Generate Hibernate ORM InstantiationOptimizers to avoid reflection

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

@@ -3,10 +3,12 @@
 import static io.quarkus.deployment.annotations.ExecutionTime.RUNTIME_INIT;
 import static io.quarkus.deployment.annotations.ExecutionTime.STATIC_INIT;
 import static io.quarkus.hibernate.orm.deployment.HibernateConfigUtil.firstPresent;
+import static io.quarkus.hibernate.orm.runtime.service.bytecodeprovider.QuarkusRuntimeBytecodeProviderInitiator.INSTANTIATOR_SUFFIX;
 import static org.hibernate.cfg.AvailableSettings.JAKARTA_SHARED_CACHE_MODE;
 import static org.hibernate.cfg.AvailableSettings.USE_DIRECT_REFERENCE_CACHE_ENTRIES;
 import static org.hibernate.cfg.AvailableSettings.USE_QUERY_CACHE;
 import static org.hibernate.cfg.AvailableSettings.USE_SECOND_LEVEL_CACHE;
+import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
 
 import java.io.IOException;
 import java.net.URL;
@@ -44,6 +46,7 @@
 import org.hibernate.boot.archive.scan.spi.ClassDescriptor;
 import org.hibernate.boot.archive.scan.spi.PackageDescriptor;
 import org.hibernate.boot.beanvalidation.BeanValidationIntegrator;
+import org.hibernate.bytecode.spi.ReflectionOptimizer;
 import org.hibernate.cfg.AvailableSettings;
 import org.hibernate.id.SequenceMismatchStrategy;
 import org.hibernate.integrator.spi.Integrator;
@@ -80,6 +83,7 @@
 import io.quarkus.datasource.common.runtime.DatabaseKind;
 import io.quarkus.deployment.Capabilities;
 import io.quarkus.deployment.Capability;
+import io.quarkus.deployment.GeneratedClassGizmoAdaptor;
 import io.quarkus.deployment.IsDevelopment;
 import io.quarkus.deployment.annotations.BuildProducer;
 import io.quarkus.deployment.annotations.BuildStep;
@@ -108,6 +112,10 @@
 import io.quarkus.deployment.recording.RecorderContext;
 import io.quarkus.deployment.util.IoUtil;
 import io.quarkus.deployment.util.ServiceUtil;
+import io.quarkus.gizmo.ClassCreator;
+import io.quarkus.gizmo.MethodCreator;
+import io.quarkus.gizmo.MethodDescriptor;
+import io.quarkus.gizmo.ResultHandle;
 import io.quarkus.hibernate.orm.PersistenceUnit;
 import io.quarkus.hibernate.orm.deployment.HibernateOrmConfigPersistenceUnit.IdentifierQuotingStrategy;
 import io.quarkus.hibernate.orm.deployment.integration.HibernateOrmIntegrationRuntimeConfiguredBuildItem;
@@ -612,6 +620,58 @@ public HibernateModelClassCandidatesForFieldAccessBuildItem candidatesForFieldAc
         return new HibernateModelClassCandidatesForFieldAccessBuildItem(jpaModel.getManagedClassNames());
     }
 
