(pekko-grpc) 01/01: refactor: replace Constructor.newInstance with MethodHandle for code generator loading

[he...@apache.org]

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He-Pin pushed a commit to branch refactor/replace-reflection-with-methodhandles
in repository https://gitbox.apache.org/repos/asf/pekko-grpc.git

commit 7960006dfb7fcf75bfa0471ad6d5819e5b62a378
Author: 虎鸣 <he...@alibaba-inc.com>
AuthorDate: Mon Jul 6 16:28:59 2026 +0800

    refactor: replace Constructor.newInstance with MethodHandle for code generator loading
    
    Motivation:
    Class.forName().getDeclaredConstructor().newInstance() bypasses JIT
    optimization for constructor invocation in code generator loading.
    
    Modification:
    Replace getDeclaredConstructor().newInstance() with MethodHandles.lookup()
    .unreflectConstructor().invoke() in both the protoc plugin Main and the
    Maven plugin AbstractGenerateMojo for extra generator instantiation.
    
    Result:
    MethodHandle-based invocation enables JIT inlining of constructor calls,
    providing a consistent reflection migration across the project.
    
    Tests:
    - sbt "codegen / compile" - success
    - sbt "maven-plugin / compile" - success
    
    References:
    None - internal refactoring
---
 codegen/src/main/scala/org/apache/pekko/grpc/gen/Main.scala      | 8 +++++++-
 .../scala/org/apache/pekko/grpc/maven/AbstractGenerateMojo.scala | 9 +++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/codegen/src/main/scala/org/apache/pekko/grpc/gen/Main.scala b/codegen/src/main/scala/org/apache/pekko/grpc/gen/Main.scala
index 9b7ad4d6..dea2702f 100644
--- a/codegen/src/main/scala/org/apache/pekko/grpc/gen/Main.scala
+++ b/codegen/src/main/scala/org/apache/pekko/grpc/gen/Main.scala
@@ -14,6 +14,7 @@
 package org.apache.pekko.grpc.gen
 
 import java.io.ByteArrayOutputStream
+import java.lang.invoke.MethodHandles
 import java.net.URLDecoder
 
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest
@@ -83,7 +84,12 @@ object Main {
         else throw new IllegalArgumentException("At least one of generateClient or generateServer must be enabled")
       }
     val loadedExtraGenerators =
-      extraGenerators.map(cls => Class.forName(cls).getDeclaredConstructor().newInstance().asInstanceOf[CodeGenerator])
+      extraGenerators.map { cls =>
+        val clazz = Class.forName(cls)
+        val ctor = clazz.getDeclaredConstructor()
+        ctor.setAccessible(true)
+        MethodHandles.lookup().unreflectConstructor(ctor).invoke().asInstanceOf[CodeGenerator]
+      }
 
     (codeGenerators ++ loadedExtraGenerators).foreach { g =>
       val gout = g.run(req, logger)
diff --git a/maven-plugin/src/main/scala/org/apache/pekko/grpc/maven/AbstractGenerateMojo.scala b/maven-plugin/src/main/scala/org/apache/pekko/grpc/maven/AbstractGenerateMojo.scala
index 61c7475c..61a297d5 100644
--- a/maven-plugin/src/main/scala/org/apache/pekko/grpc/maven/AbstractGenerateMojo.scala
+++ b/maven-plugin/src/main/scala/org/apache/pekko/grpc/maven/AbstractGenerateMojo.scala
@@ -14,6 +14,7 @@
 package org.apache.pekko.grpc.maven
 
 import java.io.{ ByteArrayOutputStream, File, PrintStream }
+import java.lang.invoke.MethodHandles
 
 import org.apache.pekko
 import pekko.grpc.gen.{ CodeGenerator, Logger, ProtocSettings }
@@ -181,8 +182,12 @@ abstract class AbstractGenerateMojo @Inject() (buildContext: BuildContext) exten
     } else {
       import scala.jdk.CollectionConverters._
       val loadedExtraGenerators =
-        extraGenerators.asScala.map(cls =>
-          Class.forName(cls).getDeclaredConstructor().newInstance().asInstanceOf[CodeGenerator])
+        extraGenerators.asScala.map { cls =>
+          val clazz = Class.forName(cls)
+          val ctor = clazz.getDeclaredConstructor()
+          ctor.setAccessible(true)
+          MethodHandles.lookup().unreflectConstructor(ctor).invoke().asInstanceOf[CodeGenerator]
+        }
 
       val targets = language match {
         case Java =>


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