From 41b5c52b5a20a4234f64f22ca7963a255c55a16d Mon Sep 17 00:00:00 2001
From: Gregory Moskaliuk <mosckalyuck@gmail.com>
Date: Fri, 23 Oct 2026 18:56:30 +0200
Subject: [PATCH] Parse each Java TurboModule method's JNI signature once

JavaTurboModule::invokeJavaMethod parsed the method's JNI signature into a
vector of argument type strings on every call, and cut the return type
out of it again for number and boolean methods. Keep both in a MethodInfo
per method, keyed by its jmethodID, like ObjCTurboModule does on iOS.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../android/ReactCommon/JavaTurboModule.cpp   | 29 ++++++++++++++-----
 .../android/ReactCommon/JavaTurboModule.h     | 12 ++++++++
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.cpp b/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.cpp
index 0db4927a6338..df3b9bbfc436 100644
--- a/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.cpp
+++ b/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.cpp
@@ -588,6 +588,24 @@ void rejectWithException(
 
 } // namespace
 
+const JavaTurboModule::MethodInfo& JavaTurboModule::getMethodInfo(
+    jmethodID methodID,
+    const std::string& methodSignature) {
+  std::lock_guard<std::mutex> lock(methodInfosMutex_);
+  auto entry = methodInfos_.find(methodID);
+  if (entry == methodInfos_.end()) {
+    entry = methodInfos_
+                .emplace(
+                    methodID,
+                    MethodInfo{
+                        getMethodArgTypesFromSignature(methodSignature),
+                        methodSignature.substr(
+                            methodSignature.find_last_of(')') + 1)})
+                .first;
+  }
+  return entry->second;
+}
+
 jsi::Value JavaTurboModule::invokeJavaMethod(
     jsi::Runtime& runtime,
     TurboModuleMethodValueKind valueKind,
@@ -689,14 +707,13 @@ jsi::Value JavaTurboModule::invokeJavaMethod(
     return returnValue;
   }
 
-  std::vector<std::string> methodArgTypes =
-      getMethodArgTypesFromSignature(methodSignature);
+  const MethodInfo& methodInfo = getMethodInfo(methodID, methodSignature);
 
   JNIArgs jniArgs = convertJSIArgsToJNIArgs(
       env,
       runtime,
       methodNameStr,
-      methodArgTypes,
+      methodInfo.argTypes,
       args,
       argCount,
       jsInvoker_,
@@ -712,8 +729,7 @@ jsi::Value JavaTurboModule::invokeJavaMethod(
 
   switch (valueKind) {
     case BooleanKind: {
-      std::string returnType =
-          methodSignature.substr(methodSignature.find_last_of(')') + 1);
+      const std::string& returnType = methodInfo.returnType;
       if (returnType == "Ljava/lang/Boolean;") {
         auto returnObject =
             env->CallObjectMethodA(instance, methodID, jargs.data());
@@ -749,8 +765,7 @@ jsi::Value JavaTurboModule::invokeJavaMethod(
       }
     }
     case NumberKind: {
-      std::string returnType =
-          methodSignature.substr(methodSignature.find_last_of(')') + 1);
+      const std::string& returnType = methodInfo.returnType;
       if (returnType == "Ljava/lang/Double;" ||
           returnType == "Ljava/lang/Float;" ||
           returnType == "Ljava/lang/Integer;") {
diff --git a/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.h b/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.h
index f5c7fde52394..e8df215df712 100644
--- a/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.h
+++ b/packages/react-native/ReactCommon/react/nativemodule/core/platform/android/ReactCommon/JavaTurboModule.h
@@ -9,7 +9,10 @@
 
 #include <react/cxxstableapi/UmbrellaGuard.h>
 
+#include <mutex>
 #include <string>
+#include <unordered_map>
+#include <vector>
 
 #include <React/Bridging.h>
 #include <React/CallInvoker.h>
@@ -61,6 +64,15 @@ class JSI_EXPORT JavaTurboModule : public TurboModule {
   // instance_ can be of type JTurboModule, or JNativeModule
   jni::global_ref<jobject> instance_;
   std::shared_ptr<NativeMethodCallInvoker> nativeMethodCallInvoker_;
+
+  // A method's JNI signature, parsed on its first call since it doesn't change.
+  struct MethodInfo {
+    std::vector<std::string> argTypes;
+    std::string returnType;
+  };
+  std::unordered_map<jmethodID, MethodInfo> methodInfos_;
+  std::mutex methodInfosMutex_;
+  const MethodInfo &getMethodInfo(jmethodID methodID, const std::string &methodSignature);
 };
 
 } // namespace facebook::react