Feature: Add a MethodHandles.Lookup SPI (#3535)

SentryMan · rbygrave · web-flow · commit de81dfc0672c · 2025-02-12T19:30:05.000+13:00
* ServiceLoad lookups

* remove more reflection

* address comments

* Update DefaultTypeManager.java

* Javadoc and format changes

---------

Co-authored-by: Rob Bygrave &lt;robin.bygrave@gmail.com&gt;
diff --git a/ebean-api/src/main/java/io/ebean/config/ClassLoadConfig.java b/ebean-api/src/main/java/io/ebean/config/ClassLoadConfig.java
@@ -1,5 +1,7 @@
 package io.ebean.config;
 
+import io.ebean.plugin.Lookups;
+
 /**
  * Helper to find classes taking into account the context class loader.
  */
@@ -73,9 +75,8 @@ public boolean isJacksonObjectMapperPresent() {
    */
   public Object newInstance(String className) {
     try {
-      Class<?> cls = forName(className);
-      return cls.getDeclaredConstructor().newInstance();
-    } catch (Exception e) {
+      return Lookups.newDefaultInstance(forName(className));
+    } catch (Throwable e) {
       throw new IllegalArgumentException("Error constructing " + className, e);
     }
   }
diff --git a/ebean-api/src/main/java/io/ebean/config/LookupProvider.java b/ebean-api/src/main/java/io/ebean/config/LookupProvider.java
@@ -0,0 +1,15 @@
+package io.ebean.config;
+
+import java.lang.invoke.MethodHandles.Lookup;
+
+/**
+ * Provides a Lookup instance for accessing entity/dto fields.
+ */
+public interface LookupProvider {
+
+  /**
+   * Return the Lookup.
+   */
+  Lookup provideLookup();
+
+}
diff --git a/ebean-api/src/main/java/io/ebean/event/ClassUtil.java b/ebean-api/src/main/java/io/ebean/event/ClassUtil.java
@@ -1,5 +1,6 @@
 package io.ebean.event;
 
+import io.ebean.plugin.Lookups;
 
 /**
  * Helper to find classes taking into account the context class loader.
@@ -12,8 +13,8 @@ class ClassUtil {
   static Object newInstance(String className) {
     try {
       Class<?> cls = forName(className);
-      return cls.getDeclaredConstructor().newInstance();
-    } catch (Exception e) {
+      return Lookups.newDefaultInstance(cls);
+    } catch (Throwable e) {
       String msg = "Error constructing " + className;
       throw new IllegalArgumentException(msg, e);
     }
diff --git a/ebean-api/src/main/java/io/ebean/plugin/Lookups.java b/ebean-api/src/main/java/io/ebean/plugin/Lookups.java
@@ -0,0 +1,41 @@
+package io.ebean.plugin;
+
+import static java.util.stream.Collectors.toMap;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.invoke.MethodType;
+import java.util.Map;
+import java.util.ServiceLoader;
+
+import io.ebean.config.LookupProvider;
+
+/**
+ * Provides Lookup instances using potentially module specific Lookups.
+ */
+public final class Lookups {
+
+  private static final Map<String, Lookup> LOOKUP_MAP =
+      ServiceLoader.load(LookupProvider.class).stream()
+          .collect(toMap(p -> p.type().getModule().getName(), p -> p.get().provideLookup()));
+
+  private static final Lookup DEFAULT_LOOKUP = MethodHandles.publicLookup();
+
+  private static final MethodType VOID = MethodType.methodType(void.class);
+
+  /**
+   * Return a Lookup ideally for the module associated with the given type.
+   */
+  public static Lookup getLookup(Class<?> type) {
+    return LOOKUP_MAP.getOrDefault(type.getModule().getName(), DEFAULT_LOOKUP);
+  }
+
+  /**
+   * Find the default constructor and return a new instance for the given type
+   * potentially using a module specific Lookup instance.
+   */
+  @SuppressWarnings("unchecked")
+  public static <T> T newDefaultInstance(Class<?> type) throws Throwable {
+    return (T) getLookup(type).findConstructor(type, VOID).invoke();
+  }
+}
diff --git a/ebean-api/src/main/java/module-info.java b/ebean-api/src/main/java/module-info.java
@@ -1,6 +1,7 @@
 module io.ebean.api {
 
