ArC removes indirect referenced beans

[dkellenb]

Quarkus in version 19.1 removes indirect referenced beans.

Lets have following scenario. You define an interface for your strategies and an services that depending on any argument, returns the appropriate strategy. These strategies are defined as beans. As these beans are not referenced directly with injections, but only through the interface, the are removed by ArC. The only way to fix it, is by setting quarkus.arc.remove-unused-beans=false

public interface Exporter<T extends Exportable> {
    boolean accept(Class<T> clazz);
    String export(T object);
}

@ApplicationScoped
public class ApplicationExporter implements Exporter<Application> {
   boolean accept(Class<Application> clazz) { return clazz instanceof Application; }
   String export(Application application) {
     ...
   }
}

@ApplicationScoped
public class ExporterService {
  @Inject
  Instance<Exporter<? extends Exportable>> exporters; 
  public <T>Exporter<T> getExporter(Class<T> exporterClazz) {
    // BUG: exporters are empty!
    return StreamSupport.stream(exporters.spliterator(), false)
            .filter(exporter -> exporter.accept(exporterClazz))
            .findFirst().orElseThrow(...);
  }
}

If there is an @Inject javax.enterprise.inject.Instance<T> Quarkus (ArC) should keep all classes implementing T.

[geoand]

Although not a real solution, you can use quarkus.arc.remove-unused-beans=framework instead of the more invasive quarkus.arc.remove-unused-beans=false.

Furthermore you could also annotate your exporters with @Unremovable

[dkellenb]

Unfortunately we are not able to use @Unremovable or =framework, as these beans are from other libraries. But these notes may be interesting for other readers.

[geoand]

I see

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you!
We are doing this automatically to ensure out-of-date issues does not stay around indefinitely.
If you believe this issue is still relevant please put a comment on it on why and if it truly needs to stay request or add 'pinned' label.

[gsmet]

@mkouba should we improve the removal algorithm to deal with this case?

[mkouba]

If there is an @Inject javax.enterprise.inject.Instance Quarkus (ArC) should keep all classes implementing T.

@dkellenb We do keep those beans but there's probably a bug with matching a parameterized type with a wildcard. I'm going to verify this particular use case.

[mkouba]

Yep, it's a bug. I'll send a PR with a fix shortly.

[dkellenb]

Yep, it's a bug. I'll send a PR with a fix shortly.

Great, looking forward to the fix.

[mkouba]

@dkellenb Are you sure the injection point is Instance<Exporter<? extends Exportable>> and not something like Instance<? extends Exporter<? extends Exportable>>? It seems the bug I've found only occurs if the Instance param is wildcard or type variable... it should work if the param is a parameterized type though.