Package io.quarkus.arc

Annotation Interface WithCaching

@Target({PARAMETER,FIELD})
@Retention(RUNTIME)
public @interface WithCaching

An injected Instance annotated with this annotation will cache the result of the Provider.get() operation.

The result is "computed" on the first call to Provider.get() and the same value is returned for all subsequent calls, even for Dependent beans.

Example

 
  class Producer {

     long nextLong = 0;
     int nextInt = 0;

     @Dependent
     @Produces
     Integer produceInt() {
       return nextInt++;
     }

     @Dependent
     @Produces
     Long produceLong() {
       return nextLong++;
     }
  }

  class Consumer {

     @Inject
     Instance<Long> longInstance;

     @WithCaching
     @Inject
     Instance<Integer> intInstance;

     // this method should always return true and Producer#produceInt() is only called once
     boolean pingInt() {
        return intInstance.get().equals(intInstance.get());
     }

     // this method should always return false and Producer#produceLong() is always called twice
     boolean pingLong() {
        return longInstance.get().equals(longInstance.get());
     }
  }
  
 

Cache Invalidation

It is possible to invalidate the cache via the InjectableInstance.clearCache() method.

 
  class Consumer {

     @WithCaching
     @Inject
     InjectableInstance<Integer> instance;

     int ping(boolean clearCache) {
        if (clearCache) {
          instance.clearCache();
        }
        return instance.get();
     }
  }
  
 

See Also:

• Instance
• InjectableInstance.clearCache()