   uses io.ebean.config.AutoConfigure;
+  uses io.ebean.config.LookupProvider;
   uses io.ebean.datasource.DataSourceAlertFactory;
   uses io.ebean.service.BootstrapService;
   uses io.ebean.service.SpiJsonService;
@@ -21,15 +22,15 @@
   exports io.ebean;
   exports io.ebean.bean;
   exports io.ebean.cache;
-  exports io.ebean.meta;
+  exports io.ebean.common;
   exports io.ebean.config;
   exports io.ebean.config.dbplatform;
+  exports io.ebean.docstore;
   exports io.ebean.event;
   exports io.ebean.event.readaudit;
   exports io.ebean.event.changelog;
-  exports io.ebean.common;
-  exports io.ebean.docstore;
   exports io.ebean.plugin;
+  exports io.ebean.meta;
   exports io.ebean.metric;
   exports io.ebean.search;
   exports io.ebean.service;
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/core/bootup/BootupClasses.java b/ebean-core/src/main/java/io/ebeaninternal/server/core/bootup/BootupClasses.java
@@ -11,14 +11,15 @@
 import io.ebean.event.changelog.ChangeLogRegister;
 import io.ebean.event.readaudit.ReadAuditLogger;
 import io.ebean.event.readaudit.ReadAuditPrepare;
+import io.ebean.plugin.Lookups;
 import io.ebean.util.AnnotationUtil;
 import io.ebeaninternal.api.CoreLog;
-
 import jakarta.persistence.AttributeConverter;
 import jakarta.persistence.Embeddable;
 import jakarta.persistence.Entity;
 import jakarta.persistence.Table;
 import java.lang.annotation.Annotation;
+import java.lang.invoke.MethodType;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
 import java.util.List;
@@ -94,9 +95,9 @@ public BootupClasses(Set<Class<?>> classes) {
   public void runServerConfigStartup(DatabaseBuilder config) {
     for (Class<?> cls : serverConfigStartupCandidates) {
       try {
-        ServerConfigStartup newInstance = (ServerConfigStartup) cls.getDeclaredConstructor().newInstance();
+        ServerConfigStartup newInstance = Lookups.newDefaultInstance(cls);
         newInstance.onStart(config);
-      } catch (Exception e) {
+      } catch (Throwable e) {
         // assume that the desired behavior is to fail - add your own try catch if needed
         throw new IllegalStateException("Error running ServerConfigStartup " + cls, e);
       }
@@ -206,12 +207,12 @@ public void addChangeLogInstances(DatabaseBuilder.Settings config) {
    */
   private <T> T create(Class<T> cls, boolean logOnException) {
     try {
-      return cls.getConstructor().newInstance();
+      return Lookups.newDefaultInstance(cls);
     } catch (NoSuchMethodException e) {
       log.log(DEBUG, "Ignore/expected - no default constructor: {0}", e.getMessage());
       return null;
 
-    } catch (Exception e) {
+    } catch (Throwable e) {
       if (logOnException) {
         // not expected but we log and carry on
         log.log(ERROR, "Error creating " + cls, e);
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanDescriptor.java b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanDescriptor.java
@@ -23,6 +23,7 @@
 import io.ebean.plugin.BeanDocType;
 import io.ebean.plugin.BeanType;
 import io.ebean.plugin.ExpressionPath;
+import io.ebean.plugin.Lookups;
 import io.ebean.plugin.Property;
 import io.ebean.util.SplitName;
 import io.ebeaninternal.api.*;
@@ -414,8 +415,8 @@ EntityBean createPrototypeEntityBean(Class<T> beanType) {
       return null;
     }
     try {
-      return (EntityBean) beanType.getDeclaredConstructor().newInstance();
-    } catch (Exception e) {
+      return Lookups.newDefaultInstance(beanType);
+    } catch (Throwable e) {
       throw new IllegalStateException("Error trying to create the prototypeEntityBean for " + beanType, e);
     }
   }
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementEmbedded.java b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementEmbedded.java
@@ -3,6 +3,7 @@
 import io.ebean.PersistenceIOException;
 import io.ebean.SqlUpdate;
 import io.ebean.bean.EntityBean;
+import io.ebean.plugin.Lookups;
 import io.ebeaninternal.api.json.SpiJsonReader;
 import io.ebeaninternal.api.json.SpiJsonWriter;
 import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
@@ -22,8 +23,8 @@ class BeanDescriptorElementEmbedded<T> extends BeanDescriptorElement<T> {
   BeanDescriptorElementEmbedded(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
     super(owner, deploy, elementHelp);
     try {
-      this.prototype = (EntityBean) beanType.getDeclaredConstructor().newInstance();
-    } catch (Exception e) {
+      this.prototype = Lookups.newDefaultInstance(beanType);
+    } catch (Throwable e) {
       throw new IllegalStateException("Unable to create entity bean prototype for "+beanType);
     }
     BeanPropertyAssocOne<?>[] embedded = propertiesEmbedded();
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/meta/DeployBeanDescriptor.java b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/meta/DeployBeanDescriptor.java
@@ -10,6 +10,7 @@
 import io.ebean.config.dbplatform.PlatformIdGenerator;
 import io.ebean.event.*;
 import io.ebean.event.changelog.ChangeLogFilter;
+import io.ebean.plugin.Lookups;
 import io.ebean.text.PathProperties;
 import io.ebean.util.SplitName;
 import io.ebeaninternal.api.ConcurrencyMode;
@@ -24,7 +25,7 @@
 import jakarta.persistence.Entity;
 import jakarta.persistence.MappedSuperclass;
 
-import java.lang.reflect.Field;
+import java.lang.invoke.MethodHandles.Lookup;
 import java.util.*;
 
 /**
@@ -48,6 +49,7 @@ public int compare(DeployBeanProperty o1, DeployBeanProperty o2) {
 
   private final DatabaseBuilder.Settings config;
   private final BeanDescriptorManager manager;
+
   /**
    * Map of BeanProperty Linked so as to preserve order.
    */
@@ -144,8 +146,8 @@ public BindMaxLength bindMaxLength() {
 
   private String[] readPropertyNames() {
     try {
-      Field field = beanType.getField("_ebean_props");
-      return (String[]) field.get(null);
+      final Lookup lookup = Lookups.getLookup(beanType);
+      return (String[]) lookup.findStaticVarHandle(beanType, "_ebean_props", String[].class).get();
     } catch (Exception e) {
       throw new IllegalStateException("Error getting _ebean_props field on type " + beanType, e);
     }
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/dto/DtoMetaConstructor.java b/ebean-core/src/main/java/io/ebeaninternal/server/dto/DtoMetaConstructor.java
@@ -1,20 +1,19 @@
 package io.ebeaninternal.server.dto;
 
-import io.ebean.core.type.DataReader;
-import io.ebean.core.type.ScalarType;
-import io.ebeaninternal.server.type.TypeManager;
-
 import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 import java.lang.reflect.Constructor;
 import java.sql.SQLException;
 
+import io.ebean.core.type.DataReader;
+import io.ebean.core.type.ScalarType;
+import io.ebean.plugin.Lookups;
+import io.ebeaninternal.server.type.TypeManager;
+
 final class DtoMetaConstructor {
 
   private final Class<?>[] types;
   private final MethodHandle handle;
-  private static final MethodHandles.Lookup LOOKUP = MethodHandles.publicLookup();
   private final ScalarType<?>[] scalarTypes;
 
   DtoMetaConstructor(TypeManager typeManager, Constructor<?> constructor, Class<?> someClass) throws NoSuchMethodException, IllegalAccessException {
@@ -23,7 +22,7 @@ final class DtoMetaConstructor {
     for (int i = 0; i < types.length; i++) {
       scalarTypes[i] = typeManager.type(types[i]);
     }
-    this.handle = LOOKUP.findConstructor(someClass, typeFor(types));
+    this.handle = Lookups.getLookup(someClass).findConstructor(someClass, typeFor(types));
   }
 
   private MethodType typeFor(Class<?>[] types) {
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/dto/DtoMetaProperty.java b/ebean-core/src/main/java/io/ebeaninternal/server/dto/DtoMetaProperty.java
@@ -1,19 +1,17 @@
 package io.ebeaninternal.server.dto;
 
-import io.ebean.core.type.DataReader;
-import io.ebean.core.type.ScalarType;
-import io.ebeaninternal.server.type.TypeManager;
-
 import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 import java.lang.reflect.Method;
 import java.lang.reflect.Type;
 import java.sql.SQLException;
 
-final class DtoMetaProperty implements DtoReadSet {
+import io.ebean.core.type.DataReader;
+import io.ebean.core.type.ScalarType;
+import io.ebean.plugin.Lookups;
+import io.ebeaninternal.server.type.TypeManager;
 
-  private static final MethodHandles.Lookup LOOKUP = MethodHandles.publicLookup();
+final class DtoMetaProperty implements DtoReadSet {
 
   private final Class<?> dtoType;
   private final String name;
@@ -33,7 +31,7 @@ final class DtoMetaProperty implements DtoReadSet {
   }
 
   private static MethodHandle lookupMethodHandle(Class<?> dtoType, Method method) throws NoSuchMethodException, IllegalAccessException {
-    return LOOKUP.findVirtual(dtoType, method.getName(), MethodType.methodType(method.getReturnType(), method.getParameterTypes()));
+    return Lookups.getLookup(dtoType).findVirtual(dtoType, method.getName(), MethodType.methodType(method.getReturnType(), method.getParameterTypes()));
   }
 
