removal of entries.

      If the cache is supposed to be compatible with CompletableFuture and reactive interactions, the clear operation needs to be effectively non-blocking, with any backend write-through happening asynchronously. This goes along with a cache implemented and configured to support Cache.retrieve(Object) and Cache.retrieve(Object, Supplier).

      Specified by:
      clear in interface Cache
      See Also:

    • invalidate

      public boolean invalidate()
      Description copied from interface: Cache
      Invalidate the cache through removing all mappings, expecting all entries to be immediately invisible for subsequent lookups.
      Specified by:
      invalidate in interface Cache
      Returns:
      true if the cache was known to have mappings before, false if it did not (or if prior presence of entries could not be determined)
      See Also: