@ -98,9 +98,9 @@ through its `key` attribute. You can use xref:core/expressions.adoc[SpEL] to pic
@@ -98,9 +98,9 @@ through its `key` attribute. You can use xref:core/expressions.adoc[SpEL] to pic
arguments of interest (or their nested properties), perform operations, or even
invoke arbitrary methods without having to write any code or implement any interface.
This is the recommended approach over the
xref:integration/cache/annotations.adoc#cache-annotations-cacheable-default-key[default generator], since methods tend to be
quite different in signatures as the code base grows. While the default strategy might
work for some methods, it rarely works for all methods.
@ -160,12 +159,11 @@ For applications that work with several cache managers, you can set the
@@ -160,12 +159,11 @@ For applications that work with several cache managers, you can set the
----
<1> Specifying `anotherCacheManager`.
You can also replace the `CacheResolver` entirely in a fashion similar to that of
replacing xref:integration/cache/annotations.adoc#cache-annotations-cacheable-key[key generation]. The resolution is
requested for every cache operation, letting the implementation actually resolve
the caches to use based on runtime arguments. The following example shows how to
The resolution is requested for every cache operation, letting the implementation
actually resolve the caches to use based on runtime arguments. The following example
shows how to specify a `CacheResolver`:
[source,java,indent=0,subs="verbatim,quotes"]
----
@ -174,7 +172,6 @@ specify a `CacheResolver`:
@@ -174,7 +172,6 @@ specify a `CacheResolver`:
----
<1> Specifying the `CacheResolver`.
[NOTE]
====
Since Spring 4.1, the `value` attribute of the cache annotations are no longer
@ -211,6 +208,65 @@ NOTE: This is an optional feature, and your favorite cache library may not suppo
@@ -211,6 +208,65 @@ NOTE: This is an optional feature, and your favorite cache library may not suppo
All `CacheManager` implementations provided by the core framework support it. See the
documentation of your cache provider for more details.
[[cache-annotations-cacheable-reactive]]
=== Caching with CompletableFuture and Reactive Return Types
As of 6.1, cache annotations take `CompletableFuture` and reactive return types
into account, automatically adapting the cache interaction accordingly.
For a method returning a `CompletableFuture`, the object produced by that future
will be cached whenever it is complete, and the cache lookup for a cache hit will
be retrieved via a `CompletableFuture`:
[source,java,indent=0,subs="verbatim,quotes"]
----
@Cacheable("books")
public CompletableFuture<Book> findBook(ISBN isbn) {...}
----
For a method returning a Reactor `Mono`, the object emitted by that Reactive Streams
publisher will be cached whenever it is available, and the cache lookup for a cache
hit will be retrieved as a `Mono` (backed by a `CompletableFuture`):
[source,java,indent=0,subs="verbatim,quotes"]
----
@Cacheable("books")
public Mono<Book> findBook(ISBN isbn) {...}
----
For a method returning a Reactor `Flux`, the objects emitted by that Reactive Streams
publisher will be collected into a `List` and cached whenever that list is complete,
and the cache lookup for a cache hit will be retrieved as a `Flux` (backed by a
`CompletableFuture` for the cached `List` value):
[source,java,indent=0,subs="verbatim,quotes"]
----
@Cacheable("books")
public Flux<Book> findBooks(String author) {...}
----
Such `CompletableFuture` and reactive adaptation also works for synchronized caching,
computing the value only once in case of a concurrent cache miss:
[source,java,indent=0,subs="verbatim,quotes"]
----
@Cacheable(cacheNames="foos", sync=true) <1>
public CompletableFuture<Foo> executeExpensiveOperation(String id) {...}
----
<1> Using the `sync` attribute.
NOTE: In order for such an arrangement to work at runtime, the configured cache
needs to be capable of `CompletableFuture`-based retrieval. The Spring-provided
`ConcurrentMapCacheManager` automatically adapts to that retrieval style, and
`CaffeineCacheManager` natively supports it when its asynchronous cache mode is
enabled: set `setAsyncCacheMode(true)` on your `CaffeineCacheManager` instance.
Last but not least, be aware that annotation-driven caching is not appropriate
for sophisticated reactive interactions involving composition and back pressure.
If you choose to declare `@Cacheable` on specific reactive methods, consider the
impact of the rather coarse-granular cache interaction which simply stores the
emitted object for a `Mono` or even a pre-collected list of objects for a `Flux`.
[[cache-annotations-cacheable-condition]]
=== Conditional Caching
@ -229,7 +285,6 @@ argument `name` has a length shorter than 32:
@@ -229,7 +285,6 @@ argument `name` has a length shorter than 32:
----
<1> Setting a condition on `@Cacheable`.
In addition to the `condition` parameter, you can use the `unless` parameter to veto the
adding of a value to the cache. Unlike `condition`, `unless` expressions are evaluated
after the method has been invoked. To expand on the previous example, perhaps we only
@ -242,7 +297,6 @@ want to cache paperback books, as the following example does:
@@ -242,7 +297,6 @@ want to cache paperback books, as the following example does:
----
<1> Using the `unless` attribute to block hardbacks.
The cache abstraction supports `java.util.Optional` return types. If an `Optional` value
is _present_, it will be stored in the associated cache. If an `Optional` value is not
present, `null` will be stored in the associated cache. `#result` always refers to the
@ -342,9 +396,12 @@ other), such declarations should be avoided. Note also that such conditions shou
@@ -342,9 +396,12 @@ other), such declarations should be avoided. Note also that such conditions shou
on the result object (that is, the `#result` variable), as these are validated up-front to
confirm the exclusion.
As of 6.1, `@CachePut` takes `CompletableFuture` and reactive return types into account,
performing the put operation whenever the produced object is available.
[[cache-annotations-evict]]
== The `@CacheEvict` annotation
== The `@CacheEvict` Annotation
The cache abstraction allows not just population of a cache store but also eviction.
This process is useful for removing stale or unused data from the cache. As opposed to
@ -384,6 +441,9 @@ trigger, the return values are ignored (as they do not interact with the cache).
@@ -384,6 +441,9 @@ trigger, the return values are ignored (as they do not interact with the cache).
not the case with `@Cacheable` which adds data to the cache or updates data in the cache
and, thus, requires a result.
As of 6.1, `@CacheEvict` takes `CompletableFuture` and reactive return types into account,
performing an after-invocation evict operation whenever processing has completed.
[[cache-annotations-caching]]
== The `@Caching` Annotation
@ -402,7 +462,7 @@ The following example uses two `@CacheEvict` annotations:
@@ -402,7 +462,7 @@ The following example uses two `@CacheEvict` annotations:
[[cache-annotations-config]]
== The `@CacheConfig` annotation
== The `@CacheConfig` Annotation
So far, we have seen that caching operations offer many customization options and that
you can set these options for each operation. However, some of the customization options