Allocate a local JVM frame when binding interface methods.

#95

duktape/src/main/jni/LocalFrame.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2017 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef DUKTAPE_ANDROID_LOCALFRAME_H
+#define DUKTAPE_ANDROID_LOCALFRAME_H
+
+#include <jni.h>
+
+/**
+ * RAII wrapper that allocates a new local reference frame for the JVM and releases it when leaving
+ * scope.
+ */
+struct LocalFrame {
+  LocalFrame(JNIEnv* env, std::size_t capacity)
+      : m_env(*env) {
+    if (m_env.PushLocalFrame(capacity)) {
+      // Out of memory.
+      throw std::bad_alloc();
+    }
+  }
+
+  ~LocalFrame() {
+    m_env.PopLocalFrame(nullptr);
+  }
+
+  // No copying allowed.
+  LocalFrame(const LocalFrame&) = delete;
+  LocalFrame& operator=(const LocalFrame&) = delete;
+
+private:
+  JNIEnv& m_env;
+};
+
+#endif //DUKTAPE_ANDROID_LOCALFRAME_H

duktape/src/main/jni/java/JavaMethod.cpp

@@ -20,6 +20,7 @@
 #include "GlobalRef.h"
 #include "JavaExceptions.h"
 #include "JavaType.h"
+#include "../LocalFrame.h"
 
 JavaMethod::JavaMethod(JavaTypeMap& typeMap, JNIEnv* env, jobject method) {
   jclass methodClass = env->GetObjectClass(method);
@@ -32,6 +33,8 @@ JavaMethod::JavaMethod(JavaTypeMap& typeMap, JNIEnv* env, jobject method) {
   jobjectArray parameterTypes =
       static_cast<jobjectArray>(env->CallObjectMethod(method, getParameterTypes));
   const jsize numArgs = env->GetArrayLength(parameterTypes);
+  // Release any local objects allocated in this frame when we leave this scope.
+  const LocalFrame localFrame(env, numArgs);
   m_argumentLoaders.resize(numArgs);
   for (jsize i = 0; i < numArgs; ++i) {
     auto parameterType = env->GetObjectArrayElement(parameterTypes, i);
@@ -57,24 +60,6 @@ JavaMethod::JavaMethod(JavaTypeMap& typeMap, JNIEnv* env, jobject method) {
   };
 }
 
-namespace {
-
-struct LocalFrame {
-  LocalFrame(JNIEnv* env, std::size_t capacity)
-      : m_env(*env) {
-    m_env.PushLocalFrame(capacity);
-  }
-
-  ~LocalFrame() {
-    m_env.PopLocalFrame(nullptr);
-  }
-
-private:
-  JNIEnv& m_env;
-};
-
-} // anonymous namespace
-
 duk_ret_t JavaMethod::invoke(duk_context* ctx, JNIEnv* env, jobject javaThis) const {
   const auto argCount = duk_get_top(ctx);
   const auto minArgs = m_isVarArgs

duktape/src/main/jni/javascript/JavaScriptObject.cpp

@@ -21,6 +21,7 @@
 #include "../java/JavaExceptions.h"
 #include "../java/JavaType.h"
 #include "../StackChecker.h"
+#include "../LocalFrame.h"
 
 namespace {
 
@@ -227,7 +228,8 @@ JavaScriptObject::MethodBody buildMethodBody(JavaTypeMap& typeMap, JNIEnv* env,
   jobjectArray parameterTypes =
       static_cast<jobjectArray>(env->CallObjectMethod(method, getParameterTypes));
   const jsize numArgs = env->GetArrayLength(parameterTypes);
-
+  // Release any local objects allocated in this frame when we leave this scope.
+  const LocalFrame localFrame(env, numArgs);
   std::vector<const JavaType*> argumentLoaders(numArgs);
   for (jsize i = 0; i < numArgs; ++i) {
     auto parameterType = env->GetObjectArrayElement(parameterTypes, i);