Issue 4442 - Cache class and ctors references in JNI_Load/UnLoad

libadblockplus-android/jni/Utils.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <string>
 
 #include "Utils.h"
 
+// precached in JNI_OnLoad and released in JNI_OnUnload
+JniGlobalReference<jclass>* arrayListClass;
+jmethodID  arrayListCtor;
+
+JniGlobalReference<jclass>* filterClass;
+jmethodID filterCtor;
+
+JniGlobalReference<jclass>* subscriptionClass;
+jmethodID subscriptionCtor;
+
+JniGlobalReference<jclass>* notificationClass;
+jmethodID notificationCtor;
+
+JniGlobalReference<jclass>* exceptionClass;
+
+void JniUtils_OnLoad(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  arrayListClass = new JniGlobalReference<jclass>(env, env->FindClass("java/util/ArrayList"));
+  arrayListCtor = env->GetMethodID(arrayListClass->Get(), "<init>", "()V");
+
+  filterClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("Filter")));
+  filterCtor = env->GetMethodID(filterClass->Get(), "<init>", "(J)V");
+
+  subscriptionClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("Subscription")));
+  subscriptionCtor = env->GetMethodID(subscriptionClass->Get(), "<init>", "(J)V");
+
+  notificationClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("Notification")));
+  notificationCtor = env->GetMethodID(notificationClass->Get(), "<init>", "(J)V");
+
+  exceptionClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("AdblockPlusException")));
+}
+
+void JniUtils_OnUnload(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  if (arrayListClass)
+  {
+    delete arrayListClass;
+    arrayListClass = NULL;
+  }
+
+  if (filterClass)
+  {
+    delete filterClass;
+    filterClass = NULL;
+  }
+
+  if (subscriptionClass)
+  {
+    delete subscriptionClass;
+    subscriptionClass = NULL;
+  }
+
+  if (notificationClass)
+  {
+    delete notificationClass;
+    notificationClass = NULL;
+  }
+
+  if (exceptionClass)
+  {
+    delete exceptionClass;
+    exceptionClass = NULL;
+  }
+}
+
 std::string JniJavaToStdString(JNIEnv* env, jstring str)
 {
   if (!str)
   {
     return std::string();
   }
 
   const char* cStr = env->GetStringUTFChars(str, 0);
   std::string ret(cStr);
   env->ReleaseStringUTFChars(str, cStr);
 
   return ret;
 }
 
 jobject NewJniArrayList(JNIEnv* env)
 {
-  JniLocalReference<jclass> clazz(env, env->FindClass("java/util/ArrayList"));
-  jmethodID ctor = env->GetMethodID(*clazz, "<init>", "()V");
-  return env->NewObject(*clazz, ctor);
+  return env->NewObject(arrayListClass->Get(), arrayListCtor);
+}
+
+jmethodID JniGetAddToListMethod(JNIEnv* env, jobject list)
+{
+  JniLocalReference<jclass> clazz(env, env->GetObjectClass(list));
+  return env->GetMethodID(*clazz, "add", "(Ljava/lang/Object;)Z");
+}
+
+void JniAddObjectToList(JNIEnv* env, jobject list, jmethodID addMethod, jobject value)
+{
+  env->CallBooleanMethod(list, addMethod, value);
 }
 
 void JniAddObjectToList(JNIEnv* env, jobject list, jobject value)
 {
-  JniLocalReference<jclass> clazz(env, env->GetObjectClass(list));
-  jmethodID add = env->GetMethodID(*clazz, "add", "(Ljava/lang/Object;)Z");
-  env->CallBooleanMethod(list, add, value);
+  jmethodID addMethod = JniGetAddToListMethod(env, list);
+  JniAddObjectToList(env, list, addMethod, value);
 }
 
 void JniThrowException(JNIEnv* env, const std::string& message)
 {
-  JniLocalReference<jclass> clazz(env,
-      env->FindClass(PKG("AdblockPlusException")));
-  env->ThrowNew(*clazz, message.c_str());
+  env->ThrowNew(exceptionClass->Get(), message.c_str());
 }
 
 void JniThrowException(JNIEnv* env, const std::exception& e)
 {
   JniThrowException(env, e.what());
 }
 
 void JniThrowException(JNIEnv* env)
 {
   JniThrowException(env, "Unknown exception from libadblockplus");
@@ skipping 16 matching lines @@
 
 JNIEnvAcquire::~JNIEnvAcquire()
 {
   if (attachmentStatus == JNI_EDETACHED)
   {
     javaVM->DetachCurrentThread();
   }
 }
 
 template<typename T>
-static jobject NewJniObject(JNIEnv* env, const T& value, const char* javaClass)
+static jobject NewJniObject(JNIEnv* env, const T& value, jclass clazz, jmethodID ctor)
 {
   if (!value.get())
   {
     return 0;
   }
 
-  JniLocalReference<jclass> clazz(
-      env,
-      env->FindClass(javaClass));
-  jmethodID method = env->GetMethodID(*clazz, "<init>", "(J)V");
+  return env->NewObject(clazz, ctor, JniPtrToLong(new T(value)));
+}
 
-  return env->NewObject(
-      *clazz,
-      method,
-      JniPtrToLong(new T(value)));
+template<typename T>
+static jobject NewJniObject(JNIEnv* env, const T& value, const char* javaClass)
+{
+  JniLocalReference<jclass> clazz( env, env->FindClass(javaClass));
+  jmethodID ctor = env->GetMethodID(*clazz, "<init>", "(J)V");
+  return NewJniObject(env, value, *clazz, ctor);
 }
 
 jobject NewJniFilter(JNIEnv* env, const AdblockPlus::FilterPtr& filter)
 {
-  return NewJniObject(env, filter, PKG("Filter"));
+  return NewJniObject(env, filter, filterClass->Get(), filterCtor);
 }
 
 jobject NewJniSubscription(JNIEnv* env,
     const AdblockPlus::SubscriptionPtr& subscription)
 {
-  return NewJniObject(env, subscription, PKG("Subscription"));
+  return NewJniObject(env, subscription, subscriptionClass->Get(), subscriptionCtor);
 }
 
 jobject NewJniNotification(JNIEnv* env,
     const AdblockPlus::NotificationPtr& notification)
 {
-  return NewJniObject(env, notification, PKG("Notification"));
+  return NewJniObject(env, notification, notificationClass->Get(), notificationCtor);
 }