Automatically register custom value generators for reflection

Author: yrodiere

extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/ClassNames.java

@@ -62,6 +62,10 @@ private static DotName createConstant(String fqcn) {
     public static final DotName HIBERNATE_CACHE = createConstant("org.hibernate.Cache");
     public static final DotName PERSISTENCE_UNIT_UTIL = createConstant("jakarta.persistence.PersistenceUnitUtil");
 
+    public static final DotName GENERIC_GENERATOR = createConstant("org.hibernate.annotations.GenericGenerator");
+    public static final DotName ID_GENERATOR_TYPE = createConstant("org.hibernate.annotations.IdGeneratorType");
+    public static final DotName VALUE_GENERATION_TYPE = createConstant("org.hibernate.annotations.ValueGenerationType");
+
     public static final DotName INTERCEPTOR = createConstant("org.hibernate.Interceptor");
     public static final DotName STATEMENT_INSPECTOR = createConstant("org.hibernate.resource.jdbc.spi.StatementInspector");
     public static final DotName FORMAT_MAPPER = createConstant("org.hibernate.type.format.FormatMapper");

extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/GraalVMFeatures.java

@@ -26,6 +26,8 @@ NativeImageFeatureBuildItem staticNativeImageFeature() {
 
     // TODO try to limit registration to those that are actually needed, based on configuration + mapping.
     //   https://github.com/quarkusio/quarkus/pull/32433#issuecomment-1497615958
+    //   See also io.quarkus.hibernate.orm.deployment.JpaJandexScavenger.enlistClassReferences for
+    //   the beginning of a solution (which only handles custom types, not references by name such as 'sequence').
     @BuildStep
     ReflectiveClassBuildItem registerGeneratorAndOptimizerClassesForReflections() {
         return ReflectiveClassBuildItem

extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/JpaJandexScavenger.java

@@ -94,6 +94,10 @@ public JpaModelBuildItem discoverModelAndRegisterForReflection() throws BuildExc
             enlistPotentialCdiBeanClasses(collector, annotation);
         }
 
+        enlistPotentialClassReferences(collector, ClassNames.GENERIC_GENERATOR, "type", "strategy");
+        enlistPotentialClassReferences(collector, ClassNames.ID_GENERATOR_TYPE, "value");
+        enlistPotentialClassReferences(collector, ClassNames.VALUE_GENERATION_TYPE, "generatedBy");
+
         for (JpaModelPersistenceUnitContributionBuildItem persistenceUnitContribution : persistenceUnitContributions) {
             enlistExplicitMappings(collector, persistenceUnitContribution);
         }
@@ -214,10 +218,16 @@ private void enlistOrmXmlMappingManagedClass(Collector collector, String package
             String nodeName) {
         String name = safeGetClassName(packagePrefix, managed, nodeName);
         enlistExplicitClass(collector, name);
-        if (managed instanceof JaxbEntity) {
+        if (managed instanceof JaxbEntity entity) {
             // The call to 'enlistExplicitClass' above may not
             // detect that this class is an entity if it is not annotated
             collector.entityTypes.add(name);
+
+            // Generators may be instantiated reflectively
+            if (entity.getGenericGenerator() != null) {
+                var generator = entity.getGenericGenerator();
+                enlistPotentialClassReference(collector, generator == null ? null : generator.getClazz());
+            }
         }
 
         enlistOrmXmlMappingListeners(collector, packagePrefix, managed.getEntityListenerContainer());
@@ -437,6 +447,47 @@ private void enlistPotentialCdiBeanClasses(Collector collector, DotName dotName)
         }
     }
 
+    private void enlistPotentialClassReferences(Collector collector, DotName dotName, String... referenceAttributes) {
+        Collection<AnnotationInstance> jpaAnnotations = index.getAnnotations(dotName);
+
+        if (jpaAnnotations == null) {
+            return;
+        }
+
+        for (AnnotationInstance annotation : jpaAnnotations) {
+            for (String referenceAttribute : referenceAttributes) {
+                var referenceValue = annotation.value(referenceAttribute);
+                if (referenceValue == null) {
+                    continue;
+                }
+                String reference = switch (referenceValue.kind()) {
+                    case CLASS -> referenceValue.asClass().name().toString();
+                    case STRING -> {
+                        String stringRef = referenceValue.asString();
+                        if (stringRef.isEmpty() || index.getClassByName(stringRef) == null) {
+                            // No reference, or reference to a built-in strategy name like 'sequence'
+                            // (which we can't resolve here and handle through GraalVMFeatures.registerGeneratorAndOptimizerClassesForReflections)
+                            yield null;
+                        }
+                        yield stringRef;
+                    }
+                    default -> null;
+                };
+                enlistPotentialClassReference(collector, reference);
+            }
+        }
+    }
+
+    /**
+     * Add the class to the reflective list with only constructor and method access.
+     */
+    private void enlistPotentialClassReference(Collector collector, String reference) {
+        if (reference == null) {
+            return;
+        }
+        collector.javaTypes.add(reference);
+    }
+
     /**
      * Add the class to the reflective list with full method and field access.
      * Add the superclasses recursively as well as the interfaces.