   static Type propertyType(Method method) {
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/type/DefaultTypeManager.java b/ebean-core/src/main/java/io/ebeaninternal/server/type/DefaultTypeManager.java
@@ -7,6 +7,7 @@
 import io.ebean.config.dbplatform.DatabasePlatform;
 import io.ebean.config.dbplatform.DbPlatformType;
 import io.ebean.core.type.*;
+import io.ebean.plugin.Lookups;
 import io.ebean.types.Cidr;
 import io.ebean.types.Inet;
 import io.ebean.util.AnnotationUtil;
@@ -20,6 +21,7 @@
 import jakarta.persistence.AttributeConverter;
 import jakarta.persistence.EnumType;
 import java.io.File;
+import java.lang.invoke.MethodType;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.lang.reflect.ParameterizedType;
@@ -597,19 +599,20 @@ private ScalarTypeEnum<?> createEnumScalarType(Class enumType, Map<String, Strin
   private void initialiseCustomScalarTypes(BootupClasses bootupClasses) {
     for (Class<? extends ScalarType<?>> cls : bootupClasses.getScalarTypes()) {
       try {
+        var lookup = Lookups.getLookup(cls);
         ScalarType<?> scalarType;
         if (objectMapper == null) {
-          scalarType = cls.getDeclaredConstructor().newInstance();
+          scalarType = Lookups.newDefaultInstance(cls);
         } else {
           try {
             // first try objectMapper constructor
-            scalarType = cls.getDeclaredConstructor(ObjectMapper.class).newInstance(objectMapper);
+            scalarType = (ScalarType<?>) lookup.findConstructor(cls, MethodType.methodType(ObjectMapper.class)).invoke(objectMapper);
           } catch (NoSuchMethodException e) {
-            scalarType = cls.getDeclaredConstructor().newInstance();
+            scalarType = Lookups.newDefaultInstance(cls);
           }
         }
         add(scalarType);
-      } catch (Exception e) {
+      } catch (Throwable e) {
         log.log(ERROR, "Error loading ScalarType " + cls.getName(), e);
       }
     }
@@ -639,11 +642,11 @@ private void initialiseScalarConverters(BootupClasses bootupClasses) {
         if (wrappedType == null) {
           throw new IllegalStateException("Could not find ScalarType for: " + paramTypes[1]);
         }
-        ScalarTypeConverter converter = foundType.getDeclaredConstructor().newInstance();
+        ScalarTypeConverter converter = Lookups.newDefaultInstance(foundType);
         ScalarTypeWrapper stw = new ScalarTypeWrapper(logicalType, wrappedType, converter);
         log.log(DEBUG, "Register ScalarTypeWrapper from {0} -> {1} using:{2}", logicalType, persistType, foundType);
         add(stw);
-      } catch (Exception e) {
+      } catch (Throwable e) {
         log.log(ERROR, "Error registering ScalarTypeConverter " + foundType.getName(), e);
       }
     }
@@ -663,11 +666,11 @@ private void initialiseAttributeConverters(BootupClasses bootupClasses) {
         if (wrappedType == null) {
           throw new IllegalStateException("Could not find ScalarType for: " + paramTypes[1]);
         }
-        AttributeConverter converter = foundType.getDeclaredConstructor().newInstance();
+        AttributeConverter converter =  Lookups.newDefaultInstance(foundType);
         ScalarTypeWrapper stw = new ScalarTypeWrapper(logicalType, wrappedType, new AttributeConverterAdapter(converter));
         log.log(DEBUG, "Register ScalarTypeWrapper from {0} -> {1} using:{2}", logicalType, persistType, foundType);
         add(stw);
-      } catch (Exception e) {
+      } catch (Throwable e) {
         log.log(ERROR, "Error registering AttributeConverter " + foundType.getName(), e);
       }
     }

Original file line number	Diff line number	Diff line change
`@@ -23,6 +23,7 @@`
`23`	`23`	`import io.ebean.plugin.BeanDocType;`
`24`	`24`	`import io.ebean.plugin.BeanType;`
`25`	`25`	`import io.ebean.plugin.ExpressionPath;`
	`26`	`+import io.ebean.plugin.Lookups;`
`26`	`27`	`import io.ebean.plugin.Property;`
`27`	`28`	`import io.ebean.util.SplitName;`
`28`	`29`	`import io.ebeaninternal.api.*;`
`@@ -414,8 +415,8 @@ EntityBean createPrototypeEntityBean(Class<T> beanType) {`
`414`	`415`	`return null;`
`415`	`416`	`}`
`416`	`417`	`try {`
`417`		`- return (EntityBean) beanType.getDeclaredConstructor().newInstance();`
`418`		`- } catch (Exception e) {`
	`418`	`+ return Lookups.newDefaultInstance(beanType);`
	`419`	`+ } catch (Throwable e) {`
`419`	`420`	`throw new IllegalStateException("Error trying to create the prototypeEntityBean for " + beanType, e);`
`420`	`421`	`}`
`421`	`422`	`}`