+    /**
+     * Generate {@link org.hibernate.bytecode.spi.ReflectionOptimizer.InstantiationOptimizer}s for
+     * managed classes to avoid using reflection when Hibernate creates new instances.
+     * <p>
+     * For example, the generated bytecode for an entity {@code com.example.MyEntity} will look something like:
+     *
+     * <pre>
+     * {@code
+     * package com.example;
+     *
+     * import org.hibernate.bytecode.spi.ReflectionOptimizer;
+     *
+     * public class MyEntity$QuarkusInstantiator implements ReflectionOptimizer.InstantiationOptimizer {
+     *     public Object newInstance() {
+     *         return new MyEntity();
+     *     }
+     * }
+     * }
+     * </pre>
+     */
+    @BuildStep
+    void instantiationOptimizers(JpaModelBuildItem jpaModel, JpaModelIndexBuildItem index,
+            BuildProducer<GeneratedClassBuildItem> generatedClasses,
+            List<AdditionalJpaModelBuildItem> additionalJpaModelBuildItems,
+            List<PersistenceUnitDescriptorBuildItem> persistenceUnitDescriptorBuildItems) {
+        GeneratedClassGizmoAdaptor classOutput = new GeneratedClassGizmoAdaptor(generatedClasses, true);
+        // Collect all managed class names to generate optimizers for
+        Set<String> managedClassAndPackageNames = new HashSet<>(jpaModel.getManagedClassNames());
+        for (PersistenceUnitDescriptorBuildItem pud : persistenceUnitDescriptorBuildItems) {
+            managedClassAndPackageNames.addAll(pud.getManagedClassNames());
+        }
+        for (AdditionalJpaModelBuildItem additionalJpaModelBuildItem : additionalJpaModelBuildItems) {
+            managedClassAndPackageNames.add(additionalJpaModelBuildItem.getClassName());
+        }
+        // Generate InstantiationOptimizers for all managed classes
+        for (String i : managedClassAndPackageNames) {
+            ClassInfo classInfo = index.getIndex().getClassByName(i);
+            if (classInfo != null && !classInfo.isAbstract() && classInfo.hasNoArgsConstructor()) {
+                String className = classInfo.name() + INSTANTIATOR_SUFFIX;
+                try (ClassCreator classCreator = ClassCreator.builder().classOutput(classOutput)
+                        .interfaces(ReflectionOptimizer.InstantiationOptimizer.class).className(className).build()) {
+                    MethodCreator method = classCreator
+                            .getMethodCreator("newInstance", Object.class)
+                            .setModifiers(ACC_PUBLIC);
+                    ResultHandle constructorHandle = method
+                            .newInstance(MethodDescriptor.ofConstructor(classInfo.name().toString()));
+                    method.returnValue(constructorHandle);
+                }
+            }
+        }
+    }
+
     @BuildStep
     @Record(RUNTIME_INIT)
     public void build(HibernateOrmRecorder recorder, HibernateOrmConfig hibernateOrmConfig,

extensions/hibernate-orm/runtime/src/main/java/io/quarkus/hibernate/orm/runtime/service/bytecodeprovider/QuarkusRuntimeBytecodeProviderInitiator.java

@@ -9,6 +9,7 @@
 import io.quarkus.hibernate.orm.runtime.customized.QuarkusRuntimeProxyFactoryFactory;
 
 public final class QuarkusRuntimeBytecodeProviderInitiator implements StandardServiceInitiator<BytecodeProvider> {
+    public static final String INSTANTIATOR_SUFFIX = "$QuarkusInstantiator";
 
     private final QuarkusRuntimeProxyFactoryFactory statefulProxyFactory;
 

extensions/hibernate-orm/runtime/src/main/java/io/quarkus/hibernate/orm/runtime/service/bytecodeprovider/RuntimeBytecodeProvider.java

@@ -1,5 +1,7 @@
 package io.quarkus.hibernate.orm.runtime.service.bytecodeprovider;
 
+import static io.quarkus.hibernate.orm.runtime.service.bytecodeprovider.QuarkusRuntimeBytecodeProviderInitiator.INSTANTIATOR_SUFFIX;
+
 import java.util.Map;
 
 import org.hibernate.bytecode.enhance.spi.EnhancementContext;
@@ -35,6 +37,26 @@ public ReflectionOptimizer getReflectionOptimizer(
 
     @Override
     public ReflectionOptimizer getReflectionOptimizer(Class<?> clazz, Map<String, PropertyAccess> propertyAccessMap) {
+        try {
+            Class<?> instantiatorClass = Class.forName(clazz.getName() + INSTANTIATOR_SUFFIX, true,
+                    Thread.currentThread().getContextClassLoader());
+            ReflectionOptimizer.InstantiationOptimizer optimizer = (ReflectionOptimizer.InstantiationOptimizer) instantiatorClass
+                    .getDeclaredConstructor().newInstance();
+            return new ReflectionOptimizer() {
+                @Override
+                public InstantiationOptimizer getInstantiationOptimizer() {
+                    return optimizer;
+                }
+
+                @Override
+                public AccessOptimizer getAccessOptimizer() {
+                    return null;
+                }
+            };
+        } catch (Exception e) {
+            // Some mapped classes will not have an optimizer, e.g. abstract entities or classes missing a no-args constructor.
+            // If we didn't find the optimizer class, just ignore the exception and return null
+        }
         return null;
     }